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BACKGROUND Vitis vinifera L. ‘Cabernet Gernischt’ grapes from the Yantai wine region of China usually form dense clusters and contain low phenolic content. We applied five concentrations (ranged from 5 to 25 mg L−1) of gibberellic acid (GA3) to ‘Cabernet Gernischt’ before anthesis to decrease cluster compactness in two consecutive vintages. Yield indices, grape maturity, and wine phenolic compounds were determined. RESULTS GA3 application significantly reduced cluster compactness, bunch weight, and yield per vine, but it did not significantly improve fruit ripening. The levels of total phenolics, total tannins, and total anthocyanins in wine were enhanced by GA3 application, with 10 and 15 mg L−1 GA3 treatments consistently producing a significant increase in the concentrations of mavidin, cyanidin, and their derivatives. Specifically, trans‐resveratrol was consistently significantly increased by 15 mg L−1 GA3 application. Principal component analysis of phenolic compounds demonstrated the differences among wines produced from GA3 treatment groups and the control. CONCLUSION Overall, wine phenolic profiles could be significantly modified by application of low concentrations of GA3 before anthesis. Application of high levels of GA3 is not recommended due to significant yield decrease. © 2022 Society of Chemical Industry.

In some wine regions of China, Cabernet Gernischt (CG; Vitis vinifera L.) grape berries usually exhibit low pigment content and titratable acidity, and low sensory quality of the resulting wine. The aim of this study was to evaluate co-winemaking of CG wines using the red grape cultivar Beibinghong (BBH; Vitis amurensis Rupr.) at different proportions in terms of alcohols, phenolic compounds, and sensory properties of the wines. The results showed that the co-winemaking wines contained a similar content of higher alcohols, whereas the methanol content increased with an increase in BBH proportion, although this was still corresponded with the national standard. Significantly higher levels of titratable acidity were observed in co-winemaking wines at the ratio of 6:4 and 5:5, compared with monocultivar CG wines. All co-winemaking wines, except CG:BBH (9:1) wine, showed significantly higher levels of total anthocyanins, total phenolics, total tannins, and total flavan-3-ols. Further, individual phenolics, primarily diglucoside anthocyanins and non-anthocyanins (trans-ferulic acid, myricetin, viniferin, trans-caffeic acid, 3,4-dihydroxybenzoic acid), as important contributors to wine color intensity, permitted the differentiation of the wines via principal component analysis. In most cases, co-winemaking wines exhibited higher scores of the 10 sensory attributes on color, aroma, mouthfeel, and overall quality compared with monocultivar wines.Co-winemaking CG wines with BBH at 7:3 ratio demonstrated the highest scores of color intensity, aroma intensity, aroma quality, and overall quality. The results indicate that co-winemaking with V. amurensis grape variety may be useful to enhance V. vinifera wine quality by modifying wine composition.