Ultrasonic replacement of natural aging: Potential strategies for improving the color, antioxidant activity, and volatile compound profile of astragalus mead

The growing demand for natural and functional beverages has driven research aimed at improving the quality of herbal meads. This study investigates the use of non-thermal processing methods, ultrasonic, microwave, and high hydrostatic pressure processing, as alternatives to traditional natural aging for improving the physicochemical properties, antioxidant activity, color stability, and volatile compound profile of astragalus mead. Response surface methodology was employed to optimize fermentation conditions, which yielded the highest flavonoid content and sensory quality at an impregnation time of 12 h, an impregnation temperature of 10 °C, and a fermentation temperature of 20 °C. Among the processing methods evaluated (natural aging, ultrasound, microwave irradiation, and high hydrostatic pressure), ultrasound treatment resulted in the most significant improvements. Specifically, it increased total phenol content by 7.22 %, total flavonoid content by 9.41 %, and antioxidant capacity by 65.43 %. Volatile compound analysis also revealed a 191.30 % increase in ester content, significantly enhancing floral and fruity notes. Sensory analysis using quantitative descriptive analysis, partial least squares discriminant analysis, and weighted gene co-expression network analysis confirmed the efficacy of ultrasound, with ethyl caprylate identified as a key aroma contributor. These findings suggest that ultrasound is an effective non-thermal processing technique for improving the aging process and overall quality of astragalus mead. This study provides valuable insights for the industrial application of non-thermal processing technologies in astragalus mead production.