By Harold McGee
The appearance of a wine can give some important clues about how it will taste. If the wine is cloudy and the particles don’t settle with a few hours’ standing, it has probably undergone an unintended bacterial fermentation in the bottle, and its flavor is likely to be off. Tiny crystals (which do settle) are usually salts of excess tartaric or oxalic acid, and are not signs of spoilage; in fact they indicate a good level of acidity. “White” wines actually range in color from straw yellow to deep amber. The darker the color, the older the wine—the yellow pigments turn brownish when oxidized—and the more mature the flavor. Most red wines retain a deep, ruby-like color for some years, along with a fruity character in the flavor. As they age, the anthocyanin pigments complex with some of the tannins and precipitate, leaving more of the brownish tannins visible. The wine develops an amber or tawny tint, which goes along with its less fruity, more complex flavor.