Abstract: In this study, four prebiotics including inulin, fructo-oligosaccharides (FOS), galacto-oligosaccharides (GOS), and yeast β-glucan were added singly (inulin) or in different combinations (inulin + FOS + GOS and inulin + FOS + GOS + yeast β-glucan) to fermented milk containing Bifidobacterium animalis subsp. lactis PB200. The titratable acidity, pH, whey syneresis and total viable count of the fermented milk were measured during storage periods. Moreover, the rheological and textural properties were measured. The aim was to clarify the effect of different prebiotic combinations on the yogurt system in order to obtain the optimal probiotic combination. Compared with the control group with no prebiotic added, the addition of prebiotics significantly delayed the post-acidification, and promoted the growth of B. animalis subsp. lactis PB200. Besides, the titratable acidity of fermented milk added with inulin, FOS, GOS and β-glucan was the lowest , and the titratable acidity increased slowly and whey syneresis was less with the extension of storage time. The addition of all four prebiotics could maintain a higher viable count of B. animalis subsp. lactis PB200. The results of rheological and textural analysis showed that yogurt added with all four prebiotics had higher gel strength, hardness, cohesiveness, gumminess, adhesiveness and springiness, showing better texture. In summary, the addition of inulin, FOS, GOS and β-glucan resulted in better quality of probiotic fermented milk with B. animalis subsp. lactis PB200.

Key words: fermented milk; prebiotics; Bifidobacterium animalis subsp. lactis PB200; rheological property; texture property

摘要： 将菊粉、低聚果糖（fructo-oligosaccharide，FOS）、低聚半乳糖（galacto-oligosaccharide，GOS）及酵母β-葡聚糖4 种益生元以不同组合添加至含有乳双歧杆菌PB200的发酵乳中，测定发酵乳在贮藏期间的滴定酸度、pH值、乳清析出率及乳酸菌活菌数变化，并分析其流变学与质构特性，以阐明各组益生元配方对发酵乳体系的影响，并获得最佳的益生元组合。结果表明，与不添加益生元相比，添加益生元可有效延缓发酵乳后酸化，促进乳双歧杆菌PB200生长，其中菊粉＋FOS＋GOS＋β-葡聚糖组发酵乳滴定酸度最低，随贮藏时间延长，滴定酸度升高较缓且乳清析出较少。添加益生元可使乳双歧杆菌PB200的活菌数维持在更高水平。流变学特性和质构特性分析结果表明，菊粉＋FOS＋GOS＋β-葡聚糖组发酵乳具有较高的凝胶强度，且硬度、内聚性、胶着性、黏附性及弹性较好，具有较好的质地和组织状态。综上，菊粉＋FOS＋GOS＋β-葡聚糖益生元组合可以获得品质特性更优的乳双歧杆菌PB200益生菌发酵乳。

关键词: 发酵乳；益生元；乳双歧杆菌PB200；流变学特性；质构特性