Viticulture and Winemaking
Zinfandel vines are quite vigorous and grow best in climates that are warm but not too hot, because grapes may shrivel in hot weather. Zinfandel's thin-skinned grapes grow in large, tight bunches that are sometimes prone to bunch rot. The fruit ripen fairly early and produce juice with high sugar levels. If weather conditions permit, the grapes may be late-harvested to make dessert wine. Zinfandel is often praised for its ability to reflect both its terroir and its winemaker's style and skill.
The grapes are known for their uneven pattern of ripening: a single bunch may contain both raisin-like, over-ripe grapes and green, unripened grapes. Some winemakers choose to vinify the bunches with these varying levels of ripeness, while others hand-harvest the bunches, even by single berries, through multiple passes through the vineyards over several weeks. This extensively laborious practice is one component in the high cost of some Zinfandels.
Red Zinfandel wines have been criticized for being too "hot" (too alcoholic), although modern winemaking techniques have helped make them more approachable. On the other hand, Zinfandel producers such as Joel Peterson of Ravenswood believe that alcohol-removing technologies, such as reverse osmosis and spinning cones, remove a sense of terroir from the wine. If a wine has the tannins and other components to balance 15% alcohol, Peterson argues, it should be accepted on its own terms.
When grapes are harvested, the length of fermentation, the length of the maceration period with skin contact and the level of oak aging affect the wine's taste. The degrees Brix at which the grapes are harvested dramatically affect the wine's flavor as well. White Zinfandel is normally harvested early at 20°Bx when the grapes have yet to develop much varietal character, though some examples can develop hints of tobacco and apple skin. At 23°Bx (the degree that most red wine is considered "ripe"), strawberry flavors develop. Cherry flavors appear at 24°Bx followed by blackberry notes at 25°Bx.
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