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Pressurized Solvent Extraction of Genistein and Its β‐Glucoside Conjugates from Soybean Flours and Soy‐Based Foods
Author(s) -
Downing J. M.,
Chung O. K.,
Seib P. A.,
Hubbard J. D.
Publication year - 2007
Publication title -
cereal chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.558
H-Index - 100
eISSN - 1943-3638
pISSN - 0009-0352
DOI - 10.1094/cchem-84-1-0044
Subject(s) - phone , library science , chemistry , computer science , philosophy , linguistics
A study was conducted to extract genistein from soyabeans and soy foods by low- and high-pressure extraction methods and to compare the levels of total genistein in the extracts by HPLC. A secondary objective was to develop a rapid, automated high-pressure extraction method. Compared with the method of Barnes requiring stirring with extraction solvent for 60 minutes, the pressurized solvent extraction (PSE) required 20 minutes and required no filtration. Total time for the chromatographic separation and column reequilibration was 40 minutes. Recovery experiments utilized ground soy that was spiked with three levels of THB. The recovery of 2,4,4′ trihydroxydeoxybenzoin (THB, model substance for isoflavones) from the ground soy was satisfactory. The levels of genistein extracted by the PSE extraction method closely matched those of a 1-h stir extraction method. Heat used during PSE extraction caused significantly less acetyl-genistin to be present in extracts when compared with the atmospheric extraction method where ambient temperature was used. The change in the forms of genistein was due to heat-induced deesterification of the acetylgenistin to genistin, except for soy nuts. When soy nuts were subjected to the PSE extraction method, deesterification of both acetyl genistin and malonyl genistin occurred. It is concluded that PSE offers a rapid alternative to the atmospheric extraction method to recover genistein from soy flour and soy foods. Other advantages of the PSE extraction are automated operation and the fact that no filtration step is required. Disadvantages of the method are the initial cost of purchasing the extraction instrument and the need for a greater volume of methanol per sample extraction.