Calcium propionate is a preservative that helps keep your food safe to eat. It's used in baked goods, cheeses, jams, puddings and frostings, according to the U.S. Food and Drug Administration (FDA).
Chemical names can seem mysterious. Unlike other items in the ingredient list (think: flour and eggs), it's harder to know what precisely these are.
Propionate acids occur naturally in cheese and butter, per the FDA. They're a short-chain fatty acid, according to the American Council on Science and Health. Calcium propionate is the calcium salt of propionic acid, while sodium propionate is the sodium salt of that same acid.
Calcium propionate and sodium propionate are antifungal and also help stop the growth of certain bacteria, according to the FDA.