title: Continuous microwave-assisted isoflavone extraction system: design and performance evaluation.
abstract: The purpose of this research was to design, test, and optimize a continuous microwave extraction method using temperature and residence time during and after microwave exposure as optimizing parameters for extraction of major isoflavones (genistin, genistein, daidzin, and daidzein) from soy flour. The extraction yield of four isoflavones at different heating temperatures (55 and 73 degrees C) and extraction times (0, 4, 8, 12, and 16 min) were investigated and compared with yields provided by a conventional solvent extraction method. The microwave prototype consisted of multiple, commercially available, batch-type, house-hold microwave units placed on top of each other in series to impart a continuous operation. The optimum parameters for microwave-assisted extraction of isoflavones were 73 degrees C for 8 min using a 3:1 ethanol-to soy flour ratio. At these parameters, the total yield of isoflavones extracted doubled, while the amount of oil extracted was 12%. Continuous microwave-assisted solvent extraction is a viable method for extraction of soybean isoflavones at relatively short residence times and high throughput.
authors.affiliation: Louisiana State University Agricultural Center, BAE Department, Baton Rouge, LA 70803, USA.
authors.forename: B G
authors.initials: BG
authors.lastname: Terigar
authors.forename: S
authors.initials: S
authors.lastname: Balasubramanian
authors.forename: D
authors.initials: D
authors.lastname: Boldor
authors.forename: Z
authors.initials: Z
authors.lastname: Xu
authors.forename: M
authors.initials: M
authors.lastname: Lima
authors.forename: C M
authors.initials: CM
authors.lastname: Sabliov
mesh_terms: D001709:Biotechnology / Q000295:instrumentation* / Q000379:methods*; D004867:Equipment Design; D019833:Genistein / Q000302:isolation & purification; D007529:Isoflavones / Q000302:isolation & purification*; D008872:Microwaves; D010938:Plant Oils / Q000302:isolation & purification; D013025:Glycine max / Q000737:chemistry / Q000648:ultrastructure; D013696:Temperature; D013997:Time Factors
chemical_list: D007529:Isoflavones; D010938:Plant Oils; C040641:genistin; C013908:daidzin; C004742:daidzein; D019833:Genistein