Organic Acids contain the active carboxyl grouping -COOH. They are produced by living organisms, hence the name “organic.” Mineral-based acids are called inorganic. Organic acids in food and beverages tend to be highly flavorful, in addition to being predominantly sour. See sourness. In beer, small amounts of certain acids promote a sense of freshness, whereas an excessive amount—unless a characteristic of a particular beer style—tends to be an indicator that the beer is spoiled, often from an infection by spoilage microbes that produce acetic acid. See acetic acid bacteria (acetobacter). Lactic acid bacteria, on the other hand, which are naturally present on malt, acidify the mash and thus the resulting beer, which may contain as much as 1.2% lactic acid in solution. Some Belgian-style beers are intentionally brewed to be sour. These are surprisingly pleasant tasting precisely because of their acidity. Lambics, for instance, are particularly prized for their tartness. They are fermented with both yeast and acid-producing bacteria. Some lambics, such as kriek, acquire some of their acidity from the addition of sour fruit, which contain such organic acids as tartaric, malic, and citric acid. See kriek. One malt-derived organic acid, oxalic acid, is of particular concern not because of its flavor, but because of its precipitate, oxalate, which can serve as a collection point for carbon dioxide bubbles in and cause gushing when the beer is opened. See gushing. the finished beer

See also acidification, citric acid, lactic acid, oxalates, and sour beer.