The Role of Spermidine in Postharvest Fruit Physiology: Effects on Quality Characteristics and Metabolite Content of Sweet Cherry Fruit during Cold Storage

In this study, 0.5, 1.0, and 1.5 mM spermidine were applied to sweet cherry fruit before storage and the fruit were stored for 30 days. In addition, the fruit were stored for 30 days as a control without any treatment. Weight loss, decay rate, soluble solids content (SSC), titratable acidity (TA), pH, respiration rate, phenolic compounds, organic acids, and vitamin C parameters were assessed in fruit during storage. As a result of the study, according to different spermidine treatments, increases in weight loss, SSC, pH, respiration, and decay rates and decreases in titratable acidity were detected in control fruit at different storage periods (10, 20, and 30 days). Among the different spermidine doses applied, it was determined that the highest dose of spermidine applications was 1.5 mM, which prevented the degradation of phenolic compounds, organic acids, and vitamin C contents in sweet cherry fruit. Succinic acid was the dominant organic acid in sweet cherry fruit, with the highest value recorded at 10.30 g kg^-1 during the harvest period and the lowest value measured at 6.89 g kg^-1 in the control group at the end of storage (30 days). After succinic acid, malic and citric acids were found to have the highest concentrations, both of which showed a decrease during storage. It was determined that the 1.5 mM dose was the most effective in preventing this decrease. It was also found that gallic acid (30 days: 68.36 mg 100 g^-1) was the most abundant phenolic compound in the fruit, followed by quercetin (30 days: 9.81 mg 100 g^-1) and rutin (30 days: 10.09 mg 100 g^-1), respectively. As a result, it was concluded that exogenous application of spermidine can be used as a postharvest tool in preserving the quality and storage life of sweet cherry fruit.