| Flat peach is one of the characteristic fruit in Xinjiang.It is harvested in high temperature and high humidity season,and has the characteristics of rapid ripening after harvest and pericarp damage easily.Cold storage is the most commonly used storage method of flat peach,but long-term cold storage can easily cause chilling injury such as peel browning(PB)and flesh woolliness,which will affect the flavor and commodity value of flat peach.This experiment takes “Yinggeer” flat peach as the test material,the fruit of low temperature conditioning(LTC)groups(LTC synergistic preservative paper(HZ),LTC synergistic preservative(HJ),LTC was used as control(HCK))and cold storage groups(cold storage synergistic preservative paper(JZ),cold storage synergistic preservative(JJ),cold storage was used as control(JCK))were stored at 0±0.5 °C,80 %-85 % relative humidity.The changes of storage quality and fatty acid content of flat peach were studied;The changes of the types and contents of aroma substances and the activities of enzymes related to aroma were also studied;The main influencing factors of PB were analyzed by path analysis and correlation analysis;Redundancy analysis(RDA)and correlation analysis were used to analyze the correlation among fatty acids,key enzymes and aroma substances,and principal component analysis(PCA)was used to evaluate the fruit quality comprehensively,the best preservation method was determined.It provides theoretical basis for enhancing storage quality and flavor of flat peach,and practical reference for the application of preservation technology of flat peach.The main research results are as follows:(1)JZ,JJ,HZ and HJ four treatments delayed the decrease of soluble solids content(SSC)and titratable acids(TA),inhibited the increase of malondialdehyde(MDA)content and relative electrolyte leakage,decreased the activities of polyphenol oxidase(PPO)and peroxidase(POD),and increased the activities of catalase(CAT),thus reduced the increase of PB index and delayed the decrease of fruit firmness.A total of 10 fatty acids were identified and quantified in all stored fruit under cold storage groups,including 6 kinds of saturated fatty acids(lauric acid,palmitic acid,margaric acid,stearic acid,arachidic acid and lignoceric acid)and four kinds of unsaturated fatty acids(elaidic acid,oleic acid,linoleic acid(LA)and linolenic acid(Ln A)).It was one more lignoceric acid than in LTC groups.Correlation analysis showed that PB of 4 treatments was significantly positively correlated with the MDA,relative electrolyte leakage,PPO and POD.Path analysis showed that MDA,relative electrolyte leakage,CAT,POD and PPO were the main factors affecting PB of flat peach in 4 treatments.(2)Compared with other treatments,HZ treatment had the largest variety of aldehydes,alcohols,esters and lactones,and the highest content of aroma substances in flat peach.A total of 67 aroma substances were identified in peach fruit,aldehydes were the most abundant,followed by esters and alcohols,but a few lactones,ketones,acids,hydrocarbons and others.A total of 59 aroma substances were identified in LTC groups,including 17 aldehydes,13 esters,10 alcohols,4 lactones,2 acids,3 ketones,5alkenes,2 alkanes and 3 others.A total of 50 aroma substances were identified in cold storage groups,including 17 aldehydes,6 alcohols,11 esters,3 lactones,4 ketones,2 acids.The maximum Lipoxygenase(LOX)activity in LTC group was always higher than that of the cold storage groups.The overall LOX activity levels of HZ and JZ treatments were higher than those of HJ and JJ treatments,respectively.(3)The effects of LA and Ln A on total aroma contents of fruit in cold storage groups and LTC groups may be greater than those of key enzymes.The fruit quality results of PCA evaluation 4 treatments showed that HZ>HJ>JZ>JJ.The quality of LTC group was better than that of cold storage group.Under the same treatment,the fruit quality of preservative paper was superior to the preservative. |
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