| The growth and metabolism of non-Saccharomyces cerevisiae can contribute more flavor substances to wine,but its weak fermentation ability and poor tolerance make it unable to participate in alcohol fermentation too much.To solve this problem,in this study,K.marxianus YK screened from grape skin surface was mutated by ARTP mutagenesis technology,and the strains with strong aroma-producing ability were selected.Then,the mutagenic strain was used as the starting strain,which was inoculated with S.cerevisiae in different inoculum proportions at the same time in grape mash for alcohol fermentation,and the changes of yeast number,ethanol Volume fraction and total sugar during alcohol fermentation were monitored,and the kinetics of wine fermentation was analyzed.Finally,the influence of mutant strains on the overall quality of wine was analyzed,and the safety of wine was evaluated.The main research results are as follows:(1)In this experiment,two mutagenesis strains YK-1 and YK-29 were obtained through the preliminary screening of tolerance and the re-screening of aroma-producing ability of the mutagenesis strains.The genetic stability of the mutagenesis strains was tested after five successive passages.The results showed that the two strains had strong genetic stability.Two strains have strong genetic stableility.Two mutagenic strains are applied to wine fermentation,YK-1,YK-29 yielding alcohol is increased by 149%,169%respectively.By quantitative description analysis,mutant strains bring obvious fruit aroma for wine.This research is expected to break the monolithic situation of wine quality,with extensive application prospects.(2)K.Marxianus YK-29 was used as the starting strain,S.Cerevisiae and K.Marxianus YK-29 were simultaneously inoculated into grape mash in different proportions for alcohol fermentation.S.Cerevisiae pure fermentation was used as the control CK.The results showed that the mixed inoculation of K.Marxianus YK-29 and S.Cerevisiae in grape mash could ensure the completion of wine alcohol,and the final total number of yeast could be maintained at 10~8CFU/m L;control group CK alcohol fermentation cycle is 120 h,K.marxianus YK-29 and S.cerevisiae vaccination ratio is K8:1,K 4:1 give essence cycle48 h compared with the control group CK.The Logistic model is greater than 0.9000 for the nonlinear fitting R~2of the data.The model is more accurate quantitative analysis of a certain amount of yeast and ethanol Volume fraction during the alcohol fermentation process;through the validation of the model,the average relative deviation of the cell growth kinetics model was between 1.99-4.25%,and the average relative deviation of the product formation kinetics model was between 4.97-9.64%,both lower than 10%,indicating that the model had high accuracy in data prediction.The study provides theoretical basis for the control of wine fermentation process and industrial production.(3)The Volatile aroma components of wine brewed by K.marxianus YK-29 and S.cerevisiae with different inoculation proportions were analyzed.The results showed that,when the inoculation ratio of K.marxianus YK-29 to S.cerevisiae reached K4:1,there were 41 Volatile aroma compounds in wine;compared with CK,the inoculation ratio of K4:1 and K8:1 can obviously increase the relative content of alcohols in wine,and the alcohol-producing capacity is increased by 122.5%and 122.0%respectively.The analysis of sensory characteristics showed that K.marxianus YK-29 participated in the fermentation of wine,which significantly improved the wine flavor,and endowed the wine with floral,black berry,spice,green,chemical and plant aroma;when the inoculation ratio K4:1 was used,the aroma complexity of the wine was high and the sensory score was high.When the inoculation ratio K4:1 was used,the aroma complexity of the wine was high and the sensory score was high.K.marxianus YK-29 shows excellent aroma-producing characteristics.Inoculation with S.cerevisiae in the ratio of K4:1 can obviously increase the complexity of wine aroma,which has theoretical and practical significance for wine aroma-enhancing brewing.(4)The quality analysis of wine brewed by K.marxianus YK-29 and S.cerevisiae with different inoculation proportions showed that the mixed fermentation wine of K.marxianus YK-29 and S.cerevisiae could ensure the wine to complete alcohol fermentation,and K.marxianus YK-29 with different inoculation proportions had the ability to increase the glycerol content in wine,with the range of 139-179%;at the same time,K.marxianus YK-29 also has a certain alcohol reducing ability.Compared with the control group,the volume fraction of ethanol is reduced by 0.05-0.50%.The results of safety analysis show that the safety indexes of wine fermented by K.marxianus YK-29 are within the international and national limits.The EC content is in a low range,ranging from 1.53±0.06-9.98±0.18 mg/L;OTA detection rate is low,content between 0.15±0.01-0.18±0.01μg/kg,between two substances and inoculation there is no obvious connection.In BA,the tetrame-thylenediamine and 1,5-pentanediamine detection rate were 100%,and the control group ck tetrame-thylenediamine was significantly higher than the treatment group,which was 46.93±0.86 mg/L,K.marxianus YK-29 has significantly reduced the effect of 1,5-pentanediamine.In summary,K.marxianus YK-29 is used in wine fermentation in the premise of ensuring product quality and safety,it is of great significance for the quality of wine quality,which will be used in the later non-Saccharomyces cerevisiae to provide data support. |
PDF Full Text Request