Production of Functional Low-Fat Yogurt Fortified with Soy Protein Isolate

The purpose of this study was to produce the low fat yogurt using soy protein isolate. The soy protein isolate in concentrations of 0.5, 1.0 and 1.5 was used in low-fat yogurt formulation and the physicochemical properties (pH, acidity, non fat dry matter, syneresis, viscosity) and microbial (growth of mold and yeast) and sensory properties (color, firmness, taste, sourness, spiciness, oldness and moldy and overall appearance) were evaluated on 1, 7, 14 and 21 days of storage. The results showed that with increase in soy protein isolate concentration, acidity, non fat dry matter and viscosity were significantly increased and the yogurt syneresis was significantly decreased, while it had no significant effect on pH (p > 0.05). The most desirable sensory properties were observed in the first days in the control and samples containing 0.5 and 1.0% soy protein isolate (p < 0.05). The results showed that the use of soy protein isolate due to its nutritious compounds can be considered as an offer in the industrial production of functional low fat yogurt.