On food and cooking the science and lore of the kitchen ( PDFDrive ) 1508

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 Omega-3 fatty acids Omega-3 fatty acids are unsaturated fatty acids whose first double bond begins at the third carbon atom from the end (The most common unsaturated fatty acids are omega-6 fatty acids.) They are essential in our diet for, among other things, the proper function of the immune and cardiovascular systems Linolenic acid has double bonds among its 18 carbon atoms, and is found in green leaves and in some seed oils Eicosapentaenoic acid has 20 carbons and double bonds, and is found almost exclusively in seafood (p 183) The Smoke Point Most fats begin to decompose at temperatures well below their boiling points, and may even spontaneously ignite on the stovetop if their fumes come into contact with the gas flame These facts limit the maximum useful temperature of cooking fats The characteristic temperature at which a fat breaks down into visible gaseous products is called the smoke point Not only are the smoky fumes obnoxious, but the other materials that remain in the liquid, including chemically active free fatty acids, tend to ruin the flavor of the food being cooked The smoke point depends on the initial free fatty acid content of the fat: the lower the free fatty acid content, the more stable the fat, and the higher the smoke point Free fatty acid levels are generally lower in vegetable oils than in animal fats, lower in refined oils than unrefined ones, and lower in fresh fats and oils than in old ones Fresh refined vegetable oils begin to smoke around 450ºF/230ºC, ... the flavor of the food being cooked The smoke point depends on the initial free fatty acid content of the fat: the lower the free fatty acid content, the more stable the fat, and the higher the smoke point Free fatty acid... Not only are the smoky fumes obnoxious, but the other materials that remain in the liquid, including chemically active free fatty acids, tend to ruin the flavor of the food being cooked The smoke point depends on the initial free.. .The Smoke Point Most fats begin to decompose at temperatures well below their boiling points, and may even spontaneously ignite on the stovetop if their fumes come into contact with the gas flame