Compositional differences of β-glucan-rich extracts from three relevant mushrooms obtained through a sequential extraction protocol

In this work, a sequential fractionation protocol (cold and hot aqueous and alkaline extractions) and detailed compositional analysis (gross composition, monosaccharide analysis, FTIR, TGA) was applied to three relevant mushrooms in terms of global production (Grifola frondosa, Lentinula edodes and Pleurotus ostreatus) aiming to understand what is preferentially extracted during fractionation and how β-glucan extraction is affected by mushroom source. Room temperature aqueous extracts showed highest overall yields (56.3-82%) consisting of proteins, sugars and polyphenols. β-glucan content was highest in P. ostreatus and was concentrated in the more soluble fractions. On the contrary, a recalcitrant β-glucan in G. frondosa was mainly present in the residue (7.38%). L. edodes showed β-glucan populations distributed along aqueous and alkaline extracts, higher abundance of non-glucan polysaccharides and higher chitin purity (47.78%) in the residue. This work sets the basis for the rational design of extraction processes aiming to valorise mushroom biomass.