The Effect of L-glutathione Postharvest Treatment on the Physicochemical Characteristics of Sabrina Strawberry Fruit during Cold Storage

IntroductionDue to the high rate of respiration, strawberry is prone to water loss, mechanical damage and fungal decay post-harvesting, which may reduce its shelf life (Yan et al., 2019). Food waste is an important global challenge that estimated about 30% of the world's agricultural land. Every year, about 9.5 million tons of food is lost in the post-harvest phase of agriculture crops (Bishop et al., 2021). Post-harvest storage of strawberry at low temperature without using other combined treatments may reduce its shelf life due to its highly perishable nature. Therefore, in addition to low temperature storage, other post-harvest techniques have also been reported to increase the shelf life of strawberry fruits after harvest. One of these techniques is using chemicals (Kahramanoglu et al., 2019).Glutathione is present in various plant tissues in concentrations of 2 to 3 mM and plays an important role in many cellular processes such as cell differentiation, enzyme regulation, cell signaling and cell death and acts as an antioxidant. (Diaz-Vivancos et al., 2015). During the experiment, spraying GSH on strawberry plants increased the amount of total flavonoids and ascorbic acid in the harvested fruits, and the results showed that the application of GSH can increase the shelf life of strawberries. (Ge et al., 2019). It has been reported that application of glutathione after harvesting okra has reduced browning and prevented its weight loss, which has created a suitable market for it, also GSH has increased the level of total phenol and the activity of ascorbate peroxidase enzyme and reduced the level of ROS and malondialdehyde, which can increase the shelf life of okra in cold storage after harvesting (Li et al., 2023).Materials and MethodsSabrina strawberry fruit was obtained from a commercial greenhouse located in Urmia in the full maturity stage. The fruits were transported to the laboratory of Horticultural Sciences Department of Urmia University, observing the necessary precautions to prevent mechanical damage. The fruits were separated in terms of size and uniformity, so that the fruits were divided into 5 groups of 15, one group as a control group and 4 groups treated with different concentrations of L-glutathione (4, 16, 32 and 64 mM respectively). After drying, the treated fruits were placed in zipped nylon bags and stored for 15 days in a cold room at ± 0.5 °C and a relative humidity of 90-95%. Also, three biological replicates at each time interval were included in the analysis. Samples obtained at each of specified time were placed to evaluate skin color, titratable acidity, soluble solids, taste index, pH, weight loss, total antioxidant capacity, total phenol content, and polyphenol oxidase enzyme activity.Results and DiscussionThe results of variance analysis showed that the effect of GSH treatment after harvesting, the effect of storage and the interaction between them  differently affect each of the studied indicators. In terms of color, no significant effect was found. The effect of storage (p≤0.01) and post-harvest treatment (p≤0.05) were significant on TA trait and its highest value was observed in 10 days of storage with 32 mM. In terms of antioxidant capacity (p≤0.05) and PPO activity (p≤0.01), the effect of GSH treatment after harvest was significant, and the highest amount was observed in 16 and 64 mM treatment, respectively. Also, the effect of storage time (p≤0.05) and the effect of GSH treatment after harvesting (p≤0.01) were significant in the trait of total phenol content, and the highest amount was observed in 15 days of storage and 64 mM treatment. However, both the storage (p≤0.01) and the post-harvest GSH treatment (p≤0.05) effects on fruit weight reduction were significant and the lowest weight loss was observed in 5 days of storage and 64 mM treatment. There were no significant changes in indices such as TSS, taste index and pH.ConclusionAccording to the obtained results, the treatment of 64 mM GSH is the best concentration of GSH to increase the shelf life of harvested strawberry fruits in cold storage.Author ContributionsManda-Hakki: conceptualization, data management, financing, research and review, resources, validation, visualization, writing-main draft, Hassanpour: formal analysis, methodology, project management, software, supervision, Writing - review and editingFunding SourcesPart of this project was financially supported by Urmia University.AcknowledgementWe appreciate and thank all those who were with us in this project, especially the officials of Horticulture Laboratory, Faculty of Agriculture, Urmia University.