Continuous hot pressurized fluids extraction of isoflavones and soyasaponins from defatted soybean flakes

Abstract

This work examined the effect of pressure (413–4410 kPa), temperature (333–393 K), solvent flow rate (10–25 mL/min), ethanol-to-water ratio (0–95%) and the feed loading (80–450 g) on hot pressurized fluids extraction of isoflavones and soyasaponins from defatted soybean flakes. A four-factor Taguchi experimental design was employed to optimize operational conditions of these extractions. Experimental results indicated that 95% of isoflavones and 76% soyasaponins were recovered from defatted soybean flakes by using hot pressurized 80% ethanol extraction at 383 K, 551 kPa and 25 mL/min with a 80 g feed loading. The recovered isoflavones were further purified by a solid–liquid column packed with Amberlite XAD 16-HP resin. The content of isoflavones in the collected fraction could be enhanced from 1 to 58% by weight.