【作者】 石月锋；

【导师】 杨海燕； 尹活泼；

【作者基本信息】 新疆农业大学 ， 食品科学， 2009， 硕士

【摘要】 从新疆乌鲁木齐市周边地区和新疆伊犁地区采集到26份自制奶制品样品,经过分离纯化得到了35株乳酸菌。通过单菌牛奶发酵和组合牛奶发酵的方式,对乳酸菌进行了各方面的评定并对其进行筛选。最终确定了E-2杆:D-2球和E-4杆:D-2球这两对组合。而对这两对组合发酵的酸奶进行了14天的保藏,并进行了酸度、总酸度、粘度以及活菌数检测,同时对口感进行了评定,发现E-2杆:D-2球这对组合在储存期间保持了良好的风味和流变学特性,并且后酸化程度较小,适合作为凝固型酸奶发酵剂。对E-2杆:D-2球进行了中试实验。结合工厂条件和实验室条件对这对组合进行了工艺调整,最终确定的各工艺参数为发酵温度42,将乳酸菌分别在含10%番茄汁的牛奶培养基中活化,然后按照两株菌1:1(V/V)、4%的接种量发酵牛奶作为发酵剂(prelude),中试时总接种量为3%。对所分离的29株乳酸菌进行了耐酸实验和体外模拟实验,发现GD-8杆、GD-10杆、D-T杆、S-2双球、I-2链球、I-3杆、D-T双球都有较高的胃酸耐受性,肠液环境下对其存活基本不产生影响。降胆固醇实验表明GD-8杆、I-3杆、D-T杆降胆固醇效果较好,胆固醇去除率分别为20.32%、19.52%、15.68%。各特性之间没有表现出相关性。更多还原

【Abstract】 From the surrounding areas of the city of Urumqi in Xinjiang and Yili region,26 samples of dairy products were collected. After separation and purification, 33 lactic acid bacteria(LAB)were obtained. By means of single strain and combined strains of fermentation in milk ,as well as that various aspects of assessment were carried out,finally three stain(stwo groups)were determined. They were: E-4 bacillus, D-2 streptococcus, and E-2 bacillus. These combination of the two yogurt fermented by these two groups of LAB were preserved for 14 days, and pH,total acidity,viscosity, as well as the number of viable cells was detected, and the taste was evaluated and found that E-2 bacillus: D-2 streptococcus maintained a good flavor and a less extent of acidification during storage. They were suitable to be used as commercial starter.Pilot experiments of E-2 bacillus: D-2 streptococcus was carried out.Factory conditions and laboratory conditions were both considered and adjustment was made. The final parameters of the process was as follows:the fermentation temperature was 42℃, the lactic acid bacteria was activated in the milk medium containing 10% tomato juice,when making prelude,the ratio of the two kinds of milk fermented was 1:1(V/V),inoculum was 4%, the total inoculum was 3% in pilot experiments in factory.In vitro experiments were made for 29 lactic acid bacteria. the results showed that GD-8 bacillus, GD-10 bacillus, D-T bacillus, S-2 streptococcus, I-2 streptococcus, I-3 bacillus, DT streptococcus to have a relatively high acid tolerance, intestinal juice had almost none impact on them.GD-8 bacillus, I-3 bacillus, DT bacillus had better ability of degrading cholesterol. removal effect were 20.32%, 19.52%, 15.68% respectively. Between the various characteristics there had no correlation.更多还原