Fats and Heat

Appears in
On Food and Cooking

By Harold McGee

Published 2004

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Most fats do not have sharply defined melting points. Instead, they soften gradually over a broad temperature range. As the temperature rises, the different kinds of fat molecules melt at different points and slowly weaken the whole structure. (An interesting exception to this rule is cocoa butter). This behavior is especially important in making pastries and cakes, and it’s what makes butter spreadable at room temperature.

Melted fats do eventually change from a liquid to a gas: but only at very high temperatures, from 500° to 750°F/260– 400°C. This high boiling point, far above water’s, is the indirect result of the fats’ large molecular size. While they can’t form hydrogen bonds, the carbon chains of fats do form weaker bonds with each other. Because fat molecules are capable of forming so many bonds along their lengthy hydrocarbon chains, the individually weak interactions have a large net effect: it takes a lot of heat energy to knock the molecules apart from each other.