Evaluation of microwave-assisted and pressurized liquid extractions to obtain β-d-glucans from mushrooms

Microwave-assisted extraction (MAE) and pressurized liquid extraction (PLE) were compared as advanced technologies to obtain polysaccharides (particularly biologically active β-glucans) from Pleurotus ostreatus and Ganoderma lucidum fruiting bodies. Extraction effectiveness was compared by a full-factorial experimental design (response surface methodology, RSM), using water as extraction solvent. Total carbohydrate content of the obtained extracts and polysaccharide yields were the variable responses investigated, while temperature and extraction time were the experimental factors. Temperature showed stronger influence in the polysaccharide extraction than time. The latter factor slightly affected MAE but not PLE extractions. Optimal conditions within the studied range were determined for each extraction method and species based on the desirability functions. Regarding the polysaccharide composition, the main differences between the species were more quantitative rather than qualitative, since NMR analyses indicated that all extracts contained mainly β- and α-glucans and heteropolysaccharides. Both extraction systems were effective for polysaccharide extraction from mushrooms.