Effects Of Salicylic Acid Treatment Combined With Gas Atmospheric Control On Storage Quality And Physiological Activities Of Wolfberries(Lycium Barbarum L.)

Wolfberry(Lycium barbarum L.)is a valuable traditional Chinses herbal medicine and food.It has developed into emerging sectors of strategic importance in Ningxia Hui Autonomous Region.With high nutrient contents and tender surface,wolfberry is perishable easily during storage.These characteristics limited the capacities of wolfberry for long term storage and long-distance transport.Atmospheric modifications have been widely applied to vegetables and fruit in postharvest,which can extend shelflife of vegetables and fruit.However,atmospheric modifications could also break the redox balance and result in consumption of antioxidant substance.And this will have adverse effect on storage quality.Meanwhile,SA could enhance antioxidant capability to balance the redox state of cell during storage.Therefore,SA and atmospheric modifications present potential for compensating each other.It is expected to achieve better preservation of wolfberry under the hurdle technology.The feasibility of the hurdle technology to extend shelflife of wolfberry at 7 ? and the regulation from SA treatment and atmospheric modification in wolfberry was investigated in the current study.Wolfberry was treated with SA or non-SA solution(distilled water)and stored in three different atmospheric conditions [ambient atmosphere(air),controlled atmosphere(CA),modified atmosphere(MA)].Both of metabolites and enzyme activity can affect the postharvest physiology in wolfberry.Here we measured ascorbic acid(As A),reduced glutathione(GSH),polyphenols,alternative oxidase(AOX)and glutathione reductase(GR)as physiology and quality parameters in this study.Quality attributes were analyzed by principal component analysis(PCA)to distinguish the main indicators of wolfberry quality.The current study clarified the differential metabolism pathways and the interaction between SA treatment and atmospheric modification in wolfberry during the storage.The main research results are as follows:1.Based on the comprehensive evaluation of multivariate statistical analysis,PCA showed that the wolfberry treated with SA+CA processed the shortest distance from the fresh ones after 28 d storage at 7 ?,which proved that the quality of wolfberry in SA+CA was highly maintained.Weight loss(WL),total soluble solids(TSS),firmness(F)and decay index(DI)predominately affected the wolfberry quality during storage while respiration rate seldom affected the wolfberry quality.When SA was combined with atmospheric modifications,there was significant effect on F maintenance,which achieved better effects on WL,TSS,and DI than practiced single method.2.SA treatment and atmospheric modification could regulate the contents of As A,GSH,polyphenols,fatty acids(FA),sugars,organic acids(OA)and malondialdehyde(MDA)to affect the quality attributes including WL,TSS,F and DI.These metabolites were mainly regulated through multiple metabolism pathways including biosynthesis of unsaturated fatty acid pathway,pentose phosphate pathway,galactose metabolism,starch and sucrose metabolism,amino sugar and nucleotide sugar metabolism and pentose and glucoronate interconversions.SA treatment could significantly enhance As A,GSH,and polyphenols contents.Atmospheric modification could significantly inhibit MDA production and promote the biosynthesis of unsaturated fatty acid.Combine with SA treatment with atmospheric modification,polar metabolites including sugar and OA contens were increasing.SA treatment was found to have function on alleviating negative effects of atmospheric modification on As A and polyphenols contents.3.SA treatment could enhance antioxidant activity in wolfberry both by reducing oxidative stress and enhancing reactive oxygen species scavenging ability from antioxidant enzymatic system [superoxide dismutase(SOD)and catalase(CAT)] and non-enzymatic system(As A-GSH circle and polyphenols).Therefore,wolfberry in SA treatment processed higher As A,polyphenols,sugars,and OA contents.Furthermore,wolfberry in SA treatment present better colour quality.WL,TSS and DI were found to be inhibited under Atmospheric modifications through AOX activity activation and RR repression.When SA was combined with CA,there was significant effect on F maintenance and storage quality,which was achieved by unsaturated fatty acid biosynthesis,sugars and OA metabolisms,as well as MDA reduction.