Polysaccharides and Antioxidants from Culinary-Medicinal White Button Mushroom, Agaricus bisporus (Agaricomycetes), Waste Biomass

Agaricus bisporus, also known as the white button mushroom or champignon, is the most cultivated mushroom species worldwide. In addition to its favorable nutrient profile, it contains a number of compounds with antioxidant, antibacterial, anti-inflammatory, antitumor, and immunomodulatory activities. Waste biomass is a secondary product obtained from A. bisporus during the harvesting stage. It is underused, although it could be a cheap source of polysaccharides and antioxidants for use in food and feed production, or a source of nutraceuticals and cosmeceuticals. In this study, waste biomass was used as raw material for extraction of crude polysaccharides. The mean amount of crude polysaccharides extracted was 106 g/kg dry weight debris-free mushroom waste biomass. The crude polysaccharides recovered contained 11.57% α-glucan and 16.37% β-glucan. Total carbohydrates composed 44.18%. No significant differences were found in the Fourier transform infrared spectra, which confirmed the presence of protein, α-glucan, and β-glucan in all samples; phenols were detected only in waste biomass and market-ready A. bisporus fruiting bodies. The total phenol content in methanol extracts of waste biomass and A. bisporus fruiting bodies was 6.16 and 11.25 mg gallic acid equivalents/g extract, respectively. Antioxidant capacities of methanol extracts from waste biomass, as determined by spectrophotometric techniques, were 22.67 μmol Trolox/g extract (ABTS radical scavenging), 51.77 μmol Fe2+/g extract (ferric-reducing antioxidant power), and 51.52% (DPPH radical scavenging). Although these values were lower than those for A. bisporus fruiting bodies, the waste biomass has great potential for use in food, feed, and other bioproducts of economic importance.