Development And Application Of Compound Vegetable Fermentation Agent

The purpose of the research into compound vegetable fermentation agents is to develop the vegetable fermentation agents by modern biotechnology which can improve quality of traditional fermentation food and develop flavor-friendly, sour-britte and ready-to-use vegetables, thus making purebred lactic acid-fermention vegetables expanding from industrialization to families. The purpose of this study is to select superiority lactic acid bacteria and develop high quality solid vegetable fermentation agent by compounding different fermentation agents.The study separated 18 bacterium from 7 kinds of first-class Chinese cabbage, of which, the L1、L5、L12 strians with high sour-producing and well-tasting features were used. The compounding experiment showed that the optimal ratio of L1:L5:L12 was 1:1:1, under this condition, the fermentation period is 14 days, with pH 3.11. The finished product is sour-rich, refreshing-tasty, milky-white with moderate brittleness.The result of fermentation medium optimization:Sucrose 9.59%, Yeast extract 2.28%, Dipotassium hydrogen 0.11%, Ammonium citrate dibasic 0.2%, Sodium acetate trihydrate 0.5%, Magnesium sulfate 0.058%, Manganous sulfate 0.025%, Tween-80 0.05%. Under the optimization fermentation medium, the densities of L1, L5 and L12 can reach 5.2×109 cfu/mL,4.6×109 cfu/mL, and 4.1×109 cfu/mL, which were ten times higher than those of unoptimized ones. After centrifugation at 6000rpm for 10min, is and the survival rate reaches 98.31%,96.22%, and 94.89% for L1, L5 and L12, respectively.In the optimization process of freeze-drying protectants for vegetable fermentation agent, the optimal concentration of single protectant was determined firstly; then the effects of each protectant on the cell viabilities were studied by Plackett-Burman design, which showed that skimmed milk, glycerol and VC had significant effects. Finally, the optimum formula were determined by steepest ascent tests approaching the optimal respose regions and response surface methodology, with the cell survival rate L1 85.01%, L5 84.25%, L12 81.37% and bacterium amounts in the vegetable fermentation agent at 4.86×1010cfu/g. The shelf life of the fermentation agent can reach 12 months.Dosage of compound vegetable fermentation agent is 6.6g compound vegetable fermentationagents per 50kg Chinese cabbage. The sensory indexes were better than any other brand.