Innovative technologies as ultrasound-assisted extraction (UAE) (550 W, 60% amplitude, 50 °C) or subcritical water extraction (SWE) (200 °C, 11.7 MPa) were more effective than hot water extractions to obtain β-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 °C, 35 MPa, 3 h) before both extractions yielded extracts containing larger β-glucan concentrations. Fluorimetric/colorimetric determinations indicated that obtained fractions contained (1 → 3)- and (1 → 3),(1 → 6)-β-glucans. NMR confirmed their presence as well as (1 → 3)-α-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 β-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

This research was supported by national R+ D program from the Spanish Ministry of Science and Innovation (project AGL2014-56211-R ) and the regional program from the Community of Madrid, Spain ( S2013/ABI-2728 ).