New insights into extraction, isolation and characterization of β-glucan from edible and medicinal mushrooms

β-Glucans derived from edible and medicinal mushrooms exhibit diverse biological activities, particularly immunomodulatory, antioxidant, and anti-inflammatory effects. This review critically summarizes studies published mostly between 2015 and 2025, retrieved from Scopus, Web of Science, and ScienceDirect, to highlight recent progress in the extraction, purification, and structural characterization of fungal β-glucans. Special attention is given to the structural heterogeneity arising from variations in fungal species, linkage types [β-(1 → 3)/(1 → 6)], branching degree, and molecular weight, all of which influence solubility, conformation, and biological function. Comparative discussion of modern extraction approaches including enzymatic hydrolysis, ultrasonic-assisted, aqueous/alkaline, and green-solvent systems, demonstrates how these techniques enhance yield and maintain bioactivity. Advances in chromatographic purification and analytical tools such as NMR spectroscopy, FTIR, and HPLC are also reviewed for their contributions to elucidating structure–function relationships. By integrating recent data and identifying methodological gaps, this work provides updated insights into the optimization and application of mushroom β-glucans in functional foods, nutraceuticals, and therapeutic formulations.