【作者】 李艳；

【导师】 双全；

【作者基本信息】 内蒙古农业大学 ， 食品科学， 2011， 硕士

【摘要】 本文以内蒙古锡林郭勒和巴彦淖尔地区传统乳制品中分离鉴定的52株乳酸菌为研究对象,通过ACE抑制活性、胆汁盐耐受性、人工胃液和人工肠液耐受性试验,筛选出ACE抑制活性较高且胆汁盐和人工消化液耐受性较好的菌株,探讨了筛选菌株的生长特性,分离提纯了发酵乳中产生的ACE抑制肽,并对其稳定性进行了研究。结果表明,供试52株乳酸菌中筛选出ACE抑制活性达33%以上的乳酸菌22株,经耐胆汁盐试验筛选出6株胆汁盐耐受能力较强(存活率均大于80%)的乳酸菌,再经人工胃液、人工肠液耐受性筛选出3株能耐受pH3.0人工胃液处理3h后接着经pH8.0人工肠液处理24h的乳酸菌Lactobacillus helveticus 130B4、Lactobacillus casei 325M2、Lactobacillus delbrueckii ssp. lactis QS306,他们在人工胃液和人工肠液中的增长率分别为117%、28.30%和39.55%。筛选的乳酸菌Lactobacillus helveticus 130B4在还原脱脂乳中生长较缓慢,培养36 h的酸度为0.8%,72 h的酸度可以达到1.85%,活菌数可达1.0×109CFU/g。还原脱脂乳中添加酵母浸膏、大豆肽、核酸关联物质(腺嘌呤、鸟嘌呤、尿嘧啶和黄嘌呤)能对Lactobacillus helveticus 130B4的产酸能力、蛋白分解能力以及ACE抑制活性都有一定的促进作用。选用Lactobacillus helveticus 130B4发酵的乳清中,经Sephadex G15分离收集到具有ACE抑制活性的组分3个(组分A、组分B、组分C),其中组分B的ACE抑制率((69.92±0.79)%)最高,其IER((88.06±0.0728)g/L)显著高于其他组分(P<0.05)。分离提纯的ACE抑制肽对温度的检测结果显示,该ACE抑制肽具有良好的耐高温性能,100℃、20min处理时其ACE的抑制活性达到未处理的98.33%,在110℃、20 min处理时,仍保留原ACE抑制活性73.81%。体外酶解试验结果表明,胃蛋白酶对该ACE抑制肽的活性有一定的消解作用,但胰蛋白酶没有,两种酶混合消化处理时其ACE抑制活性下降不大。更多还原

【Abstract】 The 52 strains of Lactic acid bacteria isolated from traditional fermented milk in Xilinguole and Bayannaoer area of Inner Mongolia, China, were evaluated to ACE-inhibitory activity, resistance of bile salts, simulated and gastrointestinal juice, and the selected strains were determined to growth characteristics in milk, the ACE inhibitor was isolated from milk and its stabilities were studied. The main results were as follows: The 22 strains of lactic acid bacteria were selected by higher of ACE inhibitory activity (higher than 33%). then 6 strains were selected for higher tolerance (more than 80%); and 3 strains of Lactobacillus helveticus 130B4, Lactobacillus casei 325M2, Lactobacillus delbrueckii ssp. lactis QS306 were patient to the simulated gastric juice (pH2.0, 3h of incubation), then through the gastrointestinal juice (pH8.0, 24h of incubation), rate of incrense were 117%, 28.30% and 39.55%. The selected strain Lactobacillus helveticus 130B4 was growing slowly in skim milk for 36h, the acidity was 0.8%, after 72h, the acidity was 1.85%, the total bacteria counts could reach 1.0×109 CFU/g. The acid production ability, protein decomposition, ACE inhibitory activity of this strain could be promoted by yeast leaching, soybean peptide, nucleic acid related substances (adenine, guanine, uracil and xanthine). Three fractions (A, B and C) were collected by Sephadex G15 from fermented milk, and the ACE inhibitory activity of fraction B was the highest ((69.92±0.79) %), and its IER ((88.06±0.0728)g/L) was obviously higher than other fractions (P<0.05). The resistance of purified inhibitory fraction to changes in their ACE inhibitory activity before and after treatment with heat and gastrointestinal proteases were examined. The ACE inhibitory activity of fraction B was completed preserved after the heat treatment. The ACE inhibitory activity was degreased to 98.33% at 100℃for 20min, and 73.81% at 110℃for 20min. The ACE inhibitory activity of fraction B was completed preserved after the pepsin and trypsin.更多还原