Fats
Definition: Fats and oils have many uses, including cooking, tenderizing baked goods and adding richness, texture and flavor to foods. Fat is one of the body's basic nutrients, providing energy by furnishing calories. All forms of fat consist of fatty acids, which are the building blocks of fats. Fats and oils are saturated or unsaturated, the latter broken down into monounsaturated and polyunsaturated fats. To illustrate the difference among saturated, monounsaturated and polyunsaturated, picture a fat molecule as a train of passenger cars (carbon atoms). If every seat on the train is filled by a "passenger" (hydrogen atom), then this is a saturated fat molecule. If there's one seat open in each car where a hydrogen-atom "passenger" can sit, the molecule is monounsaturated; if there are several open, it's polyunsaturated.
Saturated Fat
In general, saturated fats come from animal sources and are solid enough to hold their shape at room temperature (about 70 degrees F). Exceptions are tropical oils such as coconut and palm, which, though of plant origin, are semisolid at room temperature and highly saturated. Saturated fats are nutritional "bad guys" because they're associated with forms of cancer and increased cholesterol levels. In addition to coconut and palm oils, the most common saturated fats are butter, lard, suet and hydrogenated vegetable oils such as margarine and vegetable shortening. Hydrogenated (or partially hydrogenated) oils have been chemically transformed from their normal liquid state (at room temperature) into solids. During this process hydrogen atoms are pumped into unsaturated fat. This creates trans fatty acids, converting the mixture into a saturated fat and obliterating any benefits it had as a polyunsaturate. Some researchers believe hydrogenated oils may be more damaging than regular saturated fats for those limiting cholesterol in their diets.
Trans Fatty Acids
Man-made or processed fats, which are made from a liquid oil. When you add hydrogen to liquid vegetable oil and then add pressure, the result is a stiffer fat, like the fat found in a can of Crisco. Trans fats are also called hydrogenated fats.
Trans fats pose a higher risk of heart disease than saturated fats, which were once believed to be the worst kind of fats. While it is true that saturated fats -- found in butter, cheese and beef, for example -- raise total cholesterol levels, trans fats go a step further. Trans fats not only raise total cholesterol levels, they also deplete good cholesterol (HDL), which helps protect against heart disease.
The stiffer and harder fats are, the more they clog up your arteries. Trans fats do the same thing in our bodies that bacon grease does to kitchen sinks. Over time, they can "clog the pipes" that feed the heart and brain, which can lead to heart attack or stroke risk.
Unsaturated Fats
Unsaturated fats are derived primarily from plants and are liquid (in the form of oil) at room temperature. Generally, oils are composed (in varying percentages) of both monounsaturated and polyunsaturated fats.Monounsaturated fats help reduce levels of LDL (bad) cholesterol. The most common oils high in monounsaturates are olive, canola and peanut oil. Polyunsaturated fats are also considered relatively healthy and include the following, ranked in descending order of polyunsaturates: safflower, soybean, corn and sesame oil.
Omega-3 Fatty Acids
Omega-3 oils are a type of fatty acids found in some plants (such as flax seed) and in the tissues of sea creatures. These special polyunsaturated oils are beneficial to coronary health (purportedly lowering bad LDL cholesterol and elevating good HDL) as well as to brain growth and development. Popular fish that are good sources of Omega-3 oil (in order of importance) are sardines, herring, mackerel, bluefish, tuna, salmon, pilchard and butterfish. High heat can destroy almost half the Omega-3 in fish, but microwave cooking doesn't seem to affect it. Canned tuna packed in water is an easy way to get Omega-3 oil, but combining it with the fat in mayonnaise offsets any positive effects. Canned salmon and sardines are also excellent Omega-3 sources.
Storing Fats
Storing fats and oils. Saturated fats such as butter, margarine and lard should be tightly wrapped and refrigerated. They can usually be stored up to 2 weeks. Hydrogenated vegetable shortening can be stored, tightly covered, at room temperature for up to 3 months. Refined oils, sealed airtight, can be stored on the kitchen shelf up to 2 months. Oils with a high proportion of monounsaturates--such as olive and peanut--are more perishable and should be refrigerated if kept longer than a month. See also almond oil; animal fat; chili oil; cocoa butter; cottonseed oil; fat substitutes; grapeseed oil; grease; hazelnut oil; milk fat; oils; pumpkin seed oil; sunflower seed oil; trans fatty acids; walnut oil.