DVS Fermentation Agent Of Sour Liquid Of Sweet Potato Starch

To optimize the enrichment medium of Lactobacillus paracasei that can flocculate the starch. Screen the carbon, nitrogen, and nutritional factors in based selected medium by the single factor and orthogonal test, after research confirmed its enrichment medium was: 0.5% sucrose, 1% yeast extract, 10% Potato juice.Under the conditions, Lactobacillus paracasei viable count was cultured by 36h at 30℃reached 2.99x109cfu/mL, and the flocculating activity reached 82.66%.Using automatic fermentation tank for the cultivation conditions of Lactobacillus paracasei were optimized. To optimize the temperature, time, pH value and the inoculation test. The results showed that Lactobacillus paracasei optimum temperature is 25℃, the best incubation time for the 36h, the best initial pH value of 6.5, the best inoculation 3%. After that culture conditions after training, the maximum bacteria number reached 3.52x109cfu/mL, and flocculating activity remained stable.By studying the different centrifugal rotation and centrifugal time on the centrifugal rate of Lactobacillus paracasei to determine the best centrifugal conditions for bacteria: 6000r/min centrifugal and10min, 95.45% was collected by centrifugation.By studying the thickness of the sample and the concentration of skim milk as freeze-dried based protective agent, the effects on survival Lactobacillus paracasei of freeze-dried bacteria to determine the optimal thickness was 0.5cm, and the optimal skim milk concentration was 10%.By the different single-factor screening on protective factors, to select lactose, and glycerol as a complex freeze-dried protective agent for orthogonal optimization, to determine the composition of the freeze-dried protective agent: 10% skim milk, 2% glycerol and 1% lactose. When the thickness of the sample freeze-dried, in the freeze protection compound protective agents, freeze-dried Lactobacillus paracasei survival rate was 79.17%, the number of freeze-dried powder of viable was 2.66x109cfu/mL.Freeze-dried ferment preserved 4 months later in the refrigerator at 4℃constant temperature, the number of live and flocculating activity were no significant changes, showing the relatively stable performance of storage.