Processing-Driven Changes in Phenolic Composition and Antioxidant Capacity During Plum Wine Production from the 'Stanley' Cultivar.

Plum fruits are a valuable raw material to produce fermented beverages and a source of phenolic compounds with antioxidant properties. However, information on changes in phenolic composition during plum wine production is still limited. In this study, the evolution of phenolic compounds and antioxidant capacity during maceration and fermentation of wine from the 'Stanley' cultivar was investigated. Total phenolics, flavonoids, anthocyanins, and antioxidant capacity were determined spectrophotometrically, while individual compounds were identified by HPLC-DAD analysis. Eleven phenolic compounds were detected, including anthocyanins, hydroxycinnamic acids, and flavonols. Neochlorogenic acid, cyanidin-3-rutinoside, and rutin were the predominant compounds in fruits and wines. Phenolic content in plum skin was more than twofold higher than in whole fruit (445.20 vs. 198.32 mg GAE/100 g FW), with markedly higher anthocyanins (180.08 vs. 36.73 mg CGE/100 g FW), while juice showed much lower levels (89.32 mg GAE/L and 1.08 mg CGE/L). Maceration increased phenolic content and antioxidant activity, whereas fermentation led to a gradual decrease in most compounds, likely due to polymerization and degradation reactions. The wine produced contained 10.80 ± 0.15% (v/v) ethanol. Principal component analysis differentiated samples according to phenolic profile and fermentation stage.