glyceride

A glyceride is a type of ester formed from glycerol and fatty acids. The term covers mono-, di-, and triglycerides, depending on how many of the glycerol’s three hydroxyl groups are esterified with fatty acids. The most common are triglycerides, in which three fatty acids are attached to the glycerol backbone; mono- and diglycerides have one or two fatty acids, respectively, and retain one or two free hydroxyl groups.

Glycerol is a triol (propane-1,2,3-triol). In a glyceride, each fatty acid forms an ester bond with a hydroxyl group of glycerol, and the properties of the molecule depend on the length and degree of saturation of the fatty acid chains. Triglycerides are the main constituents of animal fats and plant oils. They can be solid at room temperature (fats) or liquid (oils), with saturation and chain length influencing melting behavior.

Biological and nutritional roles: triglycerides serve as the primary energy reserve in many organisms, yielding about 9 kcal per gram upon oxidation. They are stored in adipose tissue and mobilized when energy is needed. Mono- and diglycerides can arise during digestion or food processing and are commonly used as emulsifiers in the food industry.

Metabolism and processing: hydrolysis of glycerides (lipolysis) yields glycerol and free fatty acids, which can be transported for energy or re-esterified into storage lipids. Industrially, glycerides are prepared by esterification of glycerol with fatty acids, and saponification of triglycerides yields glycerol and soap salts.

Distinctions: glycerides are distinct from phospholipids, which contain phosphate groups and play major roles in cell membranes.