Virtually all table wine begins with a grape, and grapes are divided into five parts, all of which can contribute to the eventual wine.
The stem or stalk is the part of the grape that attaches to the cluster and vine. It is the little handle you pluck out or pull away from the berry when eating grapes. Because it contains high amounts of tannins, stems usually are discarded in wine making in a process called “destemming,” although not always if the winemaker wants to amp up tannins for some reason.
The bush is the part of the stem inside the grape berry. When the stem is removed, the bush remains inside the grape. It is so small it has small effect on wine, but it does have tannin.
The seed—also called a pip—is inside the grape. Like the stem, it contains a large amount of tannins. Free run juice—the juice that appears before mechanical crushing simply from the weight of fellow grapes in the harvest bins and collection vessels—is not significantly affected by seed tannins. But grapes that are pressed, particularly in cheaper wines where there is intense pressing that can crack seeds, bitter tannins become part of the wine.
The pulp is the liquid center inside the grape where the juice comes from. It is mostly water with some sugars and acids. The color of the pulp of most grapes is grey, the juice almost clear.
The exterior skin does not have much influence on white wine because there is little contact between skins and juice in white wine. On the other hand, the skin is the most important ingredient in red wine. The tannins and color compounds in red wine grapes give the wine its color and some of its tannic qualities. The pigment transfers into the wine during fermentation, a process called maceration. Red wine spends significant time interacting with skins—and, for that matter, with any stems, bush, and seeds that may be in the mix.
There are 600 to 800 grapes in a 750 ml bottle of wine. Now you know what makes up each of those precious berries.
Last round: I wanted to reward myself with a hard-earned glass of wine after a difficult week. I glanced at a calendar and realized it was Wednesday. I had the glass anyway.
Email Gus at wine@cwadv.com. Facebook: Gus Clemens on Wine. Twitter: @gusclemens. Website: gusclemensonwine.com.