Effect of aqueous extraction method on total water-soluble polysaccharides content and phytochemical properties of white oyster mushroom (Pleurotus ostreatus)

Abstract

Abstract White oyster mushroom (Pleurotus ostreatus) is an important raw material for nutraceuticals because it contains various bioactive substances, including polysaccharides, vitamins, phenolic acids, terpenoids, and sterols. P. ostreatus mushroom polysaccharides possess diverse biological activities (antioxidant, hyperglycemic effects, and immunomodulatory). The extraction process impacts the yield, affecting the biological function of natural active ingredients. In this study, aqueous extraction methods, i.e., ultrasonic-assisted extraction (UAE), microwave-assisted extraction (MAE), and kinetic-assisted hot extraction (KAHE), were applied to investigate the impact of extraction methods on polysaccharides crude extract from the fruiting bodies of P. ostreatus mushroom and their phytochemical properties. Water-soluble polysaccharides content, total polyphenolic content, total terpenoid content, and antioxidant level were analyzed using the spectrophotometric method by phenol-sulfuric acid, Follin-Ciocalteau’s reagent, vanillin-perchloric acid, and 1,2-diphenyl-2-picrylhydrazyl (DPPH) scavenging assay, respectively. After the extraction process, the morphological alterations on the surface of mushroom residues were observed using Scanning Electron Microscopy (SEM). The investigation has shown that aqueous extraction methods significantly affect the yields of polysaccharides crude extract and other phytochemical properties, i.e., total phenolic content, terpenoid content, and the DPPH free radical scavenging activity. The sample from MAE had the highest total water-soluble polysaccharide content (61,73±1,35% w/w DW) and the highest total phenolic content (3,44±0,75 %w/w DW). MAE method has the best potential and efficiency compared to UAE and KAHE for extracting polysaccharides while maintaining their phytochemical properties.