Effect of Adzuki Bean Milk Supplementation in Yogurt on the Physico-Chemical and Viability of Probiotic Bacteria during Storage

Ong, Hooi Leng (2019) Effect of Adzuki Bean Milk Supplementation in Yogurt on the Physico-Chemical and Viability of Probiotic Bacteria during Storage. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

In Asian countries, Adzuki beans are commonly incorporated in their daily diet. Fermented Adzuki beans are able to produce bioactive components such as γ-aminobutyric acid (GABA), natural phenolics, bioactive peptides and vitamins which are beneficial to health. The objectives of this study were to investigate the effects of supplementation of Adzuki beans milk as a potential prebiotic source; to determine and evaluate the physio-chemical characteristics of Adzuki bean yogurt throughout storage; and to investigate the nutritional properties of yogurt supplemented with Adzuki Bean Milk. A total of 5 samples were developed in this study, control yogurt was made with fresh milk, adzuki bean yogurt was prepared by blending a mixture of 1:1 ratio of adzuki bean milk with fresh milk. The other three formulations was added with 2% inulin, 2% FOS and 15% Adzuki bean paste respectively to the above mentioned adzuki bean with fresh milk mixture. Each of the samples were supplemented with 8% sucrose and 3% starter, while fermented at 42ºC for 8 hours. The moisture content is the highest in adzuki bean yogurt. Crude protein content of the adzuki bean yogurt with 15% adzuki bean paste was the highest. The crude fat and crude fiber content of adzuki bean with 2% inulin and FOS were the highest. No significant difference was observed among the two samples. The ash content of adzuki bean yogurt added with 15% adzuki bean paste was the highest, while the carbohydrate of control yogurt was the highest among all the yogurt samples. As for the physicochemical analysis, the pH value and total soluble solids of samples showed a decreasing trend during storage of 14 days. The titratable acidity of yogurt samples showed an increasing trend throughout storage. Syneresis of yogurt samples increased while the water holding capacity of yogurt decreases. The apparent viscosity of adzuki bean yogurt was the highest. All samples showed G’ > G’’ value which indicates a gel-like structure in the yogurt samples. The probiotic viability of all the yogurt samples were able to achieve the standard requirement of 7 log cfu/mL However, the yogurt samples could not reach the threshold level of >6 log cfu/mL after simulated transit tolerance. In sensory evaluation, the mean score of overall acceptability ranged from 4.00 to 6.37 in a 7-point Hedonic Scale. The ranking test indicated that the adzuki bean yogurt with 15% adzuki bean paste was the most preferred at rank 1 (51%), while the least preferred sample is adzuki bean yogurt at rank 5 (68%). Keywords: Adzuki bean milk, Adzuki bean yogurt, Sensory Evaluation