Optimization of the Solid Fermentation Process of Hordeum vulgare Linn. by Ganoderma lucidum Mycelium and Its Antioxidant and Hypoglycemic Activities

This study focuses on the optimization of the solid fermentation conditions of highland barley (Hordeum vulgare Linn.) by Ganoderma lucidum mycelium to enhance its health benefits. The optimization was guided by triterpene content, using single-factor experiments and response surface methodology. Additionally, the antioxidant and hypoglycemic activities of the fermented product were investigated. The optimal fermentation conditions (38 g of material per 250 mL, 13% inoculum size, and a temperature of 29 ℃) resulted in a triterpene content of 14.83 mg/g, representing a 129.92% increase compared to the unfermented product. The antioxidant activity of highland barley significantly improved post-fermentation, as evidenced by enhanced DPPH radical, hydroxyl radical, and superoxide anion radical scavenging activities (P<0.05). The IC₅₀ values for DPPH, hydroxyl, and superoxide anion radicals were 1.68, 4.37, and 8.18 mg/mL, respectively, indicating the order of radical scavenging rates within the concentration range of 1~5 mg/mL as DPPH > hydroxyl > superoxide anion. Furthermore, the fermented product exhibited significantly increased inhibitory effects on α-amylase and α-glucosidase (P<0.05), and the inhibition increased with the increase of concentration within the concentration range of 15~35 mg/mL. The findings suggested that the Ganoderma lucidum-highland barley product holds potential as a functional food with substantial nutritional and health benefits.