Screening Of Thermostable Ester-producing Yeast In Maotai-flavor Fermented Grains And Daqu And Research On Its Production Of Zaozao Liquo

Stacking fermentation is a unique process of maotai-flavor liquor in baijiu making.Piled higher temperature can inhibit the growth of yeast breeding,have inhibitory effect on alcoholic fermentation.High temperature resistant yeasts can reduce the trouble and cost caused by cooling in alcohol production.Therefore,the breeding and research work of high temperature resistant yeasts are mainly focused on Saccharomyces cerevisiae,while the research on high temperature resistant ester producing yeasts is very little.In addition,China’s baijiu industry produces a large amount of distiller’s grains every year.The production of distiller’s grains by distiller’s grains can be carried out on the basis of the original equipment of the enterprise without additional equipment.It is feasible to make full use of nutrients and flavor components in distiller’s grains and reduce the waste of resources,which has certain economic value.This study uses five different culture medium,from maotai-flavor daqu and fermented grains in the fine screening yeast,based on physiological and biochemical test,molecular biology identification,tolerance test and solid-state fermentation test choose 1 strains resistant to high temperature and high yield of ester yeasts applied to distiller’s grains wine production.The main research contents and results are as follows:(1)82 yeast strains were isolated from Maotai-xiang fermented grains and Daqu by five different media.Two high temperature resistant and ester producing yeast strains,named P2 and W8,were obtained by high temperature screening,TTC method and fermentation test.P2 was Wickerhamomyces Anomalus and W8 was Pichia fermentans by morphology and 26 S rDNA.(2)The physiological characteristics of strain W8 and P2 were studied.The results indicate that,the optimum growth and fermentation temperature of P2 was 34 ℃ and p H 4.5,and that of W8 was 38 ℃ and p H 4.0.Temperature and p H had greater effects on P2 and W8,while inoculation amount had less effect on growth curve and fermentation curve.(3)The resistance of yeast strains to fermentation by-products was studied.The alcohol resistance of P2 and W8 strains was 18%(V/V)and 20%(V/V),respectively.P2 strain had a salt tolerance of 7.0% and could be fermented in 60%(W/W)glucose solution.W8 has a salt tolerance of 11.0% and can be fermented in a 65%(W/W)glucose solution.Two strains of yeast to acetic acid,glycerin and lactic acid has a certain tolerance;The results show that,explores the high temperature resistant characteristics of the two strains of yeast tolerated 56 ℃ high temperature,and 46 ℃in malt syrup(12.0 °Brix)fermentation culture medium,P2 alcohol volume fraction of 5.8%vol,project.it alcohol volume fraction of 6.0%vol.(4)The effects of single strain inoculation,mixed inoculation and sequential inoculation were studied by different inoculation and fermentation methods.The results showed that the fermentation capacity of single inoculation was 1.21-1.47g/m L higher than that of mixed inoculation and sequential inoculation.The p H value of single strain inoculation was consistent with that of mixed inoculation and sequential inoculation.The results of flavor substances in fermentation liquid showed that the phenylethyl acetate obtained by the pure fermentation of abnormal Wickham’s yeast was 1.96,1.61 and 2.19 times higher than that of the pure fermentation of pichia pastoris,mixed inoculation and sequential inoculation,respectively.Compared with the other three inoculation fermentation methods,the ester content of abnormal Wickham pure fermentation was the highest(57.48%).This was consistent with the detection results of 10 L solid fermented wine samples,and the abnormal content of esters in Pure wickham fermentation was the highest.(5)Application in the winery screening for high temperature resistant high ester’s wine yeast production.Results show that the P2 fluid produced seeds by 5.0%(v/m)35 L with 45 kg to 700 kg middle wine,700 kg without seed liquid’s wine 23 kg;The liquor yield increased from 6.57% to12.90%;By GC-MS analysis,the experimental group contained more esters,ketones and alcohols than the control group.(6)Production of distiller’s grains wine,through professional staff and the national baijiu and wine tasting processed food quality supervision and inspection center for testing.The results show that it’s distiller’s grains wine can meet the demands of maotai-flavor liquor "superior" the physical and chemical indicators.This suggests that Wickerhamomyces anomalus has a great application prospect in utilization of distiller’s grains and realizing green economic effect.