Propylene glycol is a synthetic liquid substance that is used in a variety of industries, including chemical, food, and pharmaceutical industries. Here are some of the ways propylene glycol is used:

• Food: Propylene glycol is used as an additive in many processed foods to help preserve their moisture and consistency. It is also used as an anti-caking agent, antioxidant, dough strengthener, emulsifier, flavor agent, formulation aid, stabilizer, thickener, glazing agent, and texturizer.

• Cosmetics: Propylene glycol is used in many cosmetics and personal care products to help maintain their moisture and preserve color and consistency. It is also used as a solvent to dissolve ingredients that are added to these products.

• Pharmaceuticals: Propylene glycol is used as a solvent and a base for some injectable medications, as well as in some creams and ointments that are applied to the skin.

• Industrial: Propylene glycol is used to make polyester compounds, as a base for deicing solutions, and as an ingredient in engine coolants, airplane deicers, enamels, paints, varnishes, and polyurethane cushions.

Propylene glycol is generally recognized as safe by the US Food and Drug Administration (FDA) for use in food. However, it is important to note that consuming large quantities of foods that contain propylene glycol may lead to health complications.