STUDYING ON LACTIC BACTERIA IN YOGHURT AND USING THEM TO MAKE SOYA YOGHURT

Abstract

Isolating lactic bacteria from some samples: market yoghurt, fermented soya,... We preliminarily collect 8 strains, three of them are B1, B5, B6 which congeal milk well and the product have specific aromatic flavour yoghurt. Three strains are classified at the level genus: B1: Lactobacillus sp., Bs: Streptococcus sp., B6: Streptococcus sp2.. Define the point time getting a great of mass on MRS medium is 21 hours (B1 (0.96x109 cells/ml), Bs (1.32x109 cells/ml) và B6 (0.63x109 cells/ml)). Define the method making milk and the fit indexs to make soya yoghurt: - Base on the Intsoy method (method I) but fry and then soak 2 times with NaHCO3 0.025% and NaHCO3 0.05% (method II). - The fit indexs to make soya yoghurt are: + The seed is 10° cells/ml milk. + The congealable time is 6 hours at 43°C. + The rate of seed bacilli and streptococci is 1:1 (B1/B5 = 1:1). The product have smoothly homogeneous structure, ivory-white, pretty sleeky surface, sour, aromatic, softly soya smell and protein (49.738 g/l), amin protein (2.256 g/l), and worthless ammoniac.