Inhibition Of Yellowing Of Broccoli By Trans-2-Hexenal And Preparation Of Fresh-Keeping Products

Broccoli(Brassica oleracea L.var.italica Planch)is also called green cauliflower,which is favored by consumers due to its rich nutritional value and is known as the"crown of vegetables".Broccoli is easily to yellowing during post-harvest storage and its nutritional quality decreases,which seriously affects its commercial value.Therefore,it is extremely important to find a safe and effective method to control the yellowing of post-harvest broccoli.Trans-2-hexenal is a volatile compound,which naturally exists in many plants and has inhibitory effects on many pathogenic bacteria.Moreover,It has been listed as a food additive,but there is little research on its application in post-harvest preservation of fruits and vegetables.Herein,‘Hanxiu’broccoli was selected as the experimental material.The optimal treatment conditions for trans-2-hexenal to inhibit the yellowing of broccoli were obtained by screened of fumigation concentration and fumigation time.Then,the color index,chlorophyll and carotenoid contents,chlorophyll degradation and carotenoid synthesis key enzymes and related genes of broccoli were determined.The effect of trans-2-hexenal on the etiolization of broccoli was initially explored,which provided a theoretical basis for exploring efficient and safe etiolization inhibitors of broccoli.At the same time,the selection of appropriate embedding materials for embedding trans-2-hexenal provided technical support for its application in post-harvest storage of broccoli.The main findings are as follows:(1)The optimal treatment condition of trans-2-hexenal was determined as 18μL/L fumigation for 7 hours by screened of fumigation concentration(16μL/L,18μL/L and 20μL/L)and fumigation time(6 h,7 h and 8 h).After fumigation,the broccoli could be stored at 20℃for 3 days to maintain a good commercial value.(2)Trans-2-hexenal fumigation significantly inhibited the decrease of chlorophyll content,decreased the activities of PPH and MDCase in the chlorophyll degradation pathway,and decreased the expression of chlorophyll degradation-related genes Bo SGR,Bo HCAR,Bo PPH,and Bo PAO.The accumulation of carotenoid content and the gene expression of Bo PSY and Bo LCYE in the carotenoid synthesis pathway were inhibited,thereby,inhibited the etiolation of post-harvest broccoli.(3)The gel containing trans-2-hexenal prepared from AGAR and Kedelan gel can reduce the L~*,a~*and b~*value of the gel,increase the hardness of the gel.The porous structure formed in the gel plays a sustained release effect on trans-2-hexenal.The prepared trans-2-hexenal gel can delay the browning of broccoli.