| The variety of Jinxiu yellow peach in Fengxian area of Shanghai is excellent,such as golden yellow,sweet,more sour,flexible meat,round fruit shape,high quality,but its short ripening period,concentrated listing period,short supply period of high-quality fresh yellow peach,transportation difficulties and other problems limit the development of yellow peach.In this experiment,fuzzy comprehensive evaluation combined with response surface was used to optimize the fermentation quality of yellow peach wine,and the best technological parameters of yellow peach wine fermentation were determined.Then the Saccharomyces cerevisiae for yellow peach fermentation was selected from the active dry yeast powder commonly used in the market,and the DNA extraction and identification and fermentation performance of Saccharomyces cerevisiae were studied.Fengxian "Jinxiu" yellow peach was fermented by Saccharomyces cerevisiae fermentation and mixed fermentation of Saccharomyces cerevisiae and non-Saccharomyces cerevisiae.The types and relative contents of characteristic flavor substances in fermented wine were analyzed,and the effects of different yeast strains on the fermentation quality of yellow peach wine were studied.The specific main research indicators are as follows:1.Fengxian "Jinxiu" yellow peach was fermented.Combined with the results of single factor test,taking the fuzzy evaluation results of yellow peach wine as the target,the main factor protruding comprehensive evaluation model was constructed,and the response surface analysis was carried out.The optimum fermentation conditions of yellow peach wine were obtained as follows: peeling of yellow peach by enzyme,initial p H value of yellow peach juice adjusted by citric acid to 4.0,inoculation amount of yeast 5%,fermentation at 28 ? for7 days.The yellow peach wine fermented according to the optimal technological parameters has attractive color,golden clarity,high clarity,refreshing taste,moderate sweet and sour,and rich fruit aroma.2.The commercial yeast samples were extracted by DNA,amplified by PCR,sequenced and compared with the gene sequence in NCBI by 26 S r DNA gene D1/D2 region sequence analysis,so as to realize the molecular biological identification.The three commercial yeasts were all Saccharomyces cerevisiae species.The yeast species were typed by random amplification of polymorphic DNA marker(random amplified polymorphic DNA,RAPD),and it was found that there was little difference in the gene sequences of the three commercial active dry yeasts.The growth curves of different yeasts and their tolerance in different environments were studied,and it was concluded that the growth of four kinds of yeasts needed to adjust the range of p H to 2.0-4.0,sugar content to 0.2%-0.6%,ethanol content to150-400 mg/L,and sulfur dioxide content to 150-400 mg/L during fermentation.3.The selected yeast strains were fermented in yellow peach wine according to two methods: single-strain fermentation and mixed-strain fermentation,using HP-SPME-GC-MS and GC-O to ferment yellow peaches with different yeasts and mixed fermentation The type and content of flavor compounds in wine were determined.The analysis showed that there were 88 aroma compounds.By calculating the OAV value,27 kinds of characteristic aroma compounds were determined.Among them,substances with aroma vitality values greater than20 include ?-citronellol,Z-3-hexen-1-ol,ethyl caproate,and ?-ionone.These substances give yellow peach wine a fruity,delicate,floral and Sweet aroma,together constitute the rich fruity aroma and elegant style of yellow peach wine.Using the sensory system electronic nose and electronic tongue to analyze the differences of different yellow peach wine samples,and combining with PLSR variance analysis to analyze the correlation between sensory attributes and flavor compounds,it can be seen that different fermentation bacteria and different fermentation methods will be in different degrees change the aroma components of yellow peach wine. |
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