The effects of some postharvest treatments on cold storage and quality of plums cv. Angeleno and black diamond

The aim of this study was to determine the effects of different postharvest treatments on storage life and quality of plums cv. Angeleno and Black Diamond. For this purpose, plums harvested at optimum stage were treated (dipped in an aqueous solution) with salicylic acid (SA) (1.5 mM, 10 min), putrescine (PUT) (2 mM, 6 min), oxalic acid (OA) (5 mM, 3 min) and nitric oxide (NO) (1 mM, 3 min). After treatments, plums were placed in modified atmosphere packages and stored at 0˚C and 90±5 % relative humidity (RH) for 100 days (Black Diamond) and 120 days (Angeleno). After cold storage, plums were kept at room conditions (20˚C and 60±5% RH) for 5 days to simulate commercial practice (shelf life). Some physical and chemical analysis (weight loss, fruit firmness, respiration rate, ethylene production, fruit skin and flesh color, total anthociyanin content, total phenolic content, total carotenoid content, total chrolophyll content, ascorbic acid content) were determined initially and at 20 day-intervals. All treatments were effective for maintaining fruit quality of Angeleno and Black Diamond plums throughout stroge compared to control groups. The effects of postharvest treatments on reducing ethylene production and respiration rate and maintaining fruit firmness and sensory quality were more noticeable than the effects on the other examined quality criteria. The effects of treatments on total carotenoid and sugar contents of cultivars were not clear. According to the results, it was found that the most effective treatment was SA while OA and PUT treatments had similar effects. In contrast to the studies conducted in many fruit species and varieties including plums, the expected results of nitric oxide treatment could not be obtained in both varieties in this study. As a result, when all the quality criteria are taken into account; it was determined that salicylic acid treatment prolonged the storage period for 20-30 days in Angeleno and 20 days in Black Diamond plum. These results suggest that these substances obtained from plants (SA, PUT and OA) can be used successfully to maintain quality and biochemical content and, to extend storage life of Angeleno and Black Diamond plum.