Effect of Inulin and Bacillus coagulans T242 on the Microbiological, Textural, and Physicochemical Properties of Fermented Milk.

Inulin is considered a natural water-soluble dietary fiber, while Bacillus coagulans (B. coagulans) possesses the ability to break down lactose. This study investigates the effects of inulin and B. coagulans T242 (T242) on the microbiological, textural, and physicochemical properties of fermented milk stored at 4°C for 21 days. The fermented milk produced using traditional starters, specifically Lactobacillus bulgaricus and Streptococcus thermophilus, served as the control group (CFM). Multiple indicators, including viable bacterial count, pH, titratable acidity, water holding capacity (WHC), lactose content, textural properties, rheological properties, and microstructure, were measured. The results indicated that, compared to CFM, the fermented milk with inulin alone (ICFM) significantly increased WHC and viscosity, while reducing hardness and lactose content, and delaying microbial growth and post-acidification. Compared to CFM, the fermented milk with T242 alone (TFM) promoted the growth of lactic acid bacteria while decreasing WHC, viscosity, hardness, and lactose content, and delaying post-acidification. The combined addition of T242 and inulin in fermented milk (ITFM) delayed the growth of lactic acid bacteria, enhanced cohesiveness and viscosity, reduced hardness, improved the WHC of the network structure of milk protein, and refined the microstructure of the fermented milk, despite this group exhibiting the highest lactose content during the later storage period. In summary, inulin can enhance the quality of fermented milk, T242 can reduce lactose content, but their combined use has an adverse effect on lactose breakdown.