Intervention mechanisms of cold plasma pretreatment on the quality, antioxidants and reactive oxygen metabolism of fresh wolfberries during storage

Abstract

Fresh wolfberries, a nutritious "super fruit", face limited marketing potential due to storage difficulties. This study aimed to enhance their storage stability using dielectric barrier discharge plasma (DBD) pretreatment and investigate the intervention mechanism. The results indicated that the optimal condition of DBD pretreatment for fresh wolfberries was 13.64 kV, 70 s and 2.7 kHz, which extended their shelf from 2 to 5 d at room temperature. This pretreatment reduced decay, weight loss, and firmness reduction by inactivating microorganisms and inhibiting respiration. Additionally, the decline of phenols, flavonoids, ascorbic acid, and antioxidant activity was inhibited, while maintaining high content of polysaccharides, titratable acid, and carotenoids. Interestingly, moderate DBD treatment produced reactive oxygen species (ROS) that triggered the defense response of wolfberries' ROS metabolism system and promoted the biosynthesis of flavonoids, thereby enhancing resistance to decay. The findings offer new insight into plasma effects on fruits and vegetables.

Keywords: Cold plasma; Fresh wolfberry; Nutritional quality; Postharvest physiology; Reactive oxygen metabolism.