acids are highly reactive molecules that produce a sour taste in the food we eat and the beverages we drink. Besides supplying the obvious sour taste—one of the basic tastes recognized by the palate, along with sweet, salty, bitter, and savory or umami—acids do three fairly basic things physiologically: they increase salivation, stimulate the appetite, and refresh the taste buds, allowing them to experience flavors better. This is what makes many high-acid cocktails good choices to enjoy before a meal.
The opposite of acidity is alkalinity. Measuring the acid/alkaline ratio is typically accomplished with the fourteen-point pH scale, with pure acid at 0 and pure alkaline at 14. A reading of 7 means that acid and alkaline are in balance, or neutralized. Very few edible ingredients score above 7, in the alkaline range. Lemon juice has an approximate pH of 2, tomato juice 4, coffee 5; water, sugar, and even ethanol are 7 (neutral). Milk can sometimes measure at 8, baking soda at 9; ammonia has a pH of 11, and bleach comes in with a pH of 13.
There are several different types of acid that are typically found in beverages: citric (commonly found in lemon juice), malic (apples), tartaric (grapes), ascorbic (vitamin C), acetic (vinegar), and lactic (pickles).
Both lemons and limes are commonly used in mixed drinks, and they are fairly concentrated with approximately 6 percent acid. In addition to the citric acid also found in lemons, limes also contain malic and succinic acids. It is the succinic acid in limes that contributes their distinctly bitter-salty flavor. Oranges and grapefruits (both with an approximate pH of 3.5) have less acidity and more sugars than lemon and lime, which allows them to be enjoyed directly for their actual flavor profiles, whereas the acids from lemon and lime function more as a boost to the flavors of other substances with which they are combined.
In the mid-1800s, phosphoric acid was diluted and blended with salts of calcium, magnesium, and potassium into a solution referred to as “acid phosphate.” With a pH of approximately 2, it has an acidity comparable to that of lime juice and serves as the foundation of what once were some of the most popular soda fountain drinks, which went by the name “phosphates.” One could easily find a cherry phosphate at the soda fountain shop and an Angostura phosphate at a bar. See acid phosphate.
Aperitif wines, aromatized wines, and fortified wines are frequently utilized in aromatic cocktails and, depending on their respective categories, will range from a pH of somewhere between 3 and 4. The acidity factor will also vary from one brand to another as well. While they blend seamlessly into aromatic cocktails, their lower acidity allows them to be enjoyed on their own as well (and as they were originally intended). See aperitif and digestive.
Other sources of acids used in the bar include acidic fruits such as passion fruit, mango, and tamarind, or their juices; sour beers; and champagne or other high-acid sparkling wines. Acids can also be commingled for differing effects, as in the case of the French 75, which combines the acids from both lemon juice and champagne. See French 75.
Acidity is also present in many spirits, to varying degrees. Levels tend to be higher in pot-stilled and barrel-aged ones, the former due to some acids coming in with the tails and the latter due to extraction from the oak. In general, the resulting acidity is considered a positive, giving the spirit structure, although occasionally the levels can cross into overt sourness. Whiskies, for example, have a pH range from around 3.5, where one might find an old American straight rye, to around 4.5, where one of the lighter Irish blends might be. (Some column-distilled spirits, and in particular vodkas, have a little bit of added citric acid, to brighten their flavor.)
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By: Audrey Saunders