Effect of Mixing Soy Milk with Buffalo or Cow Milk on the Chemical Composition, Microbial Properties and Sensory Evaluation of Yoghurt

The effect of blending soy milk with buffalo or cow milk on various yoghurt properties was studied. Five treatments of yoghurt were prepared from soymilk, buffalo milk, cow milk, mixture of 75% buffalo's milk + 25% soymilk and mixture of 75% cow's milk + 25% soymilk. Soy milk yoghurt had the lowest acidity, redox potential, total solids, fat, total nitrogen, ash, total volatile fatty acids, saturated fatty acids and total amino acids contents while buffalo's milk yoghurt had the highest. Mixing of soymilk with buffalo or cow milk lowered these values in the produced yoghurt. Conversely, soymilk yoghurt possessed the highest level of unsaturated fatty acids and linoleic acid and α-linolenic acid. The counts of S. thermophiles were almost similar in fresh yoghurt samples. Using soy milk only or mixed with buffalo or cow milk in yoghurt manufacture clearly decreased the count of L. bulgaricus. Blending buffalo or cow milk with soy milk increased the sensory evaluation scores of yoghurt.