Improvements in Survival of Probiotic Bacteria, Rheology and Sensory Characteristics of Yogurts during Storage

Background and Objectives: Use of aloe vera gel in dairy industries is important for increasing quality of dairy products. In the present study, effects of aloe vera gel with inulin and whey powder on survival of probiotic bacteria, rheological and sensory characteristics of yogurt were investigated. Materials and Methods: Low-fat (1.5%) probiotic yogurts were prepared from pasteurized milks, 1% of starters and 2% combinations of Lactobacillus acidophilus with Bifidobacterium animalis at 40 °C and pH 4.4. Probiotic yogurts mixed with aloe vera gels at 0, 5, 10, 15 and 20% were stored seven days at 4 oC. Since the probiotic yogurt with 10% of aloe vera gel included the best sensory scores compared to other aloe vera gel concentrations after seven days of storage at 4 oC, this formulation was mixed with inulin at 0.5, 1 and 1.5% (w/w) or whey powder at 5, 10 and 15% (w/w).  Results: Sensory evaluations showed that the probiotic yogurt with 10% of aloe vera gel and 1.5% of inulin included the highest scores of flavor, texture, aroma, color and acceptance within the samples after similar storage conditions. The probiotic yogurt with 10% of aloe vera gel and 1.5% of inulin included the highest survival of Lactobacillus acidophilus and Bifidobacterium animalis, while controls (with no aloe vera gels) showed the lowest survival rates of Lactobacillus acidophilus and Bifidobacterium animalis. Apparent viscosity and serum separation of probiotic yogurt with 10% of aloe vera gel and 1.5% of inulin respectively increased three times and decreased to less than 4%, compared to controls and whey samples at similar shear rates and storage times. The pH decrease of probiotic yogurt with 10% of aloe vera gel and 1.5% of inulin was much slower than those of the control and whey samples during storage, including no serum separations during storage. Conclusions: Aloe vera gel and inulin improved viability of probiotic bacteria and quality of yogurt samples during storage.