Abstract

The soy milk prepared from soy protein concentrate was treated with microbial protease or papain. Growth and acid production by Lactobacillus acidophilus in soy milk containing partially hydrolyzed proteins were investigated. Sensory evaluation of yogurt beverage prepared from protease treated soy milk was also performed. Protease treatment of soy milk enhanced acid production by lactic acid bacteria, particularly in case of microbial pretense and simultaneous treatment by two types of protease showed synergistic effect. pH and number of viable cells were not affected markedly by pretense treatment. Microbial pretense treatment up to 15 minutes or papain treatment up to 45 minutes enhanced acid production, but further treatment up to three hours did not affect the acidity markedly. rho sensory evaluation showed that overall acceptability and taste of soy yogurt beverage were slightly improved when soy milk was treated with microbial pretense of 0.2% or papain of 0.2%. The amount of non-protein nitrogen considerably increased by pretense treatment of 15 minutes and it increased gradually by further treatment up to three hours.

본 연구에서는 농축대두단백으로 두유를 만들고 미생물 pretense와 papain을 단독 또는 혼합 사용하여 대두단백질을 가수분해한 후, 단백질이 일부 가수분해 된 두유에서 L. acidophilus의 생육과 산생성을 관찰하고 제조된 젖산균음료의 관능성을 조사하였다. Pretense 처리로 젖산균의 산생성이 촉진되었는데 미생물 pretense가 papain보다 효과적이었으며 2종의 효소를 혼합 사용했을 때는 상승효과가 보였다. 그러나 pretense 처리로 pH와 생균수는 큰 변화가 없었다. 미생물 pretense의 경우는 가수분해시간 15분까지, papain의 경우는 가수분해시간 45분까지 산생성 촉진효과가 현저했으나 그 후에는 3시간이 경과하여도 큰 변화가 없었다. 미생물 pretense 0.2% 또는 papain 0.2% 처리로 대두젖산균음료의 전체적인 기호도와 맛이 다소 개선되었다. Protease 처리 15분에 비단백태질소의 함량이 현저하게 증가하였고 후 3시간까지 서서히 증가하였다.

Keywords

• soy yogurt;
• protease;
• lactic acid bacteria