Effects of protease treatment of soy milk on acid production by lactic acid bacteria and quality of soy yogurt
1989
Kim, K.H. | Bang, I.R. | Ko, Y.T. (Duksung Women's Univ., Seoul (Korea R.). Dept. of Foods and Nutrition)
The soy milk prepared from soy protein concentrate was treated with protease of various concentrations. Growth and acid production by Lactobacillus acidophilus or L. bulgaricus in soy milk containing partially hydrolyzed protein were investigated. Sensory evaluation of soy yogurt beverages prepared from protease treated soy milk was also performed. The treatment of soy milk with protease markedly enhanced acid production by lactic acid bacteria, particularly by L. acidiphilus, whereas pH and number of viable cells were not affected by protease treatment. Protease treatment of 15 minutes greatly enhanced acid production by lactic acid bacteria, but further treatment up to three hours did not affect the acidity markedly. The sensory evaluation showed that overall acceptability of soy yogurt beverages was slightly improved when soy milk was treated with protease of 0.1%. The amount of non-protein nitrogen was considerably increased by protease treatment of 15 minutes and it reached the maximum value by treatment of two hours
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