Effects Of GSNO-CS Nanomaterials On The Storage Qualities Of Strawberry And Cherry Fruits

With the continuous improvement of living standards,people's demand for fresh fruits is increasing.Strawberries and sweet cherries are favored by consumers because of their rich taste and nutrition,but both fruits are perishable and metamorphosed fruits.Nitric oxide?NO?and chitosan?CS?are widely used in prolonging the storage lives of the fruits.However,the roles of the combination of NO and CS in fruit preservation have not been reported.In this study,CS nanoparticles?GSNO-CS NPs?encapsulated with nitrosoglutathione?GSNO?were prepared,which could solve the problems of difficult storage and inconvenient transportation of NO,and retain the good preservation characters of CS.GSNO-CS NPs were applied to prolong the storage lives of strawberries and cherries,and the effects of GSNO-CS NPs on the postharvest physiology of strawberries and cherries were explored.In this paper,the"Fengxiang"strawberry and the"Hongdeng"cherry were used as the experimental material.The strawberries were soaked in deionized water?control?,0.5%?w/v?CS,13,26,133 mmol·L^-1 GSNO-CS NPs solution and stored at 25°C.The cherries were immersed with deionized water?control?,0.5%?w/v?CS,60 mmol·L^-11 GSNO and 60mmol·L^-1 GSNO-CS NPs solution and stored at 0°C.These fruits were used to study the effects of GSNO-CS NPs on postharvest physiology and storage of strawberry and cherry fruits.The results showed that,compared with CS treatment,GSNO-CS NPs reduced the weight loss rate and rot rate of strawberries during storage,and increased the firmness,soluble solids?SSC?,and L*values to maintain good quality of the fruits.GSNO-CS NPs reduced the contents of malondialdehyde?MDA?and total phenols,decreased the activities of lipoxygenase?LOX?and polyphenol oxidase?PPO?,thereby reduced membrane lipid peroxidation and browning,and maintained the quality of strawberries.GSNO-CS NPs increased the activities of antioxidant enzymes and reduced reactive oxygen species?ROS?content,thereby alleviated oxidative damage and delayed the senescence of strawberries during storage.GSNO-CS NPs at 26 mmol·L^-1 exhibited the most positive effects than other concentrations.The rot rate of strawberries treated with 26 mmol·L^-1 GSNO-CS NPs was only 28.6%of the control.These results suggested that the effect of GSNO-CS NPs on strawberries depended on not only CS but also GSNO in GSNO-CS NPs.Compared to the CS treatment or the GSNO treatment alone,GSNO-CS NPs reduced the activity of 1-aminocyclopropane-1-carboxylic acid synthase?ACS?,thereby reduced the content of 1-aminocyclopropane-1-carboxylic acid?ACC?,reduced ethylene production by delaying the activities of ACC oxidase?ACO?and LOX,and then delayed the senescence of cherries.GSNO-CS NPs reduced the respiration rate of cherries,thereby reduced the consumption of SSC during storage,and thus reduced the weight loss rate.During storage,GSNO-CS NPs decreased the total phenolic content and PPO activity,which reduced the browning of cherries,maintained the good postharvest quality.GSNO-CS NPs increased the content of reduced ascorbic acid?AsA?and decreased glutathione?GSH?content,maintained low contents of dehydroascorbic acid?DHA?and oxidized glutathione?GSSG?by increasing the activities of the antioxidant enzymes during storage,thereby maintained good redox states and improved the ability to scavenge ROS,reduced MDA content,thereby delayed the senescence and maintained good storage quality of cherries.These results indicated that GSNO-CS NPs fully combined the dual preservation effects of CS and GSNO,and could effectively maintain the qualities of fruits during storage.