Fermentation performance of yeast Sy22 isolated from sourdough

In order to get good dough fermentation strains,five yeast strains isolated from fermented sourdough from Inner Mongolia of China were screened according to their growing performance.Among the 5 strains,strain Sy22 showed the best growth during dough fermentation process.Strain Sy22 was identified as Saccharomyces cerevisiae according to its morphological,physiological and biochemical properties as well as 26SrDNA of the D1/D2 sequence data.Fermented at 30°C for 12 h,respectively,the dough fermentation performance of strain Sy22 as well as the combination of strain Sy22 and Lactobacillus paralimentarius 412 dough fermentation performance,the number of viable cells were studied.The results showed that,after single yeast strain fermentation,dough pH decreased from 6.07 to 5.36,its titratable acidity was increased from 3.6°T to 5.02°T and a fermenting power from 0to 1.32%(calculated as release volume of CO 2).Combined strains fermentation sourdough had a decreased pH from 5.58to 3.85,and its titratable acidity was increased from 5.24°T to 14.02°T,together with a fermenting power from 0to 1.79%,The number of viable cells was 8.2×10 8 CFU / g for strain Sy22,and 9.6×10 9 CFU / g for L.paralimentarius 412.The results also showed that the yeast strain Sy22should be very promising for the use as sourdough starter in steamedbread making,and could be involved in the fermentation of the sourdough.Its combination with L.paralimentarius 412was found to have good fermentation capacity,and showing a good symbiotic between them.