Red wines from South America: Content of phenolic compounds and chemometric distinction by origin

With the purpose of evaluating the wine grouping according to phenolic composition and geographical origin, eight individual phenolics were quantified in South American commercial red wines. Initially a simple chromatographic method was developed and validated, because there is no official method to quantify phenolic compounds in general. Then, the phenolic compounds were analyzed by HPLC-UV/Vis using gradient elution. The method was linear in the ranges (mg L− 1): 0.4 to 22.0 (catechin and quercetin-3-glucoside); 0.2 to 9.0 (gallic acid and epicatechin); 0.05-1.5 (myricetin quercetin and resveratrol) and from 0.025 to 0.3 (kaempferol), with values of r2 above 0.9958. The results recovery test on two levels ranged from 81.89 to 110.36%, for gallic acid, epicatechin, catechin, quercetin-3-glucoside, myricetin, quercetin and resveratrol; and from 71.98 to 114.63% for kaempferol. A principal component analysis (PCA) was used to investigate the differences of Brazilian and Argentine wines according to their phenolic composition. The wines from Argentina showed higher levels of gallic acid than the Brazilian wines. These results suggest that wine samples from Argentina preferentially follow the biosynthetic route phenylalanine → cinnamic acid → benzoic acid → benzoic acids derivatives (e.g. gallic acid). On the other hand, samples of the Syrah variety from the San Francisco Valley in the Northeastern of Brazil had higher individual concentrations of catechin, quercetin-3-glucoside and resveratrol than those from Argentina, suggesting a satisfactory adaptation of this variety on the natural environment of the Northeast of Brazil, the “terroir”.