Screening And Identification Of Quality Yeast Strains In Daqu Of Shanxi-Super Vinegar And Research On Fermentation

In the production of Shanxi-super vinegar, Daqu instead of grain, it is an important factor to determine the quality and yield of Shanxi-super vinegar, and Yeast is one of the main functional microorganism in Daqu of Shanxi-super vinegar, which plays important role in the fermentation of vinegar, so screening superior yeasts from Daqu to reinforce it,in order to solve problems in the brewing process of Shanxi-super vinegar, for example:the rate of utilization of materials is low; the cycle fermentation is long; the yield of vinegar is low; the quality of vinegar is not stable. This test plan to screen yeasts from Daqu of Shanxi-super vinegar and pontificate preliminary, From the two aspects of Test reducing liquor and esters to study them, explore their ability to resistant acid, high temperature, high sugar, ethanol; selected good performance of the yeast strains; Using the API 20 C AUX system and their part of it by means of molecular biology identification; By headspace gas chromatography and mass spectrometry (HS-GC-MS) technology analysis the volatile aroma components of alcohol fermentation liquor which fermented with high ester produced yeast and Daqu. Using the selected of excellent yeast to strengthen daqu, produce vinegar in the laboratory conditions, and a testing was made for their physicochemical parameters, to study the strengthening effect.Nineteen strains of yeasts were screened from the Daqu of Shanxi-super vinegar. Through morphology and biochemistry, all these strain yeasts were included:Yl and Y7 are Kloeckera; Y4,Y8,Y16 and Y17 are Saccharomyces; Y6 and Y9 are Hansenula; Y14 and Y15 are Pichia; the rest of nine strains are Candida.In the 19 strains of yeasts,8 strains are liquor-making yeast, with Angel highly active saccharomyces cerevisiae (5.0%) for comparison, from the wine Y4 (5.2%), Y8 (5.0%), Y16 (4.8%), Y17 (4.4%), the production capacity is relative taller; 11 strains are ester produced yeast and their fermenting power is very weak, the ability of producing ester is significantly higher than the angel bear dried yeast (11.10 g/L), the capacity to produce ester of Y14, Y2, Y18 are strongest and their ester yield amounts were 36.05 g/L,33.75 g/L,33.47 g/L.The isolated strains can tolerate pH2.0 acidic environment; the ability of Y4, Y8, Y16 and Y17 resistance ethanol and high temperature is high, they can tolerate the environment of 16% alcohol and 45 ? high temperature; the rest of the strains can tolerate the environment of 10% alcohol and 40 ? high temperature; 11 strains of ester produced yeasts can tolerate 50% sugar content, which is better than liquor-making yeasts(40%).Through the API 20 C AUX system, Y4?Y8?Y16?Y17 were identified as Saccharomyces cerevisiae 1, they are same with angel highly active saccharomyces cerevisiae, high ester produced yeasts were not tested; Further using 26 s rRNA D1/D2 section sequence analysis the high ester produced yeasts, the result shows:the Y2, Y18 belongs to ethanol Candida yeast Candida ethanolica, Y14 belongs to the helmet Pichia manshurica.Y2, Y14, Y18 were to be the brewery using fortified Daqu, Alcohol fermentation broth was determined as 9.65%,9.59%,9.51%, compared with the control (9.42%) were significantly improved. Throng aroma sensory evaluation, we can found that Y18's aroma was the best, Y18 had fresh fruit and Uniform wine; semi-quantitative analysis of the fermentation broth aroma components by HS-GC-MS, the result telled us the kinds of aroma components increased, the various components were improved to a certain extent, especially the content of esters were significantly improved, the volatile gas content was determined as 18.75%,26.12%,18.31%, and it was 12.92% higher than the control.Further using high ester produced yeast Y2, Y14, Y18 single strain and composite fortified Daqu, under laboratory conditions to vinegar, total ester in vinegar was significantly increased; three strains Y2, Y14, Y18, were enhanced to improve the total ester content:32.8%,40.5%,25.7%,51.1%; The total acid content increased by 3.48%,1.61%,7.49% and 1.61%; The non-volatile acid content of vinegar fermented with Y18 and Daqu is the same as the contrast, the rest of groups were reduced by 7.78%,12.22% and 7.78%; The sugar content of vinegar fermented with Y18 and Daqu increased by 2.31%, the rest of groups were reduced by 3.08%,3.85% and 3.08%; The amino nitrogen content of vinegar fermented with Y12 and Daqu increased by 3.27%, the rest of groups were reduced by 4.58%,0.65% and 4.58%.To sum up, liquor-making yeast strains screened from Daqu of Shanxi-super vinegar are accharomyces cerevisiae and are same with angel highly active saccharomyces cerevisiae; The kind of ester produced yeast is more, such as Kloeckera, Hansenula, Pichia and Candida. Using high ester produced yeast and Daqu ferment vinegar, the total ester and total acid content in vinegar increased significantly false silk saccharomyces, pichia, kloeckera, han saccharomyces, etc, will be high ester yeast with daqu fermentation vinegar, vinegar of esters and total acids content increased significantly, The part of non-volatile acids, sugar bacteria and amino nitrogen content reduce.