Plant-Derived Tragacanth Gum Coating Ameliorates Chilling Injury and Maintains Eating Quality by Downregulating Oxidative Stress in Loquat Cultivars

Loquat is a highly perishable, non-climacteric fruit that is prone to chilling injury, decay, and eating quality deterioration during cold storage. This study evaluates the effectiveness of tragacanth gum (TG) as a plant-based edible coating to mitigate postharvest chilling injury (CI) and preserve the eating quality of loquat fruit. Two commercial cultivars, 'Sufaid' and 'Surkh', were coated with 1% TG and stored at 4 ± 1 °C with 90 ± 5% relative humidity for 20 days, followed by 2 days at 20 °C ± 1 °C (specific focus on retail handling). TG-coated fruits exhibited significantly reduced weight loss and lower decay compared to controls. TG application alleviated CI symptoms and reduced respiration rates. TG-treated fruits maintained higher levels of titratable acidity, total soluble solids, and ascorbic acid. TG application also elevated phytochemical levels and antioxidant potential, reinforcing the fruit's biochemical defenses against postharvest stress. Furthermore, TG treatment suppressed oxidative stress by lowering malondialdehyde and hydrogen peroxide levels and enhanced the activities of key antioxidant enzymes (SOD, CAT and APX). TG-coated fruits also showed improved taste, flavor, and consumer acceptability at shelf after storage. In conclusion, results indicate that application of TG coating represents a sustainable, eco-friendly strategy to alleviate CI and improve postharvest eating quality of commercial loquat cultivars, offering potential for broader adoption in the fresh fruit supply chain.