Study On The Effect Of Combination Yeast Fermentation On The Quality Of Red Dragon Fruit Wine

Dragon fruit has a large planting area,high yield and high quality in China,but the way of eating is single and the intensive processing is insufficient,resulting in a lot of waste of fresh fruit.Dragon fruit wine fermented from red dragon fruit in Luodian not only greatly extends the market supply period,but also perfectly combines the nutritional value of dragon fruit with the health care function of the wine.However,dragon fruit itself does not contain flavor compounds such as organic acids and esters,so the dragon fruit wine produced is often difficult to meet the needs of consumers due to lack of flavor.In order to improve the flavor complexity and quality of dragon fruit wine,torulaspora delbrueckii PRELUDE and NS-D were applied to the pure and combined fermentation of red dragon fruit wine.Based on the physiological and biochemical characteristics and fermentation characteristics,the effects of non-Saccharomyces cerevisiae PRELUDE,NS-D and Saccharomyces cerevisiae were studied.The main research contents,results and conclusions are as follows:1)Physiological characteristics of four yeasts:The results showed that the tolerance of alcohol,sugar,SO₂and temperature of Saccharomyces cerevisiae RB2 and X16 were better than those of non-Saccharomyces cerevisiae PRELUDE and NS-D,but the OD value of PRELUDE and NS-D was higher than that of RB2 and X16,PRELUDE and NS-D at 4-8?it has good tolerance to low temperature.At the same time,the ability of four kinds of yeast to produce?-glucosidase was compared.After 48 hours of culture,the growth of four kinds of yeast on cellobiose medium were as follows:the number of colonies of Saccharomyces cerevisiae RB2 and X16 was less,the morphology was smaller,the growth rate was slow,the ability of producing?-glucosidase was weak,the ability of producing ?-glucosidase of PRELUDE was the best,followed by NS-D.2)Torulaspora delbrueckii(PRELUDE and NS-D)and Saccharomyces cerevisiae RB2 and X16 were used for pure fermentation and mixed fermentation of red dragon fruit wine respectively,and the flavor components produced by fermentation were compared.The results showed that PRELUDE and NS-D had low alcohol production ability,but they could increase the pH of fermentation broth and had the ability of biological acid reduction.Gas chromatography mass spectrometry(GC-MS)was used,The aroma components of 8 groups of red dragon fruit wine samples were detected by GC-MS,and 24 main aroma components were detected.Among them,high concentrations of phenylethanol,ethyl lactate and ethyl sunate were detected in the fermentation broth of PRELUDE and NS-D,and only 3-methyl-1-pentanol was detected in the fermentation broth of PRELUDE and NS-D.In the further PCA analysis and sensory evaluation of aroma components,the mixed fermentation of PRLUDE and RB2 could increase the type and content of esters in the wine,enhance the fruit flavor and flower flavor of the wine,and improve the flavor of red dragon fruit wine.3)The fermentation process of red dragon fruit wine was optimized by single factor and response surface methodology(RSM)experiments,with inoculation interval,inoculation ratio,initial sugar content and initial pH as change factors,sensory score and beet red pigment content as detection indexes.The best formula was as follows:the interval of inoculation was 2 days,the proportion of inoculation was PRELUDE:RB2=2.2:1,the optimal initial sugar content was 24.5°Bx,yeast dosage was 5%,sodium bisulfite dosage was 25 mg/L,fermentation temperature was 16?for 14 days.The content of beet red pigment was87.86 mg/L,the alcohol content was 12.3%vol,and the sensory score was90.83.The red dragon fruit wine had bright red color,rich aroma,moderate sweet and sour taste,and mellow aroma.