Phytochemical and Antioxidant Profiling of Traditional Fruit Vinegars: A Comparative Study of Fruit Species

In this study, natural fruit vinegars produced from gilaburu (<i>Viburnum opulus</i>), blackberry (<i>Rubus fruticosus</i>), and bitter orange (<i>Citrus aurantium</i>) using traditional fermentation methods were compared in terms of their phytochemical composition and antioxidant capacity. Total phenolic content (496.07-696.0 mg GAE·L^-1), flavonoid levels (376.10-960.97 mg QE·L^-1), antioxidant activity (DPPH assay, 82.97%-92.02%), and organic acid profiles particularly oxalic acid (105.00-109.33 mg·L^-1) and acetic acid (288.00-308.67 mg·L^-1) were analyzed. The results revealed statistically significant differences among vinegar types in terms of total phenolic compounds, flavonoid levels, and certain organic acids (<i>p</i> < 0.001). Blackberry and gilaburu vinegars exhibited the highest total phenolic content, whereas the highest flavonoid level was determined in blackberry vinegar. The lowest flavonoid levels were observed in bitter orange vinegar, whereas bitter orange vinegar was distinguished by its acetic acid content within the organic acid profile. Despite having relatively lower phenolic and flavonoid contents, bitter orange vinegar demonstrated a high antioxidant activity comparable to that of the other vinegars (<i>p</i> > 0.05). This finding is likely attributable to synergistic effects between organic acids and other bioactive compounds. Phytochemical variation and sample grouping were visualized using principal component analysis, indicating that the observed differences were largely driven by the genetic characteristics of the fruit species because of the study design, ecological effects could not be evaluated independently of genetic factors. Overall, the findings suggest that blackberry and gilaburu vinegars possess a higher potential as functional food products, whereas bitter orange vinegar represents a valuable alternative owing to its strong antioxidant capacity and distinctive organic acid profile.