“Tannin in skins and seeds of Cabernet sauvignon, Syrah, and Pinot noir berries during ripening”

Tannins are the most abundant type of phenols in grapes. Because they include a vast collection of chemical structures, measuring them is a huge task. But fortunately, it may not be necessary to know how much of each species of tannin is there in a wine. It would seem sufficient, for practical purposes, to be able to know how much of that tannin plays a role in a wine’s astringency. This is what Dr. Adams and his team achieved in this study. They started out with an old method of precipitation of tannin with protein (Hagerman and Butler, 1978), and were able to adapt it so it could be used with grapes. The result is a relatively simple assay that can be used in the winery to estimate the amount of tannin in both grapes and wines. Once the method was optimized, they used it to study how tannin levels in the skins and seeds of three major varieties change during ripening. They also analyzed the tannins in the corresponding wines. Their main findings follow.