The effect of postharvest melatonin and salicylic acid treatments on the quality changes of fresh cowpea during storage

In this study, it was aimed to maintain the quality attributes and biochemical composition and inhibit chilling injury of fresh cowpea pods by post-harvest salicylic acid (SA) and melatonin (MEL) treatments during storage. For this purpose, harvested fresh cowpea pods were dipped into solutions containing different doses of SA (1 and 2 mM) and MEL (100 and 200 µmol L-1). The control group was dipped into distilled water only. After dipping, pods were placed into 1 kg foam trays and covered with strech film. The stretched trays were stored at 4±1°C and 90±5% relative humidity for 16 days. For shelf life studies, the fresh cowpea pods were kept at 20±1°C and 60±5% relative humidity for 2 days after cold storage. Some physical and chemical quality analyses and sensory evaluations were performed at the beginning of storage and at 4-day intervals to determine the quality changes in the pods and the same analyses were repeated under shelf life conditions. It was determined that SA and MEL treatments were effective to reduce the weight loss and to suppress the respiration rate of the pods. SA and MEL treatments were more effective than the control treatment in maintaining the external appearance and reducing chilling injury and the effect of MEL treatments was more noticeable. The treatments had no significant effect on the total phenolic content and ascorbic acid content of the pods. In conclusion, it was determined that MEL treatments were the most effective treatment for maintaining the quality parameters investigated.