88-11 |
Production of enriched isoflavone aglycones during processing of soy protein isolates and soy protein concentrates |
Y. K. PARK1, M. C. Y. Lui2, and C. L. Aguiar2. (1) College of Food Engineering, State University of Campinas (UNICAMP), Caixa postal 6177, Campinas, SP., 13081-970, Brazil, (2) Department of Food Science, State University of Campinas (UNICAMP), P.O. Box 6121, Campinas, SP, 13083-970, Brazil Soybeans have been a valuable resource for foods by providing proteins and isoflavones. Isoflavones show anticancer capabilities and cholesterol-lowering property. The biological activities of isoflavone aglycones are much greater than those of glucoside isoflavones. The objective of this investigation was to evaluate the processing of soy protein isolates (SPI) and soy protein concentrates (SPC) for the production of higher concentrations of isoflavone aglycones in extracted soy isoflavones using b-glucosidase. SPI was prepared as follows: Defatted soy flour (50g) was extracted with 1000 mL water, adjusted to pH 9 with NaOH at room temperature. The insoluble residue was separated by filtration and the extract adjusted to pH 4.5 with HCl to precipitate proteins. The precipitated proteins were removed by centrifugation. The supernatant was treated with b-glucosidase at 45ºC for 1 h. The insoluble residue, SPI, and the supernatant was treated with separately freeze-dried. SPC was prepared as follows: The defatted soy flour (50g) was dispersed in 1000 mL water adjusted to pH 4.5 with HCl for 1 h. The precipitated proteins were removed by centrifugation. The supernatant was treated with the enzyme. The enzyme treated supernatant and the precipitated SPC were processed as described for SPI. The respective freeze-dried samples (1g) were mixed with 10 mL methanol to extract isoflavones for analysis by HPLC. The investigation revealed that about 18 and 42% of the total isoflavones in the defatted soy flour remained in SPI and SPC. About 52% of total isoflavones remained in the supernatant during precipitation of SPI and 47% of total isoflavones dissolved in the acid solution during SPC processing. The glucoside isoflavones in supernatant and acid solution were transformed into aglycones. These experiments suggest that 52 and 42% of total isoflavones respectively lost during production of SPI and SPC, can be recovered for the transformed into aglycones which possess more biological activity.
Session 88, Nutraceuticals & Functional Foods: General
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