Laboratory Optimization and Antioxidant Evaluation of β-Glucan Extracted from Lignosus rhinocerus Mycelium using Microwave-Assisted Extraction

This study aimed to optimize the cultivation of Lignosus rhinocerus mycelium at a laboratory level and evaluate the antioxidant activity of β-glucan extracted from the mycelium. Using the Response Surface Methodology (RSM) and Central Composite Design (CCD), optimal conditions for mycelium growth were identified at a temperature of 31.5 °C, 15 % potato powder, and 3.5 % glucose concentration, yielding a maximum mycelial biomass of 44.7 g/L and β-glucan production of 15.08 g/L. The β-glucan was extracted using a household microwave, significantly improving the extraction efficiency. The extracted β-glucan demonstrated notable antioxidant activity, with DPPH radical scavenging activity at approximately 53.31 % and ABTS radical scavenging activity around 47.31 %, albeit slightly lower than the 71.94 % activity of ascorbic acid. Comparative analyses highlighted the consistency in antioxidant capacities across different morphological stages, with aqueous methanol extracts of mycelium (LR-MH, LR-MT) and culture broth (LR-BH, LR-BT) showing either higher or comparable antioxidant activities to sclerotium extracts (LR-SC). Field Emission Scanning Electron Microscopy (FESEM) and Fourier Transform Infrared (FTIR) spectroscopy confirmed the structural integrity of the extracted β-glucan. The findings support the feasibility of using mycelium for β-glucan extraction, offering a sustainable alternative to traditional methods. HIGHLIGHTS Optimized Mycelium Growth: Achieved optimal growth conditions for Lignosus rhinocerus mycelium, maximizing biomass and β-glucan production. Microwave Extraction: Used a household microwave for efficient β-glucan extraction, improving yield and reducing costs. Strong Antioxidant Activity: Extracted β-glucan showed significant antioxidant activity, comparable to ascorbic acid. Comparable Antioxidant Levels: Mycelium extracts displayed antioxidant activities similar to those of sclerotium extracts. Confirmed Structural Integrity: Structural integrity of β-glucan was validated using FESEM and FTIR spectroscopy. GRAPHICAL ABSTRACT