Screening,Interaction And Enhancement Of Excellent Yeast And Lactic Acid Bacteria In Shanxi Aged Vinegar

Shanxi aged vinegar was a traditional solid natural fermentation process in which sorghum was used as raw material and daqu was used as a starter for saccharification,liquefaction,alcohol fermentation,acetic acid fermentation and smoked sputum.In this study,the physical and chemical indicators and the number of yeast and lactic acid bacteria were measured in Shanxi aged vinegar during fermentation.The yeast and lactic acid bacteria with excellent performance were isolated and screened,and the interaction between them was studied and used to enhance in the fermentation of Shanxi aged vinegar.The results were following:During the fermentation of Shanxi aged vinegar,alcohol and total acid increaed quickly at first and then fluctuated steadily,alcohol reached to 8.4% and total acid reached to5.12g/100 g finally.The number of yeast increased first and then decreased,reaching a maximum of 2.23×109cfu/m L on the third day of alcohol fermentation.40 strains of yeast were isolated and purified,34 strains were from the jiulao and 6strains from the cupei.To study alcohol-producing?ester-producing?the me Tableolic of flavor substances fermentation characteristics and the tolerance of different temperatures,alcohol content,initial sugar content and organic acid(lactic acid,acetic acid,butyric acid,caproic acid),three yeasts with excellent performance were screened and identified by ITS.The Saccharomyces cerevisiae JL39 had good organic acid metableolism and superior alcohol resistance and the Saccharomyces cerevisiae JL421 had a high-alcohol(7%)? good organic acids ? alcohols and ketones me Tableolism with high tolerance to high temperature,high sugar and high organic acid.The 1608 which grew well under high sugar environment was Candida humilis had high-ester(10.706 g/100 m L),and the me Tableolism of esters and acids were better.These excellent strains provided strain basis for the study of the strains and the quality and efficiency of Shanxi aged vinegar.During the fermentation of Shanxi aged vinegar,the number of lactic acid bacteria increased first and then decreased,reaching a maximum of 3.90×108 cfu/g on the fifth day of acetic acid fermentation.30 strains of lactic acid bacteria(12 strains from jiulao and 18 strains from cupei)were isolated and purified by morphology and16 S r DNA identification as 10 strains of Lactobacillus plantarum,8 strains of Lactobacillus brevis,7 strains of Pediococcus pentosaceus,1 strains of Enterococcus durans,Lactobacillus helveticus,Lactococcus lactis,Lactobacillus fermentum and Lactobacillus amylovoru respectively.In the RAPD study,16 strains of lactic acid bacteria which randomly selected,the same kind of lactic acid bacteria had different types,and the strains had genetic diversity.To study acid,non-volatile acid,acetoin production,the metableolic of flavor substances fermentation characteristics,holesterol lowering,DPPH scavenging,decomposition nitrite beneficial viability and tolerance under different temperatures,alcohol content,acidity,initial sugar content and bile salt concentration.A strain of Lactobacillus plantarum JL7 with excellent performance was obtained,which had high acid,non-volatile acid and acetoin production,and had good organic acid metableolism,strong probiotic viability,and was highly tolerant to the environment.Saccharomyces cerevisiae JL421 and Lactobacillus plantarum JL7 were co-cultured at different inoculation rates.When the inoculation ratio was 1:1,the content of total alcohol and total ester in the co-culture system did not change significantly.The content of total acid and acetoin was obviously higher than others,and the content of non-volatile acid increased significantly,which has increased by175.35% than pure culture of lactic acid bacteria.The content of organic acids increased evidently,with malic acid content of 1.1582g/L,lactic acid content of0.6762 g/L,citric acid content of 0.0767 g/L and succinic acid content of 0.2850g/L.The mass spectrum of ester,acid and alcohol flavors is abundant,and its concentration is obviously increased.The ethyl acetate with fruit aroma increased distinctly by 17.67% compared with the pure culture of yeast,the isoamyl alcohol with apple brandy aroma and spicy taste reached 4.2288 g/L,and the acetoin reached0.7105 g/ L.The Saccharomyces cerevisiae JL421 and Lactobacillus plantarum JL7 were applied to the intensive brewing of Shanxi aged vinegar,and the basic physical and chemical indicators and flavor indexes of the fermentation process were determined.It was found that 5% Saccharomyces cerevisiae JL421 and 5% Lactobacillus plantarum JL7 were added to the alcohol fermentation,and 5% Lactobacillus plantarum JL7 was added during the acetic acid fermentation to increase the quality of Shanxi aged vinegar.The total acid content of the extracting and finished vinegar was 5.08g/100 m L,the non-volatile acid content was 3.38 g/100 m L,the total ester content was5.44 g/100 m L,the total amount of organic acid was 3.4717 g/L,and 33 kinds of the volatile aroma components were detected,the esters total content of was 47.73 g/L,the alcohols total content of was 20.42 g/L,and the acids total content of was 5.29g/L,besides,ethyl acetate(15.15g/L)and phenylacetate(9.3 g/L)with fruit flavor,Isoamyl hexanoate(2.77 g/L)with apple and pineapple flavor,ethyl laurate with peanut aroma(1.07 g/L),isoamyl alcohol with apple brandy aroma(3.89 g/L),soft and sweet rose phenitol(3.18 g/L)and 2,3-butanediol(3.14 g/L),functional substance acetoin(0.72 g/L)and Furfural(26.37 g/L)improved the taste and quality of Shanxi aged vinegar.