Effects of geographical origin, variety and farming system on the chemical markers and in vitro antioxidant capacity of Brazilian purple grape juices

Abstract The effects of farming system, geographical origin, and grape variety on the in vitro antioxidant capacity, some physicochemical properties and chemical composition were investigated. Major and minor phenolic compounds, reducing and antioxidant assays using chemical and biological systems were determined in n = 62 100% purple grape Brazilian juices ( Vitis labrusca L.) from organic and conventional systems from the three largest producing regions. Results were subjected to ANOVA, MANOVA, and principal component analysis. No distinction was observed between organic and conventional grape juices regarding the in vitro antioxidant/reducing capacities, but only through the analysis of individual phenolic acids. The geographical origin and grape variety played a more important role in distinguishing Brazilian grape juices according to the antioxidant activity and some chemical markers. MANOVA was applied and the combined effect of farming system and geographical origin was only significant for tonality (p = 0.044) and protocatechuic acid content (p = 0.030). Correlation analysis was performed and results showed that total phenolic content, total flavonoids, flavonols, anthocyanins, and condensed tannins were statistically associated (p