Physical and chemical stability

Young wines are supersaturated in tartrates; refrigeration and cold filtration will reduce the concentration of tartrates below the level that would subsequently form crystals in the bottle.

Young white wines often contain high concentrations of rapidly browning phenolics which, if left in the wine, will cause undue darkening of the wine after bottling. Selective fining, with casein, for example, can remove the offending type of phenolic and ensure longer light colour in young white wines. Young red wines may also contain excessive amounts of tannins which taste bitter and astringent. If they are designed to be drunk young, they can be fined to remove some of these tannins.