On food and cooking the science and lore of the kitchen ( PDFDrive ) 1509

animal fats around 375ºF/190ºC Fats that contain other substances, such as emulsifiers, preservatives, and in the case of butter, proteins and carbohydrates, will smoke at lower temperatures than pure fats Fat breakdown during deep frying can be slowed by using a tall, narrow pan and so reducing the area of contact between fat and atmosphere The smoke point of a deep-frying fat is lowered every time it’s used, since some breakdown is inevitable even at moderate temperatures, and trouble-making particles of food are always left behind Emulsifiers: Phospholipids, Lecithin, Monoglycerides Some very useful chemical relatives of the true fats, the triglycerides, are the diglycerides and monoglycerides These molecules act as emulsifiers to make fine, cream-like mixtures of fat and water — such sauces as mayonnaise and hollandaise — even though fat and water don’t normally mix with each other The most prominent natural emulsifiers are the diglyceride phospholipids in egg yolks, the most abundant of which is lecithin (it makes up about a third of the yolk lipids) Diglycerides have only two fatty-acid chains attached to the glycerol frame, and monoglycerides just one, with the remaining positions on the frame being occupied by small polar groups of atoms These molecules are thus water-soluble at the head, and fatsoluble at the tail In cell membranes, the phospholipids assemble themselves in two layers, with one set of polar heads facing the watery interior, the other set the watery exterior, and the tails of both sets mingling in between When the cook whisks some fat into a water-based liquid that contains emulsifiers — oil into egg yolks, for example — the fat forms tiny droplets that would normally coalesce and separate again But the emulsifier tails become dissolved in the ... lecithin (it makes up about a third of the yolk lipids) Diglycerides have only two fatty-acid chains attached to the glycerol frame, and monoglycerides just one, with the remaining positions on the frame being occupied by... small polar groups of atoms These molecules are thus water-soluble at the head, and fatsoluble at the tail In cell membranes, the phospholipids assemble themselves in two layers, with one set of polar heads facing the. .. layers, with one set of polar heads facing the watery interior, the other set the watery exterior, and the tails of both sets mingling in between When the cook whisks some fat into a water-based liquid that contains emulsifiers