The use of stevia as a sugar substitute in probiotic yogurt production with red beetroot

In this study, probiotic gel fermentation and functional characteristics of reduced sugar yoghurt with red beetroot (Beta vulgaris L.) bioactive components and steviol glycosides from Stevia rebaudiana extracts as natural source of non-caloric sweeteners were investigated. Lactobacillus acidophilus and Lactobacillus casei cultures were used in production of probiotic yogurts. The number of probiotic bacteria, pH and titratable acidity, serum separation, color values (L*, a*, b*, ΔE*, H°, C*), texturally firmness, consistency, index of viscosity, cohesiveness and sensorial properties, general acceptability and purchase intent were determined on the 1., 14., and 28. days of storage. In addition, total antioxidant capacity (DPPH and FRAP), total phenolic, ash, and reduced sugar contents were analyzed in the probiotic yogurt samples. In the evaluation, it was determined that the viability of Lactobacillus acidophilus and Lactobacillus casei was maintained within probiotic and therapeutic levels (>8 log cfu g-1), due to the possible prebiotic effect of stevia and biologically metabolized compounds of red beetroot, during storage of the probiotic yogurts. It was detected that red beetroot and stevia addition increased the total phenolic content and antioxidant activity of probiotic yogurts as well as improving yogurt gel textural properties. While sensory appreciation increased during storage in terms of appearance, color and taste, all samples were generally equally appreciated. As a result, probiotic yogurts produced with stevia as a calorie-free sweetener and red beetroot, which naturally contains colour components, can be an alternative to therapeutic dairy products with reduced sugar content, with components that have positive synergistic interactions containing probiotic bacteria.