青海牧区酸奶中乳酸菌分离及发酵性能的研究

Isolation of lactic acid bacteria from yoghourt in Qinghai pasturing area and their fermentation performance

采用MRS、Elliker、SL和番茄汁四种选择性培养基,从青海海北牧区酸奶中分离出5株产酸率高、发酵乳黏度高的乳酸菌菌株,初步鉴定QH1为杆菌,QH2、QH3、QH4、QH5为球菌。对其发酵性能进行测定,结果表明:QH4、QH5在发酵过程中产酸能力较强;QH1的产酸速率较QH2、QH3高;QH3、QH4、QH5后酸化能力弱;QH3的乙醛含量变化最大,双乙酰含量变化最小;QH4发酵酸奶的外观、组织状态和风味均高于其他菌株发酵的酸奶,表现出良好的品质。

Five strains of lactic acid bacteria from yoghourt in Haibei pasturing area of Qinghai province were isolated by MRS, Elliker, SL and tomato juice culture medium, and primarily identified.QH1 was /actobacillus, and QH2,QH3,QH4,QH5 were lactococcus.The results of their fermented performance showed that QH4 and QH5 had a good ability of producing acid.The velocity of producing acid of QH1 was higher than QH2 and QH3. Back acidification ability of QH3, QH4 and QH5 were weak.During the storage,the quantity of acetaldehyde of yoghourt fermented by OH3 was more than others, but the content of its diacetyl was lowest.The appearance,organization state and flavor of yoghourt fermented by QH4 were the best.