A study looked at making yogurt from milk with added soy proteins. They tested different additives and bacteria to see how they affected acid production and yogurt quality. Soy proteins helped bacteria make more acid than skim milk powder. Lactic acid and acetic acid increased during fermentation, while citric acid decreased. Lactic acid was the main acid produced. Adding soy proteins affected the taste of the yogurt, with soy protein concentrate or isolate being preferred. After two weeks, the yogurt's acidity, pH, and bacteria count stayed the same.