Analysis of the nutritional quality and micro components of textured and ordinary onions

Analysis of the nutritional quality and micro components of textured and ordinary onions | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Analysis of the nutritional quality and micro components of textured and ordinary onions Yuxin Zhang, Jialin Kuai, Guobin Zhang, Qinglong Xu, Yanxia Ma, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7226130/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The goal of this study is to establish a theoretical foundation for the further development and utilization of textured onions' edible value and health benefits, thereby laying the groundwork for a quality evaluation system. The experiment selected three onion varieties as subjects of the research: the yellow-skinned “Jinbao” onion, the Powdered onions “Qin Hongbao” onion, and the taste-type “Baiyu” onion. The experiment then measured and analyzed the flavor quality of these onions. The results showed that the polyphenol content of the three onion varieties ranged from 69.11 to 129.34 (mg/kg). Testy onions had a polyphenol content more than 1.3 times higher than ordinary onions, indicating a higher antioxidant capacity. The range of organic acid content is 2,952.01–34,773.03 µg/g. Taste-type onions have an organic acid content more than seven times higher than ordinary onions. In terms of sugar content, the range is between 18.39 and 41.29 mg/g. The sugar content of testy onions is more than 1.2 times that of ordinary onions, which is the key factor contributing to their higher sweetness compared to ordinary onions. In terms of amino acid content, the content was 878.38–1757.49 µg/g, and the content of taste-type onion was the highest, reaching 1757.49 ug/g, which was more than twice that of yellow-skinned onion. Based on the analysis of the above indicators, the comprehensive quality of tasty onion is significantly better than that of ordinary onion, and it has more advantages in terms of edible value and health care function, and has a broad application prospect and development potential. Biological sciences/Biochemistry Health sciences/Health care Biological sciences/Plant sciences Taste-type onion Amino acid Fatty acid polyphenols Correlation analysis Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 1. Introduction Onions, as a traditional farm vegetable, have both edible and medicinal functions. Their nutritional value and health benefits are topics of close attention among scholars both domestically and internationally [ 1 , 2 ] . In-depth research into its functional components will help develop high-value health products. The health benefits of onions are due to the fact that they contain volatile oils that have a variety of functions, such as antibacterial, anti-inflammatory, and antioxidant [ 3 ] . Research has shown that sulfur-containing compounds in onions can inhibit bacterial growth [ 4 ] . Patra et al. found that allicin compounds in onions can react with compounds containing sulfhydryl groups, thereby inhibiting bacterial growth [ 5 ] . Sima discovered that the thiosulfonates produced by onions can indirectly exert anti-inflammatory and anti-asthmatic effects by inhibiting the arachidonic acid metabolic pathway [ 6 ] . Onions are classified according to the color of their bulb skin, with the main types being pink-skinned, yellow-skinned, and white-skinned onions. Powder-skinned onions are known for their higher yields and strong pungency, and at the same time, they also have strong storage and transportation resistance, mainly in medium- and late-maturing varieties, and are widely cultivated in Jiangsu, Zhejiang, Shanghai, and other places in China [ 7 ] . The spicy taste of yellow-skinned onions is moderate, some varieties are slightly sweet, have good storage resistance, and the yield is slightly lower than that of powder-skinned onions, and its varieties cover early, medium and late ripening, suitable for export, and the representative varieties include Dabao 13 and Lianyungang 84 − 1 [ 8 ] . Although white onions have relatively low yields, they are highly prized by consumers for their excellent nutritional qualities. They are primarily early-maturing varieties, with representative varieties including Hamid White and Xi Xuan Bai [ 9 ] . In addition, according to the demand for sunshine hours for onion bulbs, they can also be divided into long-day type, medium-day type, and short-day type [ 10 , 11 ] . Long-day onions have a high demand for light, and more than 14 hours of light per day are required to promote bulb expansion [ 12 ] . Short-day onions, on the other hand, require only 11 to 13 hours of light to form bulbs [ 13 ] . Tasty onions, also known as fruit onions, are a special variety of onions. On November 7, 2007, Nanjing Agricultural University announced that it had successfully cultivated a new type of onion, which has a fresh fragrance and sweet taste, which is significantly different from ordinary onions. The fruit onion is unique in that it does not release a spicy and nasal odor when peeled, and this mild property allows it not to irritate the eyes or nose during processing. In addition, fruit onions have a sweet taste and natural sweetness when eaten raw, which complements their name as a "fruit". This sweetness is due to its low sulfur content and does not produce irritating gases when cut [ 14 , 15 ] . At the same time, fruit onions have a higher moisture content, which is also an important reason for their crisp and juicy taste [ 16 , 17 ] . The emergence of fruit onions, similar to the "fruit peppers" introduced in recent years, represents a new food trend in which the characteristics of traditional ingredients are modified to create foods that retain their original flavors but have new characteristics. This innovation not only enriches people's dietary choices, but also provides new options for those who seek healthy and delicious food, demonstrating the great potential of modern agricultural technologies to improve the taste and nutritional value of ingredients. With the continuous improvement of people's living standards, higher requirements have been put forward for the medicinal value and taste quality of onions. Therefore, this study used representative onion varieties from Gansu Province—powder skin onion, yellow skin onion, and tasty onion—as experimental materials. It analyzed their agronomic traits, amino acids, fatty acids, and organic acids to thoroughly investigate their nutritional quality and provide a reliable theoretical basis for evaluating the nutritional quality and resource development and utilization of textured onions. 2. Materials and Methods 2.1 Test Materials and Location The test materials used in this study were powdered onions, yellow onions, and textured onions, all provided by Newem Seed Co., Ltd. Details regarding the varieties, skin colors, and origins are shown in Table 1 . Breeding began on February 10, 2024, and open-field planting took place on April 8. The experimental site is located in Shuangwan Village, Jincheng City. A randomized block design was used in the field, with three replicates. The plot size was 9.8 m long and 8.8 m wide, with an area of 86.24 m². The row spacing was 20 cm and the plant spacing was 15 cm. The entire planting process followed uniform conventional cultivation conditions, with consistent fertilizer application and irrigation. On August 10, 2024, after the onion bulbs had matured, subsequent analysis was conducted using multi-point sampling and mixed testing. Table 1 Information on onion test materials Variety Breed name Skin color Source Yellow onion Jinbao Yellow Nunnem Seeds Ltd Powdered onions Qin Hongbao powder Nunnem Seeds Ltd Taste-type onion Baiyu White Nunnem Seeds Ltd 2.2 Measurement indicators and methods 2.2.1 Organic acid components Determination of organic acid components in onions using ultra-high performance liquid chromatography. Weigh 1 g of onion sample into a 50 mL centrifuge tube, add 25 mL of ultrapure water, and homogenize. Sonicate for 30 minutes, transfer the filtrate to a 25 mL volumetric flask, dilute to the mark with water, mix thoroughly, and filter through a 0.22 µm membrane filter. Determine the 10 organic acids in the onion. The organic acid chromatography equipment and analytical conditions are shown in Table 2 . Table 2 Organic acid chromatography equipment and analysis conditions Measurement index 10 types of organic acids Analytical equipment Instrument model Thermo Fisher U3000 High Performance Liquid Chromatograph Chromatography column LP-C18 column (4.6 mm × 250 mm, 5 µm) Mobile phase A 0.1% phosphoric acid solution Mobile phase B Acetonitrile Column temperature 35 ± 2℃ Detection wavelength 210 nm Flow velocity 0.8 mL/min Sample volume 10 µL Elution procedure Time(min) Mobile phase A(%) Mobile phase B(%) 0 100 0 15 100 0 20 50 50 25 50 50 30 100 0 2.2.2 Amino acid components Determination of amino acid components in onions using ultra-high performance liquid chromatography.1 g of onion sample was accurately weighed for homogenization, transferred to a 50 mL centrifuge tube, 10 mL of 50% ethanol was added for sonication for 30 min, the filtrate was spun dry at 80°C, and finally reconstituted with deionized water and reduced to 1 mL. Pipette 200 µL of the sample solution and place it in a 2 mL centrifuge tube, add 1:4 (V: V) triethylamine-acetonitrile solution and 1:80 (V: V) 100 µL of phenyl isothiocyanate (PITC)-acetonitrile solution, shake well, stand for 1 h at room temperature, add 400 µL of n-hexane, shake well and let stand for 10 min to stratify. Remove the lower layer of solution, filter it through a 0.22 µm filter membrane, and then use the equipment to determine the 21 free amino acids in onions. The chromatographic analysis equipment and conditions for amino acid substances are shown in Table 3 . Table 3 Chromatographic analysis equipment and conditions for amino acid substances Measurement index 21 types of free amino acids Analytical equipment Instrument model Thermo Fisher U3000 High Performance Liquid Chromatograph Chromatography column LP-C18 column (4.6 mm × 250 mm, 5 µm) Mobile phase A Ammonium acetate (pH 6.5) Mobile phase B Acetonitrile Column temperature 40 ± 2℃ Detection wavelength 254 nm Flow velocity 1.0 mL/min Sample volume 2 µL Elution procedure Time(min) Mobile phase A(%) Mobile phase B(%) 0 94 6 14 90 10 20 90 10 21 88 12 27 84 16 28 82 18 43 68 32 46 42 58 49 42 58 51 94 6 2.2.3 Sugar components Determination of sugar components in onions using ultra-high performance liquid chromatography. Approximately 2 g of fresh onion tissue was weighed into a 50 mL centrifuge tube, mixed with 40 mL of 50% methanol, and sonicated for 30 min for extraction. The extract was filtered, transferred to a 50 mL volumetric flask, diluted to the mark with 50% methanol, and thoroughly mixed. A 1 mL aliquot was then diluted to 5 mL with deionized water, filtered through a 0.22 µm membrane, and analyzed using a Waters HPLC system under the conditions specified in Table 4 for the quantification of fructose, sucrose, and glucose. Table 4 Chromatographic analysis equipment and conditions for sugar substances Measurement index Sugars Analytical equipment Instrument model Waters e-2695 Chromatography column AcclaimTM 120 C18 Chromatography Column (4.6 mm × 250 mm, 5 µm) Mobile phase A 0.1% triethylamine Mobile phase B Acetonitrile Column temperature 40 ± 2℃ Drift tube temperature 82℃ Carrier gas pressure 30.0 psi Sample volume 10 µL Elution procedure Time(min) Mobile phase A(%) Mobile phase B(%) 0 10 80 20 10 80 2.2.4 Fatty acid composition A 10 g onion sample was accurately weighed into a 50 mL centrifuge tube, mixed with 0.1 g pyrogallic acid, 2 mL 95% ethanol, and 4 mL water, then hydrolyzed at 75°C for 40 min with shaking every 10 min. After cooling, 10 mL 95% ethanol was added, and the mixture was transferred to a separatory funnel for extraction with 50 mL petroleum ether. The ether layer was collected, concentrated to dryness by rotary evaporation, and derivatized by adding 8 mL 2% NaOH-methanol solution (refluxed at 80 ± 1°C until oil droplets disappeared) followed by 7 mL 15% boron trifluoride-methanol (refluxed for 2 min). After cooling, 5 mL n-heptane was added for extraction, washed with saturated NaCl solution, dehydrated with anhydrous Na₂SO₄, and filtered (0.22 µm). The extract was mixed with internal standard and analyzed by GC-MS (Agilent 6890N-5975C) under conditions specified in Table 5 . Table 5 Chromatographic analysis equipment and conditions for fatty acid substances Measurement index 37 fatty acid methyl esters Instrument model Agilent 6890N + 5975C Chromatography column Agilent DB-23 column (30 m × 0.25 mm, 0.25 µm) Injector temperature 250 ℃ Detector temperature 280 ℃ Programmed temperature increase Initial temperature: 40°C, sustained for 1 minute; 40–200°C, heating rate 10°C/min, hold for 10 min; 200–230°C, heating rate 4°C/min, hold for 10 min. Carrier gas Helium Sampling method No diversion Injection volume 1 µL 2.2.5 Mineral element content A 0.5 g aliquot of oven-dried and ground onion sample was accurately weighed into a 150 mL conical flask, moistened with ultrapure water, and treated with 5 mL concentrated H2SO4 before overnight standing; subsequent digestion was performed on a heating plate with sequential additions of 30% H2O2 until complete clarification, whereupon the digest was diluted to 100 mL with ultrapure water and analyzed for K, Ca, Mg, Cu, Fe, and Mn concentrations using a ZEEnit 700P atomic absorption spectrometer. 2.3 Statistical analysis Data were subjected to one-way ANOVA with Duncan’s multiple range test (p < 0.05) using the statistical software SPSS 25.0. Histograms of the expression of interest were constructed using Origin 2022, and the values of the final plotted graphs represent the means of three replicates. 3. Results 3.1 Analysis of agronomic traits of different onion varieties Table 6 Agronomic traits of different onion varieties Bulb length (mm) Bulbs transverse (mm) Discoid stem diameter (mm) Bulb stem thickness (mm) Number of scales Number of scales Bulb quality (g) Yellow onions 91.28 ± 1.59 a 91.59 ± 2.83 a 20.49 ± 1.39 a 13.52 ± 1.21 a 11 1 417.67 ± 9.28 a Powdered onions 88.39 ± 1.88 a 92.38 ± 3.31 a 21.11 ± 1.29 a 14.14 ± 1.28 a 10 2 371.66 ± 10.74 b Taste-type onions 92.23 ± 2.00 a 93.42 ± 3.73 a 21.94 ± 0.79 a 12.66 ± 0.69 a 8 1 421.57 ± 6.11 a Note: different lowercase letters in the table indicate significant differences at the level of 0.05 among different treatments An analysis of seven major agronomic traits in three onion germplasm resources revealed that the distribution of these traits exhibited significant diversity (Table 6 ). Specifically, the longitudinal diameter of onion bubles ranged from 88.39 to 92.23 mm, with the largest longitudinal diameter of the taste type onion and the smallest longitudinal diameter of the powdered onion. The differences in the transverse diameter of onion bulbs are relatively small, ranging from 91.59 to 93.42 mm, with the transverse diameter of bulb onions being the widest. The diameter of the bulbous stem ranges from 20.49 to 21.94 mm, with the largest diameter found in onions of the taste type. The weight of the onion bulb primarily ranges from 371.66 to 421.67 g, with the highest weight observed in onions of the taste type. Comprehensive analysis shows that the overall agronomic traits of taste-type onions are superior to those of yellow onions and powdered onions. 3.2 Mineral element analysis of different onion varieties Table 7 Mineral element content of different varieties of onions Content (mg/kg) Taste-type onions Yellow onions Powdered onions Ca 5569.33 ± 686.08 b 6724.33 ± 398.25 ab 7939.67 ± 463.91 a Cu 0.83 ± 0.05 a 0.78 ± 0.05 a 0.51 ± 0.08 b Fe 23.01 ± 2.00 a 23.33 ± 4.61 a 17.74 ± 4.60 a Mn 4.87 ± 0.13 b 6.14 ± 0.04 a 4.99 ± 0.22 b Mg 5235.00 ± 431.66 a 4430.00 ± 267.13 a 2857.70 ± 102.37 b K 17445.33 ± 944.72 a 13382.67 ± 449.59 a 12045.33 ± 492.81 b Note: different lowercase letters in the table indicate significant differences at the level of 0.05 among different treatments The mineral content directly reflects the absorption and accumulation of various mineral nutrients by onions during their growth process and is one of the key characteristics for measuring the nutritional quality of onions. Table 7 shows the mineral element content of different onion varieties. Among all onion varieties, the content of K was the highest, followed by Ca, and Cu was the lowest. Compared with ordinary onions (Yellow onions and powdered onions), taste-type onions have relatively high levels of K, Mg and Cu, but lower levels of Ca, Fe and Mn. The K content in taste onion reaches 17,445.33 mg/kg, representing a significant increase of 30.36% compared to yellow onion and 44.83% higher than powdered onion. Similarly, its Mg content stands at 5,235.00 mg/kg, showing an 18.17% elevation over yellow onion and a remarkable 83.19% advantage compared to powdered onion. In summary, the taste type onion has significant advantages over ordinary onions in terms of K, Mg, Cu and other mineral element contents, especially in the content of K and Mg, which indicates that taste onions have unique advantages and development potential in terms of nutritional quality 3.3 Analysis of amino acid components of different varieties of onions Table 8 Amino acid content in different onion varieties Amino acid(ug/g) Yellow onions Powdered onions Taste-type onion Aspartic acid 20.33 ± 0.89 b 37.99 ± 2.65 a 9.96 ± 0.48 c Glutamic acid 41.95 ± 1.42 c 101.29 ± 3.80 b 130.80 ± 8.29 a Asparagine 144.88 ± 2.25 b 249.00 ± 19.37 a 271.11 ± 5.25 a Serine 14.59 ± 0.57 b 49.29 ± 3.85 a 21.05 ± 1.00 b Glutamine 30.10 ± 1.77 c 110.00 ± 4.19 b 152.26 ± 1.50 a Glycine 33.82 ± 0.66 a 21.26 ± 1.58 b 32.75 ± 1.82 a Cysteine 54.32 ± 1.88 a 60.01 ± 4.17 a 38.02 ± 6.43 b Gamma-aminobutyric acid 14.95 ± 0.41 b 20.44 ± 1.43 a 20.79 ± 1.08 a Alanine 17.28 ± 0.37 b 13.59 ± 0.58 c 42.41 ± 1.27 a Proline 21.68 ± 0.53 c 27.74 ± 1.10 b 47.48 ± 0.71 a Theanine 5.63 ± 0.06 b 8.09 ± 0.71 a 9.18 ± 1.19 a Tyrosine 36.88 ± 1.55 c 49.42 ± 2.45 b 175.56 ± 2.61 a Histidine 5.19 ± 0.25 b 11.17 ± 0.56 a 6.64 ± 0.50 b Threonine 7.91 ± 0.49 c 32.12 ± 0.97 b 56.59 ± 0.41 a Arginine 355.64 ± 8.35 c 454.92 ± 23.73 b 534.26 ± 14.05 a Valine 16.66 ± 0.49 b 39.96 ± 1.43 a 16.61 ± 1.24 b Methionine 11.97 ± 0.51 b 20.04 ± 1.31 a 24.39 ± 1.63 a Isoleucine 5.76 ± 0.28 b 15.91 ± 0.78 a 6.66 ± 0.23 b Leucine 18.29 ± 0.86 c 47.61 ± 0.97 b 123.33 ± 1.36 a Phenylalanine 6.67 ± 0.25 c 27.89 ± 0.56 a 17.62 ± 1.15 b Tryptophan 13.88 ± 0.92 c 27.32 ± 1.09 a 20.05 ± 1.35 b Note: different lowercase letters in the table indicate significant differences at the level of 0.05 among different treatments As shown in Table 8 , there are significant differences in the free amino acid content among different onion varieties. In this study, amino acid profiling was conducted on three onion varieties, and a total of 21 amino acids were detected. Among these amino acids, arginine has the highest content, ranging from 355.64 to 534.26 µg/g; aspartic acid follows with a content ranging from 144.88 to 271.11 µg/g; while the content of theanine is the lowest, at only 5.63 to 9.18 µg/g. Further comparative analysis revealed that taste-type onions have significantly higher levels of various amino acids than ordinary varieties, specifically glutamic acid, aspartic acid, glutamine, alanine, proline, tyrosine, threonine, arginine, and leucine. Notably, taste-type onions exhibit substantially higher leucine content compared to conventional varieties, with levels 574.30% greater than yellow-skinned onions and 159.04% higher than Powdered onions. Taste-type onions also performed well in terms of the total content of non-essential amino acids and essential amino acids, ranking first among the 3 different varieties of onions, followed by powder onions, while yellow onions were relatively lowest. In terms of total amino acid content, the total amino acid content of the taste-type onion reached 1,757.49 µg/g, which was more than 1.2 times that of ordinary onions (as shown in Fig. 1 ). This indicates that the flavor-type onion has a significant advantage in terms of amino acid nutritional quality, and its rich amino acid composition makes it more promising in terms of edible value and health benefits. The results of the amino acid Pearson correlation analysis (Fig. 2 ) revealed significant positive correlations between various amino acids in onions, including glutamine and glutamic acid (r = 0.98), tyrosine and alanine (r = 0.98), tyrosine and proline (r = 0.98), serine and histidine (r = 0.99), glutamine and threonine (r = 0.98), and tryptophan and phenylalanine (r = 0.97) exhibit extremely significant positive correlations (P < 0.01). This suggests that these amino acids may undergo mutual conversion or jointly participate in certain metabolic pathways during metabolic processes, exhibiting high levels of synergy. In addition, proline and asparagine (r = 0.76), theanine and glutamic acid (r = 0.73), tyrosine and glutamic acid (r = 0.80), and phenylalanine and asparagine (r = 0.75) also exhibit significant positive correlations (P < 0.05), further revealing their close relationship in onion metabolism. These correlation analysis results not only help to deepen our understanding of the amino acid metabolic mechanisms in onions but also provide important theoretical basis for the assessment of onion nutritional quality, variety improvement, and health functional studies. 3.4 Analysis of fatty acid composition in different onion varieties Table 9 Analysis results of fatty acid composition in three types of onions Content (µg/g) Compound Molecular formula Yellow onion Powdered onions Taste-type onion Butyric acid C3H7COOH 0.71 ± 0.01 a 0.52 ± 0.02 b 0.67 ± 0.05 a Lauric acid C12H24O2 0.09 ± 0.01 — — Myristic acid C14H28O2 0.18 ± 0.02 b 0.33 ± 0.02 a 0.32 ± 0.02 a Pentadecanoic acid C15H30O2 0.04 ± 0.01 b 0.04 ± 0.01 b 0.19 ± 0.01 a Pentadecenoic acid C15H28O2 0.18 ± 0.02 b 0.33 ± 0.01 a 0.41 ± 0.02 a Palmitic acid C16H32O2 5.00 ± 0.82 b 3.36 ± 1.47 b 14.31 ± 0.81 a Stearic acid C18H36O2 0.78 ± 0.11 b 0.65 ± 0.02 b 1.39 ± 0.10 a Elaidic acid C18H34O2‌‌ 0.24 ± 0.04 a 0.19 ± 0.01 a 0.16 ± 0.02 a Oleic acid C18H34O2 3.16 ± 0.72 a 1.51 ± 0.37 a 3.17 ± 0.08 a Linoleic acid C18H32O2 7.45 ± 0.57 b 5.28 ± 0.45 b 26.39 ± 0.97 a Alpha-linolenic acid C18H30O2 0.36 ± 0.01 b 0.49 ± 0.04 b 1.53 ± 0.06 a Arachidic acid C20H40O2‌ — — 0.31 ± 0.01 Arachidonic acid C20H32O2 0.32 ± 0.02 — — Eicosatrienoic acid C20H34O2 0.26 ± 0.02 — — Docosanoic acid C22H44O2 — — 0.41 ± 0.02 Erucic acid C22H42O2‌ 0.38 ± 0.02 — — Squalenic acid C24H46O2 1.86 ± 0.04 — — Note: different lowercase letters in the table indicate significant differences at the level of 0.05 among different treatments,"-" means not detected Fatty acid content is an important indicator for measuring the types and quantities of fatty acids in onions. It reflects the nutritional components and quality characteristics of onions and has significant implications in many respects. As shown in Table 5 , significant variations were observed in fatty acid composition among different onion cultivars. A total of 17 fatty acids were detected. In terms of fatty acid diversity, yellow onions exhibited the highest number of compounds (15 species), followed by taste-type onions (12 species), while Powdered onions showed the lowest diversity with only 10 detected compounds. In terms of endemic compounds, two kinds of taste-type onions were detected, namely arachidic acid and docaneic acid, while neither yellow onion nor powdered onion produced any endemic compounds. In terms of fatty acid content, linoleic acid was the highest among the three onion varieties, followed by palmitic acid, with oleic acid being the lowest (Fig. 3 ). Among them, the linoleic acid content of the taste-type onion was 26.39 µg/g, which was 254.23% and 399.81% higher than that of the yellow onion and Powdered onion, respectively. Analysis of total fatty acid content revealed significant differences among onion cultivars (Fig. 4 ). Notably, the taste-type onion exhibited the highest fatty acid accumulation (49.17 µg/g), followed by yellow onion (21.01 µg/g), while Powdered onion showed the lowest content (12.68 µg/g). Compared to yellow onion and Powdered onion varieties, the taste-type onion demonstrated 134.03% and 287.78% higher fatty acid levels, respectively. These pronounced variations suggest distinct physiological characteristics in fatty acid biosynthesis among different onion cultivars. Further Pearson correlation analysis of fatty acids (Fig. 5 ) revealed intrinsic relationships between different fatty acids in onions. The results showed a highly significant positive correlation between Elaidic acid and pentadecanoic acid (r = 0.99), indicating that these two fatty acids may be subject to similar regulatory mechanisms during metabolism or exert synergistic effects in the physiological functions of onions. Similarly, shark acid and lauric acid (r = 0.99) as well as eicosatrienoic acid and erucic acid (r = 0.99) also showed extremely high positive correlations, which may suggest that they have similar metabolic pathways or functional associations in the fatty acid synthesis and metabolism pathways of onions. Moreover, a significant positive correlation was observed between oleic acid and butyric acid (r = 0.69), suggesting potential interactions within the fatty acid metabolic network of onions. In summary, onion cultivars exhibited marked differences in fatty acid composition, accompanied by complex interrelationships among individual fatty acids. These findings provide a critical theoretical foundation for targeted cultivar improvement and nutritional quality enhancement in onion breeding programs. 3.5 Analysis of sugar and acid components in different varieties of onions 3.5.1 Sugar components Table 10 Sugar content of different onion varieties Sugar (mg/g) Yellow onions Powdered onions Taste-type onion Fructose 6.70 ± 0.14 c 9.24 ± 0.49 b 14.88 ± 0.51 a Glucose 7.28 ± 0.10 b 14.07 ± 0.32 a 14.35 ± 0.60 b Sucrose 4.41 ± 0.03 c 10.90 ± 0.13 b 12.05 ± 0.32 a Note: different lowercase letters in the table indicate significant differences at the level of 0.05 among different treatments. As shown in Table 10 , there are differences in the sugar component content among different onion varieties. When analyzing three onion varieties, three types of sugar components—fructose, glucose, and sucrose—were detected. In taste-type onions, fructose content was the highest, followed by glucose, while sucrose content was relatively low. Further comparison revealed that the sugar component content in taste-type onions was higher than that in ordinary onions. Specifically, compared to yellow onions, the taste-type cultivar demonstrated significantly elevated sugar content, with fructose, glucose, and sucrose levels increasing by 122.09%, 97.12%, and 173.24%, respectively. Regarding total sugar content (Fig. 6 ), the three onion varieties exhibited a range of 18.39 to 41.29 mg/g, with the taste-type onion showing the highest accumulation (41.29 mg/g) and yellow onion the lowest (18.39 mg/g). Notably, the taste-type onion contained 121.16% and 20.70% more total sugars than yellow and Powdered onions, respectively. 3.5.2 Organic acids Table 12 Organic acid content in different onion varieties Organic acid (µg/g) Yellow onions Powdered onions Taste-type onion Oxalic acid 115.67 ± 5.85 a 284.40 ± 8.83 c 185.52 ± 9.96 b Tartaric acid — — — Formic acid 303.66 ± 22.76 c 401.26 ± 8.83 b 541.41 ± 15.44 a Malic acid 604.92 ± 20.66 c 1100.76 ± 72.12 b 1448.45 ± 20.76 a Lactic acid 145.10 ± 3.08 b 192.74 ± 1.31 b 30133.03 ± 254.90 a Citric acid 44.95 ± 0.77 b 37.40 ± 1.00 c 54.39 ± 1.78 a Maleic acid 1.63 ± 0.10 c 16.76 ± 0.83 a 5.69 ± 0.16 b Succinic acid — — — Fumaric acid 0.99 ± 0.04 b 1.49 ± 0.25 b 7.91 ± 0.26 a Propionic acid 1735.10 ± 53.81 c 2720.36 ± 31.83 a 2796.61 ± 72.67 b Note: different lowercase letters in the table indicate significant differences at the level of 0.05 among different treatments,"-" means not detected. The organic acid profiles of different onion varieties are presented in Table 7 . Among the three cultivars analyzed, eight organic acids were detected, with significant variation in their concentrations. In taste type onions, lactic acid was the predominant organic acid, exhibiting concentrations ranging from 29,772.95 to 30,625.61 µg/g, followed by propionic acid (2,260.92–2,509.54 µg/g). In contrast, malic acid was present in markedly lower amounts (5.44–5.99 µg/g). When comparing different varieties, the organic acid content of taste-type onions is generally higher than that of yellow onions and Powdered onions. The organic acid content of sweet onions is significantly higher than that of yellow onions and Powdered onions. For example, the content of formic acid, malic acid, lactic acid, citric acid, and fumaric acid in sweet onions is higher than that in ordinary onions. Compared to ordinary onions, the formic acid content in taste-type onions increased by 78.29% and 34.93%, malic acid content increased by 139.44% and 31.59%; and citric acid content increased by 21.00% and 45.43%, respectively. In particular, the lactic acid content of taste-type onions is more than 156 times that of regular onions, a large difference that indicates that taste-type onions have unique physiological properties in terms of organic acid accumulation. As shown in Figs. 7 and 8 , there are significant differences in organic acid content among the three onion varieties. The organic acid content of the taste-type onion is significantly higher than that of the ordinary onion, reaching as high as 34,773.02 µg/g, which is more than seven times that of the ordinary onion. In addition, there were great differences in the composition of organic acids among the three onion varieties. In yellow onions and powdered onions, propionic acid, malic acid and formic acid content account for a large part of the organic acid content, of which propionic acid content accounts for more than half, which is the most important organic acid component of these two kinds of onions. Lactic acid, propionic acid and malic acid accounted for a large part of the organic acid content, of which lactic acid content accounted for 86.7%, which was the most important organic acid component of taste-type onions. Figure 9 shows the results of a correlation analysis of organic acids, which revealed significant correlations between various organic acids. Specifically, the correlation coefficient between lactic acid and fumaric acid was 0.99, indicating a strong positive correlation. In the sample data, this means that an increase in lactic acid content is almost always accompanied by a corresponding increase in fumaric acid content, and vice versa. Strong positive correlations were observed between specific organic acid pairs, with particularly high correlation coefficients for malic acid-formic acid (r = 0.95), maleic acid-oxalic acid (r = 0.98), and propionic acid-oxalic acid (r = 0.94). These robust correlations (all r > 0.90) suggest potentially interdependent metabolic pathways or synergistic physiological functions among these compounds. Furthermore, propionic acid and malic acid showed a slightly lower but still significant positive correlation (r = 0.72, p < 0.05), providing additional evidence for complex interrelationships within the organic acid network. These findings substantially enhance our understanding of metabolic coordination in onion organic acid biosynthesis. 4. Discussion As living standards improve, more people are placing greater emphasis on safety, health, and high-quality agricultural products. These products are gradually becoming the dominant market demand. Therefore, breeding high-quality agricultural products has become a hot research topic. This study found that taste-type onions have superior nutritional quality compared to conventional onion varieties. Taste-type onions outperform conventional onions in terms of their sugar, acid, amino acid, fatty acid, and polyphenol content, exhibiting higher levels of these components. Vegetables and fruits contain large amounts of amino acid compounds that promote plant photosynthesis and have medicinal value [ 18 ] . They are divided into non-essential and essential amino acids based on whether the human body can synthesize them on its own. They can also be divided into sweet, umami, bitter, sour, and tasteless amino acids based on their taste characteristics [ 19 ] . Histidine in onions is an acidic amino acid; aspartic acid and glutamic acid are umami amino acids; and glycine and proline are sweet amino acids [ 20 – 22 ] . Previous studies on onions have shown that there are certain differences in the amino acid content of onions of different skin colors, with white onions having higher amino acid content and purple onions having lower amino acid content [ 23 , 24 ] . Our research found that, compared with conventional onions, taste-type onions have significantly higher levels of essential amino acids, non-essential amino acids, and total amino acids. Additionally, we found that the arginine content in onions is the highest among all amino acids, accounting for 30.40–40.49% of the total content. On one hand, it participates in important processes such as protein synthesis, polyamine synthesis, and nitric oxide (NO) synthesis; on the other hand, it also participates in the ornithine (Ornithine, C5H12N2O2) cycle in the human body. Glutamic acid is one of the basic amino acids involved in nitrogen metabolism within biological organisms. It participates in the synthesis of various protein amino acids and serves as a precursor for numerous compounds, such as non-protein amino acids, chlorophyll, and hemoglobin [ 25 ] . Polyphenolic compounds contain multiple phenolic hydroxyl groups in their molecular structure, enabling them to neutralize free radicals through electron or hydrogen atom transfer. They can also form chelation reactions with metal ions, thereby exhibiting antioxidant activity [ 26 , 27 ] . In this study, we tested 9 phenolic acids and 4 flavonoids in onions. Previous studies on tillered onions found that the flavonoid content of tillered onions was much higher than that of ordinary onions [ 28 ] . In this study, it was found that the phenolic acids and flavonoids in onions accounted for a large proportion of benzoic acid and kaempferol, respectively. Benzoic acid is an aromatic acid organic compound, which mainly participates in the exertion of biological activities such as antioxidant and antibacterial, and has a certain inhibitory effect on the growth of microorganisms [ 29 , 30 ] . In addition to this, benzoic acid, as part of the polyphenol structure, can enhance the antioxidant capacity of polyphenols, neutralizing free radicals by donating electrons or hydrogen atoms, thereby protecting cells from oxidative damage [ 31 , 32 ] . Organic acids are a class of organic compounds containing carboxyl functional groups. They are widely present in plants, animals, and certain microbial fermentation products, and are one of the key indicators determining the flavor of onions. They also play a regulatory role in cellular osmotic pressure [ 33 ] . Relevant studies have shown that potassium can influence the activity of enzymes involved in organic acid metabolism, thereby affecting organic acid metabolism [ 34 , 35 ] . In this study, it was found that the malic acid content was the second highest organic acid in onions, which may be due to the fact that onions themselves have the highest potassium content, and potassium can promote the carboxylase activity of phosphoenolpyruvate and thus promote the synthesis of malic acid. In addition, potassium can also inhibit the activity of malate enzyme and delay the degradation rate of malic acid, which ultimately leads to a high content of malic acid in onions [ 36 ] . Lactic acid is the most abundant organic acid in taste onions, accounting for 86.66% of the total content, and its lactic acid content is more than 156 times that of ordinary onions. Lactic acid is a carboxyl compound containing a hydroxyl group, and in the absence of oxygen, plant cells maintain energy supply through lactic acid fermentation; Under aerobic conditions, lactic acid can be oxidized to pyruvate, which enters the metabolic pathway of the tricarboxylic acid cycle [ 37 ] . The accumulation of sugars in onion bulbs is the result of the synergistic action of multiple sugar metabolism-related enzymes. These sugars not only determine the formation of fruit flavor quality and the sweetness of onions, but also serve as an important raw material for the synthesis of other nutrients. The sugar components in fruits have a significant impact on their flavor and quality. The types and content of sugars not only affect the nutritional value of fruits but also determine their texture, thereby influencing consumers' choices [ 38 ] . The sugars in onion bulbs primarily include sucrose, glucose, and fructose, which contribute to the onion's sweetness. In the study, it was found that the sugar content of taste onions was significantly higher than that of regular onions (yellow onions and Powdered onions), which was the main reason why the sweetness of taste onions was significantly higher than that of regular onions. Currently, there is little research on fatty acids in onions, with studies limited to onion seeds. Wang Qiang [ 39 ] et al. found that yellow onion seeds have a high fatty acid content, which is consistent with the results of this study. This study detected 17 fatty acid components in onions, with linoleic acid being the most abundant, accounting for 35.46–53.67% of the total fatty acid content. Onions contain a special substance called prostaglandin A, which can dilate blood vessels and reduce blood viscosity [ 40 ] . The precursor of prostaglandin A is arachidonic acid, and linoleic acid is the raw material for synthesizing arachidonic acid. Therefore, linoleic acid plays a crucial role in the synthesis of prostaglandins. Our research found that the linoleic acid content of taste-type onions is more than three times that of conventional onions, so taste-type onions can synthesize more prostaglandin A. Oleic acid is an unsaturated fatty acid widely found in animal and vegetable oils, accounting for 6.45–15.04% of total fatty acid content. Oleic acid can lower cholesterol (LDL-C) levels, thereby helping to maintain lipid balance. Palmitic acid is the second most abundant substance in onions after linoleic acid. Palmitic acid is a saturated fatty acid and an important component of phospholipids in cell membranes, helping to maintain the stability and fluidity of cell membranes; it is closely related to the synthesis of various hormones, such as being a precursor substance for the synthesis of sex hormones, playing an important role in regulating human physiological functions [ 41 ] ; It also aids in the absorption and transport of fat-soluble vitamins (such as vitamins A, D, E, and K). Therefore, the high content of linoleic acid, oleic acid, and palmitic acid in taste-type onions can significantly lower cholesterol levels and improve the functions of various internal organs. 5. Conclusion Taste-type onions are significantly superior to conventional onions in terms of agronomic traits, amino acids, organic acids, and fatty acid composition. Therefore, taste-type onions have significantly better overall quality than conventional onions, offering superior edible value and health benefits. Declarations Conflict of interest The authors declare that they have no conflict of interest. Author Contribution Statement Guobin Zhang and Xiaowei Wang conceived and designed the research. Yuxin Zhang and Jialin Kuai conducted experiments. Qinglong Xu contributed new reagents or analytical tools. Yanxia Ma analyzed data. Yuxin Zhang wrote the manuscript. All authors read and approved the manuscript. Funding This work was supported by the National Modern Agricultural Industry Technology System (CARS-24-G-28); the Gansu Province Talent Project (2025QNGR58); and the Gansu Academy of Agricultural Sciences Mid-Career Research Fund Project (2023GAAS29). Data Availability The datasets used and/or analysed during the current study available from the corresponding author on reasonable request. References Gupta, A. J. et al. Onion nutritional and nutraceutical composition and therapeutic potential of its phytochemicals assessed through preclinical and clinical studies [J]. J. Funct. Foods. 129 , 106889 (2025). Singh, H. & Khar, A. Potential of onion ( Allium cepa ) as traditional therapeutic and functional food: An update [J]. Indian J. Agric. Sci. 92 , 1291–1297 (2022). Gorrepati, K. et al. Harnessing the nutraceutical and therapeutic potential of Allium spp .: current insights and future directions [J]. Front. Nutr. 11 , 1497953 (2024). Bhatwalkar, S. B. et al. Antibacterial Properties of Organosulfur Compounds of Garlic ( Allium sativum ) [J]. Front. Microbiol. 12 , 613077 (2021). Patra, A. K. An Overview of Antimicrobial Properties of Different Classes of Phytochemicals [M]//PATRA A K. Dietary Phytochemicals and Microbes. 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ZHAO C, J., SCHIEBER, A. & Gänzle, M. G. Formation of taste-active amino acids, amino acid derivatives and peptides in food fermentations – A review [J]. Food Res. Int. 89 , 39–47 (2016). Fredotović, Ž. et al. Comparison of Organosulfur and Amino Acid Composition between Triploid Onion Allium cornutum Clementi ex Visiani, 1842, and Common Onion Allium cepa L., and Evidences for Antiproliferative Activity of Their Extracts [J]. (2020). Plants (Basel, Switzerland), 9 : 98 . Wu, S. et al. Quality Analysis and Comprehensive Evaluation of Fruits from Different Cultivars of Pecan (Carya illinoinensis (Wangenheim) K. Koch) [J/OL] 13 : 746 (2022). Li, F. et al. Morphological Characteristics, Ultrastructure, and Chemical Constituents of the Endotesta in Ginkgo ( Ginkgo biloba L.) [J]. (2023). Plants (Basel, Switzerland), 12 : 3560 . Jang, J-R., Kwon, S-J. & Lim S Y J J O T K S O F C. Chemical Components and Biological Activities of Red Onion Powder [J]. 24 : 749–755. (2009). Muscolo, A. et al. Unlocking the Health Secrets of Onions: Investigating the Phytochemical Power and Beneficial Properties of Different Varieties and Their Parts [J/OL] 30 : 1758 (2025). Walker, M. C. & Van Der Donk, W. A. The many roles of glutamate in metabolism [J]. J. Ind. Microbiol. Biotechnol. 43 , 419–430 (2016). Zhang, H. & Tsao, R. Dietary polyphenols, oxidative stress and antioxidant and anti-inflammatory effects [J]. Curr. Opin. Food Sci. 8 , 33–42 (2016). Urquiaga, I. & Leighton, F. Plant polyphenol antioxidants and oxidative stress [J]. Biol. Res. 33 , 55–64 (2000). Jing Zhao, S. et al. Comparison of the nutritional qualities of bulb onions and regular onions [J].Journal of Northwest A&F University (Natural Science Edition). 43 : 106–110. (2015). Zhanyu Ning. Synthesis and antibacterial effect of methyl benzoate [J]. J. South. China Agricultural Univ. : 82–84. (2002). Chunhong, H. et al. The effect of sodium benzoate on the growth of Escherichia coli and Staphylococcus aureus [J]. Food Ind. Technol. 32 , 180–181 (2011). Chen, J. et al. Structure-antioxidant activity relationship of methoxy, phenolic hydroxyl, and carboxylic acid groups of phenolic acids [J]. Sci. Rep. 10 , 2611 (2020). Huang, Z. et al. Identification and Structure-Activity Relationship of Recovered Phenolics with Antioxidant and Antihyperglycemic Potential from Sugarcane Molasses Vinasse [J]. Foods (Basel Switzerland) . 11 , 3131 (2022). Panchal, P., Miller, A. J. & Giri, J. Organic acids: versatile stress-response roles in plants [J]. J. Exp. Bot. 72 , 4038–4052 (2021). Wang, Y-P. et al. Effectsof potassium on organic acid metabolism of fe-sensitive and fe-resistant rices (’Oryza sativa’ L.) [J]. Aust. J. Crop Sci. 7 , 843–848 (2013). Wang, J. et al. Effects of Potassium-Containing Fertilizers on Sugar and Organic Acid Metabolism in Grape Fruits [J]. Int. J. Mol. Sci. 25 , 2828 (2024). Zhang, W. et al. Potassium fertilization arrests malate accumulation and alters soluble sugar metabolism in apple fruit [J]. Biology open. 7 , 024745 (2018). Paventi, G. et al. L-lactate metabolism in potato tuber mitochondria [J]. FEBS J. 274 , 1459–1469 (2007). Dong, Y. et al. Analysis of the Correlation between Persimmon Fruit-Sugar Components and Taste Traits from Germplasm Evaluation [J]. Int. J. Mol. Sci. 25 , 7803 (2024). Qiang Wang, G. et al. A comparative study of the fatty acid composition of three onion seeds [J].Chinese condiments. 37 : 93–96. (2012). Attrep, K. A. et al. Separation and identification of prostaglandin A1 in onion [J]. Lipids 15 , 292–297 (1980). Carta, G. et al. Palmitic Acid: Physiological Role, Metabolism and Nutritional Implications [J]. Front. Physiol. 8 , 902 (2017). Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7226130","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":512923732,"identity":"07a12076-c197-43d0-98aa-a1043721a02a","order_by":0,"name":"Yuxin Zhang","email":"","orcid":"","institution":"Gansu Academy of Agricultural Sciences, Vegetable Research Institute","correspondingAuthor":false,"prefix":"","firstName":"Yuxin","middleName":"","lastName":"Zhang","suffix":""},{"id":512923733,"identity":"c2e51d87-6e20-4d90-9ef5-881dd39aea5a","order_by":1,"name":"Jialin Kuai","email":"","orcid":"","institution":"Gansu Academy of Agricultural Sciences, Vegetable Research Institute","correspondingAuthor":false,"prefix":"","firstName":"Jialin","middleName":"","lastName":"Kuai","suffix":""},{"id":512923734,"identity":"6c05cb83-2062-4b03-9bfc-43a9066ebfc4","order_by":2,"name":"Guobin Zhang","email":"","orcid":"","institution":"Gansu Agricultural University","correspondingAuthor":false,"prefix":"","firstName":"Guobin","middleName":"","lastName":"Zhang","suffix":""},{"id":512923735,"identity":"fae8cb4d-cff2-4c6c-a06d-e73ff2d727c9","order_by":3,"name":"Qinglong Xu","email":"","orcid":"","institution":"Gansu Agricultural University","correspondingAuthor":false,"prefix":"","firstName":"Qinglong","middleName":"","lastName":"Xu","suffix":""},{"id":512923736,"identity":"a4ac84c9-4e67-4f09-85fe-d30376f09bfd","order_by":4,"name":"Yanxia Ma","email":"","orcid":"","institution":"Gansu Academy of Agricultural Sciences, Vegetable Research Institute","correspondingAuthor":false,"prefix":"","firstName":"Yanxia","middleName":"","lastName":"Ma","suffix":""},{"id":512923737,"identity":"1e31c203-b773-402f-a9f6-34e22d6e2604","order_by":5,"name":"Xiaowei Wang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAvElEQVRIiWNgGAWjYPACG9K1pJGu5TAJag2Onz38mrftvN389uPXPjDU3CFCy5m8NMuZbbeTN5zJKZ7BcOwZYS1mB3LMDD5uu51swJCTzMDYQIQLzc6/MTNI3HYuWb7/DbFabuQYP/i47YAdw430w8Rpsb/xxoxx5r/kBIMbb5gZEo4RoUWyP8f4M88ZO3v5/vTHDB9qiAttNgkgkdjAwGPAkECUBgYG5g8gBzIwsD8gUsMoGAWjYBSMNAAAJYA/rmekzDIAAAAASUVORK5CYII=","orcid":"","institution":"Gansu Academy of Agricultural Sciences, Vegetable Research Institute","correspondingAuthor":true,"prefix":"","firstName":"Xiaowei","middleName":"","lastName":"Wang","suffix":""}],"badges":[],"createdAt":"2025-07-27 12:23:10","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7226130/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7226130/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":91162895,"identity":"9002f073-4ad9-47a8-9035-2d16dab4ed2f","added_by":"auto","created_at":"2025-09-12 09:42:22","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":183357,"visible":true,"origin":"","legend":"\u003cp\u003eNon-essential and essential amino acid contents of different varieties of onion\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-7226130/v1/138b45889b802734563210b0.png"},{"id":91162907,"identity":"c01a97cb-925b-4f9c-a8ef-e3acc0d6c9c4","added_by":"auto","created_at":"2025-09-12 09:42:22","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":813236,"visible":true,"origin":"","legend":"\u003cp\u003ePearson correlation analysis of metabolites of amino acid fractions\u003c/p\u003e","description":"","filename":"image2.png","url":"https://assets-eu.researchsquare.com/files/rs-7226130/v1/eac9f2a83f4f202e4a935009.png"},{"id":91162896,"identity":"183f610a-ff63-4dec-b6a4-12ab6247336e","added_by":"auto","created_at":"2025-09-12 09:42:22","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":304366,"visible":true,"origin":"","legend":"\u003cp\u003eRadar chart of fatty acid composition of three onions. (A) Taste-type onion (B) Powdered onion (C) Yellow onion.\u003c/p\u003e","description":"","filename":"image3.png","url":"https://assets-eu.researchsquare.com/files/rs-7226130/v1/2be31b65d93f57fb1646b2f2.png"},{"id":91164147,"identity":"23090d94-fcef-472e-8eee-14c0a5095b2d","added_by":"auto","created_at":"2025-09-12 09:58:22","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":95822,"visible":true,"origin":"","legend":"\u003cp\u003eTotal fatty acid content of different varieties of onions\u003c/p\u003e","description":"","filename":"image4.png","url":"https://assets-eu.researchsquare.com/files/rs-7226130/v1/87da8591e22727a6b1462090.png"},{"id":91162906,"identity":"410ba3ce-cb3c-47ff-a4f7-bcb8211b9042","added_by":"auto","created_at":"2025-09-12 09:42:22","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":789990,"visible":true,"origin":"","legend":"\u003cp\u003ePearson correlation analysis of fatty acid fraction metabolites\u003c/p\u003e","description":"","filename":"image5.png","url":"https://assets-eu.researchsquare.com/files/rs-7226130/v1/d6a56dc239724dce4231ee38.png"},{"id":91163203,"identity":"de2c9212-333e-45c2-857e-5f2240856eaf","added_by":"auto","created_at":"2025-09-12 09:50:22","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":95848,"visible":true,"origin":"","legend":"\u003cp\u003eTotal content of sugar fractions in different varieties of onion\u003c/p\u003e","description":"","filename":"image6.png","url":"https://assets-eu.researchsquare.com/files/rs-7226130/v1/7a3badd127fe87709841e7aa.png"},{"id":91163205,"identity":"ec664ebe-6d66-404c-9a7c-b2f7aabe575c","added_by":"auto","created_at":"2025-09-12 09:50:22","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":122045,"visible":true,"origin":"","legend":"\u003cp\u003eOrganic acid content among different varieties of onions\u003c/p\u003e","description":"","filename":"image7.png","url":"https://assets-eu.researchsquare.com/files/rs-7226130/v1/79197fb77eeb0efd37dfb583.png"},{"id":91163206,"identity":"2ffead74-51b1-44cd-a0c0-02045a7c1e96","added_by":"auto","created_at":"2025-09-12 09:50:22","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":257228,"visible":true,"origin":"","legend":"\u003cp\u003ePercentage of organic acid fractions in different varieties of onion. (A) Yellow onions (B) Powdered onions (C) Taste-type onion\u003c/p\u003e","description":"","filename":"image8.png","url":"https://assets-eu.researchsquare.com/files/rs-7226130/v1/7199f64cc6d5e3ab85ef7d47.png"},{"id":91163213,"identity":"e2b97828-e09d-4e8d-ab1b-82571c67b79b","added_by":"auto","created_at":"2025-09-12 09:50:22","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":321498,"visible":true,"origin":"","legend":"\u003cp\u003ePearson correlation analysis of organic acid metabolites\u003c/p\u003e","description":"","filename":"image9.png","url":"https://assets-eu.researchsquare.com/files/rs-7226130/v1/2291fcf8bbfbf28065aa29af.png"},{"id":93072284,"identity":"5dc3cc9e-b4af-4173-9810-d9697ac9fa58","added_by":"auto","created_at":"2025-10-08 18:04:08","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4047736,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7226130/v1/54ccf279-2ab9-4bd3-a9f8-45d55e1cf60b.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Analysis of the nutritional quality and micro components of textured and ordinary onions","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eOnions, as a traditional farm vegetable, have both edible and medicinal functions. Their nutritional value and health benefits are topics of close attention among scholars both domestically and internationally\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/sup\u003e. In-depth research into its functional components will help develop high-value health products. The health benefits of onions are due to the fact that they contain volatile oils that have a variety of functions, such as antibacterial, anti-inflammatory, and antioxidant\u003csup\u003e[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/sup\u003e. Research has shown that sulfur-containing compounds in onions can inhibit bacterial growth\u003csup\u003e[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003e. Patra et al. found that allicin compounds in onions can react with compounds containing sulfhydryl groups, thereby inhibiting bacterial growth\u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e. Sima discovered that the thiosulfonates produced by onions can indirectly exert anti-inflammatory and anti-asthmatic effects by inhibiting the arachidonic acid metabolic pathway\u003csup\u003e[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eOnions are classified according to the color of their bulb skin, with the main types being pink-skinned, yellow-skinned, and white-skinned onions. Powder-skinned onions are known for their higher yields and strong pungency, and at the same time, they also have strong storage and transportation resistance, mainly in medium- and late-maturing varieties, and are widely cultivated in Jiangsu, Zhejiang, Shanghai, and other places in China\u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e. The spicy taste of yellow-skinned onions is moderate, some varieties are slightly sweet, have good storage resistance, and the yield is slightly lower than that of powder-skinned onions, and its varieties cover early, medium and late ripening, suitable for export, and the representative varieties include Dabao 13 and Lianyungang 84\u0026thinsp;\u0026minus;\u0026thinsp;1\u003csup\u003e[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/sup\u003e. Although white onions have relatively low yields, they are highly prized by consumers for their excellent nutritional qualities. They are primarily early-maturing varieties, with representative varieties including Hamid White and Xi Xuan Bai\u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e. In addition, according to the demand for sunshine hours for onion bulbs, they can also be divided into long-day type, medium-day type, and short-day type\u003csup\u003e[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e. Long-day onions have a high demand for light, and more than 14 hours of light per day are required to promote bulb expansion\u003csup\u003e[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e. Short-day onions, on the other hand, require only 11 to 13 hours of light to form bulbs\u003csup\u003e[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eTasty onions, also known as fruit onions, are a special variety of onions. On November 7, 2007, Nanjing Agricultural University announced that it had successfully cultivated a new type of onion, which has a fresh fragrance and sweet taste, which is significantly different from ordinary onions. The fruit onion is unique in that it does not release a spicy and nasal odor when peeled, and this mild property allows it not to irritate the eyes or nose during processing. In addition, fruit onions have a sweet taste and natural sweetness when eaten raw, which complements their name as a \"fruit\". This sweetness is due to its low sulfur content and does not produce irritating gases when cut\u003csup\u003e[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]\u003c/sup\u003e. At the same time, fruit onions have a higher moisture content, which is also an important reason for their crisp and juicy taste\u003csup\u003e[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/sup\u003e. The emergence of fruit onions, similar to the \"fruit peppers\" introduced in recent years, represents a new food trend in which the characteristics of traditional ingredients are modified to create foods that retain their original flavors but have new characteristics. This innovation not only enriches people's dietary choices, but also provides new options for those who seek healthy and delicious food, demonstrating the great potential of modern agricultural technologies to improve the taste and nutritional value of ingredients.\u003c/p\u003e\u003cp\u003eWith the continuous improvement of people's living standards, higher requirements have been put forward for the medicinal value and taste quality of onions. Therefore, this study used representative onion varieties from Gansu Province\u0026mdash;powder skin onion, yellow skin onion, and tasty onion\u0026mdash;as experimental materials. It analyzed their agronomic traits, amino acids, fatty acids, and organic acids to thoroughly investigate their nutritional quality and provide a reliable theoretical basis for evaluating the nutritional quality and resource development and utilization of textured onions.\u003c/p\u003e"},{"header":"2. Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1 Test Materials and Location\u003c/h2\u003e\u003cp\u003eThe test materials used in this study were powdered onions, yellow onions, and textured onions, all provided by Newem Seed Co., Ltd. Details regarding the varieties, skin colors, and origins are shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Breeding began on February 10, 2024, and open-field planting took place on April 8. The experimental site is located in Shuangwan Village, Jincheng City. A randomized block design was used in the field, with three replicates. The plot size was 9.8 m long and 8.8 m wide, with an area of 86.24 m\u0026sup2;. The row spacing was 20 cm and the plant spacing was 15 cm. The entire planting process followed uniform conventional cultivation conditions, with consistent fertilizer application and irrigation. On August 10, 2024, after the onion bulbs had matured, subsequent analysis was conducted using multi-point sampling and mixed testing.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eInformation on onion test materials\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVariety\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBreed name\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eSkin color\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eSource\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eYellow onion\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eJinbao\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eYellow\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eNunnem Seeds Ltd\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePowdered onions\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eQin Hongbao\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003epowder\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eNunnem Seeds Ltd\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTaste-type onion\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBaiyu\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eWhite\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eNunnem Seeds Ltd\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e2.2 Measurement indicators and methods\u003c/h2\u003e\u003cdiv id=\"Sec5\" class=\"Section3\"\u003e\u003ch2\u003e2.2.1 Organic acid components\u003c/h2\u003e\u003cp\u003eDetermination of organic acid components in onions using ultra-high performance liquid chromatography. Weigh 1 g of onion sample into a 50 mL centrifuge tube, add 25 mL of ultrapure water, and homogenize. Sonicate for 30 minutes, transfer the filtrate to a 25 mL volumetric flask, dilute to the mark with water, mix thoroughly, and filter through a 0.22 \u0026micro;m membrane filter. Determine the 10 organic acids in the onion. The organic acid chromatography equipment and analytical conditions are shown in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eOrganic acid chromatography equipment and analysis conditions\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMeasurement index\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e10 types of organic acids\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"7\" rowspan=\"8\"\u003e\u003cp\u003eAnalytical equipment\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eInstrument model\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003eThermo Fisher U3000 High Performance Liquid Chromatograph\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eChromatography column\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003eLP-C18 column (4.6 mm \u0026times; 250 mm, 5 \u0026micro;m)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMobile phase A\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e0.1% phosphoric acid solution\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMobile phase B\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003eAcetonitrile\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eColumn temperature\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e35\u0026thinsp;\u0026plusmn;\u0026thinsp;2℃\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDetection wavelength\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e210 nm\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFlow velocity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e0.8 mL/min\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSample volume\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e10 \u0026micro;L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e\u003cp\u003eElution procedure\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTime(min)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMobile phase A(%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMobile phase B(%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e100\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e100\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e50\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e50\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e30\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e100\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec6\" class=\"Section3\"\u003e\u003ch2\u003e2.2.2 Amino acid components\u003c/h2\u003e\u003cp\u003eDetermination of amino acid components in onions using ultra-high performance liquid chromatography.1 g of onion sample was accurately weighed for homogenization, transferred to a 50 mL centrifuge tube, 10 mL of 50% ethanol was added for sonication for 30 min, the filtrate was spun dry at 80\u0026deg;C, and finally reconstituted with deionized water and reduced to 1 mL. Pipette 200 \u0026micro;L of the sample solution and place it in a 2 mL centrifuge tube, add 1:4 (V: V) triethylamine-acetonitrile solution and 1:80 (V: V) 100 \u0026micro;L of phenyl isothiocyanate (PITC)-acetonitrile solution, shake well, stand for 1 h at room temperature, add 400 \u0026micro;L of n-hexane, shake well and let stand for 10 min to stratify. Remove the lower layer of solution, filter it through a 0.22 \u0026micro;m filter membrane, and then use the equipment to determine the 21 free amino acids in onions. The chromatographic analysis equipment and conditions for amino acid substances are shown in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eChromatographic analysis equipment and conditions for amino acid substances\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMeasurement index\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e21 types of free amino acids\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"7\" rowspan=\"8\"\u003e\u003cp\u003eAnalytical equipment\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eInstrument model\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003eThermo Fisher U3000 High Performance Liquid Chromatograph\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eChromatography column\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003eLP-C18 column (4.6 mm \u0026times; 250 mm, 5 \u0026micro;m)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMobile phase A\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003eAmmonium acetate (pH 6.5)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMobile phase B\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003eAcetonitrile\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eColumn temperature\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e40\u0026thinsp;\u0026plusmn;\u0026thinsp;2℃\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDetection wavelength\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e254 nm\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFlow velocity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e1.0 mL/min\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSample volume\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e2 \u0026micro;L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"10\" rowspan=\"11\"\u003e\u003cp\u003eElution procedure\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTime(min)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMobile phase A(%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMobile phase B(%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e94\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e90\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e90\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e88\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e12\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e27\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e84\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e16\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e82\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e18\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e43\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e68\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e32\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e46\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e42\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e58\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e49\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e42\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e58\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e51\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e94\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec7\" class=\"Section3\"\u003e\u003ch2\u003e2.2.3 Sugar components\u003c/h2\u003e\u003cp\u003eDetermination of sugar components in onions using ultra-high performance liquid chromatography. Approximately 2 g of fresh onion tissue was weighed into a 50 mL centrifuge tube, mixed with 40 mL of 50% methanol, and sonicated for 30 min for extraction. The extract was filtered, transferred to a 50 mL volumetric flask, diluted to the mark with 50% methanol, and thoroughly mixed. A 1 mL aliquot was then diluted to 5 mL with deionized water, filtered through a 0.22 \u0026micro;m membrane, and analyzed using a Waters HPLC system under the conditions specified in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e for the quantification of fructose, sucrose, and glucose.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eChromatographic analysis equipment and conditions for sugar substances\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMeasurement index\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003eSugars\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"7\" rowspan=\"8\"\u003e\u003cp\u003eAnalytical equipment\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eInstrument model\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003eWaters e-2695\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eChromatography column\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003eAcclaimTM 120 C18 Chromatography Column (4.6 mm \u0026times; 250 mm, 5 \u0026micro;m)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMobile phase A\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e0.1% triethylamine\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMobile phase B\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003eAcetonitrile\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eColumn temperature\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e40\u0026thinsp;\u0026plusmn;\u0026thinsp;2℃\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDrift tube temperature\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e82℃\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCarrier gas pressure\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e30.0 psi\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSample volume\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e10 \u0026micro;L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eElution procedure\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTime(min)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMobile phase A(%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMobile phase B(%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e80\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e80\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec8\" class=\"Section3\"\u003e\u003ch2\u003e2.2.4 Fatty acid composition\u003c/h2\u003e\u003cp\u003eA 10 g onion sample was accurately weighed into a 50 mL centrifuge tube, mixed with 0.1 g pyrogallic acid, 2 mL 95% ethanol, and 4 mL water, then hydrolyzed at 75\u0026deg;C for 40 min with shaking every 10 min. After cooling, 10 mL 95% ethanol was added, and the mixture was transferred to a separatory funnel for extraction with 50 mL petroleum ether. The ether layer was collected, concentrated to dryness by rotary evaporation, and derivatized by adding 8 mL 2% NaOH-methanol solution (refluxed at 80\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u0026deg;C until oil droplets disappeared) followed by 7 mL 15% boron trifluoride-methanol (refluxed for 2 min). After cooling, 5 mL n-heptane was added for extraction, washed with saturated NaCl solution, dehydrated with anhydrous Na₂SO₄, and filtered (0.22 \u0026micro;m). The extract was mixed with internal standard and analyzed by GC-MS (Agilent 6890N-5975C) under conditions specified in Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eChromatographic analysis equipment and conditions for fatty acid substances\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"2\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMeasurement index\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003e37 fatty acid methyl esters\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eInstrument model\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAgilent 6890N\u0026thinsp;+\u0026thinsp;5975C\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eChromatography column\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAgilent DB-23 column (30 m \u0026times; 0.25 mm, 0.25 \u0026micro;m)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eInjector temperature\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e250 ℃\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDetector temperature\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e280 ℃\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eProgrammed temperature increase\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eInitial temperature: 40\u0026deg;C, sustained for 1 minute;\u003c/p\u003e\u003cp\u003e40\u0026ndash;200\u0026deg;C, heating rate 10\u0026deg;C/min, hold for 10 min;\u003c/p\u003e\u003cp\u003e200\u0026ndash;230\u0026deg;C, heating rate 4\u0026deg;C/min, hold for 10 min.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCarrier gas\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eHelium\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSampling method\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNo diversion\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eInjection volume\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1 \u0026micro;L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec9\" class=\"Section3\"\u003e\u003ch2\u003e2.2.5 Mineral element content\u003c/h2\u003e\u003cp\u003eA 0.5 g aliquot of oven-dried and ground onion sample was accurately weighed into a 150 mL conical flask, moistened with ultrapure water, and treated with 5 mL concentrated H2SO4 before overnight standing; subsequent digestion was performed on a heating plate with sequential additions of 30% H2O2 until complete clarification, whereupon the digest was diluted to 100 mL with ultrapure water and analyzed for K, Ca, Mg, Cu, Fe, and Mn concentrations using a ZEEnit 700P atomic absorption spectrometer.\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\u003ch2\u003e2.3 Statistical analysis\u003c/h2\u003e\u003cp\u003eData were subjected to one-way ANOVA with Duncan\u0026rsquo;s multiple range test (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) using the statistical software SPSS 25.0. Histograms of the expression of interest were constructed using Origin 2022, and the values of the final plotted graphs represent the means of three replicates.\u003c/p\u003e\u003c/div\u003e"},{"header":"3. Results","content":"\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003e3.1 Analysis of agronomic traits of different onion varieties\u003c/h2\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab6\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eAgronomic traits of different onion varieties\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"9\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBulb length\u003c/p\u003e\u003cp\u003e(mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eBulbs transverse (mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eDiscoid stem diameter (mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003eBulb stem thickness\u003c/p\u003e\u003cp\u003e(mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eNumber of scales\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eNumber of scales\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003eBulb quality\u003c/p\u003e\u003cp\u003e(g)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eYellow onions\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e91.28\u0026thinsp;\u0026plusmn;\u0026thinsp;1.59 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e91.59\u0026thinsp;\u0026plusmn;\u0026thinsp;2.83 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003e20.49\u0026thinsp;\u0026plusmn;\u0026thinsp;1.39 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e13.52\u0026thinsp;\u0026plusmn;\u0026thinsp;1.21 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e417.67\u0026thinsp;\u0026plusmn;\u0026thinsp;9.28 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePowdered onions\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e88.39\u0026thinsp;\u0026plusmn;\u0026thinsp;1.88 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e92.38\u0026thinsp;\u0026plusmn;\u0026thinsp;3.31 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003e21.11\u0026thinsp;\u0026plusmn;\u0026thinsp;1.29 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e14.14\u0026thinsp;\u0026plusmn;\u0026thinsp;1.28 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e371.66\u0026thinsp;\u0026plusmn;\u0026thinsp;10.74 b\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTaste-type onions\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e92.23\u0026thinsp;\u0026plusmn;\u0026thinsp;2.00 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e93.42\u0026thinsp;\u0026plusmn;\u0026thinsp;3.73 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003e21.94\u0026thinsp;\u0026plusmn;\u0026thinsp;0.79 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e12.66\u0026thinsp;\u0026plusmn;\u0026thinsp;0.69 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e421.57\u0026thinsp;\u0026plusmn;\u0026thinsp;6.11 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"9\"\u003eNote: different lowercase letters in the table indicate significant differences at the level of 0.05 among different treatments\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eAn analysis of seven major agronomic traits in three onion germplasm resources revealed that the distribution of these traits exhibited significant diversity (Table\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). Specifically, the longitudinal diameter of onion bubles ranged from 88.39 to 92.23 mm, with the largest longitudinal diameter of the taste type onion and the smallest longitudinal diameter of the powdered onion. The differences in the transverse diameter of onion bulbs are relatively small, ranging from 91.59 to 93.42 mm, with the transverse diameter of bulb onions being the widest. The diameter of the bulbous stem ranges from 20.49 to 21.94 mm, with the largest diameter found in onions of the taste type. The weight of the onion bulb primarily ranges from 371.66 to 421.67 g, with the highest weight observed in onions of the taste type. Comprehensive analysis shows that the overall agronomic traits of taste-type onions are superior to those of yellow onions and powdered onions.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003e3.2 Mineral element analysis of different onion varieties\u003c/h2\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab7\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 7\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eMineral element content of different varieties of onions\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eContent (mg/kg)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTaste-type onions\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eYellow onions\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003ePowdered onions\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCa\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5569.33\u0026thinsp;\u0026plusmn;\u0026thinsp;686.08 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e6724.33\u0026thinsp;\u0026plusmn;\u0026thinsp;398.25 ab\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e7939.67\u0026thinsp;\u0026plusmn;\u0026thinsp;463.91 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCu\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.83\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.78\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.51\u0026thinsp;\u0026plusmn;\u0026thinsp;0.08 b\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFe\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e23.01\u0026thinsp;\u0026plusmn;\u0026thinsp;2.00 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e23.33\u0026thinsp;\u0026plusmn;\u0026thinsp;4.61 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e17.74\u0026thinsp;\u0026plusmn;\u0026thinsp;4.60 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMn\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4.87\u0026thinsp;\u0026plusmn;\u0026thinsp;0.13 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e6.14\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e4.99\u0026thinsp;\u0026plusmn;\u0026thinsp;0.22 b\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5235.00\u0026thinsp;\u0026plusmn;\u0026thinsp;431.66 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4430.00\u0026thinsp;\u0026plusmn;\u0026thinsp;267.13 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2857.70\u0026thinsp;\u0026plusmn;\u0026thinsp;102.37 b\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eK\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e17445.33\u0026thinsp;\u0026plusmn;\u0026thinsp;944.72 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e13382.67\u0026thinsp;\u0026plusmn;\u0026thinsp;449.59 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e12045.33\u0026thinsp;\u0026plusmn;\u0026thinsp;492.81 b\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"4\"\u003eNote: different lowercase letters in the table indicate significant differences at the level of 0.05 among different treatments\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThe mineral content directly reflects the absorption and accumulation of various mineral nutrients by onions during their growth process and is one of the key characteristics for measuring the nutritional quality of onions. Table\u0026nbsp;\u003cspan refid=\"Tab7\" class=\"InternalRef\"\u003e7\u003c/span\u003e shows the mineral element content of different onion varieties. Among all onion varieties, the content of K was the highest, followed by Ca, and Cu was the lowest. Compared with ordinary onions (Yellow onions and powdered onions), taste-type onions have relatively high levels of K, Mg and Cu, but lower levels of Ca, Fe and Mn. The K content in taste onion reaches 17,445.33 mg/kg, representing a significant increase of 30.36% compared to yellow onion and 44.83% higher than powdered onion. Similarly, its Mg content stands at 5,235.00 mg/kg, showing an 18.17% elevation over yellow onion and a remarkable 83.19% advantage compared to powdered onion. In summary, the taste type onion has significant advantages over ordinary onions in terms of K, Mg, Cu and other mineral element contents, especially in the content of K and Mg, which indicates that taste onions have unique advantages and development potential in terms of nutritional quality\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\u003ch2\u003e3.3 Analysis of amino acid components of different varieties of onions\u003c/h2\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab8\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 8\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eAmino acid content in different onion varieties\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAmino acid(ug/g)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eYellow onions\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePowdered onions\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eTaste-type onion\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAspartic acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e20.33\u0026thinsp;\u0026plusmn;\u0026thinsp;0.89 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e37.99\u0026thinsp;\u0026plusmn;\u0026thinsp;2.65 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e9.96\u0026thinsp;\u0026plusmn;\u0026thinsp;0.48 c\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGlutamic acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e41.95\u0026thinsp;\u0026plusmn;\u0026thinsp;1.42 c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e101.29\u0026thinsp;\u0026plusmn;\u0026thinsp;3.80 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e130.80\u0026thinsp;\u0026plusmn;\u0026thinsp;8.29 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAsparagine\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e144.88\u0026thinsp;\u0026plusmn;\u0026thinsp;2.25 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e249.00\u0026thinsp;\u0026plusmn;\u0026thinsp;19.37 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e271.11\u0026thinsp;\u0026plusmn;\u0026thinsp;5.25 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSerine\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e14.59\u0026thinsp;\u0026plusmn;\u0026thinsp;0.57 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e49.29\u0026thinsp;\u0026plusmn;\u0026thinsp;3.85 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e21.05\u0026thinsp;\u0026plusmn;\u0026thinsp;1.00 b\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGlutamine\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e30.10\u0026thinsp;\u0026plusmn;\u0026thinsp;1.77 c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e110.00\u0026thinsp;\u0026plusmn;\u0026thinsp;4.19 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e152.26\u0026thinsp;\u0026plusmn;\u0026thinsp;1.50 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGlycine\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e33.82\u0026thinsp;\u0026plusmn;\u0026thinsp;0.66 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e21.26\u0026thinsp;\u0026plusmn;\u0026thinsp;1.58 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e32.75\u0026thinsp;\u0026plusmn;\u0026thinsp;1.82 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCysteine\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e54.32\u0026thinsp;\u0026plusmn;\u0026thinsp;1.88 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e60.01\u0026thinsp;\u0026plusmn;\u0026thinsp;4.17 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e38.02\u0026thinsp;\u0026plusmn;\u0026thinsp;6.43 b\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGamma-aminobutyric acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e14.95\u0026thinsp;\u0026plusmn;\u0026thinsp;0.41 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e20.44\u0026thinsp;\u0026plusmn;\u0026thinsp;1.43 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e20.79\u0026thinsp;\u0026plusmn;\u0026thinsp;1.08 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAlanine\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e17.28\u0026thinsp;\u0026plusmn;\u0026thinsp;0.37 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e13.59\u0026thinsp;\u0026plusmn;\u0026thinsp;0.58 c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e42.41\u0026thinsp;\u0026plusmn;\u0026thinsp;1.27 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eProline\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e21.68\u0026thinsp;\u0026plusmn;\u0026thinsp;0.53 c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e27.74\u0026thinsp;\u0026plusmn;\u0026thinsp;1.10 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e47.48\u0026thinsp;\u0026plusmn;\u0026thinsp;0.71 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTheanine\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5.63\u0026thinsp;\u0026plusmn;\u0026thinsp;0.06 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e8.09\u0026thinsp;\u0026plusmn;\u0026thinsp;0.71 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e9.18\u0026thinsp;\u0026plusmn;\u0026thinsp;1.19 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTyrosine\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e36.88\u0026thinsp;\u0026plusmn;\u0026thinsp;1.55 c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e49.42\u0026thinsp;\u0026plusmn;\u0026thinsp;2.45 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e175.56\u0026thinsp;\u0026plusmn;\u0026thinsp;2.61 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHistidine\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5.19\u0026thinsp;\u0026plusmn;\u0026thinsp;0.25 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e11.17\u0026thinsp;\u0026plusmn;\u0026thinsp;0.56 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e6.64\u0026thinsp;\u0026plusmn;\u0026thinsp;0.50 b\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eThreonine\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e7.91\u0026thinsp;\u0026plusmn;\u0026thinsp;0.49 c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e32.12\u0026thinsp;\u0026plusmn;\u0026thinsp;0.97 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e56.59\u0026thinsp;\u0026plusmn;\u0026thinsp;0.41 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eArginine\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e355.64\u0026thinsp;\u0026plusmn;\u0026thinsp;8.35 c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e454.92\u0026thinsp;\u0026plusmn;\u0026thinsp;23.73 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e534.26\u0026thinsp;\u0026plusmn;\u0026thinsp;14.05 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eValine\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e16.66\u0026thinsp;\u0026plusmn;\u0026thinsp;0.49 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e39.96\u0026thinsp;\u0026plusmn;\u0026thinsp;1.43 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e16.61\u0026thinsp;\u0026plusmn;\u0026thinsp;1.24 b\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMethionine\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e11.97\u0026thinsp;\u0026plusmn;\u0026thinsp;0.51 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e20.04\u0026thinsp;\u0026plusmn;\u0026thinsp;1.31 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e24.39\u0026thinsp;\u0026plusmn;\u0026thinsp;1.63 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eIsoleucine\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5.76\u0026thinsp;\u0026plusmn;\u0026thinsp;0.28 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e15.91\u0026thinsp;\u0026plusmn;\u0026thinsp;0.78 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e6.66\u0026thinsp;\u0026plusmn;\u0026thinsp;0.23 b\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLeucine\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e18.29\u0026thinsp;\u0026plusmn;\u0026thinsp;0.86 c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e47.61\u0026thinsp;\u0026plusmn;\u0026thinsp;0.97 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e123.33\u0026thinsp;\u0026plusmn;\u0026thinsp;1.36 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePhenylalanine\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e6.67\u0026thinsp;\u0026plusmn;\u0026thinsp;0.25 c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e27.89\u0026thinsp;\u0026plusmn;\u0026thinsp;0.56 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e17.62\u0026thinsp;\u0026plusmn;\u0026thinsp;1.15 b\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTryptophan\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e13.88\u0026thinsp;\u0026plusmn;\u0026thinsp;0.92 c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e27.32\u0026thinsp;\u0026plusmn;\u0026thinsp;1.09 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e20.05\u0026thinsp;\u0026plusmn;\u0026thinsp;1.35 b\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"4\"\u003eNote: different lowercase letters in the table indicate significant differences at the level of 0.05 among different treatments\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eAs shown in Table\u0026nbsp;\u003cspan refid=\"Tab8\" class=\"InternalRef\"\u003e8\u003c/span\u003e, there are significant differences in the free amino acid content among different onion varieties. In this study, amino acid profiling was conducted on three onion varieties, and a total of 21 amino acids were detected. Among these amino acids, arginine has the highest content, ranging from 355.64 to 534.26 \u0026micro;g/g; aspartic acid follows with a content ranging from 144.88 to 271.11 \u0026micro;g/g; while the content of theanine is the lowest, at only 5.63 to 9.18 \u0026micro;g/g. Further comparative analysis revealed that taste-type onions have significantly higher levels of various amino acids than ordinary varieties, specifically glutamic acid, aspartic acid, glutamine, alanine, proline, tyrosine, threonine, arginine, and leucine. Notably, taste-type onions exhibit substantially higher leucine content compared to conventional varieties, with levels 574.30% greater than yellow-skinned onions and 159.04% higher than Powdered onions.\u003c/p\u003e\u003cp\u003eTaste-type onions also performed well in terms of the total content of non-essential amino acids and essential amino acids, ranking first among the 3 different varieties of onions, followed by powder onions, while yellow onions were relatively lowest. In terms of total amino acid content, the total amino acid content of the taste-type onion reached 1,757.49 \u0026micro;g/g, which was more than 1.2 times that of ordinary onions (as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). This indicates that the flavor-type onion has a significant advantage in terms of amino acid nutritional quality, and its rich amino acid composition makes it more promising in terms of edible value and health benefits.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe results of the amino acid Pearson correlation analysis (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) revealed significant positive correlations between various amino acids in onions, including glutamine and glutamic acid (r\u0026thinsp;=\u0026thinsp;0.98), tyrosine and alanine (r\u0026thinsp;=\u0026thinsp;0.98), tyrosine and proline (r\u0026thinsp;=\u0026thinsp;0.98), serine and histidine (r\u0026thinsp;=\u0026thinsp;0.99), glutamine and threonine (r\u0026thinsp;=\u0026thinsp;0.98), and tryptophan and phenylalanine (r\u0026thinsp;=\u0026thinsp;0.97) exhibit extremely significant positive correlations (P\u0026thinsp;\u0026lt;\u0026thinsp;0.01). This suggests that these amino acids may undergo mutual conversion or jointly participate in certain metabolic pathways during metabolic processes, exhibiting high levels of synergy. In addition, proline and asparagine (r\u0026thinsp;=\u0026thinsp;0.76), theanine and glutamic acid (r\u0026thinsp;=\u0026thinsp;0.73), tyrosine and glutamic acid (r\u0026thinsp;=\u0026thinsp;0.80), and phenylalanine and asparagine (r\u0026thinsp;=\u0026thinsp;0.75) also exhibit significant positive correlations (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05), further revealing their close relationship in onion metabolism. These correlation analysis results not only help to deepen our understanding of the amino acid metabolic mechanisms in onions but also provide important theoretical basis for the assessment of onion nutritional quality, variety improvement, and health functional studies.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e\u003ch2\u003e3.4 Analysis of fatty acid composition in different onion varieties\u003c/h2\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab9\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 9\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eAnalysis results of fatty acid composition in three types of onions\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003eContent (\u0026micro;g/g)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCompound\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMolecular formula\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eYellow onion\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003ePowdered onions\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eTaste-type onion\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eButyric acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eC3H7COOH\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.71\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.52\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.67\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLauric acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eC12H24O2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.09\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMyristic acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eC14H28O2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.18\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.33\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.32\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePentadecanoic acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eC15H30O2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.04\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.04\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.19\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePentadecenoic acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eC15H28O2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.18\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.33\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.41\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePalmitic acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eC16H32O2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5.00\u0026thinsp;\u0026plusmn;\u0026thinsp;0.82 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e3.36\u0026thinsp;\u0026plusmn;\u0026thinsp;1.47 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e14.31\u0026thinsp;\u0026plusmn;\u0026thinsp;0.81 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eStearic acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eC18H36O2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.78\u0026thinsp;\u0026plusmn;\u0026thinsp;0.11 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.65\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.39\u0026thinsp;\u0026plusmn;\u0026thinsp;0.10 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eElaidic acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eC18H34O2\u0026zwnj;\u0026zwnj;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.24\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.19\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.16\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOleic acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eC18H34O2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3.16\u0026thinsp;\u0026plusmn;\u0026thinsp;0.72 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.51\u0026thinsp;\u0026plusmn;\u0026thinsp;0.37 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3.17\u0026thinsp;\u0026plusmn;\u0026thinsp;0.08 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLinoleic acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eC18H32O2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7.45\u0026thinsp;\u0026plusmn;\u0026thinsp;0.57 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e5.28\u0026thinsp;\u0026plusmn;\u0026thinsp;0.45 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e26.39\u0026thinsp;\u0026plusmn;\u0026thinsp;0.97 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAlpha-linolenic acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eC18H30O2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.36\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.49\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.53\u0026thinsp;\u0026plusmn;\u0026thinsp;0.06 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eArachidic acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eC20H40O2\u0026zwnj;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.31\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eArachidonic acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eC20H32O2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.32\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eEicosatrienoic acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eC20H34O2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.26\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDocosanoic acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eC22H44O2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.41\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eErucic acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eC22H42O2\u0026zwnj;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.38\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSqualenic acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eC24H46O2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.86\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"5\"\u003eNote: different lowercase letters in the table indicate significant differences at the level of 0.05 among different treatments,\"-\" means not detected\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eFatty acid content is an important indicator for measuring the types and quantities of fatty acids in onions. It reflects the nutritional components and quality characteristics of onions and has significant implications in many respects. As shown in Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e, significant variations were observed in fatty acid composition among different onion cultivars. A total of 17 fatty acids were detected. In terms of fatty acid diversity, yellow onions exhibited the highest number of compounds (15 species), followed by taste-type onions (12 species), while Powdered onions showed the lowest diversity with only 10 detected compounds. In terms of endemic compounds, two kinds of taste-type onions were detected, namely arachidic acid and docaneic acid, while neither yellow onion nor powdered onion produced any endemic compounds. In terms of fatty acid content, linoleic acid was the highest among the three onion varieties, followed by palmitic acid, with oleic acid being the lowest (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Among them, the linoleic acid content of the taste-type onion was 26.39 \u0026micro;g/g, which was 254.23% and 399.81% higher than that of the yellow onion and Powdered onion, respectively.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eAnalysis of total fatty acid content revealed significant differences among onion cultivars (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Notably, the taste-type onion exhibited the highest fatty acid accumulation (49.17 \u0026micro;g/g), followed by yellow onion (21.01 \u0026micro;g/g), while Powdered onion showed the lowest content (12.68 \u0026micro;g/g). Compared to yellow onion and Powdered onion varieties, the taste-type onion demonstrated 134.03% and 287.78% higher fatty acid levels, respectively. These pronounced variations suggest distinct physiological characteristics in fatty acid biosynthesis among different onion cultivars.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFurther Pearson correlation analysis of fatty acids (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e) revealed intrinsic relationships between different fatty acids in onions. The results showed a highly significant positive correlation between Elaidic acid and pentadecanoic acid (r\u0026thinsp;=\u0026thinsp;0.99), indicating that these two fatty acids may be subject to similar regulatory mechanisms during metabolism or exert synergistic effects in the physiological functions of onions. Similarly, shark acid and lauric acid (r\u0026thinsp;=\u0026thinsp;0.99) as well as eicosatrienoic acid and erucic acid (r\u0026thinsp;=\u0026thinsp;0.99) also showed extremely high positive correlations, which may suggest that they have similar metabolic pathways or functional associations in the fatty acid synthesis and metabolism pathways of onions. Moreover, a significant positive correlation was observed between oleic acid and butyric acid (r\u0026thinsp;=\u0026thinsp;0.69), suggesting potential interactions within the fatty acid metabolic network of onions. In summary, onion cultivars exhibited marked differences in fatty acid composition, accompanied by complex interrelationships among individual fatty acids. These findings provide a critical theoretical foundation for targeted cultivar improvement and nutritional quality enhancement in onion breeding programs.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec16\" class=\"Section2\"\u003e\u003ch2\u003e3.5 Analysis of sugar and acid components in different varieties of onions\u003c/h2\u003e\u003cdiv id=\"Sec17\" class=\"Section3\"\u003e\u003ch2\u003e3.5.1 Sugar components\u003c/h2\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab10\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 10\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eSugar content of different onion varieties\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSugar (mg/g)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eYellow onions\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePowdered onions\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eTaste-type onion\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFructose\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e6.70\u0026thinsp;\u0026plusmn;\u0026thinsp;0.14 c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e9.24\u0026thinsp;\u0026plusmn;\u0026thinsp;0.49 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e14.88\u0026thinsp;\u0026plusmn;\u0026thinsp;0.51 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGlucose\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e7.28\u0026thinsp;\u0026plusmn;\u0026thinsp;0.10 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e14.07\u0026thinsp;\u0026plusmn;\u0026thinsp;0.32 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e14.35\u0026thinsp;\u0026plusmn;\u0026thinsp;0.60 b\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSucrose\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4.41\u0026thinsp;\u0026plusmn;\u0026thinsp;0.03 c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10.90\u0026thinsp;\u0026plusmn;\u0026thinsp;0.13 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e12.05\u0026thinsp;\u0026plusmn;\u0026thinsp;0.32 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"4\"\u003eNote: different lowercase letters in the table indicate significant differences at the level of 0.05 among different treatments.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eAs shown in Table\u0026nbsp;\u003cspan refid=\"Tab10\" class=\"InternalRef\"\u003e10\u003c/span\u003e, there are differences in the sugar component content among different onion varieties. When analyzing three onion varieties, three types of sugar components\u0026mdash;fructose, glucose, and sucrose\u0026mdash;were detected. In taste-type onions, fructose content was the highest, followed by glucose, while sucrose content was relatively low. Further comparison revealed that the sugar component content in taste-type onions was higher than that in ordinary onions. Specifically, compared to yellow onions, the taste-type cultivar demonstrated significantly elevated sugar content, with fructose, glucose, and sucrose levels increasing by 122.09%, 97.12%, and 173.24%, respectively. Regarding total sugar content (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e), the three onion varieties exhibited a range of 18.39 to 41.29 mg/g, with the taste-type onion showing the highest accumulation (41.29 mg/g) and yellow onion the lowest (18.39 mg/g). Notably, the taste-type onion contained 121.16% and 20.70% more total sugars than yellow and Powdered onions, respectively.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec18\" class=\"Section3\"\u003e\u003ch2\u003e3.5.2 Organic acids\u003c/h2\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab11\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 12\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eOrganic acid content in different onion varieties\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOrganic acid (\u0026micro;g/g)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eYellow onions\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePowdered onions\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eTaste-type onion\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOxalic acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e115.67\u0026thinsp;\u0026plusmn;\u0026thinsp;5.85 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e284.40\u0026thinsp;\u0026plusmn;\u0026thinsp;8.83 c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e185.52\u0026thinsp;\u0026plusmn;\u0026thinsp;9.96 b\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTartaric acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFormic acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e303.66\u0026thinsp;\u0026plusmn;\u0026thinsp;22.76 c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e401.26\u0026thinsp;\u0026plusmn;\u0026thinsp;8.83 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e541.41\u0026thinsp;\u0026plusmn;\u0026thinsp;15.44 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMalic acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e604.92\u0026thinsp;\u0026plusmn;\u0026thinsp;20.66 c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1100.76\u0026thinsp;\u0026plusmn;\u0026thinsp;72.12 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1448.45\u0026thinsp;\u0026plusmn;\u0026thinsp;20.76 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLactic acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e145.10\u0026thinsp;\u0026plusmn;\u0026thinsp;3.08 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e192.74\u0026thinsp;\u0026plusmn;\u0026thinsp;1.31 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e30133.03\u0026thinsp;\u0026plusmn;\u0026thinsp;254.90 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCitric acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e44.95\u0026thinsp;\u0026plusmn;\u0026thinsp;0.77 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e37.40\u0026thinsp;\u0026plusmn;\u0026thinsp;1.00 c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e54.39\u0026thinsp;\u0026plusmn;\u0026thinsp;1.78 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMaleic acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.63\u0026thinsp;\u0026plusmn;\u0026thinsp;0.10 c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e16.76\u0026thinsp;\u0026plusmn;\u0026thinsp;0.83 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e5.69\u0026thinsp;\u0026plusmn;\u0026thinsp;0.16 b\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSuccinic acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFumaric acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.99\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.49\u0026thinsp;\u0026plusmn;\u0026thinsp;0.25 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e7.91\u0026thinsp;\u0026plusmn;\u0026thinsp;0.26 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePropionic acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1735.10\u0026thinsp;\u0026plusmn;\u0026thinsp;53.81 c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2720.36\u0026thinsp;\u0026plusmn;\u0026thinsp;31.83 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2796.61\u0026thinsp;\u0026plusmn;\u0026thinsp;72.67 b\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"4\"\u003eNote: different lowercase letters in the table indicate significant differences at the level of 0.05 among different treatments,\"-\" means not detected.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThe organic acid profiles of different onion varieties are presented in Table\u0026nbsp;\u003cspan refid=\"Tab7\" class=\"InternalRef\"\u003e7\u003c/span\u003e. Among the three cultivars analyzed, eight organic acids were detected, with significant variation in their concentrations. In taste type onions, lactic acid was the predominant organic acid, exhibiting concentrations ranging from 29,772.95 to 30,625.61 \u0026micro;g/g, followed by propionic acid (2,260.92\u0026ndash;2,509.54 \u0026micro;g/g). In contrast, malic acid was present in markedly lower amounts (5.44\u0026ndash;5.99 \u0026micro;g/g). When comparing different varieties, the organic acid content of taste-type onions is generally higher than that of yellow onions and Powdered onions. The organic acid content of sweet onions is significantly higher than that of yellow onions and Powdered onions. For example, the content of formic acid, malic acid, lactic acid, citric acid, and fumaric acid in sweet onions is higher than that in ordinary onions. Compared to ordinary onions, the formic acid content in taste-type onions increased by 78.29% and 34.93%, malic acid content increased by 139.44% and 31.59%; and citric acid content increased by 21.00% and 45.43%, respectively. In particular, the lactic acid content of taste-type onions is more than 156 times that of regular onions, a large difference that indicates that taste-type onions have unique physiological properties in terms of organic acid accumulation.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eAs shown in Figs.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e and \u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e, there are significant differences in organic acid content among the three onion varieties. The organic acid content of the taste-type onion is significantly higher than that of the ordinary onion, reaching as high as 34,773.02 \u0026micro;g/g, which is more than seven times that of the ordinary onion. In addition, there were great differences in the composition of organic acids among the three onion varieties. In yellow onions and powdered onions, propionic acid, malic acid and formic acid content account for a large part of the organic acid content, of which propionic acid content accounts for more than half, which is the most important organic acid component of these two kinds of onions. Lactic acid, propionic acid and malic acid accounted for a large part of the organic acid content, of which lactic acid content accounted for 86.7%, which was the most important organic acid component of taste-type onions.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e shows the results of a correlation analysis of organic acids, which revealed significant correlations between various organic acids. Specifically, the correlation coefficient between lactic acid and fumaric acid was 0.99, indicating a strong positive correlation. In the sample data, this means that an increase in lactic acid content is almost always accompanied by a corresponding increase in fumaric acid content, and vice versa. Strong positive correlations were observed between specific organic acid pairs, with particularly high correlation coefficients for malic acid-formic acid (r\u0026thinsp;=\u0026thinsp;0.95), maleic acid-oxalic acid (r\u0026thinsp;=\u0026thinsp;0.98), and propionic acid-oxalic acid (r\u0026thinsp;=\u0026thinsp;0.94). These robust correlations (all r\u0026thinsp;\u0026gt;\u0026thinsp;0.90) suggest potentially interdependent metabolic pathways or synergistic physiological functions among these compounds. Furthermore, propionic acid and malic acid showed a slightly lower but still significant positive correlation (r\u0026thinsp;=\u0026thinsp;0.72, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05), providing additional evidence for complex interrelationships within the organic acid network. These findings substantially enhance our understanding of metabolic coordination in onion organic acid biosynthesis.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eAs living standards improve, more people are placing greater emphasis on safety, health, and high-quality agricultural products. These products are gradually becoming the dominant market demand. Therefore, breeding high-quality agricultural products has become a hot research topic. This study found that taste-type onions have superior nutritional quality compared to conventional onion varieties. Taste-type onions outperform conventional onions in terms of their sugar, acid, amino acid, fatty acid, and polyphenol content, exhibiting higher levels of these components.\u003c/p\u003e\u003cp\u003eVegetables and fruits contain large amounts of amino acid compounds that promote plant photosynthesis and have medicinal value\u003csup\u003e[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e. They are divided into non-essential and essential amino acids based on whether the human body can synthesize them on its own. They can also be divided into sweet, umami, bitter, sour, and tasteless amino acids based on their taste characteristics\u003csup\u003e[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]\u003c/sup\u003e. Histidine in onions is an acidic amino acid; aspartic acid and glutamic acid are umami amino acids; and glycine and proline are sweet amino acids\u003csup\u003e[\u003cspan additionalcitationids=\"CR21\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/sup\u003e. Previous studies on onions have shown that there are certain differences in the amino acid content of onions of different skin colors, with white onions having higher amino acid content and purple onions having lower amino acid content\u003csup\u003e[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]\u003c/sup\u003e. Our research found that, compared with conventional onions, taste-type onions have significantly higher levels of essential amino acids, non-essential amino acids, and total amino acids. Additionally, we found that the arginine content in onions is the highest among all amino acids, accounting for 30.40\u0026ndash;40.49% of the total content. On one hand, it participates in important processes such as protein synthesis, polyamine synthesis, and nitric oxide (NO) synthesis; on the other hand, it also participates in the ornithine (Ornithine, C5H12N2O2) cycle in the human body. Glutamic acid is one of the basic amino acids involved in nitrogen metabolism within biological organisms. It participates in the synthesis of various protein amino acids and serves as a precursor for numerous compounds, such as non-protein amino acids, chlorophyll, and hemoglobin\u003csup\u003e[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003ePolyphenolic compounds contain multiple phenolic hydroxyl groups in their molecular structure, enabling them to neutralize free radicals through electron or hydrogen atom transfer. They can also form chelation reactions with metal ions, thereby exhibiting antioxidant activity\u003csup\u003e[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]\u003c/sup\u003e. In this study, we tested 9 phenolic acids and 4 flavonoids in onions. Previous studies on tillered onions found that the flavonoid content of tillered onions was much higher than that of ordinary onions\u003csup\u003e[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]\u003c/sup\u003e. In this study, it was found that the phenolic acids and flavonoids in onions accounted for a large proportion of benzoic acid and kaempferol, respectively. Benzoic acid is an aromatic acid organic compound, which mainly participates in the exertion of biological activities such as antioxidant and antibacterial, and has a certain inhibitory effect on the growth of microorganisms\u003csup\u003e[\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]\u003c/sup\u003e. In addition to this, benzoic acid, as part of the polyphenol structure, can enhance the antioxidant capacity of polyphenols, neutralizing free radicals by donating electrons or hydrogen atoms, thereby protecting cells from oxidative damage\u003csup\u003e[\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eOrganic acids are a class of organic compounds containing carboxyl functional groups. They are widely present in plants, animals, and certain microbial fermentation products, and are one of the key indicators determining the flavor of onions. They also play a regulatory role in cellular osmotic pressure\u003csup\u003e[\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]\u003c/sup\u003e. Relevant studies have shown that potassium can influence the activity of enzymes involved in organic acid metabolism, thereby affecting organic acid metabolism\u003csup\u003e[\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]\u003c/sup\u003e. In this study, it was found that the malic acid content was the second highest organic acid in onions, which may be due to the fact that onions themselves have the highest potassium content, and potassium can promote the carboxylase activity of phosphoenolpyruvate and thus promote the synthesis of malic acid. In addition, potassium can also inhibit the activity of malate enzyme and delay the degradation rate of malic acid, which ultimately leads to a high content of malic acid in onions\u003csup\u003e[\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]\u003c/sup\u003e. Lactic acid is the most abundant organic acid in taste onions, accounting for 86.66% of the total content, and its lactic acid content is more than 156 times that of ordinary onions. Lactic acid is a carboxyl compound containing a hydroxyl group, and in the absence of oxygen, plant cells maintain energy supply through lactic acid fermentation; Under aerobic conditions, lactic acid can be oxidized to pyruvate, which enters the metabolic pathway of the tricarboxylic acid cycle\u003csup\u003e[\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eThe accumulation of sugars in onion bulbs is the result of the synergistic action of multiple sugar metabolism-related enzymes. These sugars not only determine the formation of fruit flavor quality and the sweetness of onions, but also serve as an important raw material for the synthesis of other nutrients. The sugar components in fruits have a significant impact on their flavor and quality. The types and content of sugars not only affect the nutritional value of fruits but also determine their texture, thereby influencing consumers' choices\u003csup\u003e[\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]\u003c/sup\u003e. The sugars in onion bulbs primarily include sucrose, glucose, and fructose, which contribute to the onion's sweetness. In the study, it was found that the sugar content of taste onions was significantly higher than that of regular onions (yellow onions and Powdered onions), which was the main reason why the sweetness of taste onions was significantly higher than that of regular onions.\u003c/p\u003e\u003cp\u003eCurrently, there is little research on fatty acids in onions, with studies limited to onion seeds. Wang Qiang\u003csup\u003e[\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]\u003c/sup\u003e et al. found that yellow onion seeds have a high fatty acid content, which is consistent with the results of this study. This study detected 17 fatty acid components in onions, with linoleic acid being the most abundant, accounting for 35.46\u0026ndash;53.67% of the total fatty acid content. Onions contain a special substance called prostaglandin A, which can dilate blood vessels and reduce blood viscosity\u003csup\u003e[\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]\u003c/sup\u003e. The precursor of prostaglandin A is arachidonic acid, and linoleic acid is the raw material for synthesizing arachidonic acid. Therefore, linoleic acid plays a crucial role in the synthesis of prostaglandins. Our research found that the linoleic acid content of taste-type onions is more than three times that of conventional onions, so taste-type onions can synthesize more prostaglandin A. Oleic acid is an unsaturated fatty acid widely found in animal and vegetable oils, accounting for 6.45\u0026ndash;15.04% of total fatty acid content. Oleic acid can lower cholesterol (LDL-C) levels, thereby helping to maintain lipid balance. Palmitic acid is the second most abundant substance in onions after linoleic acid. Palmitic acid is a saturated fatty acid and an important component of phospholipids in cell membranes, helping to maintain the stability and fluidity of cell membranes; it is closely related to the synthesis of various hormones, such as being a precursor substance for the synthesis of sex hormones, playing an important role in regulating human physiological functions\u003csup\u003e[\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]\u003c/sup\u003e; It also aids in the absorption and transport of fat-soluble vitamins (such as vitamins A, D, E, and K). Therefore, the high content of linoleic acid, oleic acid, and palmitic acid in taste-type onions can significantly lower cholesterol levels and improve the functions of various internal organs.\u003c/p\u003e"},{"header":"5. Conclusion","content":"\u003cp\u003eTaste-type onions are significantly superior to conventional onions in terms of agronomic traits, amino acids, organic acids, and fatty acid composition. Therefore, taste-type onions have significantly better overall quality than conventional onions, offering superior edible value and health benefits.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eConflict of interest\u003c/h2\u003e\n\u003cp\u003eThe authors declare that they have no conflict of interest.\u003c/p\u003e\n\u003ch2\u003eAuthor Contribution Statement\u003c/h2\u003e\n\u003cp\u003eGuobin Zhang and Xiaowei Wang conceived and designed the research. Yuxin Zhang and Jialin Kuai conducted experiments. Qinglong Xu contributed new reagents or analytical tools. Yanxia Ma analyzed data. Yuxin Zhang wrote the manuscript. All authors read and approved the manuscript.\u003c/p\u003e\n\u003ch2\u003eFunding\u003c/h2\u003e\n\u003cp\u003eThis work was supported by the National Modern Agricultural Industry Technology System (CARS-24-G-28); the Gansu Province Talent Project (2025QNGR58); and the Gansu Academy of Agricultural Sciences Mid-Career Research Fund Project (2023GAAS29).\u003c/p\u003e\n\u003ch2\u003eData Availability\u003c/h2\u003e\n\u003cp\u003eThe datasets used and/or analysed during the current study available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eGupta, A. J. et al. Onion nutritional and nutraceutical composition and therapeutic potential of its phytochemicals assessed through preclinical and clinical studies [J]. \u003cem\u003eJ. Funct. 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(2012).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAttrep, K. A. et al. Separation and identification of prostaglandin A1 in onion [J]. \u003cem\u003eLipids\u003c/em\u003e \u003cb\u003e15\u003c/b\u003e, 292\u0026ndash;297 (1980).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCarta, G. et al. Palmitic Acid: Physiological Role, Metabolism and Nutritional Implications [J]. \u003cem\u003eFront. Physiol.\u003c/em\u003e \u003cb\u003e8\u003c/b\u003e, 902 (2017).\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Taste-type onion, Amino acid, Fatty acid, polyphenols, Correlation analysis","lastPublishedDoi":"10.21203/rs.3.rs-7226130/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7226130/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe goal of this study is to establish a theoretical foundation for the further development and utilization of textured onions' edible value and health benefits, thereby laying the groundwork for a quality evaluation system. The experiment selected three onion varieties as subjects of the research: the yellow-skinned \u0026ldquo;Jinbao\u0026rdquo; onion, the Powdered onions \u0026ldquo;Qin Hongbao\u0026rdquo; onion, and the taste-type \u0026ldquo;Baiyu\u0026rdquo; onion. The experiment then measured and analyzed the flavor quality of these onions. The results showed that the polyphenol content of the three onion varieties ranged from 69.11 to 129.34 (mg/kg). Testy onions had a polyphenol content more than 1.3 times higher than ordinary onions, indicating a higher antioxidant capacity. The range of organic acid content is 2,952.01\u0026ndash;34,773.03 \u0026micro;g/g. Taste-type onions have an organic acid content more than seven times higher than ordinary onions. In terms of sugar content, the range is between 18.39 and 41.29 mg/g. The sugar content of testy onions is more than 1.2 times that of ordinary onions, which is the key factor contributing to their higher sweetness compared to ordinary onions. In terms of amino acid content, the content was 878.38\u0026ndash;1757.49 \u0026micro;g/g, and the content of taste-type onion was the highest, reaching 1757.49 ug/g, which was more than twice that of yellow-skinned onion. Based on the analysis of the above indicators, the comprehensive quality of tasty onion is significantly better than that of ordinary onion, and it has more advantages in terms of edible value and health care function, and has a broad application prospect and development potential.\u003c/p\u003e","manuscriptTitle":"Analysis of the nutritional quality and micro components of textured and ordinary onions","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-12 09:42:17","doi":"10.21203/rs.3.rs-7226130/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"71f3ffca-8cf8-462d-9372-cf61a7a84dcd","owner":[],"postedDate":"September 12th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":54482613,"name":"Biological sciences/Biochemistry"},{"id":54482614,"name":"Health sciences/Health care"},{"id":54482615,"name":"Biological sciences/Plant sciences"}],"tags":[],"updatedAt":"2025-10-08T17:55:50+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-12 09:42:17","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7226130","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7226130","identity":"rs-7226130","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}