This is why doughnuts are never fried in copper pans! This is made worse by combination with certain metals, such as copper. Oxidation (exposure to air) causes rancidity in fats over time. Unsalted butter, for example, will go rancid quickly if left outside the refrigerator, especially in warm climates. The fat takes on an unpleasant flavour when exposed to air and heat. Rancid is a term used to indicate that fat has spoiled. Table 6: Characteristics of Fatty Acids Type of Fatty Acid Table 6 shows the characteristics of three fatty acids. An example of such a fat is coconut fat: one second it is solid, the next, liquid. Fats that melt all of a sudden mean that the fatty acids are of the same or similar type and have melting points within a narrow range. The reason that some fat melts gradually is that as the temperature rises, each fatty acid will, in turn, soften, as its melting point is reached. Fatty acids are defined as short, medium, or long chain, depending on the number of atoms in the molecule. For example, stearic acid is the major fatty acid in beef fat, and linoleic acid is dominant in seed oils. The nature of the fatty acid will determine the consistency of the fat or oil. Composition of fats (triglycerides) Fatty AcidsĮach kind of fat or oil has a different combination of fatty acids. (The mono and diglycerides that are used as emulsifiers have one and two fatty acids respectively.) Figure 3.
Triglycerides is another chemical name for the most common type of fats found in the body, indicating that they are usually made up of three (tri) fatty acids and one molecule of glycerol (glycerine is another name) as shown in Figure 3. Baking books may talk about the “lipid content of eggs,” for example. In baking, lipids is generally a synonym for fats. There are many types of fats and oils and a number of terms and concepts associated with them, which are detailed further here. Fats and Oils 25 Understanding Fats and Oilsįats and oils are organic compounds that, like carbohydrates, are composed of the elements carbon (C), hydrogen (H), and oxygen (O), arranged to form molecules.
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