INFLUENCE OF RAW MILK QUALITY ON LACTOBACILLUS ACIDOPHILUS MULTIPLICATION AND PROBIOTIC YOGHURT PRODUCTION
Considering that the quality of raw milk is a prerequisite condition to obtain a good quality probiotic yoghurt, our studies aimed the measurement of milk factors which can affect the multiplication of probiotic lactic acid bacteria (LABs) Lactobacillus acidophilus (LA-5). The probiotic strains Bifidobacterium BB-12 and Lactobacillus acidophilus LA-5-we used for trials- are tested probiotics by Christian Hansen company. We studied comparatively raw and pasteurized milk, their chemical composition and the correlations between the spontaneous microbial flora (NTG) found in milk samples and the impact of this flora on the multiplication of LABs. We investigated as well the effect milk proteins, added prebiotics (lactose, molasses) on pH and LAB development, the influence of NTG (number of total germs), NCS (somatic cells number) in raw milk before and after pasteurization, on lactic fermentations and LA-5 (Lactobacillus acidophilus) Generally multiplication of LA-5 strains was reversely correlated with NTG values. There is a direct correlation between presence of prebiotics and probiotic bacteria activity.
Key words: yoghurt, probiotics, lactic acid, NTG, pasteurization