Impact of GABA and 1-MCP on qualitative attributes of apples (Malus domestica Borkh. cv. Fuji) during cold storage

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Fuji) during cold storage | 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 Impact of GABA and 1-MCP on qualitative attributes of apples (Malus domestica Borkh. cv. Fuji) during cold storage Yanju Xiang, Yanqing Dang#, Adila Abudula, Xujie Hou, Yunfeng PU This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7306968/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 19 Mar, 2026 Read the published version in Scientific Reports → Version 1 posted 12 You are reading this latest preprint version Abstract This study investigated the efficacy of γ-aminobutyric acid (GABA) and 1-methylcyclopropene (1-MCP), individually and in combination, in mitigating sugar core disappearance, flesh browning, and postharvest quality in apples during 180 days storage. The results showed that the combined GABA + 1-MCP treatment outperformed individual applications, significantly delaying sugar core disappearance by preserving sucrose and sorbitol while moderating glucose and fructose accumulation. Furthermore, the combined treatment significantly reduced flesh browning compared to the control, likely attributed to suppressed polyphenol oxidase activity and enhanced antioxidant capacity. This approach also minimized weight loss and maintained firmness and titratable acidity. Although total phenolics and total flavonoids increased progressively during storage, their levels were effectively regulated by the GABA + 1-MCP treatment. These results indicate that the combined exogenous application of GABA and 1-MCP is a potentially effective method to improve postharvest quality, and enhance storage efficiency of apple fruit. Biological sciences/Biochemistry Biological sciences/Biotechnology Physical sciences/Chemistry Biological sciences/Plant sciences γ-Aminobutyric acid 1-MCP Apple Watercore Flesh browning Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 1. Introduction The environmental and climatic conditions in Xinjiang are favorable for apple growth, creating a unique quality of watercore apples, which has become a symbol product, and selected as the recommended fruit for the Beijing Olympic Games in 2008[1]. Although watercore is a physiological disorder of apple characterized by glassy or translucent tissue in the flesh[2], and visible only when the fruit is cut in half[3], watercore apples are safe and edible[4]. In some countries, watercore appearance is a desirable trait for apples, as an indicator of full ripeness [5, 6]. However, watercore tissues tend to disappear during storage, leading to a significant loss of unique identity and market value[6]. Additionally, long-term storage often results in flesh browning[4]. Hence, these challenges highlight the need for effective postharvest treatments to maintain post-harvest quality in watercore apples. γ-Aminobutyric acid (GABA), a non-proteinogenic amino acid, can be rapidly accumulated in response to biotic and abiotic stresses and involves in signaling or regulatory mechanisms, nitrogen and carbon metabolism, and amino acid biosynthesis[7, 8]. Previous reports have shown that GABA postharvest treatments delay the senescence of horticultural commodities and increase fruit chilling tolerance, with additional effects on fruit quality preservation after storage at low temperatures[9-11]. Additionally, Aydin Shekari[12] found that GABA treatment could be employed for retarding cap browning and maintaining the sensory and nutritional quality of button mushrooms during cold storage. On the other hand, 1-MCP, a synthetic compound that works by competitively binding to ethylene receptors and inhibits ethylene action, has been widely used to delay ripening and senescence in climacteric fruits such as apples[13-15]. Although both GABA and 1-MCP are effective individually in preserving fruit quality, their combined effect has not been investigated, specifically in watercore apples. It was speculated that the combined GABA and 1-MCP treatment could improve the ability of fruit to resist external environmental stress and prolong the storage period. This study aims to evaluate the efficacy of GABA and 1-MCP, individually and in combination, in postharvest quality of apples during long-term storage. The findings of this study could provide a new perspective for extending the shelf life of watercore apples. 2. Materials and methods 2.1. Plant materials and treatment Apple fruits (Malus domestica Borkh. cv. Fuji ) at commercial maturity were hand harvested from an orchard in Wensu, Xinjiang, and transported to the laboratory at the same day with cartons. The fruit with good texture, uniform size and maturity, free of physical injuries and pest were randomly divided into four groups. The first group(G) was immersed in 1.0 mmol/L GABA solutions for 20 min, and the second group(M) was exposed to 1 µL L − 1 1-MCP at room temperature for 24 h, and the third group(G + M) was treated same as the first group, after desiccating at room temperature, and then treated same as the second group, and the fourth group (CK) was untreated and served as a control. The four groups were then packed in corrugated boxes (30 fruits each), and stored at 0 ± 1 ◦C. The samples were analyzed periodically and randomly collected at 30 d intervals to evaluate the postharvest quality. 2.2Watercore incidence and internal browning After determining fruit weight, fruit were cut at the equatorial region and visually scored for watercore incidence according to the method described by Li[ 16 ]. Internal browning was calculated according the method described by Wood[ 17 ]. 2.3 Weight loss, firmness, and titratable acidity Fruit weight loss was measured by the difference of final weight from initial weight and expressed as percentage weight loss. The firmness was evaluated following the method reported by Yuan[ 18 ]on a Texture Analyzer (GY-4; Zhejiang Top Instrument Co., Ltd., China) equipped with a 3.5 mm diameter cylindrical probe. Five apples were measured for each treatment, and the results were expressed as kg/cm 2 . Titratable acidity (TA) was measured according to the method described by Pu[ 19 ], and the TA results were expressed in terms of % malic acid. 2.4 Glucose, sorbitol, fructose and sucrose The contents of individual sugars were determined using a LC-20A HPLC with a RID-10A detector (Shimadzu, Japan), as per the method described by Pu[ 19 ], and the results were expressed as g/kg FW. 2.5 Total phenolics and total flavonoids Total phenolics content was measured according to the Folin-Ciocalteu colorimetric method[ 19 ], and the results were expressed as gallic acid equivalents per gram of fruit (g GAE/kg FW). The total flavonoid content (TFC) was evaluated as per the process described by Pu[ 19 ], and the results were expressed as milligrams of rutin equivalent per gram of fruit (g RE/kg FW). 2.6 Statistical Analysis All the experiments were performed in triplicate independently, and three samples were analyzed for each group. The data was subjected to one-way analysis of variance using the SPSS statistical software (Version 20.0; SPSS, Chicago, IL, USA), and the significant differences were compared by the Duncan’s test (P < 0.05). Furthermore, principal composition analysis (PCA) was performed using Unscrambler 10.1 (CAMO AS, Trondheim, Norway) software. 3. Results and discussion 3.1 Watercore incidence (WI) and Internal browning As shown in Figs. 1 and 2 , the WI exhibited a progressive decline throughout the refrigerated storage period. During the incipient storage phase, all samples exhibited pronounced watercore distribution(WI>90%), with affected regions predominantly localized in vascular bundles (Fig. 1 ). However, as storage duration increased, the watercore gradually decreases and eventually disappears. Similar behavior was observed by Li[ 16 ] and Saquet[ 20 ]. At 60-day storage, the G, M and G + M groups demonstrated significantly elevated watercore incidence compared to the CK group (P<0.05), with distinct spatial distribution patterns observable through image quantification(Figs. 1 and 2 ). Notably, after 90-day storage, CK and M groups exhibited accelerated watercore remission (WI < 20%), whereas GABA-treated groups maintained elevated WI values exceeding 50% (G: 56.67%; G + M:63.33%), preserving the characteristic translucent parenchyma. Intriguingly, the watercore completely disappears in CK and M groups by 120-day storage, while GABA-treated groups retained diagnostically significant watercore manifestations (G: 6.67%; G + M:13.33%) until 150-day storage. The IB of apples during cold storage was significantly affected by postharvest treatments (P < 0.05, Figs. 1 and 3 ). Control (CK) group manifested initial flesh browning (IB = 3.33%) at 90 days postharvest, progressing to severe discoloration (IB = 73.33%) by storage terminus. 1-MCP-treated (M) group exhibited delayed onset, with first browning symptoms (IB = 3.33%) emerging at 120 days, contrasting with complete absence in GABA-treated groups (Fig. 3 ). Additionally, the GABA treated groups did not exhibit fruit flesh browning throughout the entire storage period. Li[ 21 ] demonstrated that GABA application enhances the mitochondrial antioxidant system and reduces peel browning in pears following removal from cold storage. Similarly, Shekari[ 12 ] reported that GABA-treated mushrooms exhibited elevated activity and gene expression of phenylalanine ammonia-lyase (PAL) alongside reduced polyphenol oxidase (PPO) activity, collectively resulting in retarded cap browning. Consistent with these findings, other studies have shown that exogenous GABA treatment effectively protects membrane integrity in various fruits, as reflected by reduced electrolyte leakage and malondialdehyde (MDA) content, thereby delaying flesh browning during cold storage[ 12 ]. In contrast, Jung[ 22 ] observed that late-harvested fruit treated with 1-methylcyclopropene (1-MCP) were more susceptible to flesh browning during prolonged storage, primarily due to a compromised antioxidant defense mechanism under stress, along with elevated polyphenol oxidase (PPO) activity and electrolyte leakage rates. Collectively, these results demonstrate that GABA treatments not only delay watercore dissipation but also effectively inhibit flesh browning. 3.2 Weight loss The weight loss of apples progressively increased during 180-day cold storage across all treatments. The highest weight loss (9.56%) was observed in control fruit. In this study, 1-MCP and GABA treatments alone or in combination significantly (P < 0.05) reduced weight loss of apple fruit compared to control treatment and the lowest weight loss (7.57%) was found in fruit treated with 1-MCP + GABA (Fig. 4 ). The increase in weight loss during storage is likely attributable to water loss resulting from respiration, transpiration and metabolic activity[ 23 ]. Regarding the inhibitory effect of 1-MCP, its reduction of postharvest water loss in tomato has been linked to its regulation of epidermal cuticle composition and morphology[ 24 ]. Specifically for apples, 1-MCP treatment may influence quality during cold storage by delaying increases in cuticular wax density and inhibiting wax crystal melting, potentially through reducing the expression of MdCER6[ 25 ]. GABA, on the other hand, might mitigate weight loss by reducing membrane lipid peroxidation via modulation of lipoxygenase enzyme activity, thereby enhancing cell wall stability [ 26 ]. Additionally, GABA treatment could decrease weight loss by reducing membrane damage, preserving cell membrane integrity, and suppressing malondialdehyde (MDA) production[ 8 ]. 3.3 Firmness Firmness serves as a critical determinant of edible quality, consumer acceptability, and commercial value in apples. As illustrated in Fig. 5 , both treatment type and storage duration exerted significant effects (p ≤ 0.05) on fruit firmness. All treatments exhibited progressive firmness loss during storage, with the most pronounced decline observed in control fruit. After 180 days, the combined 1-MCP + GABA treatment maintained the highest firmness (6.69 kg/cm²), significantly surpassing individual GABA (6.03 kg/cm²), 1-MCP (5.83 kg/cm²), and control (5.01 kg/cm²) groups (P < 0.05). 3.4 Titratable acid Titratable acidity (TA) constitutes a critical determinant of apple flavor quality, with both treatment and storage duration significantly influencing its retention (p ≤ 0.05; Fig. 6 ). All treatments exhibited a gradual decline in organic acid content throughout storage, indicative of their catabolism serving as respiratory substrates within senescence-associated metabolic pathways[ 27 , 28 ]. This reduction in titratable acidity (TA) is primarily driven by the characteristic increase in respiration rate during storage. Under these conditions, organic acids are metabolized via the TCA cycle to generate cellular energy, leading to the observed decrease in TA[ 29 ]. Notably, the combined 1-MCP + GABA treatment proved significantly more effective in mitigating acid degradation than either treatment applied individually. After 180 days of storage, the TA level maintained by the combinatorial treatment was 0.19%, which was higher than that preserved by 1-MCP alone (0.16%) or GABA alone (0.17%). This superior efficacy suggests a synergistic interaction between 1-MCP and GABA, collectively preserving organic acid reserves more effectively. 3.5 Glucose, fructose, sorbitol and sucrose As shown in Fig. 7 , sucrose and sorbitol exhibited a consistent decline throughout the storage period in all treatment groups. In the control group, sucrose content decreased sharply during the first 60 days of storage, primarily due to the activity of invertase enzymes, which hydrolyze sucrose into glucose and fructose. Similarly, sorbitol content declined steadily, as it was metabolized into fructose via the sorbitol dehydrogenase pathway. The 1-MCP treatment slowed the degradation of sucrose and sorbitol compared to the control, likely due to its inhibition of ethylene-mediated senescence, which reduced overall metabolic activity. GABA treated groups also showed a moderate effect in preserving sucrose and sorbitol, possibly by enhancing cellular stability and reducing stress-induced metabolic shifts. However, the combined treatment of 1-MCP and GABA demonstrated the most effective preservation of sucrose and sorbitol, suggesting a synergistic effect in maintaining sugar metabolism stability. In contrast to sucrose and sorbitol, glucose and fructose levels increased progressively during storage in all treatment groups. This increase is attributed to the hydrolysis of sucrose and the metabolic conversion of sorbitol into fructose. In the control group, glucose and fructose accumulation was most pronounced, reflecting the high activity of invertase and sorbitol dehydrogenase. The 1-MCP treatment significantly slowed the accumulation of glucose and fructose, as ethylene inhibition reduced the overall metabolic rate and delayed sucrose hydrolysis. GABA treatment also moderated the increase in glucose and fructose, likely by stabilizing cellular membranes and reducing stress-induced enzymatic activity. The combined treatment of 1-MCP and GABA resulted in the slowest accumulation of glucose and fructose, further supporting the synergistic effect of these treatments in regulating sugar metabolism. 3.6 Total phenolic content and total flavonoids content The changes in total phenolics and total flavonoids during storage were significantly influenced by both storage duration and postharvest treatments (Fig. 8 ). The total phenolic content increased progressively throughout the storage period in all treatment groups. The control group exhibited the highest rate of phenolic accumulation, likely due to the greater oxidative stress experienced by untreated fruit. The 1-MCP and GABA treatments showed a slower but steady increase in total phenolics. The combined treatment of 1-MCP and GABA resulted in the lowest rate of phenolic accumulation. In contrast to TPC, the total flavonoid content exhibited a dynamic trend during storage, characterized by an initial decline followed by a subsequent increase. In the control group, the total flavonoid content decreased significantly during the first 60 days of storage. However, after 60 days, the flavonoid content began to increase. Similar trends were observed in the 1-MCP and GABA treatment groups, although the extent of the initial decline was less pronounced compared to the control. The combined treatment of 1-MCP and GABA maintained the highest stability in flavonoid content throughout storage, exhibiting the smallest initial decline and the most gradual increase during later stages. While water loss during storage may partially contribute to the observed increases in total phenolic content (TPC) and total flavonoid content (TFC) of apple fruit. Wang[ 8 ] demonstrated that GABA treatment promoted the accumulation of total phenolics and proline and enhanced antioxidant defense system of banana fruit during storage. Similarly, Ali[ 11 ] reported that the GABA application increased phenylalanine ammonia-lyase (PAL) activity, suppressed polyphenol oxidase (PPO) activity, and consequently elevated total phenol levels. Further supporting this, Ge[ 30 ] reported that GABA treatment enhanced the accumulation of total phenolics and flavonoids in blueberry fruit by regulating phenylpropanoid pathway. These results suggests that the combined treatment effectively mitigated oxidative stress and preserved flavonoid and phenolic compounds stability, likely through the synergistic effects of ethylene inhibition and enhanced antioxidant activity. 3.7Principal component analysis Principal component analysis (PCA) was performed to comparatively evaluate the effects of different treatments on the postharvest quality of apple fruits. This multivariate approach visually represents relationships between the treatments and measured quality indices. The PCA loading plot extracted two principal components (PC-1 and PC-2) accounting for 99% of total variance, revealing distinct clustering patterns among apples from different treatments. The correlation loadings plot (Fig. 9 ) showed samples and indices segregated into three distinct groups: Group 1 (Right Plane) clustered sucrose, sorbitol, firmness, titratable acidity (TA), and watercore incidence (WI); Group 2 grouped all samples centrally; Group 3 (Left Plane) clustered glucose, fructose, total phenolic content (TPC), and weight loss (WL). Group 1 exhibited high levels of its constituent indices during early storage, while Group 3 showed high levels in the final storage stage. Based on their positions and associations, sucrose, sorbitol, firmness, TA, and WI are characteristic of fresh apple fruit, whereas glucose, fructose, TPC, and WL are characteristic of apples after long-term storage. 4 Conclusion In the present study, the combined 1-MCP and GABA treatment remarkably improved the postharvest quality of apple fruits, exhibiting synergistic effects on most indexes, including watercore incidence, internal browning firmness, TA, sucrose, sorbitol, TPC and TFC, compared with the control. The efficacy of the combined treatment became increasingly pronounced with longer storage duration. These findings indicate that the 1-MCP and GABA composite treatment is highly beneficial for preserving the physicochemical quality and freshness of apples during storage. Further research is warranted to elucidate the underlying mechanisms and optimize treatment protocols for commercial implementation. Declarations Funding This work was supported by the National-Local Joint Engineering Laboratory for High-Efficiency Cultivation and Value-Added Processing of Characteristic Fruit Trees in South Xinjiang (FE201905), Bingtuan science and technology program（2023AB063）and Industrial technology innovation team support program (XJLGCYJSTX04-0224-14). Data Availability All data supporting the results of this study are available from the corresponding author (email: [email protected] ). References Yang M, Lin Q, Luo Z, Ban Z, Li X, Reiter RJ, et al. Ongoings in the apple watercore: First evidence from proteomic and metabolomic analysis. Food Chem. 2023;402:134226. Epub 2022/09/21. doi: 10.1016/j.foodchem.2022.134226. PubMed PMID: 36126580. Liu Z, Du M, Liu H, Zhang K, Xu X, Liu K, et al. Chitosan films incorporating litchi peel extract and titanium dioxide nanoparticles and their application as coatings on watercored apples. 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Cite Share Download PDF Status: Published Journal Publication published 19 Mar, 2026 Read the published version in Scientific Reports → Version 1 posted Editorial decision: Revision requested 22 Dec, 2025 Reviews received at journal 21 Dec, 2025 Reviewers agreed at journal 21 Dec, 2025 Reviewers agreed at journal 15 Dec, 2025 Reviews received at journal 20 Aug, 2025 Reviewers agreed at journal 12 Aug, 2025 Reviewers agreed at journal 12 Aug, 2025 Reviewers invited by journal 11 Aug, 2025 Editor assigned by journal 11 Aug, 2025 Editor invited by journal 11 Aug, 2025 Submission checks completed at journal 08 Aug, 2025 First submitted to journal 08 Aug, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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PU","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAt0lEQVRIiWNgGAWjYDAC5gMMDB8Y2EBMAyK1sCUwMM4gWQszD4RJpBaDY7zHpG3+8CU2sDdvk2CouUOMFr406RwetsQGnmNlEgzHnhGh5X6PmXSOBFCLRI6ZBGPDYWJs4TGTtjAAapF/Q4oWhgSQLTxEapE8xpds2XOAzbiNJ63YIuEYEVr4jvEevPHjzzHZfvbDG298qCFCi8IBcKQcg0RmAmENDAzyDWAtNcSoHQWjYBSMgpEKAPsBM6ZaLpjaAAAAAElFTkSuQmCC","orcid":"","institution":"Tarim University","correspondingAuthor":true,"prefix":"","firstName":"Yunfeng","middleName":"","lastName":"PU","suffix":""}],"badges":[],"createdAt":"2025-08-06 07:38:28","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7306968/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7306968/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41598-026-44765-1","type":"published","date":"2026-03-19T15:59:11+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":89375975,"identity":"ff661f1d-e198-47e0-95e3-726f8f65898c","added_by":"auto","created_at":"2025-08-19 11:03:57","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":231057,"visible":true,"origin":"","legend":"\u003cp\u003eEffects of different treatments on visual quality\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7306968/v1/41f6009912652df771a72d28.png"},{"id":89376935,"identity":"61a343ba-4fe1-4f46-a283-491c374ff613","added_by":"auto","created_at":"2025-08-19 11:19:57","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":141927,"visible":true,"origin":"","legend":"\u003cp\u003eChange in watercore incidence of apples during cold storage.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7306968/v1/2e7171b276c1fa281cf6652b.png"},{"id":89375457,"identity":"f6a468d7-c237-4899-8e14-fba4da97826c","added_by":"auto","created_at":"2025-08-19 10:55:57","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":139379,"visible":true,"origin":"","legend":"\u003cp\u003eChange in flesh browning of apples during cold storage.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-7306968/v1/915df7279c415c419950b70c.png"},{"id":89375460,"identity":"af76f85b-d5fd-40c1-a53f-90eb31512cd0","added_by":"auto","created_at":"2025-08-19 10:55:57","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":141185,"visible":true,"origin":"","legend":"\u003cp\u003eChange in weight loss of apples during cold storage.\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-7306968/v1/736017b980aa5684bf0409d4.png"},{"id":89375470,"identity":"9450c213-40fa-428d-a218-78583b5d169d","added_by":"auto","created_at":"2025-08-19 10:55:57","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":143100,"visible":true,"origin":"","legend":"\u003cp\u003eChange in firmness of apples during cold storage.\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-7306968/v1/492b007c0228e0371cc59c8f.png"},{"id":89376809,"identity":"c7f0bd8c-38cd-45f4-b607-5f23fd13aeda","added_by":"auto","created_at":"2025-08-19 11:11:57","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":150152,"visible":true,"origin":"","legend":"\u003cp\u003eChange in titratable acid of apples during cold storage.\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-7306968/v1/67ee0a5348824d7bc8f624b4.png"},{"id":89375981,"identity":"41792db1-9bb9-4eda-84cb-af7f7fb001c6","added_by":"auto","created_at":"2025-08-19 11:03:57","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":203343,"visible":true,"origin":"","legend":"\u003cp\u003eChange in sugars of apples during cold storage.\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-7306968/v1/5c4712f562e7e865028dbb54.png"},{"id":89376937,"identity":"9ac9e600-e3b1-4ca6-874e-c54abe173cad","added_by":"auto","created_at":"2025-08-19 11:19:57","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":108081,"visible":true,"origin":"","legend":"\u003cp\u003eChange in TFC and TPC of apples during cold storage.\u003c/p\u003e","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-7306968/v1/9958397e96bde516924cbc68.png"},{"id":89376808,"identity":"6ff989fd-a1ed-4b72-b8da-e21235e76e06","added_by":"auto","created_at":"2025-08-19 11:11:57","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":580763,"visible":true,"origin":"","legend":"\u003cp\u003eCorrelation loadings plots of principal component analysis (PCA).\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-7306968/v1/ad20e320439d4a99dd986654.png"},{"id":105224170,"identity":"a6b3461a-438d-4bf8-8d38-4c75857b1f53","added_by":"auto","created_at":"2026-03-23 16:12:58","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2204744,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7306968/v1/18201be3-663c-4c78-adb3-fddcd0944336.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Impact of GABA and 1-MCP on qualitative attributes of apples (Malus domestica Borkh. cv. Fuji) during cold storage","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eThe environmental and climatic conditions in Xinjiang are favorable for apple growth,\u0026nbsp;creating a unique quality of watercore apples, which has become a symbol product, and selected as the recommended fruit for the Beijing Olympic Games in 2008[1].\u0026nbsp;Although watercore is a physiological disorder of apple characterized by glassy or translucent tissue in the flesh[2], and visible only when the fruit is cut in half[3], watercore apples are safe and edible[4]. In some countries, watercore appearance is a desirable trait for apples, as an indicator of full ripeness\u0026nbsp;[5, 6]. However, watercore tissues tend to disappear during storage, leading to a significant loss of unique identity and market value[6]. Additionally, long-term storage often results in flesh browning[4]. Hence, these challenges highlight the need for effective postharvest treatments to maintain post-harvest quality in watercore apples.\u003c/p\u003e\n\u003cp\u003e\u0026gamma;-Aminobutyric acid (GABA),\u0026nbsp;a non-proteinogenic amino acid, can be rapidly accumulated in response to\u0026nbsp;biotic and abiotic stresses and involves in signaling or regulatory mechanisms, nitrogen and carbon metabolism, and amino acid biosynthesis[7, 8]. Previous reports have shown that GABA postharvest treatments delay the senescence of horticultural commodities and increase fruit chilling tolerance, with additional effects on fruit quality preservation after storage at low temperatures[9-11]. Additionally,\u0026nbsp;Aydin Shekari[12]\u0026nbsp;found that\u0026nbsp;GABA treatment could be employed for retarding cap browning and maintaining the sensory and nutritional quality of button mushrooms during cold storage. On the other hand, 1-MCP, a synthetic compound that works by competitively binding to ethylene receptors and inhibits ethylene action, has been widely used to delay ripening and senescence in climacteric fruits such as apples[13-15]. Although both GABA and 1-MCP are effective individually in preserving fruit quality, their combined effect has not been investigated, specifically in watercore apples.\u003c/p\u003e\n\u003cp\u003eIt was speculated that the combined GABA and 1-MCP treatment could improve the ability of fruit to resist external environmental stress and prolong the storage period. This study aims to evaluate the efficacy of GABA and 1-MCP, individually and in combination, in postharvest quality of apples during long-term storage. The findings of this study could provide a new perspective for extending the shelf life of watercore apples.\u003c/p\u003e"},{"header":"2. Materials and methods","content":"\u003cdiv id=\"Sec2\" class=\"Section2\"\u003e\u003ch2\u003e2.1. Plant materials and treatment\u003c/h2\u003e\u003cp\u003eApple fruits \u003cem\u003e(Malus domestica Borkh. cv. Fuji\u003c/em\u003e) at commercial maturity were hand harvested from an orchard in Wensu, Xinjiang, and transported to the laboratory at the same day with cartons. The fruit with good texture, uniform size and maturity, free of physical injuries and pest were randomly divided into four groups. The first group(G) was immersed in 1.0 mmol/L GABA solutions for 20 min, and the second group(M) was exposed to 1 \u0026micro;L L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e 1-MCP at room temperature for 24 h, and the third group(G\u0026thinsp;+\u0026thinsp;M) was treated same as the first group, after desiccating at room temperature, and then treated same as the second group, and the fourth group (CK) was untreated and served as a control. The four groups were then packed in corrugated boxes (30 fruits each), and stored at 0\u0026thinsp;\u0026plusmn;\u0026thinsp;1 ◦C. The samples were analyzed periodically and randomly collected at 30 d intervals to evaluate the postharvest quality.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.2Watercore incidence and internal browning\u003c/h2\u003e\u003cp\u003eAfter determining fruit weight, fruit were cut at the equatorial region and visually scored for watercore incidence according to the method described by Li[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Internal browning was calculated according the method described by Wood[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e2.3 Weight loss, firmness, and titratable acidity\u003c/h2\u003e\u003cp\u003eFruit weight loss was measured by the difference of final weight from initial weight and expressed as percentage weight loss. The firmness was evaluated following the method reported by Yuan[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]on a Texture Analyzer (GY-4; Zhejiang Top Instrument Co., Ltd., China) equipped with a 3.5 mm diameter cylindrical probe. Five apples were measured for each treatment, and the results were expressed as kg/cm\u003csup\u003e2\u003c/sup\u003e. Titratable acidity (TA) was measured according to the method described by Pu[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], and the TA results were expressed in terms of % malic acid.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003e2.4 Glucose, sorbitol, fructose and sucrose\u003c/h2\u003e\u003cp\u003eThe contents of individual sugars were determined using a LC-20A HPLC with a RID-10A detector (Shimadzu, Japan), as per the method described by Pu[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], and the results were expressed as g/kg FW.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003e2.5 Total phenolics and total flavonoids\u003c/h2\u003e\u003cp\u003eTotal phenolics content was measured according to the Folin-Ciocalteu colorimetric method[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], and the results were expressed as gallic acid equivalents per gram of fruit (g GAE/kg FW). The total flavonoid content (TFC) was evaluated as per the process described by Pu[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], and the results were expressed as milligrams of rutin equivalent per gram of fruit (g RE/kg FW).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003e2.6 Statistical Analysis\u003c/h2\u003e\u003cp\u003eAll the experiments were performed in triplicate independently, and three samples were analyzed for each group. The data was subjected to one-way analysis of variance using the SPSS statistical software (Version 20.0; SPSS, Chicago, IL, USA), and the significant differences were compared by the Duncan\u0026rsquo;s test (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Furthermore, principal composition analysis (PCA) was performed using Unscrambler 10.1 (CAMO AS, Trondheim, Norway) software.\u003c/p\u003e\u003c/div\u003e"},{"header":"3. Results and discussion","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\u003ch2\u003e3.1 Watercore incidence (WI) and Internal browning\u003c/h2\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eAs shown in Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, the WI exhibited a progressive decline throughout the refrigerated storage period. During the incipient storage phase, all samples exhibited pronounced watercore distribution(WI\u0026gt;90%), with affected regions predominantly localized in vascular bundles (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). However, as storage duration increased, the watercore gradually decreases and eventually disappears. Similar behavior was observed by Li[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e] and Saquet[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. At 60-day storage, the G, M and G\u0026thinsp;+\u0026thinsp;M groups demonstrated significantly elevated watercore incidence compared to the CK group (P\u0026lt;0.05), with distinct spatial distribution patterns observable through image quantification(Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Notably, after 90-day storage, CK and M groups exhibited accelerated watercore remission (WI\u0026thinsp;\u0026lt;\u0026thinsp;20%), whereas GABA-treated groups maintained elevated WI values exceeding 50% (G: 56.67%; G\u0026thinsp;+\u0026thinsp;M:63.33%), preserving the characteristic translucent parenchyma. Intriguingly, the watercore completely disappears in CK and M groups by 120-day storage, while GABA-treated groups retained diagnostically significant watercore manifestations (G: 6.67%; G\u0026thinsp;+\u0026thinsp;M:13.33%) until 150-day storage.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe IB of apples during cold storage was significantly affected by postharvest treatments (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05, Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Control (CK) group manifested initial flesh browning (IB\u0026thinsp;=\u0026thinsp;3.33%) at 90 days postharvest, progressing to severe discoloration (IB\u0026thinsp;=\u0026thinsp;73.33%) by storage terminus. 1-MCP-treated (M) group exhibited delayed onset, with first browning symptoms (IB\u0026thinsp;=\u0026thinsp;3.33%) emerging at 120 days, contrasting with complete absence in GABA-treated groups (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Additionally, the GABA treated groups did not exhibit fruit flesh browning throughout the entire storage period. Li[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e] demonstrated that GABA application enhances the mitochondrial antioxidant system and reduces peel browning in pears following removal from cold storage. Similarly, Shekari[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] reported that GABA-treated mushrooms exhibited elevated activity and gene expression of phenylalanine ammonia-lyase (PAL) alongside reduced polyphenol oxidase (PPO) activity, collectively resulting in retarded cap browning. Consistent with these findings, other studies have shown that exogenous GABA treatment effectively protects membrane integrity in various fruits, as reflected by reduced electrolyte leakage and malondialdehyde (MDA) content, thereby delaying flesh browning during cold storage[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. In contrast, Jung[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e] observed that late-harvested fruit treated with 1-methylcyclopropene (1-MCP) were more susceptible to flesh browning during prolonged storage, primarily due to a compromised antioxidant defense mechanism under stress, along with elevated polyphenol oxidase (PPO) activity and electrolyte leakage rates. Collectively, these results demonstrate that GABA treatments not only delay watercore dissipation but also effectively inhibit flesh browning.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\u003ch2\u003e3.2 Weight loss\u003c/h2\u003e\u003cp\u003eThe weight loss of apples progressively increased during 180-day cold storage across all treatments. The highest weight loss (9.56%) was observed in control fruit. In this study, 1-MCP and GABA treatments alone or in combination significantly (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05) reduced weight loss of apple fruit compared to control treatment and the lowest weight loss (7.57%) was found in fruit treated with 1-MCP\u0026thinsp;+\u0026thinsp;GABA (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). The increase in weight loss during storage is likely attributable to water loss resulting from respiration, transpiration and metabolic activity[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Regarding the inhibitory effect of 1-MCP, its reduction of postharvest water loss in tomato has been linked to its regulation of epidermal cuticle composition and morphology[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Specifically for apples, 1-MCP treatment may influence quality during cold storage by delaying increases in cuticular wax density and inhibiting wax crystal melting, potentially through reducing the expression of MdCER6[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. GABA, on the other hand, might mitigate weight loss by reducing membrane lipid peroxidation via modulation of lipoxygenase enzyme activity, thereby enhancing cell wall stability [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Additionally, GABA treatment could decrease weight loss by reducing membrane damage, preserving cell membrane integrity, and suppressing malondialdehyde (MDA) production[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003e3.3 Firmness\u003c/h2\u003e\u003cp\u003eFirmness serves as a critical determinant of edible quality, consumer acceptability, and commercial value in apples. As illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e, both treatment type and storage duration exerted significant effects (p\u0026thinsp;\u0026le;\u0026thinsp;0.05) on fruit firmness. All treatments exhibited progressive firmness loss during storage, with the most pronounced decline observed in control fruit. After 180 days, the combined 1-MCP\u0026thinsp;+\u0026thinsp;GABA treatment maintained the highest firmness (6.69 kg/cm\u0026sup2;), significantly surpassing individual GABA (6.03 kg/cm\u0026sup2;), 1-MCP (5.83 kg/cm\u0026sup2;), and control (5.01 kg/cm\u0026sup2;) groups (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003e3.4 Titratable acid\u003c/h2\u003e\u003cp\u003eTitratable acidity (TA) constitutes a critical determinant of apple flavor quality, with both treatment and storage duration significantly influencing its retention (p\u0026thinsp;\u0026le;\u0026thinsp;0.05; Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). All treatments exhibited a gradual decline in organic acid content throughout storage, indicative of their catabolism serving as respiratory substrates within senescence-associated metabolic pathways[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. This reduction in titratable acidity (TA) is primarily driven by the characteristic increase in respiration rate during storage. Under these conditions, organic acids are metabolized via the TCA cycle to generate cellular energy, leading to the observed decrease in TA[\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Notably, the combined 1-MCP\u0026thinsp;+\u0026thinsp;GABA treatment proved significantly more effective in mitigating acid degradation than either treatment applied individually. After 180 days of storage, the TA level maintained by the combinatorial treatment was 0.19%, which was higher than that preserved by 1-MCP alone (0.16%) or GABA alone (0.17%). This superior efficacy suggests a synergistic interaction between 1-MCP and GABA, collectively preserving organic acid reserves more effectively.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003e3.5 Glucose, fructose, sorbitol and sucrose\u003c/h2\u003e\u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e, sucrose and sorbitol exhibited a consistent decline throughout the storage period in all treatment groups. In the control group, sucrose content decreased sharply during the first 60 days of storage, primarily due to the activity of invertase enzymes, which hydrolyze sucrose into glucose and fructose. Similarly, sorbitol content declined steadily, as it was metabolized into fructose via the sorbitol dehydrogenase pathway. The 1-MCP treatment slowed the degradation of sucrose and sorbitol compared to the control, likely due to its inhibition of ethylene-mediated senescence, which reduced overall metabolic activity. GABA treated groups also showed a moderate effect in preserving sucrose and sorbitol, possibly by enhancing cellular stability and reducing stress-induced metabolic shifts. However, the combined treatment of 1-MCP and GABA demonstrated the most effective preservation of sucrose and sorbitol, suggesting a synergistic effect in maintaining sugar metabolism stability.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eIn contrast to sucrose and sorbitol, glucose and fructose levels increased progressively during storage in all treatment groups. This increase is attributed to the hydrolysis of sucrose and the metabolic conversion of sorbitol into fructose. In the control group, glucose and fructose accumulation was most pronounced, reflecting the high activity of invertase and sorbitol dehydrogenase. The 1-MCP treatment significantly slowed the accumulation of glucose and fructose, as ethylene inhibition reduced the overall metabolic rate and delayed sucrose hydrolysis. GABA treatment also moderated the increase in glucose and fructose, likely by stabilizing cellular membranes and reducing stress-induced enzymatic activity. The combined treatment of 1-MCP and GABA resulted in the slowest accumulation of glucose and fructose, further supporting the synergistic effect of these treatments in regulating sugar metabolism.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\u003ch2\u003e3.6 Total phenolic content and total flavonoids content\u003c/h2\u003e\u003cp\u003eThe changes in total phenolics and total flavonoids during storage were significantly influenced by both storage duration and postharvest treatments (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e). The total phenolic content increased progressively throughout the storage period in all treatment groups. The control group exhibited the highest rate of phenolic accumulation, likely due to the greater oxidative stress experienced by untreated fruit. The 1-MCP and GABA treatments showed a slower but steady increase in total phenolics. The combined treatment of 1-MCP and GABA resulted in the lowest rate of phenolic accumulation. In contrast to TPC, the total flavonoid content exhibited a dynamic trend during storage, characterized by an initial decline followed by a subsequent increase. In the control group, the total flavonoid content decreased significantly during the first 60 days of storage. However, after 60 days, the flavonoid content began to increase. Similar trends were observed in the 1-MCP and GABA treatment groups, although the extent of the initial decline was less pronounced compared to the control. The combined treatment of 1-MCP and GABA maintained the highest stability in flavonoid content throughout storage, exhibiting the smallest initial decline and the most gradual increase during later stages. While water loss during storage may partially contribute to the observed increases in total phenolic content (TPC) and total flavonoid content (TFC) of apple fruit. Wang[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] demonstrated that GABA treatment promoted the accumulation of total phenolics and proline and enhanced antioxidant defense system of banana fruit during storage. Similarly, Ali[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] reported that the GABA application increased phenylalanine ammonia-lyase (PAL) activity, suppressed polyphenol oxidase (PPO) activity, and consequently elevated total phenol levels. Further supporting this, Ge[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e] reported that GABA treatment enhanced the accumulation of total phenolics and flavonoids in blueberry fruit by regulating phenylpropanoid pathway. These results suggests that the combined treatment effectively mitigated oxidative stress and preserved flavonoid and phenolic compounds stability, likely through the synergistic effects of ethylene inhibition and enhanced antioxidant activity.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e\u003ch2\u003e3.7Principal component analysis\u003c/h2\u003e\u003cp\u003ePrincipal component analysis (PCA) was performed to comparatively evaluate the effects of different treatments on the postharvest quality of apple fruits. This multivariate approach visually represents relationships between the treatments and measured quality indices. The PCA loading plot extracted two principal components (PC-1 and PC-2) accounting for 99% of total variance, revealing distinct clustering patterns among apples from different treatments. The correlation loadings plot (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e) showed samples and indices segregated into three distinct groups: Group 1 (Right Plane) clustered sucrose, sorbitol, firmness, titratable acidity (TA), and watercore incidence (WI); Group 2 grouped all samples centrally; Group 3 (Left Plane) clustered glucose, fructose, total phenolic content (TPC), and weight loss (WL). Group 1 exhibited high levels of its constituent indices during early storage, while Group 3 showed high levels in the final storage stage. Based on their positions and associations, sucrose, sorbitol, firmness, TA, and WI are characteristic of fresh apple fruit, whereas glucose, fructose, TPC, and WL are characteristic of apples after long-term storage.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"4 Conclusion","content":"\u003cp\u003eIn the present study, the combined 1-MCP and GABA treatment remarkably improved the postharvest quality of apple fruits, exhibiting synergistic effects on most indexes, including watercore incidence, internal browning firmness, TA, sucrose, sorbitol, TPC and TFC, compared with the control. The efficacy of the combined treatment became increasingly pronounced with longer storage duration. These findings indicate that the 1-MCP and GABA composite treatment is highly beneficial for preserving the physicochemical quality and freshness of apples during storage. Further research is warranted to elucidate the underlying mechanisms and optimize treatment protocols for commercial implementation.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by\u0026nbsp;the National-Local Joint Engineering Laboratory for High-Efficiency Cultivation and Value-Added Processing of Characteristic Fruit Trees in South Xinjiang (FE201905), Bingtuan science and technology program（2023AB063）and Industrial technology innovation team support program (XJLGCYJSTX04-0224-14).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data supporting the results of this study are available from the corresponding author (email: [email protected]).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eYang M, Lin Q, Luo Z, Ban Z, Li X, Reiter RJ, et al. 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Food Packaging and Shelf Life. 2018;16:168-77. doi: 10.1016/j.fpsl.2018.03.010.\u003c/li\u003e\n\u003cli\u003eGe Y, Duan B, Li C, Tang Q, Li X, Wei M, et al. \u0026gamma;-Aminobutyric acid delays senescence of blueberry fruit by regulation of reactive oxygen species metabolism and phenylpropanoid pathway. Scientia Horticulturae. 2018;240:303-9. doi: 10.1016/j.scienta.2018.06.044.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"γ-Aminobutyric acid, 1-MCP, Apple, Watercore, Flesh browning","lastPublishedDoi":"10.21203/rs.3.rs-7306968/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7306968/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study investigated the efficacy of γ-aminobutyric acid (GABA) and 1-methylcyclopropene (1-MCP), individually and in combination, in mitigating sugar core disappearance, flesh browning, and postharvest quality in apples during 180 days storage. The results showed that the combined GABA\u0026thinsp;+\u0026thinsp;1-MCP treatment outperformed individual applications, significantly delaying sugar core disappearance by preserving sucrose and sorbitol while moderating glucose and fructose accumulation. Furthermore, the combined treatment significantly reduced flesh browning compared to the control, likely attributed to suppressed polyphenol oxidase activity and enhanced antioxidant capacity. This approach also minimized weight loss and maintained firmness and titratable acidity. Although total phenolics and total flavonoids increased progressively during storage, their levels were effectively regulated by the GABA\u0026thinsp;+\u0026thinsp;1-MCP treatment. These results indicate that the combined exogenous application of GABA and 1-MCP is a potentially effective method to improve postharvest quality, and enhance storage efficiency of apple fruit.\u003c/p\u003e","manuscriptTitle":"Impact of GABA and 1-MCP on qualitative attributes of apples (Malus domestica Borkh. cv. Fuji) during cold storage","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-19 10:55:52","doi":"10.21203/rs.3.rs-7306968/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-12-23T04:31:15+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-21T13:01:48+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"109381533506825444427141372224183717178","date":"2025-12-21T09:54:52+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"297613688041954674172799643449133526521","date":"2025-12-16T04:58:25+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-08-20T12:31:10+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"38521787067296310801189427120677231804","date":"2025-08-12T06:52:46+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"6515750740671180679930152434393893223","date":"2025-08-12T06:31:19+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-08-11T20:48:53+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-08-11T20:46:13+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-08-11T17:44:44+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-08-08T07:35:18+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2025-08-08T07:32:12+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"180dff74-0a59-4104-9a0c-5c75f0866ef4","owner":[],"postedDate":"August 19th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":53081523,"name":"Biological sciences/Biochemistry"},{"id":53081524,"name":"Biological sciences/Biotechnology"},{"id":53081525,"name":"Physical sciences/Chemistry"},{"id":53081526,"name":"Biological sciences/Plant sciences"}],"tags":[],"updatedAt":"2026-03-23T16:07:45+00:00","versionOfRecord":{"articleIdentity":"rs-7306968","link":"https://doi.org/10.1038/s41598-026-44765-1","journal":{"identity":"scientific-reports","isVorOnly":false,"title":"Scientific Reports"},"publishedOn":"2026-03-19 15:59:11","publishedOnDateReadable":"March 19th, 2026"},"versionCreatedAt":"2025-08-19 10:55:52","video":"","vorDoi":"10.1038/s41598-026-44765-1","vorDoiUrl":"https://doi.org/10.1038/s41598-026-44765-1","workflowStages":[]},"version":"v1","identity":"rs-7306968","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7306968","identity":"rs-7306968","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}