Deep-Frying

Since fats and oils are used for high temperature cooking, their reaction when heated is vital. The most important temperature is the “smoking point”, at which the fat begins to smoke and smell sharp. Beyond this point, the structure of the fat changes, giving it an unpleasant taste; it should not be used again, even at a reduced heat. The smoking point of animal fats is around 375°F/190°C, while some vegetable oils can withstand higher temperatures of 400°F/200°C or higher. Exact smoking points are extremely difficult to specify. For fats, the smoking point depends on how a fat has been refined and on its moisture content, particularly for butter. Pure oils can vary from harvest to harvest and from pressing to pressing, while the smoking point of general-purpose oils will differ according to blend and method of processing. Many such oils have unexpectedly low smoking points because they contain emulsifiers and preservatives.