Propylene glycol is an odorless and colorless liquid, usually used as a solvent and wetting substance, making it a popular ingredient in shampoo, conditioner, toothpaste and cosmetics. While this alcohol-based but non-toxic substance serves as a chemical addition to non-food products, it's also an additive in certain processed foods.
The use of propylene glycol in ice cream serves as an antifreeze product, preventing ice crystals from forming. It also helps ice cream retain its shape once packed as well as maintain its creamy texture. However, the presence of propylene glycol in ice cream has created controversy among ice cream lovers because antifreeze is typically used in automobile radiators.
In the artificial sweetener sorbitol, propylene glycol acts as a humectant -- a component that preserves moisture and prevents the development of bacteria and mold. This effect helps sorbitol maintain its hygienic quality. In essence, it also acts as a preservative that extends shelf life.
Propylene glycol is also present in food stabilizers, the most common of which is alginate, an additive used in icings. Propylene glycol acts as an emulsifier that maximizes the ability of the icing to foam.
Soft drinks use propylene glycol to maintain the suspension of fatty acids, which helps ensure optimum flavor during storage for later consumption. Propylene glycol's inherent ability to function as an emulsifier, stabilizer and bacteria inhibitor as well as its flavor retention properties make it an ideal component in soft drinks.