Effects of Inulin and Xylitol on the Probiotic Bacteria Survival, Physicochemical Properties, and Sensory Acceptability of Strawberry Frozen Yoghurt

Tan, Su Yi (2024) Effects of Inulin and Xylitol on the Probiotic Bacteria Survival, Physicochemical Properties, and Sensory Acceptability of Strawberry Frozen Yoghurt. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

Frozen yoghurt is a frozen dairy dessert characterized by the acidic taste of yoghurt and the cooling effect and physical properties of ice cream. In general, the sucrose level of commercialized frozen yoghurt is usually between 15% and 28% of the total ingredients and it consists of lower probiotic bacteria levels than yoghurt due to the unfavourable conditions in frozen yoghurt. Therefore, this study used xylitol as a sugar substitute, while inulin as a prebiotic to produce strawberry frozen yoghurt. The objective is to determine the effects of inulin and xylitol on the survival of probiotic bacteria, as well as the physicochemical properties and sensory acceptability of strawberry frozen yoghurt. Xylitol’s effect was found to be insignificant (p > 0.05) in the physical and chemical properties of frozen yoghurt, except for the springiness, viscosity, melting trend, and total sugar content (p < 0.05). It was also found to influence the Streptococcus thermophilus growth insignificantly (p > 0.05), but the growth of Lactobacillus spp. and total bacteria was increased prominently (p < 0.05). As for inulin, its effect was mostly found significant (p < 0.05). When compared to the xylitol sample without inulin, the xylitol sample with inulin was significantly affecting most of the physical, chemical and microbiological properties, except for the springiness, cohesiveness, lightness (L*), yellowness (b*), as well as Streptococcus thermophilus count and total bacteria count. In terms of sensory evaluation, xylitol alone did not affect the intensity and overall acceptability of each attribute while the xylitol sample with 2% inulin adversely affected the overall sensory acceptability. Overall, both xylitol frozen yoghurt with and without 2% inulin have a high potential to be commercialized. Optimizing the concentration of inulin is recommended to enhance the sensory acceptability of xylitol-frozen yoghurt