Soy protein fortification affects sensory, chemical, and microbiological properties of dairy yogurts

Chemical, microbiological, and sensory properties for low fat yogurts forti fied with 0, 1, 2.5, or 5% soy protein concentrate were determined through 1 mo storage at 5 degreesC. Yogurts were adjusted to equivalent total solid s with nonfat dried milk. Microbiological counts, fermentation time, and fi nal develop ed acidity were not affected by soy protein. Instrumental visco sity and sensory thickness, soy aroma, and soy flavor Increased with soy pr otein addition (P less than or equal to 0.05). Soy flavor and aroma did not increase with storage time. Yogurt with 5% soy protein was darker, more ch alky, and less sweet compared to control yogurt or yogurts with lower conce ntrations of soy protein (P less than or equal to 0.05). Yogurts with 1 or 2.5% soy protein were most similar to control yogurt.