Pressurized hot water extraction of crude polysaccharides, β-glucan, and phenolic compounds from dried gray oyster mushroom

Abstract

This study aimed to investigate the effects of temperature (100 °C–140 °C), pressure (0.4–1.0 MPa), and extraction time (20–60 min) on the extraction yield of crude polysaccharides, β-glucan, and total phenolic compounds with pressurized hot water extraction of gray oyster mushrooms (Pleurotus sajor-caju (Fr.) Singer). The extraction conditions were optimized by maximizing all responses, using a central composite design (CCD)-based response surface methodology. Temperature mainly affected the increase in the extracted yield and phenolic content. However, exceeded temperature and extraction time negatively affected the β-glucan yield. The optimal extraction conditions were at 140 °C, 0.92 MPa, and 40 min with a corresponding extraction yield of 3.20 ± 0.17 g/100 g, as well as β-glucan and total phenolic contents of 43.84 ± 3.86 mg/100 g and 8.49 ± 0.66 mg gallic acid equivalent/100 g dried extract, respectively. The antioxidant activities of extracts were estimated by in vitro biological assays. The SC50 values of DPPH, NO, and ABTS assays were 1.66 ± 0.02, 1.50 ± 0.19, and 6.94 ± 1.04 mg/mL, respectively. This work demonstrates an alternative approach to valorize over-produced mushrooms.