Doctor of Philosophy (PhD)


School of Nutrition and Food Sciences

Document Type



Adequate provision of soy isoflavone and protein in soybean products is essential in meeting the soy health claim and the promotion of a healthy product. Commercial soymilks contain inadequate amounts of protein and isoflavone to meet the FDA recommended 25g and 40-50mg/day level, respectively, in 1-2 servings. This research study set out to investigate the possibility of producing a protein-isoflavone enriched (PIE) soymilk by incorporating soy germ in soymilk to provide the recommended FDA level in 1-2 servings. Three PIE soymilks containing 25 (SG25), 30 (SG30), and 35% (SG35) germ were prepared and compared to 100% whole soybean milk (WSB-control) and a commercial soymilk. Product development comprised process and formulation optimization, accompanied by physicochemical analysis, shelf life and beverage quality evaluation, as well as consumer sensory evaluation. The optimal processing method for incorporating soy germ into soymilk was at the starting stage (soaking) in soymilk production, and the WSB/SG25 was the optimal soymilk. The 25% soy germ beverage had the best composition profile closely followed by the WSB/SG30, WSB and WSB/SG35. The composition profile of the PIE beverages was better than the commercial soy milk. Shelf life and physicochemical quality of the PIE soymilk demonstrated stable shelf life, high beverage quality characterized by good colloidal stability, high degree of dispersion and less protein separation as germ amount increases. Validation of the optimal formulation from consumer perspective identified the WSB/SG25 soymilk as the most liked product by both male and female consumers. This was clearly revealed in the acceptance and purchase intent of the beverages. Spiking of the optimal formulation (WSB/SG25) with green mango, orange, almond and chocolate flavors, also revealed that green mango and almond flavor were preferred based on the overall liking, acceptance and purchase intent responses. Aroma, sweetness, overall flavor, color and mouth feel viscosity were crucial attributes that determined overall liking and in turn influenced the underlying differences among the beverages. These results suggest that incorporation of soy germ into soymilk yielded sufficient isoflavone and protein to meet the FDA requirement in 1 serving for isoflavone and 3 servings for protein.



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Release the entire work immediately for access worldwide.

Committee Chair

Witoon Prinyawiwatkul



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Life Sciences Commons