pH: Wines

The pH range of most wines is between 2.9 and 4.2 (which incidentally, since the pH of the normal stomach is about 2, means that wines are 10 to 100 times less concentrated in the acid hydrogen ion than is the stomach interior). Wines with low pHs taste very tart while those with high pHs taste flat, or ‘flabby’. White wines with a pH of 3–3.2 and reds with a pH of 3.4–3.7 not only tend to taste refreshingly rather than piercingly acid, they are also more resistant to harmful bacteria, age better, and have a clearer, brighter colour (see below). Wines with pH values higher than this tend to taste flat, look dull, and are more susceptible to bacterial attack. In the last twenty years, average pH levels have risen considerably as a result of longer hang time and a fashion for riper wines. While it is possible to manipulate pH values, with grapes and wines it is difficult because of the wine’s high ‘buffer capacity’, which roughly correlates with total acidity. The pH can be increased by decreasing the concentration of hydrogen ions, however, and vice versa. (See acidification and deacidification for discussion of the legal and practical aspects of these operations.)