| As one kind of probiotic bacteria, Lactobacillus acidophilus has itsimportant function on the host for its health benefit and prophylaxis disease,and it has become a hot subject in the field of dairy science. In this subject, thebiology characteristic of Lactobacillus acidophilus and the symbiosis withStreptococcus thermophilu were studied. The fermented milk was started byLactobacillus acidophilus and Streptococcus thermophilus in 9 kinds oftechnological process. Through the orthogonal experiment, the best productprocess was gained. The ability of Lactobacillus acidophilus to reduce thecontent of total cholesterol in blood serum was studied.Cultured in the 11% NFM substrate, Lactobacillus acidophilus had agood ability to produce acid, with 800T titratable acidity and about7.9×109cfu/mL quantity of Lactobacillus acidophilus. It could survive in thelow pH 2.5 and there was 87.1% livability after 2h. It not only survived in 3.5,4.5, and 5.5 pH, but also keeped high amount. That indicated thatLactobacillus acidophilus could endure low pH very well. And it could endure0.5% bile salt and 6% salt. 50% cholesterol could be assimilated by thisLactobacillus acidophilus. It had a good ability to hydrolyze protein, makingamino acid rising from 120μg/mL to 150μg/mL.Through the biology characteristic study, the Lactobacillus acidophilusshowed a good biology characteristic. It could survive in the bad condition andpass the gastrointestinal condition successfully. So it was beneficial to humanhealth. We can imply it into manufacturing fermented milk.The speed of producing acid was improved, and the pH was decreasedwhen it was fermented by Lactobacillus acidophilus together withStreptococcus thermophilus. They showed a good symbiosis when fermentedtogether.Through the orthogonal experiment, we gained the best processparameters to produce the fermented milk. It was 40 ℃fermentingtemperature, 8% sugar content, 4% pitch rate and 1:4 proportion of...
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