Abstract: Bifidobacterium animalis strain B, a strain that is capable of lowering cholesterol levels in the body, was screened out and used in combination with the conventional fermentation starter (composed of L.bulgaricus and S.thermophilus) for the mixed-strain fermentation of fat-free yoghurt at 43 ℃. The end point of the fermentation was reached after 5.5－6 hours. The total numbers of viable Bifidobacterium animalis and lactic acid bacteria reached an average of 4.8 × 106 CFU/g and 7.4 × 107 CFU/g respectively during 28 days of storage at 4 ℃.The yoghurt obtained showed a protein content of 2.8 g/100 g, a fat content of 0.2 g/100 g, and an acidity value of 80 °T. All of these three indexes met the requirements of the National Food Safety Standard GB 19302－2010: Fermented Milk. Meanwhile, according to the Ministry of Health,s Regulation for Food Nutrition Labeling, the yoghurt product could be labeled as fat-free fermented milk. The results of sensory evaluations revealed that it had a very gentle flavor and a strong taste of fresh cream with a smooth and exquisite texture and a good consumer acceptance. Therefore, the yoghurt developed in this study has promising commercial prospects.

Key words: probiotic；cholesterol；Bifidobacterium；mixed-stain fermentation；yoghurt

摘要： 研究降胆固醇益生菌在酸奶中的应用。筛选一株具有降低人体胆固醇水平的双歧杆菌B菌,采用此双歧杆菌B菌（Bifidobacterium animalis）和常规酸奶菌种A菌（L.bulgaricus和S.thermophilus）在43℃混合发酵,发酵5.5～6h可达到发酵终点,该酸奶产品在4℃、28d冷藏保质期内,功效双歧杆菌数和乳酸菌总数平均值分别达到4.8×106CFU/g和7.4×107CFU/g,成品理化指标检测为蛋白质含量2.8g/100g、脂肪含量0.2g/100g和酸度80°T,均符合食品安全国家标准GB 19302—2010《发酵乳：风味发酵乳》的要求,根据卫生部食品营养标签管理规范,本产品可标示为零脂风味发酵乳,从感官评价结果来看,此风味发酵乳具有非常柔和的风味及有较强鲜奶油感,质地平滑细腻,接受度好,具有一定商业前景。

关键词: 益生菌;胆固醇;双歧杆菌;混合发酵;发酵乳