Study On Isolated Strains Of Kefir Grains And The Characteristic Of Its Fermented Dairy Product

At present there is a dairy product called "XiZangLingGu"(XZLG),which is widely spreaded in Harbin and many other cities.It is said that: XZLG comes from a small village of XiZang and it has many biological functions. As a functional food, it is widely circulated among the people because of the people's consciousness of health. Up to now, there hasn't any reports on the properties and functions of XZLG being published. So this experiment studied the isolation of main strains of XZLG, the symbiosis of the strains and its effete and compared with kefir from Caucasus, in order to give some advices on how to eat the product of XZLG correctly and how to use it into industrialization.We found that XZLG is different from Caucasus kefir on appearance: Caucasus kefir grain is small (0.1?.4x0.4~0.8cm) and like curl or cauliflower, but XZLG is pieces like woodear with bulges on the surface. The activity of two kefir can be resumed by cultured for 3 桽generation continually. If cultured continually for more passages, the strains count of kefir grains will be decreased, which may be because the balance between kefir strains was destroyed. Compared with kefir from Caucasus, XZLG has stronger ability to produce aced and alcohol. Milk cultured by XZLG has more pungent sour than that cultured by Caucasus kefir grains.According to the quadratic design of viscosity and releases of whey, the optimum condition for producing kefir yogurt is that: cultured 20 hours at 25 癈 with 5% inoculated size.GC1> GSLK GSL4> PSL4> GC2> PCK PC2^ PSL2, GM1> PMK PM2 and PSL3 were isolated from two the kefir grains used whey media,Elliker media,SL media and CaCOs whey media.GCl and GSL1 was idenlified as Leuconsitic and Lactobacillus brevis respectively, GSL4 and PSL4 were identified as Lactobacillus helvetiicus , GC2> PC1> PC2 and PSL2 were identified as aceticbacillus, GM1 as Torulopsis kefir, PM1 as Pachia, PM3 and PSL3 as Kluyveromyces.By using the mixture of PSL4^ GSL1 N GCK and PSL3 to culture skim milk, we found that the acid-produing rate of the mixture is higher than kefir, and the of milk cultured by the mixture is also more viscosity than the cultured by kefir, but the favor of the former is not as strong as the later.