From byproduct to bioresource: Antioxidant potential, flavor profile, and microbiological quality of recovered water from freeze-dried and rotary evaporation dried Muscat grapes.

Grape drying generates substantial condensate (recovered water) containing soluble aroma and bioactive compounds, offering potential for value-added reutilization. This study characterized the antioxidant capacity, volatile profile, and microbiological quality of the water recovered during freeze-drying (FD) and rotary evaporation drying (RED) of Muscat grapes. Both condensates retained measurable grape-derived bioactives and volatiles (e.g., linalool, squalene). FD-recovered water exhibited peak total phenolic content (0.49 mg GAE/L) and flavonoid (0.42 mg RE/L) contents at 60 h, accompanied by increased DPPH (25.27%) and ABTS•+ (20.99%) radical scavenging activities. FD generally demonstrated higher antioxidant retention than RED, which induced greater thermal degradation. Notably, pathogenic indicators (E. coli and S. aureus) were absent across all samples. Although absolute antioxidant levels were relatively low, the retention of natural grape aromas alongside satisfactory hygiene indicators suggests the recovered water's potential as a clean-label flavoring base, though comprehensive safety and sensory evaluations remain necessary before industrial application.