44E-8 |
Bitterness of isoflavones and saponins isolated from soy flour, soy germ, and purified b-conglycinin |
V. M. SMITH1, P. A. Murphy, and C. A. Reitmeier. (1) Dept. of Food Science and Human Nutrition, Iowa State University, 2312 Food Science Bldg., Ames, IA 50011 As phytochemically-enhanced soy food increases in demand, it is essential to determine the sensory components responsible for its undesirable taste. Undesirable characteristics like bitter and astringent tastes are known to be critical limiting factors in soy food consumption. It is suggested isoflavones and saponins found in soybeans are responsible for the bitterness and astringent attributes. The objectives were to determine the attributes responsible for intense undesirable tastes associated with isoflavones and saponins and determine their detection level in water and EdensoyTM soymilk. Isoflavones and saponins were extracted from the different soy ingredients using 70% food grade ethanol and dried with nitrogen gas. Isoflavones and saponins were quantified by HPLC analysis. Isoflavone and saponin stock solutions were prepared for descriptive analysis by a trained sensory panel. Minimum detection limits for bitter taste were determined in water and soymilk. We have identified attributes describing isoflavones and saponins derived from soy flour, soy germ, and purified b-conglycinin as bitter, astringent, floral, grassy, and sour. The isoflavones and saponins extracted from purified b-conglycinin were significantly more bitter and astringent than the extracts from soy flour and soy germ. When grassy, floral, and sour attributes were measured for intensity among soy flour, soy germ, and purified b-conglycinin extracts, no significant differences were detected. Based on these results, bitterness detection thresholds were determined in water solutions and in soymilk. The threshold for isoflavones and saponins detection in water was at significantly lower concentrations than the isoflavones and saponins detected in soymilk. These results suggest foods, such as soymilk, can be enhanced with additional soy isoflavones and saponins without exceeding bitterness thresholds for these potential health protective components.
Session 44E, Nutraceuticals & Functional Foods
|