Electron Beam-Degraded β-Glucans from P. ostreatus Retain Their Structure and Biological Activity

β-glucans are biologically active biopolymers that influence metabolic activity and possess immunomodulatory, antitumor, anti-inflammatory, and wound-healing properties. The biological activity of β-glucans is influenced by both their primary structure and spatial conformation, which, in turn, depend on the natural source of the polysaccharides and their extraction methods. In this study, the water-soluble fraction of β-(1→3,1→6)-D-glucan, isolated from non-irradiated and irradiated Pleurotus ostreatus cryopowder pre-treated with alcohol, was investigated. Increasing the irradiation dose was found to increase the yield of the water-soluble glucan fraction. Furthermore, irradiation increased the solubility of glucans in water and reduced their bulk density and moisture content, which may be due to partial degradation of the biopolymer. According to FTIR and NMR spectroscopy, water-soluble glucan samples isolated from both irradiated and non-irradiated samples consist predominantly of β-(1→3,1→6)-D-glucan, protein, and a small amount of (1→3)-α-glucan. It was found that the triple-helix conformation of glucans in solution, assessed using Congo red analysis, did not change upon irradiation. Irradiation resulted in a dose-dependent increase in the antiradical activity of the glucans against the stable DPPH radical. Addition of irradiated glucans to sugar syrup used as a feed supplement for bee feeding resulted in a significant increase in the proline content of honey. Thus, electron irradiation is a promising method for obtaining β-glucans with high water solubility and contributes to enhancing their biological activity.