![]() Because light intensity is lost as light travels through the atmosphere, the light reaching higher-altitude vineyards is more intense and therefore contributes to conditions that yield more intensely tannic wines. Light intensity is a major influence in the development of skin tannins at higher altitudes. Skin tannins, in part, function as a grape’s sunscreen-the more light that reaches a grape’s surface (or the more intense that light is), the more tannins the skins produce. Warmer climates and vintages and grapes harvested later will have more developed, softened, and polymerized (larger) tannins. Cooler climates and vintages, as well as grapes that are picked earlier, tend to yield more aggressive tannins-more astringent and less polymerized (smaller) at the time the grapes are picked. Tannat and Nebbiolo, for example, are known for having especially high levels of tannins-these are wines that can often require years of aging before they’re ready to drink.Ĭonditions in the vineyard also affect the levels and types of tannins that develop. Different grape varieties have differing levels of tannins. Tannins in the skins protect the grapes from the sun. They begin accumulating during fruit set, a process that continues until the grapes begin producing anthocyanins (another type of flavonoid) at veraison, when the grapes begin to change color. ![]() Tannins develop naturally as grapes grow in the vineyard. “Then start to take these monomeric units together like Legos, and shortly you end up with many millions of combinations as unique as snowflakes.” Cultivating Tannins in the Vineyard Clark Smith, a consulting winemaker, writer, and educator based in Santa Rosa, California, offers a helpful analogy to explain the complexity of tannins in wine: “Take the dizzying array of thousands of different phenolic compounds,” he writes in his book, Postmodern Winemaking. The story of tannins, though, isn’t simply about smaller and larger. In general, smaller tannin polymers, which mainly come from seeds, stems, and newer oak, are bitter, but they become astringent as they polymerize and grow larger. When they’re abundant, barrel-derived tannins in wine tend to impart a sensation of a fine graininess on the tongue. Oak barrels can also contribute tannins to wine during the first few years of use, though the tannins yielded by barrels are primarily non-flavonoids, which can be helpful in color stabilization. In addition to the size variation in tannins among these three sources, the shape of the tannin molecules can vary significantly from one source to another. Stem tannins vary in size they can be as small as seed tannins or as large as skin tannins. Seed tannins are shorter, and therefore smaller (consisting of 2 to 20 polymerized monomers). Skin tannins are large, as they tend to polymerize more than tannins from other sources they can be formed from as few as 4 to as many as more than 100 monomers. Tannins in wine can come from five sources: grape skins, seeds, stems, oak, and additives. This is also why red wine in the spit bucket looks so much worse than white, with globs of saliva proteins having come together in the expectorated wine. When proteins are precipitated from your saliva, the saliva ceases to be an efficient lubricator, thus allowing for the astringent sensation we associate with tannins. One of the defining characteristics of tannins is that they bind with proteins and precipitate them from solutions, creating complexes that are insoluble in liquid (such as your saliva-or the liquids used in tanning hide). Non-flavonoids play a role in tannin formation as well, but from the perspective of tasting and wine structure, flavonoids-specifically those that form condensed tannins-are the primary contributors. ![]() ![]() Tannins are made up of two classes of phenols (a large and diverse category of plant compounds): The two classes are flavonoids and non-flavonoids. Tannins are formed from individual, monomeric ( mono denotes “single”) flavonoids that have bound together to form polymers ( poly means “many”)-a process called polymerization. Paying attention to the character of the tannins in a wine can give insight into the stage of a wine’s development and its potential for aging. The types of tannins in wine can be influenced by a number of factors-grape variety, conditions in the vineyard, vineyard management practices, vintage variation, and winemaking practices. ![]() White wine contains tannins as well, but in significantly lower concentrations their ageability is mostly determined by their acid and sugar levels. Tannins form the basis of structure in red wines-and they’re the primary determinant of the longevity of red wines. ![]()
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