Suitability of flavan-3-ol analysis to differentiate grapes from Vranac, Kratosija and Cabernet Sauvignon (Vitis vinifera L.) grown in Montenegro

Background and Aims Interest in the production of wines from indigenous cultivars such as Vranac and Kratosija is steadily increasing, since they offer distinct characteristics. In contrast to popular cultivars, little is known about their chemical composition, especially in Montenegro. Many important characteristics of red wines are related to phenolic substances. Therefore, it is imperative to determine the phenolic composition of these cultivars. Methods and Results Flavan-3-ol monomers of seeds were analysed by reversed phase HPLC after thioacidolysis. In the perchloric extract of skins, flavan-3-ol monomers and dimers were determined by HPLC. Catechin represented the most abundant flavan-3-ol in seeds, with a high concentration of epicatechin-3-O-gallate also found in Vranac. In the skins, procyanidin B-1 and catechin were the most abundant phenolic substances. Using multivariate statistics, a unique profile of the ratio of flavan-3-ols from each cultivar was found. Conclusions Cultivar and geographical origin considerably influenced the flavan-3-ol composition of the three cultivars. The flavan-3-ol concentration of berries exhibited characteristic varietal differences, with the order of concentration being Cabernet Sauvignon > Kratosija > Vranac. The indigenous Montenegrin cultivars had a significantly lower proportion of seed and skin mass than that of Cabernet Sauvignon, which resulted in a lower flavan-3-ol concentration in the berries. Significance of the Study The flavan-3-ol concentration of grapes from Vranac, Kratosija and Cabernet Sauvignon cultivars grown in Montenegro was determined for the first time. These results further broaden knowledge relating to characterisation of wine, optimisation of its production and authenticity control.