Screening of Dominant Strains in Lunan Sufu and Optimization of Pre-Fermentation Technology
Taking Yunnan Lunan sufu as the research object,the dominant strains in the blank samples are isolated and purified,and the dominant strains are used for single strain and double strains mixed fermentation of sufu,and the protease activity is used as the evaluation index for the optimization of pre-fermentation process,aiming to improve the quality of Lunan sufu. Research results:the five dominant strains obtained are used for fermentation of sufu inoculated with single strain and double strains,it is determined that the protease activity on the 3rd day of fermentation is 160.5 U/g and 156.05 U/g for inoculation with single strain R1 and R2 respectively,and then R1 and R2 strains are selected for mixed fermentation,it is found that when R1:R2 is 2∶1,the protease activity is the highest of 197.17 U/g on the 3rd day of fermentation. R1 and R2 strains are identified as Geotrichum candidum and Mucor nidus respectively by morphology and molecular biology. On the basis of single factor test,response surface analysis is used to optimize the concentration of bacterial solution,inoculation amount,fermentation temperature and fermentation time.Taking protease activity as the index,it is determined that the optimal fermentation conditions are bacterial solution concentration of 106 CFU/mL,inoculation amount of 2％,fermentation temperature of 28.3 ℃,and fermentation time of 3 d. At this time,the protease activity reaches 215.5 U/g. This study can provide some theoretical guidance and data references for the improvement of the quality of Lunan sufu.
万方数据
维普
