Studies On Screening Of LAB Isolated From Samples Gathered From Xinjiang Minotory Families And On Pilot Experiment Concerned

From the surrounding areas of the city of Urumqi in Xinjiang and Yili region,26 samples of dairy products were collected. After separation and purification, 33 lactic acid bacteria(LAB)were obtained. By means of single strain and combined strains of fermentation in milk ,as well as that various aspects of assessment were carried out,finally three stain(stwo groups)were determined. They were: E-4 bacillus, D-2 streptococcus, and E-2 bacillus. These combination of the two yogurt fermented by these two groups of LAB were preserved for 14 days, and pH,total acidity,viscosity, as well as the number of viable cells was detected, and the taste was evaluated and found that E-2 bacillus: D-2 streptococcus maintained a good flavor and a less extent of acidification during storage. They were suitable to be used as commercial starter.Pilot experiments of E-2 bacillus: D-2 streptococcus was carried out.Factory conditions and laboratory conditions were both considered and adjustment was made. The final parameters of the process was as follows:the fermentation temperature was 42℃, the lactic acid bacteria was activated in the milk medium containing 10% tomato juice,when making prelude,the ratio of the two kinds of milk fermented was 1:1(V/V),inoculum was 4%, the total inoculum was 3% in pilot experiments in factory.In vitro experiments were made for 29 lactic acid bacteria. the results showed that GD-8 bacillus, GD-10 bacillus, D-T bacillus, S-2 streptococcus, I-2 streptococcus, I-3 bacillus, DT streptococcus to have a relatively high acid tolerance, intestinal juice had almost none impact on them.GD-8 bacillus, I-3 bacillus, DT bacillus had better ability of degrading cholesterol. removal effect were 20.32%, 19.52%, 15.68% respectively. Between the various characteristics there had no correlation.