Optimization of Ultrasonic-Assisted Extraction of Crude Flavonoids from Moutai Distillers Grains and Evaluation of Their Antioxidant and Anti-Inflammatory Activities

Distillers grains are the main by-products of the brewing industry, with a large output but a low degree of resource utilization. Exploring more efficient comprehensive utilization technologies for distillers grains is of great significance for increasing the added value of the brewing industry. This study took Moutai distillers grains as the research object, and the ultrasonic-assisted extraction process of crude flavonoids from distillers grains was first optimized. On this basis, the in vitro antioxidant and anti-inflammatory effects of the crude flavonoid extract were further explored. The results show that the optimal process parameters for ultrasonic-assisted extraction of crude flavonoids were an ethanol concentration of 95%, liquid-to-solid ratio of 26 mL/g, and ultrasonic time of 36 min (with a fixed ultrasonic power of 500 W). Under such conditions, the yield of crude flavonoid extract from Moutai distillers grains was 25.39% ± 5.05%. In vitro antioxidant results showed that 2 mg/mL of crude flavonoid extract had good DPPH and ABTS free radical scavenging activities (78.17% and 75.21%, respectively). In vitro anti-inflammatory results showed that 0.5% crude flavonoid extract (the survival rate of HaCaT cells treated with this concentration was greater than 80%) significantly reduced the secretion of the inflammatory factors IL-6 and IL-1β induced by TNF-α and IFN-γ. In summary, this study showed that Moutai distillers grains may provide easily accessible and inexpensive raw materials for the functional food and cosmetic industries.