选取SDC4-1、MDC3-1、WDC3-1 3株从云南撒尼地区乳饼和酸乳清中分离鉴定的乳酸菌株，用耐酸、耐胆盐实验筛选其中的优势菌株；并用产酸能力、后酸化、产乙醛能力、蛋白水解酶测定和β-半乳糖苷酶测定等实验研究优势菌株的发酵性能。3株菌均能耐酸，其中MDC3-1耐酸能力最高，达254%，WDC4-1最低，为52%，但仅SDC4-1可耐受胆盐，在0.5%的胆盐中，4 h后的存活率为81%，SDC4-1是优势菌。SDC4-1发酵性能实验中，SDC4-1菌株具有很好的凝乳状态，发酵酸奶口感风味浓郁，在贮藏过程中活菌数含量高，冷藏15 d后活菌数达到了9.79 lgCFU/g，远超国家标准。产酸较快，13 h时，酸度已达82.0 °T，后酸化性好，产乙醛能力较好, 蛋白水解能力强，产β-半乳糖苷酶的量高，达7.7 μg/mol，能保证酸奶在冷藏过程中品质稳定,因而筛选出具有优良发酵特性的菌株SDC4-1可以为发酵食品提供更广泛的素材。

The lactic acid bacterial strains SDC4-1, MDC3-1, and WDC3-1 were isolated from milk cake and acid whey obtained from Sani area of Yunnan province. A superior strain was identified based on acid resistance and bile salt tolerance tests. The fermentation capability of the superior strain was studied in terms of acid production, post-acidification acetaldehyde production, protease activity, and β-galactosidase assay. All three strains were found to be acid tolerant; MDC3-1 showed the strongest acid resistance with a survival rate of 81%; WDC4-1 showed the weakest acid resistance, with survival rate of 52%. However, only SDC4-1 was tolerant to bile, and the survival rate was 81% after being in contact with 0.5% bile salt for 4 hours. Therefore, SDC4-1 was considered the superior strain. In the fermentation test that followed, SDC4-1 strain showed a perfect curd consistency and the fermented yoghourt was rich in flavors. Additionally, high viable count was noted during the storage period, reaching 9.79 lg CFU/g after a 15-day cold storage, which is far more than the national standard. SDC4-1 showed increased rate of acid production, where acidity reached 82.0°T after 13 hours. Meanwhile, SDC4-1 exhibited good post-acidification, good acetaldehyde-producing ability, strong proteolytic activity, and high β-galactosidase production (up to 7.7 μg/mol), while maintaining stable yoghurt quality during cold storage. Therefore, the selected strain, SDC4-1, showing good fermentability, can be considered for use in the preparation of fermented food.

国家自然科学基金资助项目（31260372）