14E-13 |
Development of an isoflavone aglycone enriched soymilk using soy germ, soy protein isolate and bifidobacteria |
D. TSANGALIS, Food Safety Authenticity and Quality Unit, Victoria University, PO Box 14428 Melbourne City Mail Centre, Melbourne, VIC 8001, Australia, J. Ashton, Sanitarium Health Food Co., PO Box 40, Cooranbong, NSW 2265, Australia, and N. P. Shah, School of Molecular Sciences, Victoria University, Werribee Campus, PO Box 14428, Melbourne City Mail Centre, Melbourne, Victoria, 8001, Australia. Modern soymilk prepared from soy protein isolate (SPI) has superseded traditional whole bean soymilk. However, soymilk made from SPI has a reduced level of isoflavones due to losses during protein isolation. Isoflavones are functionally similar to oestrogens and are associated with the prevention of hormone-dependent disorders. Soy germ (SG) has the highest concentration of isoflavones. Isoflavones exist in soymilk predominantly (> 90%) as biologically inactive glucosides. Fermentation with Bifidobacterium has shown to increase the concentration of bioactive and bioavailable aglycones. Our objectives were to increase the level of isoflavones in soymilk by supplementation with SG and then biotransform isoflavone glucosides to bioactive aglycones using Bifidobacterium animalis. Soymilks were prepared by reconstituting SPI and SG at ratios of 9:1 (SPISG9:1), 6:4 (SPISG6:4) and 3:7 (SPISG3:7), followed by fermentation with B. animalis. Enumeration of viable populations, pH measurements, and quantification of isoflavones using HPLC were performed at 0, 12 and 24 h of incubation and at 1, 7 and 14 d of refrigerated storage. The viable population of B. animalis increased by 1.1, 1.3 and 0.9 log10 CFU/mL after 24 h of incubation in SPISG9:1, SPISG6:4 and SPISG3:7, respectively, and did not reduce after 14 d of refrigeration. The greatest reduction in pH occurred in SPISG6:4 to 4.38 after 24 h. The total isoflavone concentration in SPISG9:1, SPISG6:4, and SPISG3:7 was 13.7, 36.9 and 60.9 mg per 100 mL, respectively. Fermentation of SPISG9:1 and SPISG6:4 biotransformed isoflavone glucosides to aglycones and their concentration in SPISG9:1 increased from 0.1% to 47.3% after 24 h. Soymilk comprising a ratio of 9:1, 6:4 and 3:7 of SPI and SG contained a total isoflavone concentration of 3-, 7- and 12-fold higher, respectively, than conventional soymilk and fermentation enriched the concentration of bioactive aglycones. Concomitant ingestion of a high level of bioactive aglycones and probiotic bifidobacteria may be of significant health benefit to consumers.
Session 14E, Nutraceuticals & Functional Foods: General I
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