Calcium propionate (along with propionic acid and sodium propionate) is used as a preservative in bread and other baked goods. It also occurs naturally in butter and some types of cheese.
It keeps bread and baked goods from spoiling by preventing mold and bacterial growth. You may be concerned about the idea of preservative use in food, but on the flip-side, you certainly don't want to eat bacteria- or mold-infested bread.
Function: Calcium propionate is also known as calcium proanoate. Calcium propionate inhibits the growth of bacteria and fungi and thus helps to increase the shelf life of foods. It is predominantly used in bread but can be found in other baked goods, processed meat and cultured whey as well as milk derivatives. Calcium propionate is formulated synthetically and is also found naturally in some cheeses and butter. As a preservative, in prevents microbes from producing the energy that they need to survive, thus inhibiting the growth of mold. Calcium propionate does not require an acidic environment to be effective. It is most effective against the Bacillus mesentericus mold strain.
As a food additive, Calcium propanoate is used as a preservative in a wide variety of products, including but not limited to bread, other baked goods, processed meat, whey, and other dairy products. In agriculture, it is used, amongst other things, to prevent milk fever in cows and as a feed supplement Propanoates prevent microbes from producing the energy they need, like benzoates do. However, unlike benzoates, propanoates do not require an acidic environment.
Calcium propanoate is used in bakery products as a mold inhibitor, typically at 0.1-0.4% (though animal feed may contain up to 1%). Mold contamination is considered a serious problem amongst bakers, and conditions commonly found in baking present near-optimal conditions for mold growth.