Phosphoric acid is deliberately added to soft drinks to give them
a sharper flavor. It also slows the growth of molds and bacteria, which would otherwise multiply
rapidly in the sugary solution.
Almost all of the acidity of soda pop comes
from the phosphoric acid and not from the carbonic acid from the
dissolved CO2. You can verify this by measuring the pH
of fresh and flat soda pop; there's very little difference.
The phosphoric acid is corrosive, but actually the acid
concentration in soda pop is lower than that in orange juice or
lemonade. Try submerging identical strips of magnesium (or iron staples) in
each of these beverages overnight. Which beverage dissolves more metal? Which dissolves
the metal fastest?
Fruit juices and drinks are also tart, but they don't use phosphoric acid as a flavor additive.
Phosphoric acid would cause many ions present in fruit juices to settle out as insoluble phosphates.
These beverages get their tang from citric acid, a substance
found in oranges, limes, lemons and grapefruits. Malic acid, found in apples and cherries,
is added to many fruit juices. Fumaric acid is used in noncarbonated soft drinks, and tartaric acid gives grape-flavored candies a subtle sour flavor.
All of these substances impart only tartness, without overpowering other flavors present.
- Steve Cockram, Director of Technical Services at Northland Cranberries, points out that tartaric acid isn't added to grape-flavored beverages because of the low solubility of some of its salts:
"... tartaric acid gives a very true flavor, but Mother Nature does not intend for
tartrates to stay in solution long. When KH-tartrate precipitates out of a juice, looking very
much like glass or metal shavings, and the consumer passes their bottle of juice to the FDA, one
really does not care about "true" flavor. We in the juice industry usually use malic or a malic
Author: Fred Senese email@example.com