Also referred to as sour salt or citric salt, citric acid is a naturally occurring, tart tasting, organic acid formed in citrus fruits. Citric acid is the crystalline material extracted from the juices of these fruits. Citric acid is used to add an acidic (sour) taste to foods and soft drinks and as a firming compound in products such as canned tomatoes.
At room temperature, most citric acids are a white, crystalline substance. Citric acid can exist either in an anhydrous (water-free) form or as a monohydrate (a compound that contains a single molecule of water). The monohydrate can be converted to the anhydrous form by heating above 172°F (78 °C). Because it occurs naturally, citric acid is usually classified as non-toxic and safe for food. It is naturally present in almost all forms of life, and excess citric acid is readily metabolized and eliminated from the body.1
Citric acid is a weak acid because of how it ionizes in water.2 While more expensive than most processed acids, citric acid is highly versatile with multiple applications. Biodegradable, citric acid is generally less harmful to the environment and therefore easier to dispose of after use than most processed acids.3