该研究分别以嗜热链球菌与5株乳杆菌组合（SN_4）、嗜热链球菌与保加利亚乳杆菌组合（SN_2）、5株乳杆菌组合（SN_3）三组益生菌组合对羊乳进行发酵，对发酵过程中（0~12 h）活菌数、pH值、酸度、持水力及凝乳点的质构特性、流变特性、菌群结构、功能性差异代谢物等进行分析研究。结果显示，SN_4、SN_2、SN_3的凝乳时间依次为4.70、5.60、10.60 h；活菌数均可达到109 CFU/mL以上；发酵至凝乳点，链球菌属和乳杆菌属均被检出；SN_4组合发酵酸乳的持水力、质构特性和流变特性等均表现最优，SN_2次之；在P<0.05水平上，SN_4与SN_2相比，18种肽类、2种糖类、7种有机酸差异代谢物中分别有13种、2种和2种上调；SN_4与SN_3相比，18种肽类、7种糖类、6种有机酸差异代谢物中分别有5种、4种和6种上调；SN_3 VS SN_2、SN_4 VS SN_2、SN_4 VS SN_3差异代谢物通路分别涉及7条、5条、4条。研究结果表明，SN_4发酵酸乳特性均优于SN_2、SN_3。研究结果可为进一步研制感官优良、功能性强的多菌群发酵酸乳提供理论依据与技术支撑。

In this study, three groups of probiotic combinations, Streptococcus thermophilus combined with 5 strains of Lactobacillus (SN_4), Streptococcus thermophilus combined with Lactobacillus bulgaricus (SN_2), and 5 strains of Lactobacillus combination (SN_3), were used to ferment goat milk. The number of viable bacteria, pH value, acidity, waterholding capacity during fermentation (0~12 h) and the texture properties, rheological characteristics, microbial community structure and functional differential metabolites at the curdling point were analyzed. The results showed that the curdling times of the SN_4, SN_2 and SN_3 yoghurts were 4.70 h, 5.60 h and 10.60 h, respectively, with the viable microbial number all reaching 109 CFU/mL or above. When fermentation reached the curdling point, both Streptococcus and Lactobacillus were detected. The water-holding capacity, textural characteristics and rheological properties of the goat yogurt fermented with SN_4 were the best, followed by the SN_2 yogurt. At the P level <0.05, the comparison of the SN_4 yoghurt with the SN_2 yoghurt revealed that 13 out of the 18 peptide differential metabolites, both the two carbohydrate differential metabolites, and 2 out of the 7 organic acid differential metabolites, were up-regulated. The comparison of the SN_4 yoghurt with the SN_3 yoghurt revealed that 5 out of the 18 peptide differential metabolites, 4 out of the 7 carbohydrate differential metabolites, and all the 6 organic acid differential metabolites, were up-regulated. There were 7, 5 and 4 differential metabolite pathways involved in SN_3 VS SN_2, SN_4 VS SN_2, SN_4 VS SN_3, respectively. The results showed that the properties of the goat yogurt fermented with SN_4 were better than those of the SN_2 and SN_3 yoghurts. The research results provide a theoretical basis and technical support for further research and development of multi-strain fermented yogurt with excellent sensory and functional properties.

国家自然科学基金面上项目（32272401）