ARS | Publication request: COMPLETE SAPONIN AND ISOFLAVONE ANALYSIS OF WHOLE SOYBEAN, GERM, HULLS, AND COTYLEDONS

Submitted to: Phytochemical Society of North America Proceedings
Publication Type: Abstract
Publication Acceptance Date: August 3, 2005
Publication Date: August 3, 2005
Citation: Berhow, M.A., Duval, S.M. 2005. Complete saponin and isoflavone analysis of whole soybean, germ, hulls, and cotyledons. Phytochemical Society of North America Proceedings.

Technical Abstract: Reproducible methodology for the recovery and analysis of all the isoforms of isoflavones and saponins in whole soybeans continues to be a problem. A standardized sample preparation and extraction method has been developed to prepare extracts for analysis of both total saponins and total isoflavones that has been shown to be reproducible in other labs as well as our own. The extracts can be analyzed with standard HPLC and LC-MS methods to identify and quantitate the malonyl-, acetyl-, glucosyl- and aglycone forms of the soy isoflavones, as well as the A-group and B-group forms (including the DMPP forms) of the soy saponins. Extractions were prepared from hand-separated soy seed components¿germ, hulls and cotyledons. As has been previously reported the germ is rich in the daidzein and glycitein isoflavone isoforms, while the hypocots are rich in the genistein isoflavone isoforms. The cotyledons contain roughly two-thirds the total isoflavones found in the seed. Saponin analysis shows a significant portion of the saponins found in the soybean is concentrated in the germ. The germ contains nearly all the A-group saponins, while the B-group saponins are nearly equally distributed between the germ and cotyledons. The hulls contain little in the way of either isoflavones or saponins.