Impact of Enzymatic Hydrolysis Combined with Fermentation on the Nutritional Quality and Flavor Characteristics of Cyperus esculentus L. Meal Beverage

To enhance the quality of Cyperus esculentus L. and diversify its product range while promoting multi-level utilization within its industry, Cyperus esculentus L. meal obtained post-oil extraction was employed as the raw material to develop a probiotic beverage via enzymatic hydrolysis coupled with fermentation. The beverage's quality characteristics were subsequently evaluated. Initially, optimal enzymatic hydrolysis and fermentation conditions were determined based on reducing sugar content and viable probiotic counts as indicators, employing single-factor and orthogonal experimental designs. Changes in physicochemical properties, antioxidant activity, and volatile compound composition during fermentation were monitored. The results indicated that the optimum enzymatic hydrolysis parameters were a cellulase concentration of 4%, a hydrolysis time of 3 hours, a temperature of 55 ℃, and a pH of 5.5. A subsequent verification experiment yielded a reducing sugar content of 5.17 g/L under these optimal conditions. The optimal fermentation conditions were determined to be a temperature of 37 ℃, a duration of 36 hours, a solid-to-liquid ratio of 1:6 (w/v), and an inoculum size of 10% (v/v). A validation experiment using this optimal protocol resulted in a final viable probiotic count of 1.10×10⁹ CFU/mL. Lactic acid fermentation significantly decreased the beverage's pH, total sugar content, and fat content, while markedly increasing soluble dietary fiber content, total phenols, total flavonoids, and reducing sugar content (P<0.05). Consequently, antioxidant activity was significantly enhanced post-fermentation compared to pre-fermentation levels (P<0.05). Noticeable difference was observed in the volatile compound composition between the pre-fermentation and post-fermentation stages. The levels of nitrogen oxides, sulfides, and methyl compounds demonstrated a clear elevation after fermentation, the fermentation process contributed the distinctive flavor profile that was typical of lactic acid bacterial fermentation. The enzymatic hydrolysis coupled with fermentation process significantly improved the flavor profile of Cyperus esculentus L. meal and enhanced its nutritional properties, providing technical reference for the development of novel plant-based probiotic beverages.