Analysis Of The Effects Of Postharvest BTH Treatment On Phospholipid Metabolism And Aroma Of Muskmelon

Muskmelon(Cucumis melo L.cv.Yujinxiang)is a climacteric fruit.BTH treatment can induce the resistance of muskmelon and also effect on the secondary metabolites such as aroma components.Phospholipids are the major constituents of cellular membranes,can be hydrolyzed to be glycerine,fatty acid,phosphoric acid and amino alcohols etc.by phospholipase and then involve in the secondary metabolism of aroma.Muskmelon(Cucumis melo L.cv.Yujinxiang)was selected as raw materials to be treated in BTH.During the postharvest storage,the effects of BTH treatment on enzymatic activities and gene expression characteristics of PLA2,PLC and PLD were analyzed;the influence of BTH treatment on mechanism of the phospholipid metabolism was discussed;and the effects of BTH induced resistance treatment on the phospholipid metabolism substrates,products and enzymatic activities was analyzed.The results showed as following:1.Postharvest BTH treatment to fruits inhibited the degradation of cell membrane;delayed the decrease of fruit hardness,TSS,and Vc TA;reduced fruit weight loss rate,respiration rate and ethylene production during storage.2.Postharvest BTH treatment inhibited the phospholipid components of PC,PI degradation;reduced gene expression and activities of PLA2,PLC and PLD.Sample of BTH treatment showed that phospholipid metabolism products such as PA and fatty acid were significantly lower than control while the degree of unsaturation of fatty acid higher than control.3.Samples of Postharvest BTH treatment showed: a)the release of C6 C9 aroma components through linoleic acid metabolism were reduced;b)the release of C6,C9 alcohol aldehydes and oleic acid metabolized products such as contains butyl,amyl and the most ester derivatives of aroma components through linolenic acid metabolism were inhibited;c)the release of esters such as(Z)-3-Hexenyl acetate,3,6-Nonadienyl acetate,Isobutyl acetate were accelerated.4.The correlation coefficient of the total aroma content from fatty acid metabolism of the samples with ethylene was higher than phospholipid metabolism,was in a significantly positive correlation,and positively correlated with PLA2 activity,negatively correlated with PI,where no significant correlation with other factors.The correlation between ethylene with aroma compoounds from fatty acid metabolism was higher than ethylene with phospholipid metabolism and phospholipid metabolism with the total aroma compounds.There was a significant positive correlation between PLA2 with the release of aroma components,and negative correlation between unsaturated fatty acids and phospholipid metabolism.BTH treatment weakened the correlation among ethylene,phospholipid metabolism and aroma components from fatty acid metabolism.In summary,postharvest BTH treatment could delay the muskmelon fruits ripening and senescence phosphatidic acid.The amount of phosphatidic acid and unsaturated fatty acids could be reduced by the inhibition of phospholipid component degradation,phospholipase activity and gene relative expression;then to inhibit the release amount of alcohols aldehydes aroma metabolized from unsaturated fatty acids.The correlation between ethylene with the aroma components from fatty acid metabolism was higher than phospholipid metabolism,that could infer to the effect of phospholipid metabolism on the release of aroma might be less than LOX metabolism.Ethylene was the key factor of affecting aroma components.Postharvest BTH treatment decreased the correlation between ethylene,phospholipid metabolism with aroma components,and subdued the effects of ethylene and phospholipid metabolism on releasing aroma.