Calcium propionate, also known as calcium propanoate, has the chemical formula Ca(C2H5COO)2. It is the calcium salt of propionic acid. Propionic acid is responsible for the decomposition of certain amino acids. This acid is a carboxylic acid found naturally in sweat, milk products, and bacterial fermentation.

Used as a food additive and preservative, calcium propionate inhibits the growth of bacteria and molds. It is also used as an additive to cow feed to prevent the spread of milk fever disease. Infrequently, it is used as a pesticide.

Calcium propionate is a preservative used in foods prone to high spoilage rates, such as bread and dairy products. It is registered as "E number 282" on Table 3 in the Codex General Standard for Food Additives, a document written by the Food and Agriculture Organization of the United Nations and the World Health Organization. The "E" rating means that it is accepted by the European Union for the same applications and definitions.

In addition to dairy and breads, it is frequently used in canned fruits, batter mixes, and other foods where mold can occur. Naturally, it can be found in raw dairy products, such as milk. Additional amounts are added during food processing to keep spoilage and bacteria growth rates down.

Calcium propionate works by stopping the energy source that the development of the bacteria depends upon. The propionic acid prevents the bacteria from feeding up its necessary enzymes. In food, it is added in concentrations of ranging from 0.1 to 0.4%, while in feed, concentrations can be as high as 1%.

Some ratings organizations consider calcium propionate to be slightly toxic. This rating, however, is common for food products. The body breaks down the calcium from the propionic acid and then processes it as a fatty acid. It is not stored.

There has been speculation that calcium propinate contributes to migraines in those patients with a history of migraines, but there has been no scientific evidence to prove this claim. There has also been speculation that calcium propionate contributes to mild allergies, such as sneezing and hives, but there has been no scientific evidence to prove this claim. Calcium propionate is found in a wide assortment of food products. It is important, therefore, to consider whether or not an individual's sensitivities can be attributed to the food product or to the calcium propionate.