Comparison of associative growth and proteolytic activity of yogurt starters in whole milk from camels and cows

Growth and proteolytic activities were studied using yogurt starter cultures incubated in pasteurized whole milk from camels and cows at 42 degrees C as single and mixed cultures. In general, the growth of four strains of Streptococcus thermophilus and three strains of Lactobacillus delbrueckii ssp, bulgaricus was higher in cow milk than in camel milk. However, proteolysis was higher in camel milk than in cow milk. Lactobacillus delbrueckii ssp. bulgaricus LB12 in combination with streptococci had lowered pH more than did the other lactobacilli. Mixed cultures released the same amount of free amino groups as the corresponding single cultures, except for L. delbrueckii ssp. bulgaricus LB12.