Screening Yeast Strains With Degradation Of 5-hydroxymethylfurfural And High Production Of Caramel Compounds And Fermentation Musalais By The Co-inoculation Of The Screened Strains

Musalais wine is a natural alcoholic beverage made from Hotan red grape through juice extraction,concentration and fermentation.It has typical caramel flavor.During the brewing process of Musalais,a large amount of toxic and harmful substances,such as 5-hydroxymethylfurfural(5-HMF),are produced from the concentrated grape juice.In order to further enhance the caramel aroma and degrade the concentration of 5-HMF in Musalais,in this study,Hotan red grape concentrated juice was used as the fermentation raw material.high degradation 5-HMF yeast and high-yield caramel aroma yeast were screened out from 65 strains of yeast isolated from grape and Musalais during the brewing process fermentation.The tolerance experiment of the screened strains was carried out,and the suitable inoculation conditions for co-inoculation strains fermentation were obtained.the suitable co-inoculation strains fermentation mode of Musalais was further studied and verified.The results are as follows:(1)In this study,a detection method for multi-furan substances(5-HMF,furfural,acetyl furan,furaneol and 5-methylfurfural)was established and verified.The results showed that this method had good stability,high recovery,and low detection limit and quantitation limit,and was suitable for the detection of furan substances in Musalais.(2)In this study,the odor activity value(OAV)and the degraded 5-HMF concentration of caramel flavor substances(furaneol,acetyl furan and 5-methylfurfural)in the Musalais fermented by 65 yeasts were analyzed,and the yeast JFB2 with high yield of caramel flavor substance was screened out,whose OAV sum was 4199.36,and the degraded 5-HMF yeast JCY2,whose degradation concentration was 0.840 g/L.As JFB2 and JCY2 were non-saccharomyces,the initial fermentation ability was insufficient.Therefore,sensory evaluation was conducted on Musalais slightly brewed by 65 yeasts.Saccharomyces cerevisiae GFP3 with prominent caramel flavor was screened out as the initial fermentation yeast of JFB2 and JCY2.(3)In this study,JCY2 was subjected to tolerance experiments with different concentrations of alcohol,different concentrations of nitrogen,different concentrations of sugar,different concentrations of 5-HMF and JFB2 was subjected to tolerance experiments with different concentrations of alcohol,different concentrations of nitrogen,different concentrations of sugar to determine the appropriate inoculation conditions in the co-inoculation strains fermentation process.The results showed that the optimal inoculation conditions of JCY2 were as follows: sugar concentration 196 g/L,nitrogen concentration 330 mg/L,alcohol concentration 8%,and 5-HMF concentration 4 g/L;The optimum inoculation conditions of JFB2 were as follows: sugar concentration 196 g/L,nitrogen concentration 140 mg/L and alcohol concentration 8%.(4)In this study,saccharomyces cerevisiae GFP3 and non-saccharomyces(JCY2 and JFB2)were subjected by the co-inoculation strains fermentation of Musalais with sequential inoculation and synchronous inoculation in different proportions.by comparing the sum of OAV of furan substances(furaneol,acetylfuran and 5-methylfurfural),the appropriate fermentation method of Musalais was determined.The results showed that the total OAV of furan-producing substances by sequential co-inoculation strains fermentation was significantly higher than that by synchronous fermentation with different proportions,and the total OAV of furan-producing substances by sequential co-inoculation strains fermentation was 4979.18.Subsequently,the caramel aroma and5-HMF degradation concentration in the slightly brewed Musalais with commercial yeast strain EC1118 were verified.The results showed that the slightly brewed Musalais had strong caramel aroma and the 5-HMF degradation concentration was significant under the sequential co-inoculation strains condition.That is to say,the suitable co-inoculation strains fermentation of mousetraps is sequential co-inoculation strains fermentation,and the fermentation mode not only can highly degrade 5-HMF,but also lays a foundation for enhancing the production of the caramel aroma of the Musalais.