Effect of Macrocystis pyrifera scalding on water reusing from the pre treatment cycles

Effect of Macrocystis pyrifera scalding on water reusing from the pre treatment cycles | 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 Research Article Effect of Macrocystis pyrifera scalding on water reusing from the pre treatment cycles Bernardo Sepúlveda, Patricia Echeverría, José María Larrazabal, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5664053/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 In the scalding pretreatment, food is immersed in water or steam at specific temperatures and times, inactivating enzymes, reducing microorganisms, and softening tissues. This requires a large volume of water and energy, and it can generate contaminated water, limiting its reuse. Macrocystis pyrifera is a brown macroalga distributed along the Chilean coast and can be used as human food. The content of As, Hg, Cd, and Pb (µm/100 g) in the process water was evaluated after each scalding cycle of M. pyrifera . During scalding, there was transfer of As from the macroalga to the process water, while the others elements were not significant. From the first to the third scalding cycle, transferred arsenic reached 1.206 mg/L. According to Chilean regulations, the maximum environmental concentration is 0.01 mg/L, limiting water reuse from the first scalding cycle. Scalding water with arsenic should not be used for other food production processes, nor should it be discharged into the environment, because the arsenic content transforms the process water into a liquid industrial waste. It is suggested to evaluate techniques to reduce the concentration of dissolved contaminants to enable reuse, within the framework of the circular economy, making blanching more sustainable. blanching water liquid food waste Atacama algae food contamination decontaminating pretreatment Figures Figure 1 Figure 2 Figure 3 Introduction Scalding is an effective pretreatment in the vegetable food industry. It involves submerging food in hot water or steam for short periods, followed by rapid cooling to reduce the microbiological load, inactivate enzymes, and improve the digestibility, texture, and flavor of the food (Kaure et al. 2021 ; Tigreros et al., 2021 ; Xiao et al., 2017 ; Zhang et al., 2021 ; Geng et al., 2022 ). Scalding can induce loss of quality in texture, soluble nutrients, pigment, and aroma in products (Deng et al., 2019 ; Xiao et al., 2017 ), related to the temperature and duration of application (Zhang et al., 2021 ). On the other hand, it is assessed that scalding has improved the quality, safety, and nutritional properties of processed foods, significantly enhancing biochemical and physical parameters. In processed beetroot, despite the decrease in bioactive compounds, the product was beneficial for consumption (Kaure et al., 2021 ). In Glycine max (soybeans), scalding (2.5 min at 100°C) reduced peroxidase activity by more than 98%, improved the intensity of the green color, and decreased the hardness of the grains; it also significantly reduced total yeasts, molds, and coliform bacteria (Xu et al., 2012 ; Karyadi et al., 2022 ). However, different reactions may occur in other vegetables, such as asparagus, where scalding with water inhibited enzymatic activity, leading to a rapid loss of nutrients and sensory values with scalding time (Nguyen et al., 2019 ). Two-stage scalding improved the firmness of vegetables such as beans, but negatively affected the colour (Seow & Lee, 1997 ); in green beans, shorter scalding times than conventional methods were achieved (Ruiz-Ojeda & Peñas, 2013 ). Inadequate application of scalding can negatively affect the sensory and nutritional characteristics of the plant material and its subsequent processing (e.g., drying) (Tigreros et al., 2021 ; Boateng, 2022 ). In the scalding of algae and other vegetables, mass transfer has been observed. Zhu et al. ( 2022 ) reported mass transfer from the edible alga Alaria esculenta to the scalding water, noting significant changes in color metrics and Na, Cu, Fe, and Mn content. For the alga Undaria pinnatifida , scalding with hot water resulted in a drastic decrease in most algae metabolites within just 20 seconds (with color changes in the algae), but it did not significantly affect amino acids or sugar composition (Hamid et al., 2020 ; Jiang et al., 2022 ). In the case of treated dates, the scalding process allowed the transfer of a large amount of organic acids, phenols, sugars, and flavonoids to the water during processing (Trigueros & Sendra, 2014 ). Magangana et al., ( 2021 ) determined that in Punica granatum peels, scalding at different temperatures and times influenced the concentration of phenols and tannins in the extract, demonstrating the mass transfer of these compounds to the scalding water. On the other hand, in the scalding of P. granatum arils, total soluble solids increased along with greater radical scavenging activity (Adetoro et al., 2020 ). In algae-based products marketed in Spain, significant concentrations of As, Cd, Hg, Pb, Zn, and Cu have been found (Besada et al., 2009 ) and Cu, Zn, and Cd were detected in the brown algae Ecklonia maxima , Macrocystis angustifolia , and Laminaria pallida (Stirk & van Staden, 2000 ). In the manufacture of food based on Amanita fulva , scalding has been reported to decrease the heavy metal content (Drewnowska et al., 2017 ). Additionally, in the case of Cantharellus cibarius and A. fulva , scalding caused the release of Hg regardless of the time and type of water used (drinking or deionised) (Falandysz & Drewnowska ,2017). In an analogous situation, a study on crabs and shrimp in Egypt found that heavy metals in samples exceeded the local concentration limit; however, scalding the foods reduced the concentration of chemical pollutants (Abd-Elghany et al., 2020 ). The mass transfer process is important because algae can be a good source of essential minerals in functional foods (Muñoz & Días, 2022). This background supports the idea that algae can release heavy metals and other components into the scalding water, with implications for the quality and safety of the final product. The above also highlights the importance of evaluating the effect of processing on the algae components, related to the mass transfer from the plant to the water during cooking. Proper scalding may be particularly important in reducing health risks related to arsenic. On the other hand, scalding water containing nutritional components and/or heavy metals could be classified as liquid industrial waste, since it is a terminal product and must be evacuated from the process. However, it could also become a raw material for water recycling through a purification process added to the scalding process (Litter et al., 2010 ; Rysulova et al., 2017 ; Macnamara & Derry, 2017 ; Ali et al., 2020 ). This work was carried out within the context of a project aimed at producing gourmet foods for human consumption from Macrocystis pyrifera , in which a scalding pretreatment was applied. The objective of this work was to determine the mass transfer of arsenic, cadmium, mercury, and lead detected in the natural algae to the scalding water, in order to establish guidelines for the management of the wastewater. Materials and methods Algae row material. This work was carried out between March 2016 and April 2017 as part of a gourmet food formulation project based on algae from the coast of Region III (Atacama). The processing plant was located in Caldera, Loreto sector (27º04'46"S, 70º50'22"W) (Fig. 1 ), and the project was executed under the Regional Research Center for Sustainable Development of Atacama (CRIDESAT), University of Atacama, Copiapó, Chile. The algal species were obtained from Bahía Chascos (27º39'S, 70º59'W), located about 60 km south of Caldera (Fig. 1 ). The collection of the algae was supervised by members of the project team. From fresh Macrocystis pyrifera , fronds and stipes in good physical condition and without perforations were selected. The chosen raw material was washed to eliminate sand and epiphytic organisms. The frond and stipe of the algae were then separated into containers, leaving them ready for moving on to the scalding process after the experimental production. Scalding of the raw material. To blanch the selected algae samples, a 100-litre gas kettle was used, filled with fresh water from the public network; the water was heated to a maximum of 70°C, for each cycle the water remains in the kettle and the fresh algae sample is renewed. During the scalding cycles, 4 to 5 L of water was used per kilogram of M. pyrifera sample, subjected to successive cycles of 5 minutes each as a pre-treatment. Subsequently, this material was used to generate human food prototypes that will be reported in subsequent articles. Between scalding cycles, a water sample was taken to perform element analysis at an external service. Chemical elements in the scalding water . In the pretreatment of algae by scalding, the heavy metal content of the process water was analyzed at the beginning and after each scalding cycle to evaluate the feasibility of reusing it in consecutive cycles. The analysis was conducted in an accredited laboratory by the National Institute of Standardization (INN) of Chile, under the Chilean standard NCH 17025 and by the American Association for Laboratory Accreditation (A2LA) under the ISO/IEC standard 17025 (2005). For the water of each scalding cycle, the concentrations of Cd (NCh 2638 Of. 01, mg/L), Hg (NCh 2667 Of. 01, mg/L), Pb (NCh 2751 Of. 03, mg/L) and As (NCh 3140 Of. 08, mg/L) were determined. For the comparative analysis, the maximum environmental limits for drinking water were as follows: 0.01 mg/L for As; 0.05 mg/L for Pb; 0.01 mg/L for Cd; and 0.001 mg/L for Hg (Health Canada, 2020 ; NORMA CHILENA, 2024 ; Sepúlveda,, 2023). Data analysis and calculations. Changes in the concentration of chemical components in the water of each scalding cycle were evaluated; with cycle zero serving as the control. The comparisons were based on the Student's T-test for paired samples with 95% confidence and α = 0.05. The "p" index indicates the statistical significance (1 > p > 0). Mass transfer was calculated in significant cases in successive scalding cycles. Results Table 1 shows the concentration of arsenic, cadmium, mercury and lead in the scalding process water. Lead was found to be below the NCh-409-1 standard norm, while mercury was 33% higher (0.002 mg/L above the NCh-409 limit); however, it was at the detection limit and did not incremented in subsequent scalding cycles. Cadmium was 50% lower than the environmental limit, so it would not be considered a threat. Conversely, the concentration of arsenic in the scalding water increased from the first cycle, reaching 1,206 times higher than the environmental reference by the third cycle, or 99.92%. Thus, arsenic is the element with the greatest impact on the water after the scalding of the algae samples. Table 1 Concentration of As, Cd, Hg and Pb in the scalding process water. Scalding cycles in water Chemical components (mg/L) As Cd Hg Pb 0 0.003 0.005 0.001 0.010 1 0.278 0.005 0.003 0.010 2 0.781 0.005 0.003 0.010 3 1.206 0.005 0.003 0.010 EM Limit 0.01 0.01 0.001 0.05 0: control water, As: Arsenic, Cd: Cadmium, Hg: Mercury, Pb: Lead. EM Limit: Environmental Maximum Limit. Figure 2 shows the net arsenic contribution in the process water by scalding cycle. The total accumulated concentration of arsenic reaches 1.206 mg/L, with the accumulation following a linear model (R² = 0.99). However, the net contribution (difference in concentration) per scalding cycle reaches 23% of the maximum concentration in the first scalding cycle, 64% in the second scalding cycle, and 100% of the concentration in the third one. This situation reflects a change in the net mass transfer rate. Figure 3 shows the mass transfer rate (MTR) of arsenic (mg/L min) from the M. pyrifera sample to the process water per scalding cycle. In the first scalding cycle, the MTR (mg/L min) was 0.275 ± 0.006 (cycle 1, 100%), decreasing at 0.252 ± 0.001 (cycle 2. 91.6%), and to 0.142 ± 0.011 (cycle 3, 51.6%.). This decrease in the MTR fits a polynomial model with R 2 = 98% and p = 0.006. This result suggests a reduced capacity of the water to extract As from the algae in each scalding cycle. Extrapolating the MTR (see trend line, Fig. 2 ) it can be seen that the mass transfer tends to zero after approximately 3,75 scalding cycles; each cycle represents 5 minutes. This indicates that water would no longer have the capacity to extract arsenic in a subsequent scalding cycle, probably, because the water is saturated. The above information implies that scalding water could be used up to the third cycle. However, but, comparing the concentration of arsenic in the process water with the environmental limit, according to the Chilean standard (drinking water 0.01 mg/L), the result shows that scalding water could only be used once at most. This information suggests that the water from the algae scalding process should be considered as a liquid industrial waste (RIL, in spanish). Discussion The Copiapó River, from the valley of the same name, originates in the Andes Mountains; its tributaries rise in areas with high mineral content, often associated with arsenides, which can be released by natural effects or accelerated by anthropogenic actions. Initially, these minerals may be poorly soluble, but they transform into easily soluble species such as arsenic (III) (e.g. As(OH) 3 ) (Bieger et al., 2022 ). In Copiapó, various sources of elements have been identified, and it is estimated that mining processes contribute 88% of Cu and 49% of As to street dust (Moya, 2017 ). Additionally, in dust samples obtained in 2015 (the year of the last and largest flood that occurred in the valley) from localities in the Atacama region: Chañaral, El Salado, Diego de Almagro, Copiapó, Tierra Amarilla, and Paipote, the presence of As, Cd, Zn, Cr, Cu, Pb, and Mn was reported both in the total fraction and in the water-soluble fraction (Cortés & Tchernitchin, 2018 ). In general, As is prevalent in 200 areas of Latin America, where it is naturally released into the environment and mobilized from geogenic sources such as: 1) volcanic rocks and emissions, the latter being transported thousands of kilometres from the source; 2) metallic mineral deposits transferred to people through drinking water and the food chain; 3) deep geothermal reserves that contaminate fresh water sources. The challenge for mitigation is increasing due to mining and related activities, with As being transported by rivers over long distances, often contaminating coastal environments (Bundschuh et al., 2021 ). Algae are bio accumulator plants that can act as concentration centers for toxic elements; to use macroalgae as food, thermal treatment is usually applied by scalding in hot water (Cascais et al., 2021 ); this is considered a mature conventional method, widely applied in food processes. However, it must be considered that scalding produces highly contaminated wastewater due to the properties and characteristics of the fruits and vegetables; therefore, it cannot be applied in the same way to all products (Xiao et al., 2017 ). Despite this thermal scalding is an essential operation in the processing of many fruits and vegetables, as it affect the quality of the products attributes. some studies have shown that in raw material of algae, the concentration of arsenic was higher and this element varied when the algae was thermally processed and when different thermal treatments were applied (Cascais et al., 2021 ). For example, in the alga Alaria esculenta , the scalding treatment significantly affected the content of Na, Cu, Fe and Mn (Zhu et al., 2022 ). Regarding the importance of heavy metals in food processes and their leaching, the content of heavy metals depends on the plant tolerance and the associated detoxification mechanisms. Lam and Lai ( 2018 ) evaluated the effect of scalding and simulated digestion on the heavy metal bio accessibility; finding that spinach species had a high accumulation capacity. From raw spinach tissues, 45 to 84% of Cd, Cr, and Ni leached after scalding (Lam & Lai, 2018 ). Although the heavy metals are necessary for physiological processes (in small quantities), it tend to accumulate in the body of living beings faster than they can be metabolized; in general As, Cd, Cr, Hg and Pb are among the most common elements in water; therefore the food chain is a very important factor in proper human nutrition. Then, depending on the bioavailability, the heavy metals enter through the diet, for example by ingesting marine foods; then, the phenomenon of bioaccumulation must be considered (Johnson et al., 2010 , Kumar et al., 2021; Octavio-Aguilar et al., 2021; Khosravi-Darani et al., 2022 ). Arsenic is toxic in animals (Johnson et al. 2010 ), and it has become a major concern in recent decades. Chronic exposure to As occurs either through drinking water or via by contaminated food chain. The introduction of arsenic into the chain happens due to its excessive absorption from the soil by plants, often as a result of irrigation with contaminated water. The main source of human exposure to As is the consumption of accumulating crops and vegetables (Punshon et al., 2017 ; Kumar et al., 2021). One problem is that As concentration varies in foods, making it impractical to establish a regulatory limit for each food (Johnson et al., 2010 ). In general, Miranda et al. (2011) state (sic) “At the global, national and local level, we find that environmental contamination by heavy metals and metalloids has increased, in such a way that it severely compromises health, population food security and the environment”. Regarding the effects of arsenic on human health, the most characteristic result of prolonged oral exposure to inorganic arsenic is hyperpigmentation and keratosis; this includes darkening of the skin and the appearance of calluses or warts on parts of the body, often associated with alterations in the blood vessels of the skin. Major symptoms include effects on the skin and circulatory and peripheral nerve disorders. With chronic exposure to arsenic, there are reports of increased mortality from lung, kidney, liver, bladder, and skin cancer. Additionally, the effect of arsenic on pregnancy has been documented (Cortés & Tchernitchin, 2018 ). Considering that macroalgae contain various water-soluble compounds and that scalding is done at high temperature, mass transfer from the algae to the water is expected. The mass transferred to the water must be quantified to determine the possibility of reusing it and to know the number of allowed scalding cycles, in order to guarantee the safety and quality of the food. Scalding has proven to be effective as pretreatment for food transformation into products, ensuring safety and preserving bioactive compounds (Tigreros et al., 2021 ). In this work, in the water of the third scalding cycle, arsenic increased after each scalding cycle. Extrapolating the mass transfer rate, it tended to zero after the third scalding. This is related to a lower capacity of the water to extract arsenic from the algae after each cycle, due to a saturation level with the transferred element. According to the Chilean standard for drinking water, the maximum permitted content of As is 0.01 mg/L, which shows that the process water could only be used in the first scalding cycle, making the possibility of reusing water inadvisable, at least in this type of process. None of the other elements showed important changes in the process water. From the point of view of the increase in arsenic content in the process water, the facts imply a decreasing in arsenic in the macroalgae raw material, representing an additional advantage of the scalding. Characterizing the impact of hydrothermal processing on the concentration of I, Na, K, Se and As in four macroalgae, Correia et al., ( 2021 ) describe that processing of macroalgae revealed a relationship between the species and the leaching pattern for I, total As and Se. The difference may be due to the subcellular localization of the elements, the way each element is complexed, the retention processes and the speciation of the different elements. These authors demonstrated that algae processing could be an excellent strategy to ensure the delivery of essential and balanced micro and macro elements for the health of consumers. Algae can contain high concentrations of heavy metals, so it is important to consider the role that process plays on the concentration of component in algae-based food products. Information like this must considered when designing product processing, to increase the retention of nutritional components and limit metallic contaminants. Advances like these could position algae-based products and further promote their dietary consumption (Ho & Redan, 202l). However, scalding can affect the quality of the products; furthermore, this process involves high water consumption and generation of effluents with a high content of organic and inorganic matter, which can impact the environment. It is important to understand the amount of used water in scalding and the factors that determine it. It is noted that for fruits and vegetables, around 1 to 2 L of water per kilo of material is usually used, for fruits such as peaches, 4 to 5 L of water per kilo may be required. In general, the proportion of water can vary with the material to be scalded and culinary preferences; there does not appear to be a defined standard (USDA, 2015 ; Boateng, 2022 ). Hamid et al. ( 2020 ) reported using 2 L of water to scald at least 6 g samples of Undaria pinnatifida (Zhu et al., 2022 ), scalded in a proportion of 200 g of algae in 800 mL of distilled water and Alaria esculenta (200 g) with 1000 mL of distilled water. According to Chilean reference institutions, a Liquid Industrial Waste (LIW, RIL in Spanish) is generally wastewater generated in industrial processes, activities, or services, which can contain a variety of contaminants such as organic compounds, heavy metals, oils, among others. From a technical point of view, the quality of RIL is determined by the discharge containing contaminants at concentrations above the environmental reference established by current legislation. Therefore, the quality of RIL requires appropriate management to avoid environmental contamination and protect public health. The arsenic content in RIL varies depending on the process; however, its high toxicity often results in sublethal effects that are not studied in a community as Copiapó, until they become lethal (ECOPRENEUR, 2024 ; CCHC, 2024; Hernández et al., 2023 ; Romero, 2024 ). This apparent lack of information on the volume of water would indicate that this is not a primary focus of the study of scalding; despite the fact that wastewater can be classified as liquid industrial waste (Anastacio & Gambini, 2019 ). Arsenic is widely distributed in the universe and its toxicity depends on its chemical forms and oxidation states (-3, 0, + 3 and + 5). The tolerable daily intake of total As is mentioned as 50 µg/kg of weight (Suarez et al., 2004). Therefore, it is convenient to consider the management of this liquid waste in food production costs; to optimize, recover and recycle scalding water, and to reduce the cost of water in the process. In general, today more than ever, there is an urgent need to take care of the water resource, especially in arid areas, to make processes more efficient and generate safe food in a sustainable way, considering health quality and compliance with current regulations (NORMA CHILENA, 2024 ). Conclusions In the scalding process, a mass transfer occurred from the macroalgae to the process water. The transfer of arsenic was progressive from one cycle to the next; however, in the first cycle, the concentration of arsenic in the process water greatly exceeded the Chilean standard for drinking water, making it advisable to use the water for scalding only once. Considering the restrictive regulations, the scalding water used for these algae cannot be used for other food or food production processes without first undergoing purification. Options for managing scalding process water as liquid industrial waste need to be investigated. It is also important to determine processes that allow process water to be recycled, within the framework of the circular economy of production. Declarations Author Contribution This study is product of the execution of a wider project to obtain healthy food based on regional algae material. So, the authors contributed to the study in Conceptualization, design, and work to the project approval: Bernardo Sepúlveda, Patricia Echeverría, Bruno Sepúlveda, Pedro Tume and René Maurelia; field work, data collection and registered, material preparation, were performed by Bernardo Sepúlveda, Patricia Echeverría, Bruno Sepúlveda; professional support and organization of the analysis were performed by all the authors, working in group, in particular the design of informs is our creation from disponible information, in particular by Bruno Sepúlveda. The first draft of the manuscript was written by Bernardo Sepúlveda, Patricia Echeverría and María Jose Larrazabal, and the final version was analyzed, commented, and changed by all authors, who read and approved the final manuscript. Acknowledgement This work was carried out in the University of Atacama, in the Regional Center for Research for Sustainable Development of Atacama (CRIDESAT), and funded by the research project “Elaboración de productos piloto para consumo humano a partir de algas nativas de la Región de Atacama” (Preparation of pilot products for human consumption from native algae of the Atacama Region) granted by the Research Fund for Competitiveness (FIC, Codex BIP 30432986), of the Regional Government of Atacama. We would like to thank the professionals who worked on the project and the support of the people who collected the algae in the Atacama region. References Abd-Elghany, S. M., Zaher, H. A., Elgazzar, M. M., & Sallam, K. I. (2020). Effect of boiling and grilling on some heavy metal residues in crabs and shrimps from the Mediterranean Coast at Damietta Region with their probabilistic health risk assessment. 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Jiang, S., Yu M., Wang Y., Yin W., Jiang P., Qiu B. & Qi H. (2022). Traditional cooking methods affect the color, texture, and bioactive nutrients of Undaria pinnatifida . Foods , 11(8), 1078. https://doi.org/10.3390/foods11081078. Johnson, M. O., Cohly H. H., Isokpehi R. D. & Awofolu O. R. (2010). The case for visual analytics of arsenic concentrations in foods. International Journal of Environmental Research and Public Health , 7(5), 1970-1983. https://doi.org/10.3390/ijerph7051970. Karyadi, J. N. W., Kamila, I., Saputro, A. D., & Ayuni, D. (2022). The effect of scalding on the quality of freeze-dried edamame. International Journal on Advanced Science, Engineering and Information Technology, 12 (2), 819-825. https://doi.org/10.18517/ijaseit.12.2.13358 Kaure, S., Kaur, N., Aggarwal, P., & Grover, K. (2021). Bioactive compounds, antioxidant activity and color retention of beetroot ( Beta vulgaris L.) powder: Effect of steam scalding with cooling and storage. Journal of Food Processing and Preservation, 45 (3), e15247. https://doi.org/10.1111/jfpp.15247 Khosravi-Darani, K., Rehman, Y., Katsoyiannis, I. A., Kokkinos, E., & Zouboulis, A. I. (2022). Arsenic exposure via contaminated water and food sources. Water, 14 (12), 1884. https://doi.org/10.3390/w14121884 Kumar, A., Basu, S., Rishu, A. K., & Kumar, G. (2022). Revisiting the mechanisms of arsenic uptake, transport and detoxification in plants. Environmental and Experimental Botany, 194 , 104730. https://doi.org/10.1016/j.envexpbot.2021.104730 Lam, C-M., & Lai, H-Y. (2018). Effect of inoculation with arbuscular mycorrhizal fungi and scalding on the bioaccessibility of heavy metals in water spinach ( Ipomoea aquatica Forsk.). Ecotoxicology and Environmental Safety, 162 , 563-570. https://doi.org/10.1016/j.ecoenv.2018.07.047 Litter, M., Morgada, M. E., & Bundschuh, J. (2010). Possible treatments for arsenic removal in Latin American waters for human consumption. Environmental Pollution, 158 (5), 1105–1118. https://doi.org/10.1016/j.envpol.2010.01.028 Macnamara, J. P., & Derry, C. (2017). Pollution removal performance of laboratory simulations of Sydney’s street stormwater biofilters. Water, 9 (11), 907. https://doi.org/10.3390/w9110907 Magangana, T. P., Makunga, N. P., Amos Fawole, O., & Opara, U. L. (2021). Effect of solvent extraction and scalding pretreatment on the phytochemicals, antioxidant properties, enzyme inactivation and antibacterial activities of pomegranate ‘Wonderful’ peel extracts. Processes, 9 (6), 1012. https://doi.org/10.3390/pr9061012 Miranda, D., Carranza, C., Rojas, C. A., Jerez, C. M., Fischer, G., & Zurita, J. (2008). Acumulación de metales pesados en suelo y plantas de cuatro cultivos hortícolas, regados con agua del río Bogotá. Revista Colombiana de Ciencias Hortícolas, 2 (2), 180-191. https://doi.org/10.17584/rcch.2008v2i2.1186 Moya, P. (2017). Identificación de fuentes contaminantes en suelos y polvos de calle: el caso de Copiapó, Chile. Tesis para Grado de Magíster en Ciencias de la Ingeniería. Facultad de Ingeniería. Pontificia Universidad Católica de Chile. Santiago de Chile. 24 pág. Muñoz, I. G. P., & Díaz, N. F. (2022). Minerals in edible seaweed: Health benefits and food safety issues. Critical Reviews in Food Science and Nutrition, 62 (6), 1592–1607. https://doi.org/10.1080/10408398.2020.1844637 Nguyen, T. V. L., Vo, T. T., Lam, T. D., & Bach, L. G. (2019). Water scalding conditions on the quality of green asparagus ( Asparagus officinalis L.) segment tail. Materials Today: Proceedings, 18 , 4799-4809. https://doi.org/10.1016/j.matpr.2019.07.468 NORMA CHILENA. (2024). Requisitos – Agua potable. https://www.depuralife.cl/wp-content/uploads/2020/06/N.Ch_.-N%C2%B0409-de-2005-Norma-de-Calidad-del-Agua-Potable.pdf Octavio-Aguilar, P., & Olmos-Palma, D. A. (2022). Efectos sobre la salud del agua contaminada por metales pesados. Herreriana, 4 (1), 43-47. https://doi.org/10.29057/h.v4i1.8630 Punshon, T., Jackson, B. P., Meharg, A. A., Warczack, T., Scheckel, K., & Guerinot, M. L. (2017). Understanding arsenic dynamics in agronomic systems to predict and prevent uptake by crop plants. Science of the Total Environment, 581 , 209-220. https://doi.org/10.1016/j.scitotenv.2016.12.111 Rysulova, M., Kaposztasova, D., & Vranayova, Z. (2017). Green walls as an approach in grey water treatment. IOP Conference Series: Materials Science and Engineering, 245 , 072049. https://doi.org/10.1088/1757-899X/245/7/072049 Romero, J. (2024). Tratamiento de Residuos Industriales Líquidos (RILES). PPT Universidad de Santiago, Santiago, Chile . Exposition. Consulted Nov. 2024. http://ambiente.usach.cl/jromero/imagenes/MECESUP/Curso_MECESUP-Riles.pdf Ruiz-Ojeda, L. M., & Peñas, F. J. (2013). Comparative study of conventional water hot and microwave scalding on the quality of green beans. Innovative Food Science and Emerging Technologies, 20 , 191-197. https://doi.org/10.1016/j.ifset.2013.09.009 Seow, C. C., & Lee, S. K. (1997). Firmness and color retention in blanched green beans and green pepper. Journal of Food Quality, 20 (4), 329-336. https://doi.org/10.1111/j.1745-4557.1997.tb00475.x Sepúlveda, B., Rojos, S., Silva, W., Sepúlveda, B., Tume, P., & Pavez, P. (2023). Uptake of Cu, Hg, and As in wild vegetation, associated to surface water in the Copiapó valley, before the 2015 alluvium. Environmental Geochemistry and Health , 45, 137-149. https://doi.org/10.1007/s10653-022-01296-8 Stirk, W. A., & van Staden, J. (2000). Removal of heavy metals from solution using dried brown seaweed material ( Sargassum sp.). Botánica Marina, 43 (5), 467-473. https://doi.org/10.1515/BOT.2000.047 Suárez, M. L., González-Delgado, F. J., González, D., Rubio, C., & Hardisson, A. (2004). Análisis, diagnóstico y tratamiento de las intoxicaciones arsenicales. Cuadernos de Medicina Forense, 35 , 05-14. Available 2024 in http://scielo.isciii.es/scielo.php?script=sci_arttext&pid=S1135-76062004000100001&lng=es&tlng=es Tigreros, J. A., Londoño, S. P., Girón, J. M., & Santos, L. E. O. (2021). Different methods of scalding and their application in fruits and vegetables. Revista Colombiana de Investigaciones Agroindustriales, 8 (1), 50-63. https://doi.org/10.23850/24220582.3710 Trigueros, L., & Sendra, E. (2014). Nutritional and antioxidant properties of date paste and scalding water obtained from by-products of Medjoul and Confitera cultivars. Food Science and Technology, 2 (3), 34-40. https://doi.org/10.13189/fst.2014.020302 USDA. (2015). Complete Guide to Home Canning . United States Department of Agriculture. National Center for Home Food Preservation. Available at https://nchfp.uga.edu/publications/publications_usda.html#gsc.tab=0 Xiao, H. W., Pan, Z., Deng, L. Z., El-Mashad, H. M., Yang, X. H., Mujumdar, A. S., & Zhang, Q. (2017). Recent developments and trends in thermal scalding: A comprehensive review. Information Processing in Agriculture, 4 (2), 101-127. https://doi.org/10.1016/j.inpa.2017.02.001 Xu, Y., Sismour, E., Pao, S., Rutto, L., Grizzard, C., & Ren, S. (2012). Textural and microbiological qualities of vegetable soybean (edamame) affected by scalding and storage conditions. Journal of Food Technology and Processing, 3 (6), 1-6. https://doi.org/10.4172/2157-7110.1000165 Zhang, Y., Sun, B. H., Pei, Y. P., Vidyarthi, S. K., Zhang, W. P., Zhang, W. K., & Xiao, H. W. (2021). Vacuum steam pulsed scalding (VSPB): An emerging scalding technology for beetroot. LWT, 147 , 111532. https://doi.org/10.1016/j.lwt.2021.111532 Zhu, X., Healy, L. E., Sevindik, O., Sun, D. W., Selli, S., Kelebek, H., & Tiwari, B. K. (2022). Impacts of novel combined scalding treatments with commercial drying methods on the physicochemical properties of Irish brown seaweed Alaria esculenta . Food Chemistry, 369 , 130949. https://doi.org/10.1016/j.foodchem.2021.130949 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted 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. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-5664053","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":392097297,"identity":"38b6d1a0-ca9a-492a-bc20-c9b0fd13dca6","order_by":0,"name":"Bernardo Sepúlveda","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABCElEQVRIiWNgGAWjYBACAwjFDOUWAPEB5gMMPECajzgtIO4BtgSwFjYStPAY4NVizt777MHPPdZyDPyHjz3mMTgsx3f8zDeJNzUM8ri0WPYcNzfseZZuzCCRlm4M1GIseSZ3m+ScYwyGbbgcdiONTYLnwOHEBgkeM2keg7TEDQdyt0nzsDEk4PTL/Wdskn9AWvjPfwNpqd9w/s0zaZ5/eLTcYGOTBtvCkANkGNgkGNwAMnjbcGux7Eljk5Y5kG7MJpFmbjjHwMZw5o1nxpZz+yRw+sWc/Rib5JsD1nL8/IefPXhTISHPdz754Y0332zk+XFogQM2tIiQIKQBpmsUjIJRMApGARYAAOKfUE3GCLyLAAAAAElFTkSuQmCC","orcid":"","institution":"Universidad de Atacama","correspondingAuthor":true,"prefix":"","firstName":"Bernardo","middleName":"","lastName":"Sepúlveda","suffix":""},{"id":392097298,"identity":"6b33ae40-e24c-4516-994f-b78cbe975fa2","order_by":1,"name":"Patricia Echeverría","email":"","orcid":"","institution":"Universidad de Atacama","correspondingAuthor":false,"prefix":"","firstName":"Patricia","middleName":"","lastName":"Echeverría","suffix":""},{"id":392097299,"identity":"3c76271a-481b-44ef-989e-589f01629e9d","order_by":2,"name":"José María Larrazabal","email":"","orcid":"","institution":"Universidad de Antofagasta","correspondingAuthor":false,"prefix":"","firstName":"José","middleName":"María","lastName":"Larrazabal","suffix":""},{"id":392097300,"identity":"86a764f0-dd1c-45dd-8dea-d138590ad069","order_by":3,"name":"Bruno Sepúlveda","email":"","orcid":"","institution":"Universidad de Atacama","correspondingAuthor":false,"prefix":"","firstName":"Bruno","middleName":"","lastName":"Sepúlveda","suffix":""},{"id":392097301,"identity":"a356a309-9c3d-4c44-b484-97f1abb7e386","order_by":4,"name":"Pedro Tume","email":"","orcid":"","institution":"Universidad Católica de la Santísima Concepción","correspondingAuthor":false,"prefix":"","firstName":"Pedro","middleName":"","lastName":"Tume","suffix":""},{"id":392097302,"identity":"a944db55-05c4-4550-b83f-50e37ada43e3","order_by":5,"name":"René Maurelia","email":"","orcid":"","institution":"Universidad de Atacama","correspondingAuthor":false,"prefix":"","firstName":"René","middleName":"","lastName":"Maurelia","suffix":""}],"badges":[],"createdAt":"2024-12-17 18:08:15","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5664053/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5664053/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":71998917,"identity":"72b78025-ea0a-41c1-a9bd-8823371af5e4","added_by":"auto","created_at":"2024-12-20 12:57:27","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":476349,"visible":true,"origin":"","legend":"\u003cp\u003eLocation of the process plant and origin of the raw material.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-5664053/v1/fae82f6237764c76d7e4f75c.png"},{"id":71998914,"identity":"ac62a628-03d4-41e2-b091-d6a7f76e9cca","added_by":"auto","created_at":"2024-12-20 12:57:27","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":30011,"visible":true,"origin":"","legend":"\u003cp\u003eNet arsenic contributions in the process water by scalding cycle.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-5664053/v1/739bd98492b26f48ef71c528.png"},{"id":71998919,"identity":"dc097f6b-a8e0-4bf9-a055-f5f80c8046b6","added_by":"auto","created_at":"2024-12-20 12:57:28","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":23872,"visible":true,"origin":"","legend":"\u003cp\u003eMass transfer rate of arsenic (mg/L min) from \u003cem\u003eM. pyrifera\u003c/em\u003e to the process water per scalding cycle.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-5664053/v1/69cdd95c690ea99bcd1330f3.png"},{"id":83789957,"identity":"6bb87dd5-6954-4d87-9dbc-c24e30ca808f","added_by":"auto","created_at":"2025-06-02 18:46:31","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1049448,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5664053/v1/27b36543-2a72-45d4-ab9b-6a93c1849fd3.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Effect of Macrocystis pyrifera scalding on water reusing from the pre treatment cycles","fulltext":[{"header":"Introduction","content":"\u003cp\u003eScalding is an effective pretreatment in the vegetable food industry. It involves submerging food in hot water or steam for short periods, followed by rapid cooling to reduce the microbiological load, inactivate enzymes, and improve the digestibility, texture, and flavor of the food (Kaure et al. \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Tigreros et al., \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Xiao et al., \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Zhang et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Geng et al., \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Scalding can induce loss of quality in texture, soluble nutrients, pigment, and aroma in products (Deng et al., \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Xiao et al., \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2017\u003c/span\u003e), related to the temperature and duration of application (Zhang et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). On the other hand, it is assessed that scalding has improved the quality, safety, and nutritional properties of processed foods, significantly enhancing biochemical and physical parameters. In processed beetroot, despite the decrease in bioactive compounds, the product was beneficial for consumption (Kaure et al., \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn \u003cem\u003eGlycine max\u003c/em\u003e (soybeans), scalding (2.5 min at 100\u0026deg;C) reduced peroxidase activity by more than 98%, improved the intensity of the green color, and decreased the hardness of the grains; it also significantly reduced total yeasts, molds, and coliform bacteria (Xu et al., \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Karyadi et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). However, different reactions may occur in other vegetables, such as asparagus, where scalding with water inhibited enzymatic activity, leading to a rapid loss of nutrients and sensory values with scalding time (Nguyen et al., \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Two-stage scalding improved the firmness of vegetables such as beans, but negatively affected the colour (Seow \u0026amp; Lee, \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e1997\u003c/span\u003e); in green beans, shorter scalding times than conventional methods were achieved (Ruiz-Ojeda \u0026amp; Pe\u0026ntilde;as, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). Inadequate application of scalding can negatively affect the sensory and nutritional characteristics of the plant material and its subsequent processing (e.g., drying) (Tigreros et al., \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Boateng, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn the scalding of algae and other vegetables, mass transfer has been observed. Zhu et al. (\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) reported mass transfer from the edible alga \u003cem\u003eAlaria esculenta\u003c/em\u003e to the scalding water, noting significant changes in color metrics and Na, Cu, Fe, and Mn content. For the alga \u003cem\u003eUndaria pinnatifida\u003c/em\u003e, scalding with hot water resulted in a drastic decrease in most algae metabolites within just 20 seconds (with color changes in the algae), but it did not significantly affect amino acids or sugar composition (Hamid et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Jiang et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). In the case of treated dates, the scalding process allowed the transfer of a large amount of organic acids, phenols, sugars, and flavonoids to the water during processing (Trigueros \u0026amp; Sendra, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). Magangana et al., (\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) determined that in \u003cem\u003ePunica granatum\u003c/em\u003e peels, scalding at different temperatures and times influenced the concentration of phenols and tannins in the extract, demonstrating the mass transfer of these compounds to the scalding water. On the other hand, in the scalding of \u003cem\u003eP. granatum\u003c/em\u003e arils, total soluble solids increased along with greater radical scavenging activity (Adetoro et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn algae-based products marketed in Spain, significant concentrations of As, Cd, Hg, Pb, Zn, and Cu have been found (Besada et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2009\u003c/span\u003e) and Cu, Zn, and Cd were detected in the brown algae \u003cem\u003eEcklonia maxima\u003c/em\u003e, \u003cem\u003eMacrocystis angustifolia\u003c/em\u003e, and \u003cem\u003eLaminaria pallida\u003c/em\u003e (Stirk \u0026amp; van Staden, \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). In the manufacture of food based on \u003cem\u003eAmanita fulva\u003c/em\u003e, scalding has been reported to decrease the heavy metal content (Drewnowska et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Additionally, in the case of \u003cem\u003eCantharellus cibarius\u003c/em\u003e and \u003cem\u003eA. fulva\u003c/em\u003e, scalding caused the release of Hg regardless of the time and type of water used (drinking or deionised) (Falandysz \u0026amp; Drewnowska ,2017). In an analogous situation, a study on crabs and shrimp in Egypt found that heavy metals in samples exceeded the local concentration limit; however, scalding the foods reduced the concentration of chemical pollutants (Abd-Elghany et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe mass transfer process is important because algae can be a good source of essential minerals in functional foods (Mu\u0026ntilde;oz \u0026amp; D\u0026iacute;as, 2022). This background supports the idea that algae can release heavy metals and other components into the scalding water, with implications for the quality and safety of the final product. The above also highlights the importance of evaluating the effect of processing on the algae components, related to the mass transfer from the plant to the water during cooking. Proper scalding may be particularly important in reducing health risks related to arsenic. On the other hand, scalding water containing nutritional components and/or heavy metals could be classified as liquid industrial waste, since it is a terminal product and must be evacuated from the process. However, it could also become a raw material for water recycling through a purification process added to the scalding process (Litter et al., \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Rysulova et al., \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Macnamara \u0026amp; Derry, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Ali et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThis work was carried out within the context of a project aimed at producing gourmet foods for human consumption from \u003cem\u003eMacrocystis pyrifera\u003c/em\u003e, in which a scalding pretreatment was applied. The objective of this work was to determine the mass transfer of arsenic, cadmium, mercury, and lead detected in the natural algae to the scalding water, in order to establish guidelines for the management of the wastewater.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cp\u003e \u003cem\u003eAlgae row material.\u003c/em\u003e This work was carried out between March 2016 and April 2017 as part of a gourmet food formulation project based on algae from the coast of Region III (Atacama). The processing plant was located in Caldera, Loreto sector (27\u0026ordm;04'46\"S, 70\u0026ordm;50'22\"W) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), and the project was executed under the Regional Research Center for Sustainable Development of Atacama (CRIDESAT), University of Atacama, Copiap\u0026oacute;, Chile. The algal species were obtained from Bah\u0026iacute;a Chascos (27\u0026ordm;39'S, 70\u0026ordm;59'W), located about 60 km south of Caldera (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The collection of the algae was supervised by members of the project team.\u003c/p\u003e \u003cp\u003eFrom fresh \u003cem\u003eMacrocystis pyrifera\u003c/em\u003e, fronds and stipes in good physical condition and without perforations were selected. The chosen raw material was washed to eliminate sand and epiphytic organisms. The frond and stipe of the algae were then separated into containers, leaving them ready for moving on to the scalding process after the experimental production.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cem\u003eScalding of the raw material.\u003c/em\u003e To blanch the selected algae samples, a 100-litre gas kettle was used, filled with fresh water from the public network; the water was heated to a maximum of 70\u0026deg;C, for each cycle the water remains in the kettle and the fresh algae sample is renewed. During the scalding cycles, 4 to 5 L of water was used per kilogram of \u003cem\u003eM. pyrifera\u003c/em\u003e sample, subjected to successive cycles of 5 minutes each as a pre-treatment. Subsequently, this material was used to generate human food prototypes that will be reported in subsequent articles. Between scalding cycles, a water sample was taken to perform element analysis at an external service.\u003c/p\u003e \u003cp\u003e \u003cem\u003eChemical elements in the scalding water\u003c/em\u003e. In the pretreatment of algae by scalding, the heavy metal content of the process water was analyzed at the beginning and after each scalding cycle to evaluate the feasibility of reusing it in consecutive cycles. The analysis was conducted in an accredited laboratory by the National Institute of Standardization (INN) of Chile, under the Chilean standard NCH 17025 and by the American Association for Laboratory Accreditation (A2LA) under the ISO/IEC standard 17025 (2005). For the water of each scalding cycle, the concentrations of Cd (NCh 2638 Of. 01, mg/L), Hg (NCh 2667 Of. 01, mg/L), Pb (NCh 2751 Of. 03, mg/L) and As (NCh 3140 Of. 08, mg/L) were determined. For the comparative analysis, the maximum environmental limits for drinking water were as follows: 0.01 mg/L for As; 0.05 mg/L for Pb; 0.01 mg/L for Cd; and 0.001 mg/L for Hg (Health Canada, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; NORMA CHILENA, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Sep\u0026uacute;lveda,, 2023).\u003c/p\u003e \u003cp\u003e \u003cem\u003eData analysis and calculations.\u003c/em\u003e Changes in the concentration of chemical components in the water of each scalding cycle were evaluated; with cycle zero serving as the control. The comparisons were based on the Student's T-test for paired samples with 95% confidence and α\u0026thinsp;=\u0026thinsp;0.05. The \"p\" index indicates the statistical significance (1\u0026thinsp;\u0026gt;\u0026thinsp;p\u0026thinsp;\u0026gt;\u0026thinsp;0). Mass transfer was calculated in significant cases in successive scalding cycles.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e shows the concentration of arsenic, cadmium, mercury and lead in the scalding process water. Lead was found to be below the NCh-409-1 standard norm, while mercury was 33% higher (0.002 mg/L above the NCh-409 limit); however, it was at the detection limit and did not incremented in subsequent scalding cycles. Cadmium was 50% lower than the environmental limit, so it would not be considered a threat. Conversely, the concentration of arsenic in the scalding water increased from the first cycle, reaching 1,206 times higher than the environmental reference by the third cycle, or 99.92%. Thus, arsenic is the element with the greatest impact on the water after the scalding of the algae samples.\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\u003eConcentration of As, Cd, Hg and Pb in the scalding process water.\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\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eScalding cycles in water\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"4\" nameend=\"c5\" namest=\"c2\"\u003e \u003cp\u003eChemical components (mg/L)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAs\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCd\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHg\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003ePb\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.003\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.005\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.010\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.278\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.005\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.003\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.010\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.781\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.005\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.003\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.010\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.206\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.005\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.003\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.010\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEM Limit\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e \u003cp\u003e0: control water, As: Arsenic, Cd: Cadmium, Hg: Mercury, Pb: Lead. EM Limit: Environmental Maximum Limit.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e shows the net arsenic contribution in the process water by scalding cycle. The total accumulated concentration of arsenic reaches 1.206 mg/L, with the accumulation following a linear model (R\u0026sup2; = 0.99). However, the net contribution (difference in concentration) per scalding cycle reaches 23% of the maximum concentration in the first scalding cycle, 64% in the second scalding cycle, and 100% of the concentration in the third one. This situation reflects a change in the net mass transfer rate.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e shows the mass transfer rate (MTR) of arsenic (mg/L min) from the \u003cem\u003eM. pyrifera\u003c/em\u003e sample to the process water per scalding cycle. In the first scalding cycle, the MTR (mg/L min) was 0.275\u0026thinsp;\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u0026plusmn;\u003c/span\u003e\u0026thinsp;0.006 (cycle 1, 100%), decreasing at 0.252\u0026thinsp;\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u0026plusmn;\u003c/span\u003e\u0026thinsp;0.001 (cycle 2. 91.6%), and to 0.142\u0026thinsp;\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u0026plusmn;\u003c/span\u003e\u0026thinsp;0.011 (cycle 3, 51.6%.). This decrease in the MTR fits a polynomial model with R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;98% and p\u0026thinsp;=\u0026thinsp;0.006. This result suggests a reduced capacity of the water to extract As from the algae in each scalding cycle. Extrapolating the MTR (see trend line, Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) it can be seen that the mass transfer tends to zero after approximately 3,75 scalding cycles; each cycle represents 5 minutes. This indicates that water would no longer have the capacity to extract arsenic in a subsequent scalding cycle, probably, because the water is saturated. The above information implies that scalding water could be used up to the third cycle. However, but, comparing the concentration of arsenic in the process water with the environmental limit, according to the Chilean standard (drinking water 0.01 mg/L), the result shows that scalding water could only be used once at most. This information suggests that the water from the algae scalding process should be considered as a liquid industrial waste (RIL, in spanish).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe Copiap\u0026oacute; River, from the valley of the same name, originates in the Andes Mountains; its tributaries rise in areas with high mineral content, often associated with arsenides, which can be released by natural effects or accelerated by anthropogenic actions. Initially, these minerals may be poorly soluble, but they transform into easily soluble species such as arsenic (III) (e.g. As(OH)\u003csub\u003e3\u003c/sub\u003e) (Bieger et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). In Copiap\u0026oacute;, various sources of elements have been identified, and it is estimated that mining processes contribute 88% of Cu and 49% of As to street dust (Moya, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Additionally, in dust samples obtained in 2015 (the year of the last and largest flood that occurred in the valley) from localities in the Atacama region: Cha\u0026ntilde;aral, El Salado, Diego de Almagro, Copiap\u0026oacute;, Tierra Amarilla, and Paipote, the presence of As, Cd, Zn, Cr, Cu, Pb, and Mn was reported both in the total fraction and in the water-soluble fraction (Cort\u0026eacute;s \u0026amp; Tchernitchin, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). In general, As is prevalent in 200 areas of Latin America, where it is naturally released into the environment and mobilized from geogenic sources such as: 1) volcanic rocks and emissions, the latter being transported thousands of kilometres from the source; 2) metallic mineral deposits transferred to people through drinking water and the food chain; 3) deep geothermal reserves that contaminate fresh water sources. The challenge for mitigation is increasing due to mining and related activities, with As being transported by rivers over long distances, often contaminating coastal environments (Bundschuh et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAlgae are bio accumulator plants that can act as concentration centers for toxic elements; to use macroalgae as food, thermal treatment is usually applied by scalding in hot water (Cascais et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2021\u003c/span\u003e); this is considered a mature conventional method, widely applied in food processes. However, it must be considered that scalding produces highly contaminated wastewater due to the properties and characteristics of the fruits and vegetables; therefore, it cannot be applied in the same way to all products (Xiao et al., \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Despite this thermal scalding is an essential operation in the processing of many fruits and vegetables, as it affect the quality of the products attributes. some studies have shown that in raw material of algae, the concentration of arsenic was higher and this element varied when the algae was thermally processed and when different thermal treatments were applied (Cascais et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). For example, in the alga \u003cem\u003eAlaria esculenta\u003c/em\u003e, the scalding treatment significantly affected the content of Na, Cu, Fe and Mn (Zhu et al., \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eRegarding the importance of heavy metals in food processes and their leaching, the content of heavy metals depends on the plant tolerance and the associated detoxification mechanisms. Lam and Lai (\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2018\u003c/span\u003e) evaluated the effect of scalding and simulated digestion on the heavy metal bio accessibility; finding that spinach species had a high accumulation capacity. From raw spinach tissues, 45 to 84% of Cd, Cr, and Ni leached after scalding (Lam \u0026amp; Lai, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Although the heavy metals are necessary for physiological processes (in small quantities), it tend to accumulate in the body of living beings faster than they can be metabolized; in general As, Cd, Cr, Hg and Pb are among the most common elements in water; therefore the food chain is a very important factor in proper human nutrition. Then, depending on the bioavailability, the heavy metals enter through the diet, for example by ingesting marine foods; then, the phenomenon of bioaccumulation must be considered (Johnson et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2010\u003c/span\u003e, Kumar et al., 2021; Octavio-Aguilar et al., 2021; Khosravi-Darani et al., \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eArsenic is toxic in animals (Johnson et al. \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2010\u003c/span\u003e), and it has become a major concern in recent decades. Chronic exposure to As occurs either through drinking water or via by contaminated food chain. The introduction of arsenic into the chain happens due to its excessive absorption from the soil by plants, often as a result of irrigation with contaminated water. The main source of human exposure to As is the consumption of accumulating crops and vegetables (Punshon et al., \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Kumar et al., 2021). One problem is that As concentration varies in foods, making it impractical to establish a regulatory limit for each food (Johnson et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). In general, Miranda et al. (2011) state (sic) \u0026ldquo;At the global, national and local level, we find that environmental contamination by heavy metals and metalloids has increased, in such a way that it severely compromises health, population food security and the environment\u0026rdquo;. Regarding the effects of arsenic on human health, the most characteristic result of prolonged oral exposure to inorganic arsenic is hyperpigmentation and keratosis; this includes darkening of the skin and the appearance of calluses or warts on parts of the body, often associated with alterations in the blood vessels of the skin. Major symptoms include effects on the skin and circulatory and peripheral nerve disorders. With chronic exposure to arsenic, there are reports of increased mortality from lung, kidney, liver, bladder, and skin cancer. Additionally, the effect of arsenic on pregnancy has been documented (Cort\u0026eacute;s \u0026amp; Tchernitchin, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eConsidering that macroalgae contain various water-soluble compounds and that scalding is done at high temperature, mass transfer from the algae to the water is expected. The mass transferred to the water must be quantified to determine the possibility of reusing it and to know the number of allowed scalding cycles, in order to guarantee the safety and quality of the food. Scalding has proven to be effective as pretreatment for food transformation into products, ensuring safety and preserving bioactive compounds (Tigreros et al., \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn this work, in the water of the third scalding cycle, arsenic increased after each scalding cycle. Extrapolating the mass transfer rate, it tended to zero after the third scalding. This is related to a lower capacity of the water to extract arsenic from the algae after each cycle, due to a saturation level with the transferred element. According to the Chilean standard for drinking water, the maximum permitted content of As is 0.01 mg/L, which shows that the process water could only be used in the first scalding cycle, making the possibility of reusing water inadvisable, at least in this type of process. None of the other elements showed important changes in the process water.\u003c/p\u003e \u003cp\u003eFrom the point of view of the increase in arsenic content in the process water, the facts imply a decreasing in arsenic in the macroalgae raw material, representing an additional advantage of the scalding. Characterizing the impact of hydrothermal processing on the concentration of I, Na, K, Se and As in four macroalgae, Correia et al., (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) describe that processing of macroalgae revealed a relationship between the species and the leaching pattern for I, total As and Se. The difference may be due to the subcellular localization of the elements, the way each element is complexed, the retention processes and the speciation of the different elements. These authors demonstrated that algae processing could be an excellent strategy to ensure the delivery of essential and balanced micro and macro elements for the health of consumers.\u003c/p\u003e \u003cp\u003eAlgae can contain high concentrations of heavy metals, so it is important to consider the role that process plays on the concentration of component in algae-based food products. Information like this must considered when designing product processing, to increase the retention of nutritional components and limit metallic contaminants. Advances like these could position algae-based products and further promote their dietary consumption (Ho \u0026amp; Redan, 202l). However, scalding can affect the quality of the products; furthermore, this process involves high water consumption and generation of effluents with a high content of organic and inorganic matter, which can impact the environment. It is important to understand the amount of used water in scalding and the factors that determine it. It is noted that for fruits and vegetables, around 1 to 2 L of water per kilo of material is usually used, for fruits such as peaches, 4 to 5 L of water per kilo may be required. In general, the proportion of water can vary with the material to be scalded and culinary preferences; there does not appear to be a defined standard (USDA, \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Boateng, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Hamid et al. (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) reported using 2 L of water to scald at least 6 g samples of \u003cem\u003eUndaria pinnatifida\u003c/em\u003e (Zhu et al., \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2022\u003c/span\u003e), scalded in a proportion of 200 g of algae in 800 mL of distilled water and \u003cem\u003eAlaria esculenta\u003c/em\u003e (200 g) with 1000 mL of distilled water.\u003c/p\u003e \u003cp\u003eAccording to Chilean reference institutions, a Liquid Industrial Waste (LIW, RIL in Spanish) is generally wastewater generated in industrial processes, activities, or services, which can contain a variety of contaminants such as organic compounds, heavy metals, oils, among others. From a technical point of view, the quality of RIL is determined by the discharge containing contaminants at concentrations above the environmental reference established by current legislation. Therefore, the quality of RIL requires appropriate management to avoid environmental contamination and protect public health. The arsenic content in RIL varies depending on the process; however, its high toxicity often results in sublethal effects that are not studied in a community as Copiap\u0026oacute;, until they become lethal (ECOPRENEUR, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; CCHC, 2024; Hern\u0026aacute;ndez et al., \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Romero, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). This apparent lack of information on the volume of water would indicate that this is not a primary focus of the study of scalding; despite the fact that wastewater can be classified as liquid industrial waste (Anastacio \u0026amp; Gambini, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Arsenic is widely distributed in the universe and its toxicity depends on its chemical forms and oxidation states (-3, 0, +\u0026thinsp;3 and +\u0026thinsp;5). The tolerable daily intake of total As is mentioned as 50 \u0026micro;g/kg of weight (Suarez et al., 2004). Therefore, it is convenient to consider the management of this liquid waste in food production costs; to optimize, recover and recycle scalding water, and to reduce the cost of water in the process. In general, today more than ever, there is an urgent need to take care of the water resource, especially in arid areas, to make processes more efficient and generate safe food in a sustainable way, considering health quality and compliance with current regulations (NORMA CHILENA, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2024\u003c/span\u003e).\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn the scalding process, a mass transfer occurred from the macroalgae to the process water. The transfer of arsenic was progressive from one cycle to the next; however, in the first cycle, the concentration of arsenic in the process water greatly exceeded the Chilean standard for drinking water, making it advisable to use the water for scalding only once. Considering the restrictive regulations, the scalding water used for these algae cannot be used for other food or food production processes without first undergoing purification. Options for managing scalding process water as liquid industrial waste need to be investigated. It is also important to determine processes that allow process water to be recycled, within the framework of the circular economy of production.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eThis study is product of the execution of a wider project to obtain healthy food based on regional algae material. So, the authors contributed to the study in Conceptualization, design, and work to the project approval: Bernardo Sep\u0026uacute;lveda, Patricia Echeverr\u0026iacute;a, Bruno Sep\u0026uacute;lveda, Pedro Tume and Ren\u0026eacute; Maurelia; field work, data collection and registered, material preparation, were performed by Bernardo Sep\u0026uacute;lveda, Patricia Echeverr\u0026iacute;a, Bruno Sep\u0026uacute;lveda; professional support and organization of the analysis were performed by all the authors, working in group, in particular the design of informs is our creation from disponible information, in particular by Bruno Sep\u0026uacute;lveda. The first draft of the manuscript was written by Bernardo Sep\u0026uacute;lveda, Patricia Echeverr\u0026iacute;a and Mar\u0026iacute;a Jose Larrazabal, and the final version was analyzed, commented, and changed by all authors, who read and approved the final manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThis work was carried out in the University of Atacama, in the Regional Center for Research for Sustainable Development of Atacama (CRIDESAT), and funded by the research project \u0026ldquo;Elaboraci\u0026oacute;n de productos piloto para consumo humano a partir de algas nativas de la Regi\u0026oacute;n de Atacama\u0026rdquo; (Preparation of pilot products for human consumption from native algae of the Atacama Region) granted by the Research Fund for Competitiveness (FIC, Codex BIP 30432986), of the Regional Government of Atacama. We would like to thank the professionals who worked on the project and the support of the people who collected the algae in the Atacama region.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAbd-Elghany, S. M., Zaher, H. A., Elgazzar, M. M., \u0026amp; Sallam, K. I. (2020). Effect of boiling and grilling on some heavy metal residues in crabs and shrimps from the Mediterranean Coast at Damietta Region with their probabilistic health risk assessment. \u003cem\u003eJournal of Food Composition and Analysis\u003c/em\u003e, 93, 103606. https://doi.org/10.1016/j.jfca.2020.103606\u003c/li\u003e\n\u003cli\u003eAdetoro, A. O., Opara, U. L., \u0026amp; Fawole, O. A. (2020). 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National Center for Home Food Preservation. Available at https://nchfp.uga.edu/publications/publications_usda.html#gsc.tab=0\u003c/li\u003e\n\u003cli\u003eXiao, H. W., Pan, Z., Deng, L. Z., El-Mashad, H. M., Yang, X. H., Mujumdar, A. S., \u0026amp; Zhang, Q. (2017). Recent developments and trends in thermal scalding: A comprehensive review. \u003cem\u003eInformation Processing in Agriculture, 4\u003c/em\u003e(2), 101-127. https://doi.org/10.1016/j.inpa.2017.02.001\u003c/li\u003e\n\u003cli\u003eXu, Y., Sismour, E., Pao, S., Rutto, L., Grizzard, C., \u0026amp; Ren, S. (2012). Textural and microbiological qualities of vegetable soybean (edamame) affected by scalding and storage conditions. \u003cem\u003eJournal of Food Technology and Processing, 3\u003c/em\u003e(6), 1-6. https://doi.org/10.4172/2157-7110.1000165\u003c/li\u003e\n\u003cli\u003eZhang, Y., Sun, B. H., Pei, Y. P., Vidyarthi, S. K., Zhang, W. P., Zhang, W. K., \u0026amp; Xiao, H. W. (2021). Vacuum steam pulsed scalding (VSPB): An emerging scalding technology for beetroot. \u003cem\u003eLWT, 147\u003c/em\u003e, 111532. https://doi.org/10.1016/j.lwt.2021.111532\u003c/li\u003e\n\u003cli\u003eZhu, X., Healy, L. E., Sevindik, O., Sun, D. W., Selli, S., Kelebek, H., \u0026amp; Tiwari, B. K. (2022). Impacts of novel combined scalding treatments with commercial drying methods on the physicochemical properties of Irish brown seaweed \u003cem\u003eAlaria esculenta\u003c/em\u003e. \u003cem\u003eFood Chemistry, 369\u003c/em\u003e, 130949. https://doi.org/10.1016/j.foodchem.2021.130949\u003c/li\u003e\n\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":"blanching water, liquid food waste, Atacama algae, food contamination, decontaminating pretreatment","lastPublishedDoi":"10.21203/rs.3.rs-5664053/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5664053/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eIn the scalding pretreatment, food is immersed in water or steam at specific temperatures and times, inactivating enzymes, reducing microorganisms, and softening tissues. This requires a large volume of water and energy, and it can generate contaminated water, limiting its reuse. \u003cem\u003eMacrocystis pyrifera\u003c/em\u003e is a brown macroalga distributed along the Chilean coast and can be used as human food. The content of As, Hg, Cd, and Pb (\u0026micro;m/100 g) in the process water was evaluated after each scalding cycle of \u003cem\u003eM. pyrifera\u003c/em\u003e. During scalding, there was transfer of As from the macroalga to the process water, while the others elements were not significant. From the first to the third scalding cycle, transferred arsenic reached 1.206 mg/L. According to Chilean regulations, the maximum environmental concentration is 0.01 mg/L, limiting water reuse from the first scalding cycle. Scalding water with arsenic should not be used for other food production processes, nor should it be discharged into the environment, because the arsenic content transforms the process water into a liquid industrial waste. It is suggested to evaluate techniques to reduce the concentration of dissolved contaminants to enable reuse, within the framework of the circular economy, making blanching more sustainable.\u003c/p\u003e","manuscriptTitle":"Effect of Macrocystis pyrifera scalding on water reusing from the pre treatment cycles","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-12-20 12:57:14","doi":"10.21203/rs.3.rs-5664053/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":"ddfca7a6-d67e-4101-9659-872bc59aa64d","owner":[],"postedDate":"December 20th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-06-02T18:38:25+00:00","versionOfRecord":[],"versionCreatedAt":"2024-12-20 12:57:14","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5664053","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5664053","identity":"rs-5664053","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}