Study On Freeze-Dried Technology Of Probiotics And Its Application In Active Goat Milk Powder

Probiotics have many healthy function, such as preventing dysentery, soothing lactose intolerance and allergy , strengthening human's immunity, reducing serum cholesterol and preventing cancer. Food must have enough quantity probiotics to develop its healthy function. So the method of multiplication of probiotics and its application in the food is one of developing directions in the modern food industry .e biological characteristics, the growth-promoting method and freeze-dried technology of lactobacillus bulyarious, streptococcus thermophilus and Lactobacillus acidophilus were studied systematically, and selected corresponding freeze-dried protectants, which the viable bacteria counts of freeze-dried powder reach above 1011 cfu/g. Adding freeze-dried powder of Lactobacillus acidophilus into goat milk powder by the dry blending method can develop active goat milk powder containing probiotics, which have quite good storage quality and stability.The main conclusions are as follows:1. LSZ can produce stable fragrant and acid substance, and its viscosity is reasonable. So it is fit for freeze-drying.2. The skimmed milk culture medium including 5% mandarin orange and 1.0% yeast extract have an evident growth-promoting function for stretocossus thermophilus. The skimmed milk culture medium including 5% mandarin orange, 0.3% liver extract, 10.0% tomato juice and 1.0% yeast extract have an obvious growth-promoting function for lactobacillus bulyarious. The optimum compose of growth-promoting substances of Lactobacillus acidophilus in 11% skim milk are 0.5%(M/V) yeast extract, 5%(V/V) tomato juice, 5%(V/V) mushroom extract, 12%(V/V) carrot extract and 5%(V/V) malt extract. Under this condition its viable bacteria counts can reach 5.46×109 cfu mL-1.3.The better medium of mixed lactobacillus bulyarious and streptococcus thermophilus is the neutral protease's enzymatic hydrolysate of skimmed milk .The optimum cultivating temperature making freeze-dried bacteria powder is at 30℃. The optimum centrifugal conditions is ten minutes at 5000r/min, and its survival rate can reach 94.32%, and the viable bacteria counts of freeze-dried powder can reach 3.5×1011 cfu/g.4. The optimum compose of freeze-dried protectants of lactobacillus bulyarious and streptococcus thermophilus are 10% skimmed milk, 0.5%Vc, 0.5% monosodium L glutamate, 1.5% gelatin . And those for lactobacillus bulyarious are adding 5% glycerol, 2% maltodextrin, 5% sucrose in the basic freeze-dried protectants.5. The suitable technology adding lactobacillus bulyarious into goat milk powder are mixing 15-25mins at below 28℃, relative humidity below 50%.When the active goat milk powder including probiotics LA5 preserve for one year at room temperature, its viable bacteria counts still maintain about 108 cfu/g, and the storage quality is good.