| The quality of blueberry wine mainly depends on the raw blueberry and fermentation process,and the yeast used is one of the main factors in the fermentation process.Due to the long-term dependence on general yeast for fruit wine yeasts,to a certain extent caused the homogenization of blueberry wine products.In order to reflect the quality characteristics of blueberries,highlight the special flavor of blueberry wine,this study selected the yeast from the peel and natural fermentation process of local blueberries.and the effects of different yeasts on the quality of blueberry wine were studied.Finally,dry yeast products were obtained.The specific results of this study are as follows:1.19 strains of yeast were isolated and purified from blueberry natural fermentation broth and blueberry peel.Two yeasts were isolated from blueberry peel and 17 yeasts were obtained from blueberry natural fermentation broth.After preliminary screening and rescreening,F6 and F7 were finally selected.,and F6 and F7 were identified as Saccharomyces cerevisiae.2.The effects of different yeasts on the quality of blueberry wine were studied.Three kinds of blueberry wine samples were obtained by fermentation of blueberry wine made with yeast F6 and F7 as well as the control Laffort wine yeast.The results showed that the fermenting force of the F6 was slightly stronger than that of the F7 and the control yeast,while the F7 had a weaker acid-reducing ability.By measuring the change of color difference after the fermentation of blueberry wine and after 90 days of storage,it is found that among the three wine samples,F7 has the greatest influence on the L* value of wine,and a*,b* of F6 and F7 both increased.The effects of different yeasts on the flavor of blueberry wine were analyzed by electronic tongue,electronic nose and GC-MS.The results of electronic tongue showed that F7 has more richness of taste than F6 and control yeast,while F6 and control yeast are more acceptable.The results of the electronic nose test showed that the F6 and F7 wine scent were relatively close compared to the control wine sample,while the odor of F6 and F7 is close and different.The results of GC-MS showed that 24,17 and 22 substances were isolated from the control wine sample,F6 and F7.The main aroma components of F6 and F7 wine samples were phenethyl alcoholl with rose aroma,and the main body aroma of F6 is more prominent.The esters was more abundant in the F6 wine sample than F7,which also confirmed the results of the the electronic nose.Finally,after comprehensive comparison,F6 yeast,which has better acid-reducing ability,less influence on the color of blueberry wine,softer taste and more prominent flavor was selected to make into dry yeast.3.The culture conditions of F6 yeast were optimized.The optimal culture temperature of F6 yeast is 28?,and the results of F6 yeast medium formula are: yeast extract powder 14.864g/L,peptone10.535g/L,glucose 43.498g/L,KH2PO4 2.906g/L.The F6 dry yeast was made by vacuum freeze-drying method and the protectant of F6 is prepared by mycose and skim milk powder in 1:1 dissolved in 3 timestotal weight of sterile water,the ratio of protective agent to slime is 2:1.Under this condition,F6 dry yeast was light brown with typical yeast odor,the viable cell count was 6.93×1010 cfu/g and the moisture content was 4.6%. |
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