Selection On Excellent Strain In Pickles And The Preliminary Study On Direct Vat Starter

As a traditional fermented vegetable food, pickle is very popular for its delicious flavor and rich nutrition. While there are also many problems of its fermentation process, such as a long period of fermentation, instability quality, small production scale and so on. To solve these problems smoothly, we need to shift our attention to artificial fermentation.This thesis focuses on the subject of separating and screening two lactic acid bacteria with fast production rate of acid and strong degradation of nitrate from several kinds of pickles, identifying them as lactobacillus plantarum and lactobacillus casei through API, and then fermenting them by different proportion and optimizing the best proportion as1:1. After calculating the total number of lactic acid bacteria, i found that the culture medium adding tomato juice could be used as enrichment medium of Direct Vat starter by adding different factors:wort,tomato juice, carrot juice. And by exploring centrifugal conditions, I preliminarily found that the survival rate of thalli is the highest under the rotational speed of3000r/min in10minutes, which is determined as the way to obtain high density thalli.Through single factor experiment with different concentrations of different protective agent,4kinds of best protective agents of them are:trehalose, maltose, glycerol, glutamate. And the best combination is determined as the best protective agent for freeze-dried by L9(34) orthogonal experiment:10%milk powder+10%maltose+10%trehalose+4%glycerol+4%glutamate. After directly using the Direct Vat starter in carrot fermentation, I found that it has the same taste as the natural fermentation by measuring PH, nitrite and sensory evaluation. While it could significantly shorten the maturity of pickles.