Sterol enriched fractions obtained from Agaricus bisporus fruiting bodies and by-products by compressed fluid technologies (PLE and SFE)

Ergosterol, ergosta7,22 dienol, ergosta 5,7 dienol, fungisterol, ergosta-4,7,2-trien-3-ona and ergosta-4,6,8(14),22-tetraen-3-ona were the fungal sterols detected in Agaricus bisporus mushrooms after optimization of a sterol extraction method. Their concentration ranged from 3.1 to 11.2 mg/g dw depending on the strain, casing soil, flush number, developmental stage and sporophore tissue analyzed. Two methods were optimized to obtain sterol enriched extracts from A. bisporus fruiting bodies using pressurized liquid extraction (PLE) and supercritical fluid extraction (SFE). PLE using ethanol as solvent at 10.7 MPa (50 °C and 100 °C) after 5 cycles of 5 min extraction (mixing in the extraction cell the sample with sand in a ratio 1:4) yielded extracts with respectively 5 and 2.9% sterols. Using SFE-CO2 at 40 °C and 9 to 30 MPa fractions containing 60% of sterols were obtained. Both technologies could be also utilized to extract sterols from mushroom by-products (the lower part of the stipe) as a method for their valorization.Industrial relevanceIn this work, two environmentally friendly methods (SFE and PLE) to obtain sterol enriched fractions from Agaricus bisporus mushrooms were optimized. Extractions from both the complete fruiting body and the lower part of the stipe (usually discarded as a by-product during harvesting) yielded extracts with high ergosterol (and derivatives) content that could be used as functional ingredients to design novel foods with hypocholesterolemic properties since fungal sterols are able to reduce cholesterol levels in serum as plant phytosterols. Moreover, if the mushroom by-products are utilized as starting material, this application can be an interesting alternative method for the commercial valorization of this residue.

► The amount of sterols in A. bisporus depended on strain and cultivation conditions.
► Fungal sterol enriched fractions can be obtained by ASE and SFE.
► Sterol enriched fractions can be also obtained from wasted mushroom by-products.