Quince and persimmon vinegars as functional foods: phenolic characterization and bioactivity assessment

The present study aimed to characterize the phenolic composition and in vitro biological potential of quince and persimmon vinegars in comparison with their unfermented ethanolic extracts. The highest total phenolic and total flavonoid contents were recorded as 102.18 ± 1.86 µg PEs/mg in Quince Vinegar 2 and 171.36 ± 1.45 µg/mg in Persimmon Vinegar 3, respectively, whereas the corresponding alcoholic extracts contained markedly lower phenolic levels (e.g., 5.70 µg PEs/mg in Q Extract 1). LC–MS/MS analysis identified quinic, caffeic, chlorogenic and gallic acids, together with quercetin and catechins, as major organic acids and phenolic constituents. Antioxidant assays revealed a strong inverse relationship between phenolic content and IC₅₀ values, with fermented vinegar samples consistently exhibiting higher activity than their unfermented counterparts. Both quince and persimmon vinegars showed pronounced inhibition of α-glucosidase, while additional in vitro inhibitory effects were observed against cholinesterase and urease enzymes. Moderate inhibition of tyrosinase, elastase and collagenase was also detected. Overall, fermented vinegars displayed broader phenolic diversity and stronger multifunctional bioactivities compared to non-fermented extracts, indicating that fermentation-related matrix effects enhance phenolic availability and biological response. These findings provide a compositional and functional basis for further investigation of fermented fruit vinegars as functional food matrices, with potential applications pending validation through in vivo and clinical studies.