44E-1 |
Isoflavone and saponin partitioning during pilot-scale fractionation of glycinin and b-conglycinin |
D. A. RICKERT1, V. M. Smith, M. A. Reuber, L. A. Johnson, and P. A. Murphy. (1) Dept. of Food Science and Human Nutrition, Iowa State University, 2312 Food Science Bldg., Ames, IA 50011 Food products containing soy may be considered functional foods. Isoflavones and saponins, soy phytochemicals, and even the soy proteins themselves may be physiologically active components of soy. Fractionation and characterization of glycinin and b-conglycinin, major soy storage proteins, permits evaluation of their potential physiological influence on human health and their unique properties for food product development. The partitioning of isoflavones and saponins into the finished protein fractions is of interest due to their reported roles as antioxidants, anticarcinogens, and cholesterol-lowering agents. Also, recovery or concentration of these soy phytochemicals from protein fractionation exit streams could lead to value-added products. The objectives were to monitor the partitioning of isoflavones, saponins, and protein during the pilot plant scale protein fractionation process, determine which fractions would be suitable for isoflavone and saponin recovery or concentration, and evaluate the efficiency of protein recovery from defatted soy flakes. Protein fractionation was performed in duplicate on 50-kg batches of defatted soy flakes. Isoflavones and saponins partitioned into the process fractions were quantified by HPLC analysis of extract from freeze-dried samples, while proteins were quantified by the Kjeldahl method. The insoluble protein/fiber fraction contained approximately 59% of the protein, 67% of the isoflavones, and 76% of the saponins compared to the starting material. The combined protein fractions contained 29%, 17%, and 22% of these fractions, respectively. The protein-diminished (whey) exit stream contained a negligible amount of saponins and only 6% and 12% of the protein and isoflavones, respectively. The unrecovered protein/fiber fraction is clearly prime for recovery of otherwise discarded isoflavones and saponins. Under modified process conditions increased recovery of protein from this fraction may also be realized. The whey stream should be considered for recovery or concentration of isoflavones. The relativley pure glycinin and b-conglycinin fractions still contained desired soy phytochemicals.
Session 44E, Nutraceuticals & Functional Foods
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