| Malolactic fermentation(MLF) is indispensable processing technology for modern wine making. in developed wine making countries, most of the vineries use commercial freeze-dried LAB to inoculate MLF. But in our country, research on this is scarcely. The key pointes are getting high-cell density cultivation and the optimum cryoprotectants. This paper studied on choiceness Oenococcus oeni SD-2a. Taking OD value, living cell count, pH value and survival rate as indexes in the process of fermentation, the experiment had studied cultivation conditions, semi-cultivation method and cryoprotectants. The purpose is to provide experimental basis for craft vacuum freeze-drying of SD-2a. The results indicated:1. Fermentation experiment indicated that the optimal culturing conditions were: culture temperature 25℃, pH4.8, inoculation size 5%.Adjusting the pH value by using CaCO3 during culturing to obtain the optimal pH value.2. With using semi-continuous way, based on the optimal condition, the cell population could obtain over 6.5×1010 cfu/ml, as almost 10 times as before.3. The optimum cryoprotectants were determined by the orthogonal trial and one factor trial, Results suggested that all of nine protectors had some effects on promoting cell count. The optimum cryoprotetants formula for Oenococcs oeni SD-2a was: lactose 2%, L-glutamate 6%, yeast extract poeder 6%, glycerine 1.2v/v .the survival rate was 90%.4. Culture starter quality test, the cell count was decreasing during storage. stored at -20 and 4℃Were better than at room temperature. And had no significant difference .So it was stored at 4℃, and the survival rate kept on 70%.5. We studied the application feature of the culture starter. Compared with traditional fluid culture SD-2a, the speed of MLF by using freeze-drying culture SD-2a was faster, and had lager decrease on total acid and lactic acid, less volatile acid, and lager increase of pH value. It improved the quality of the wine.
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