Preharvest Salicylic Acid and Oxalic Acid Decrease Bioactive and Quality Loss in Blackberry (cv. Chester) Fruits during Cold Storage

In this study, we investigated the effects of preharvest oxalic acid (2.5 mM (OA1) and 5 mM (OA2)) and salicylic acid (0.5 mM (SA1) and 1 mM (SA2)) treatments on the storage and quality of blackberry cv. Chester. We applied salicylic acid and oxalic acid to the plants seven and fourteen days before harvest and recorded the physiological, physicochemical, and external appearance characteristics of the fruits during the cold storage period (nine days). The results showed that the treatments decreased ethylene production by 29.5% (SA1) at harvest and by 28.5% (SA2) at the end of the storage period. In addition, the respiration rate was reduced between 13.0% (OA2) and 28.0% (SA2) compared to the control. Although fruit weigh loss increased as storage extended, the highest losses were observed in control with 1.35%. Titratable acidity decreased from harvest (0.46%) to the end of storage (0.39%) in the control, whereas it ranged from 0.52% (SA1) to 0.62% (OA1) in the treatment groups. Malic acid and syringic acid were the dominant organic acid and phenolic, respectively, and although their content decreased continuously in the control group, no loss was observed in the treated groups after the sixth day. These effects were positively reflected in the external appearance of the fruits, total phenolic content, total flavonoid content, and properties related to antioxidant activity. As a result of the cumulative evaluation of all parameters, it can be suggested that Chester fruits can be stored for nine days in marketable quality with the SA2 applications. Among oxalic acid concentrations, 2.5 mM can be recommended for phytochemical accumulation at harvest and short-term storage of three days.