Proprion, often referred to in the context of "propion," typically relates to propionic acid or its salts, such as calcium propionate, which are used as preservatives in food. Propionic acid is a short-chain fatty acid that occurs naturally in various fermented foods. It is known for its antifungal properties and is commonly used to prevent mold growth in baked goods. Additionally, propionates can have applications in animal feed and pharmaceuticals.