Glycerol and Fatty Acids

Appears in
On Food and Cooking

By Harold McGee

Published 2004

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Though they contain traces of other lipids, natural fats and oils are triglycerides, a combination of three fatty acid molecules with one molecule of glycerol. Glycerol is a short 3-carbon chain that acts as a common frame to which three fatty acids can attach themselves. The fatty acids are so named because they consist of a long hydrocarbon chain with one end that has an oxygen-hydrogen group and that can release the hydrogen as a proton. It’s the acidic group of the fatty acid that binds to the glycerol frame to construct a glyceride: glycerol plus one fatty acid makes a monoglyceride, glycerol plus two fatty acids makes a diglyceride, and glycerol plus three fatty acids makes a triglyceride. Before it bonds to the glycerol frame, the acidic end of the fatty acid is polar, like water, and so it gives the free fatty acid a partial ability to form hydrogen bonds with water.