Ultrasound-assisted extraction of ergosterol and antioxidant components from mushroom by-products and the attainment of a β-glucan rich residue.

Revalorization of mushroom by-product (stalks of A. bisporus) by extracting its components is proposed. The extraction kinetics at 25 °C of ergosterol, phenolic compounds and antioxidant activity by mechanical agitation (at 130 rpm) and ultrasound assistance (at 182 and 321 W/L) in 70 and 96% v/v ethanol/water solutions during 30 min were evaluated and satisfactorily modelled, using the Weibull model (mean relative error ≤ 7.8%). The effect of the ethanol concentration was high in the ergosterol extraction yield (2 times higher yields in 96% than in 70%) but slight in those of phenolic compounds and antioxidant activity. Ultrasound assistance promoted considerable yield increases (up to 2 times higher in ergosterol, 46% in phenolic compounds and 25% in antioxidant activity) depending on the ethanol concentration and ultrasound power density. The residues after extraction were characterized and constituted a potential source of high value polysaccharides as β-glucans (average 12.2 ± 1.7g/100 g dm).