Submitted to: Food Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/15/2007
Publication Date: 4/1/2008
Citation: Lee, J., Kennedy, J.A., Devlin, C., Redhead, M., Rennaker, C.D. 2008. Effect of early seed removal during fermentation on proanthocyanidin extraction in red wine: a commercial production example. Food Chemistry. 107(3): 1270-1273. Interpretive Summary: Grape growing and winemaking conditions influence what ends up in the wine. This study examined the tannin composition of Merlot grapes fermented with (control wine) or without seeds (seed-removed wine), to aid us in understanding of different winemaking strategies. Only small differences were observed between the two wines, but were enough for the winemakers to continue with their traditional winemaking method (seeds not removed until after completion of alcohol fermentation).
Technical Abstract: Wines (Vitis vinifera L. cv. Merlot) were made by a commercial winery to examine the effects of seed removal at ~10 °Brix on the extraction of proanthocyanidins during fermentation. Seeds were removed at the point when they fell to the bottom of the fermentor, and were thus easily removed during regular pump-over operations. Proanthocyanidin extraction was compared to wine made from traditional winemaking regime in which no seed removal occurred. Proanthocyanidin differences observed in the wines were minor. The control wine contained a slightly higher % molar proportion of seed proanthocyanidins ((-)-epicatechin-3-O-gallate extension and terminal subunits), demonstrating higher seed tannin extraction, and the seed-removed wine contained a higher % molar proportion of skin proanthocyanidin indicators ((-)-epigallocatechin extension subunits). Seed-removed Merlot wines had higher concentrations of total anthocyanins. Minor differences in color measurement values between the two wines were also observed. The control wine was slightly more orange (larger hue angle, h°), lighter (larger L* value), and more saturated (higher chroma value, C*) in color. This appears to be the first paper to report the effects of early seed removal in Merlot winemaking, and demonstrates how winery tannin management techniques contribute to proanthocyanidin composition.