Modulation of antioxidant defense and organic acid profiles in green beans (Phaseolus vulgaris L.) via salicylic acid and passive modified atmosphere packaging

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BACKGROUND: Green bean (Phaseolus vulgaris L.) is a vegetable species characterized by its short postharvest storage life. This study investigated the effects of different doses of salicylic acid (SA; 1 and 3 mM), passive modified atmosphere packaging (passive MAP), and the combined applications of SA and passive MAP (hereafter SA + MAP) on postharvest physiological and biochemical changes in the 'Gina' and 'Gevaş' bean cultivars. METHODS: ), antioxidant enzymes (CAT, SOD, and APX), MDA content, and organic acids (oxalic, citric, malic, succinic, fumaric, and tartaric acids) were examined. RESULTS: The study revealed significant physiological and biochemical differences between the 'Gina' and 'Gevaş' cultivars. In 'Gina', 1 mM SA + MAP was the most effective treatment for suppressing respiration, reducing it by 49% relative to the control, while external ethylene production under this treatment decreased by 30%. In 'Gevaş', 3 mM SA + MAP was the most effective treatment, reducing respiration and external ethylene production by 64% and 75%, respectively, compared with the control. Under these most effective treatment conditions, 'Gina' showed enhanced acid accumulation, with significantly higher oxalic (149%), succinic (55%), citric (40%), and fumaric acid levels (21%) than the control. Conversely, 'Gevaş' exhibited more pronounced changes in organic acid profiles, with greater depletion of fumaric (73%), succinic (79%), and tartaric acids (62%), while oxalic (97%) and malic acid levels (5%) remained above the control, and citric acid was maintained at a level comparable to the control. Furthermore, enhanced antioxidant defense effectively suppressed lipid peroxidation, reducing MDA levels by 41.8% and 69.4% relative to the control, respectively. Collectively, these findings indicate that the combined application of SA and passive MAP is an effective cultivar-specific strategy for maintaining postharvest quality during 25 days of storage in green beans.