An ester of glycerol (propane-1,2,3-triol) in which all three hydroxyl groups are esterified with a fatty acid. Triglycerides are the major constituent of fats and oils and provide a concentrated food energy store in living organisms as well as cooking fats and oils, margarines, etc. Their physical and chemical properties depend on the nature of their constituent fatty acids. In simple triglycerides all three fatty acids are identical; in mixed triglycerides two or three different fatty acids are present. During digestion, triglycerides are hydrolysed by lipase enzymes to a mixture of fatty acids and mono- and diglycerides. These lipid-soluble products pass through the epithelial cell membranes in the small intestine, where the triglycerides are resynthesized and packaged into chylomicrons for transfer into the lacteals of the intestinal villi.