Valorization of Ligusticum chuanxiong hydrosol via Eurotium cristatum biotransformation: mechanistic insights into flavor remodeling and functional enhancement.

Ligusticum chuanxiong hydrosol, a low-value distillation by-product, is usually discarded because of its offensive medicinal odor and pronounced bitterness. To overcome these sensory defects, this study employed Eurotium cristatum, a "golden flower" fungus renowned for flavor remodeling in traditional fermentation, to valorize this underexplored aqueous matrix. This represents the first systematic application of E. cristatum for hydrosol biotransformation. Under optimized conditions (39°C, pH 6.7, 7% inoculum), total phenolics reached 71.25 mg/L. Electronic nose and tongue analyses indicated changes in the aroma profile and a reduction in bitterness intensity from 8.0 to 4.0. GC-MS and GC-O revealed flavor remodeling through the elimination of 2,4-dimethylphenol and enrichment of pleasant aroma compounds, including α-terpineol, D-limonene, and citral. Fermentation also enhanced hypoglycemic potential, with α-amylase and α-glucosidase inhibition reaching 80 and 79%, respectively. In addition, the fermented hydrosol showed increased radical-scavenging activity (83% DPPH and 84% ABTS) and improved cellular protection by reducing intracellular ROS, increasing superoxide dismutase activity, and, at 1% inclusion, attenuating IL-6, IL-1α, and TNF-α. Overall, E. cristatum effectively upcycled botanical by-products into high-value functional ingredients, offering a sustainable, green strategy for simultaneously improving the sensory quality and nutritional value of plant-based foods.