IMPROVING ACID PRODUCTION IN SOY-BASED YOGURT BY ADDING CHEESE WHEY PROTEINS AND MINERAL SALTS

Studies were conducted to further elucidate factors responsible for inability of S. thermophilus and L. bulgaricus yogurt culture to produce lactic acid and flavor in soy-based yogurt made with isolated soy protein and soymilk. Partial replacement of ISP with fresh cheese whey or whey protein isolate, or addition of phosphate and citrate ions resulted in physical stability defects in soy-based yogurt. They also failed to improve acid and flavor development or provide a 1:1 number concentration ratio of the two culture bacteria types. SM-based yogurt had lower acid development than ISP-based yogurt. Addition of commercial sodium caseinate stimulated acid development in SM-based yogurt.