Interactions of Grape Skin, Seed, and Pulp on Tannin and Anthocyanin Extraction in Pinot noir Wines

Abstract

Berry tissue components (skin, seed, and pulp) were isolated from Pinot noir grapes to determine the tannin content of each component. In addition, the role of each berry component in determining the phenolic profile of the wine was investigated by omitting or doubling each berry tissue in the must and fermenting these using submerged cap microvinification. Monomeric anthocyanin, total tannin, and nonbleachable pigment concentrations in juice and wine were examined at seven time intervals from yeast inoculation (day 0) to 12-months bottle age (day 400). When included in the must, berry pulp was associated with reduced wine tannin concentration, an effect that was more selective for seed tannin. Consequently, the tannin composition of wines made with whole-berry fermentations most closely reflected that of skin tannin. The formation of nonbleachable pigments was greater in treatments where seeds were present during fermentation. However, when the contribution of seed tannin in wine was increased by doubling the complement of seeds in the must, anthocyanin concentration remained constant and the concentration of nonbleachable pigments did not increase during aging. Treatments with a double complement of grape skins were found to enhance both nonbleachable pigment and tannin in aged wines.