Testing the effect of combining innovative extraction technologies on the biological activities of obtained β-glucan-enriched fractions from Lentinula edodes

Innovative technologies as ultrasound-assisted extraction (UAE) (550 W, 60% amplitude, 50 degrees C) or subcritical water extraction (SWE) (200 degrees C, 11.7 MPa) were more effective than hot water extractions to obtain beta-glucan-enriched fractions from shiitake mushrooms. UAE required longer extraction time (60 min) than SWE (15 min). Combination of UAE + SWE or pre-treatment of the raw material with supercritical CO2 (SFE) (40 degrees C, 35 MPa, 3 h) before both extractions yielded extracts containing larger beta-glucan concentrations. Fluorimetric/colorimetric determinations indicated that obtained fractions contained (1 -> 3)- and (1 -> 3),(1 -> 6)-beta-glucans. NMR confirmed their presence as well as (1 -> 3)-alpha-glucans and heteropolymers including mannose and galactose. SWE (15 min), SFE + SWE or UAE + SWE extracts showed larger glucose levels and lower mannose and galactose residues than the other extractions suggesting certain extraction specificity towards beta-glucans. They also included more chitin-derivatives than UAE. The extracts obtained after combination of technologies partially retained their immunomodulatory properties but they showed high hypocholesterolemic activities according to in vitro studies.