三组多菌群益生菌发酵羊乳酸乳的特性分析

Characteristics Analysis of Goat Yogurt Fermented by Three Groups of Multi-strain Probiotics

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.