| The difference in flavor stability during processing and storage of the juice of Rosa roxburghii juice is a key issue affecting product quality.The characteristics of the fruit flavor compounds of Thorn pear juice under storage and processing conditions are analyzed.The variation of aroma components under different heat treatment and storage conditions,and the qualitative and quantitative study of the free and bonded aroma components of the fruit juice of Cili Pear,and the effect of different hydrolysis methods on the aroma-increasing effect of Cili Pear Juice and its bonding Substrate glycosyl species.The main research and results are as follows:1.Analyze and study volatile components of thorn pear juice,and compare the types,relative percentages,and relative molecular weights of volatile compounds extracted from thorn pear juice by different extraction heads,and obtain DVB/CAR/PDMS extraction heads for extracting thorn pear juice.The types of esters are the most abundant and the content is in the middle.The effects on the types and contents of volatile substances and the sensitivity of extraction of pear juice are all shown to be better.Therefore,the most volatile substances extracted from thorn pear juice are extracted.The best extraction head selects the DVB/CAR/PDMS extraction head.On the basis of the Plackett-Burman test,single factor and steepest climbing tests were performed on the extraction time,extraction temperature and sample volume.The results showed that the total peak area of ??the main peak detected by the inferred group was greater than the total peak area of ??the main peak of the visual analysis group.Increased by 12.80%.Finally,the optimum conditions for solid phase micro-extraction of volatile components from thorn pear juice were determined by determining the sample volume 4.5 mL,extraction temperature 45 °C,and extraction time 40 min.Under this condition,more aroma compounds that have a significant effect on thorn pear juice can be detected.2.Through fuzzy mathematics comprehensive evaluation method,the volatile compounds of cili juice were analyzed under different heat treatment conditions,and a total of 65 aroma substances were detected,including esters,olefins and alcohols.The volatile components of heat treatment juices at different temperatures were Show first increase then decrease trend.PCA method was used to statistically analyze the detected odor fingerprint data.The sum of PC1 and PC2 contribution rate reached97.74%,which could reflect the information of the original high-dimensional matrix data better.From the PCA chart,we can see that the 75°C 30 min treatment group had a thorn The aroma components of pear juice differed most from the aroma components of the original juice,but there was no significant difference in the odor components between the treatment group and the original juice at 70°C for 30 minutes.Electronic nose can effectively distinguish the odor changes of different heat treatment thorn pear juice The main component analysis of different heat-treated pear juices can be divided into two main components.The indicators reflected by the first principal component are mainly ethanol and ethyl acetate,which point to esters and olefins,and are highly positively correlated.The largest contribution of the first principal component is ethyl acetate and(Z)-3-hexenyl acetate,the least contribution is isobutyl acetate;the index of the second principal component is mainly dimethyl sulfide,2,5-Dimethyl-4-methoxy-3(2H)-furanone,pointing to other compounds,with dimethyl sulfide,2,5-dimethyl-4-methoxy-3(2H)-furanone,propyl acetate and other highly negative correlation,the second most important contribution of the main component of dimethyl sulfide,is the least contribution of ethyl isovalerate,according to the principal component analysis,for the pear juice aroma substances Substances with greater impact are mainly esters and vinyls.The aroma components of prickly pear juice were different after heat treatment.The species and relative content of aroma components treated at 70°C for 30 min were the closest to the original juice.It was the most suitable condition for the stability of flavor during the hot processing of thorn pear juice.The result was fuzzy.The mathematics comprehensive evaluation results are consistent.3.By dynamically tracking the changes of volatile compounds in different storage conditions of Rosa roxburghii juice,the results showed that there were differences in the types and changes of volatile compounds in the fruit juices of different treatments.The highest content of methyl octanoate was stored at 4°C,and ethyl isovalerate was the lowest,and ethanol,linalool,and methyl octanoate all increased with the prolongation of storage time.Ethyl acetate,?-Decantole oil olein changed little,isovanillyl alcohol and ?-limonene reached the maximum value in the 5th week and then showed a downward trend.The highest content of the pear juice was methyl octanoate at room temperature storage,and the lowest content was ?-elemene.Ethanol,linalool and isovanillin all decreased with the prolongation of storage time after the7 th week.The total content of ethyl acetate,?-decone,methyl octanoate showed a decreasing trend.Alpha-limonene was stable for 4 weeks and showed a tendency of upper body after 4 weeks.In the condition of storage at 36°C,the highest concentration of thorn pear juice is also methyl octanoate,and the lowest is ethyl isovalerate.In addition to ethyl acetate and methyl octanoate,there is an increasing trend along with the prolongation of storage time,ethanol,Linalool,?-bovisole,iso vanillin and ?-limonene all showed a decreasing trend.At the same time,the main aroma substances have different contents under different storage conditions,and the main aroma substances can be better maintained at 4°C.4.A total of 49 kinds of aroma substances were detected after the enzymatic hydrolysis and acid hydrolysis of the pear juice.Among them,31 kinds of aroma substances were explained by the enzyme.The higher contents of the aroma substances were acetaldehyde,stearic acid,and ethyl acetate.Ester,Guaiacol,etc.The substances produced by enzymatic hydrolysis are dominated by alcohols and aldehydes.The acid explains that 24 kinds of aroma substances are released,and the contents of the produced substances are 2,6-di-tert-butyl-p-cresol,puergonone and the like.Mainly olefins,ketones based.According to the analysis of ROAV value,the main aroma substances in the enzymatic hydrolysate of thorn pear juice were more than the acid hydrolyzate.The order of the contribution of the main flavor compounds(ROAV ? 1)was: 3-hydroxybutanal>?-euerol>Genophenol> Hydroxycitronellal;however,no acid was detected in the juice.Through derivatization methods to explore the different hydrolysis method to release the glycosyl composition of the bonded flavor compounds to determine the characteristics of the hydrolyzable bonded compounds,it was initially found that the enzymatic hydrolysis of glycosyl radicals in the linked flavor substance of pear juice is glucose and D.The glycosyl radicals in the acid-bound prickly pear juice-bonded flavor substances are mannose,rhamnose,and glucose.It can be seen that the glycosyl radical in the juice contains glucose,rhamnose and mannose. |
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