Microwave assisted extraction of soy isoflavones

A fast and reliable analytical method using microwave assisted extraction has been developed. Several extraction solvents (methanol (MeOH) and ethanol (EtOH), 30–70% in water and water), temperatures (50–150 °C), extraction solvent volume, as well as the sample size (1.0–0.1 g) and extraction time (5–30 min) were studied for the optimization of the extraction protocol. The optimized extraction conditions for quantitative recoveries were: 0.5 g of sample, 50 °C, 20 min and 50% ethanol as extracting solvent. No degradation of the isoflavones was observed using the developed extraction protocol and a high reproducibility was achieved (>95%).