Introduction of Oils:
Most oils are high in monounsaturated or polyunsaturated fats, and low in saturated fats. Oils from plant sources (vegetable and nut oils) do not contain any cholesterol. In fact, no plant foods contain cholesterol. A few plant oils, however, including coconut oil, palm oil, and palm kernel oil, are high in saturated fats and for nutritional purposes should be considered to be solid fats.
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| Oil Adulteration |
How Fats differ by Oils?
Solid fats are fats that are solid at room temperature and tend to be of animal origin, like butter and shortening. Solid fats come from many animal foods and can be made from vegetable oils through a process called hydrogenation. Some common fats are: butter, milk fat, beef fat (tallow, suet), chicken fat, pork fat (lard), stick margarine, shortening, and partially hydrogenated oil.
How to Vegetable oils become Solid Fats:
Solid fats mainly come from animal foods and can also be made from vegetable oils through a process called hydrogenation.
Why is it important to consume oils?
Most of the fats you eat should be polyunsaturated (PUFA) or monounsaturated (MUFA) fats. Oils are the major source of MUFAs and PUFAs in the diet. PUFAs contain some fatty acids that are necessary for health – called "essential fatty acids."
Because oils contain these essential fatty acids, there is an allowance for oils in the food guide.
The MUFAs and PUFAs found in fish, nuts, and vegetable oils do not raise LDL ("bad") cholesterol levels in the blood. In addition to the essential fatty acids they contain, oils are the major source of vitamin E in typical American diets.
The Composition Of Fats And Oils
Fats and oils are one of the three kinds of substances known as lipids.
In addition to fats, lipids include the compounds known as phospholipids
(FOS-fo-lip-ids), and those known as steroids. We will talk about phospholipids
and steroids as we go along, but for now, we are focusing
on fats.
on fats.
Fats, like carbohydrates, are composed of the same basic elements:
carbon, hydrogen, and oxygen. However, the smallest units of fats (called
molecules of fat) are larger than molecules of carbohydrates, and the relative
proportions of carbon, hydrogen, and oxygen to each other in fats is different
from those in carbohydrates.
One molecule of fat is formed by the union of one unit of a substance
called glycerol, with three units of substances called fatty acids. There are a
great many different types of fatty acids, but the dietary fats found in our
foods and in our body fat are, for the most part, formed from only three kinds
of fatty acids. (For those who are
keeping notes, these are known as oleic acid, palmitic acid, and stearic acid, and they form fats known as olein, palmitin, and stearin.)
keeping notes, these are known as oleic acid, palmitic acid, and stearic acid, and they form fats known as olein, palmitin, and stearin.)
Glycerol (GLIS-er-all), sometimes called glycerin or glycerine, has
three “arms.” Each of the three arms joins with one fatty acid to make a single
molecule of fat. This explains why fats are referred to as tri-glycerides
(usually spelled triglycerides, without the hyphen). These are the simplest
fats.
Dietary fats are mixtures of the three fats mentioned above, olein,
palmitin, and stearin. Differing amounts of each of the three result in the
different characteristics of each type of dietary fat. For example, more olein
and less of the other two lowers the melting point of the fat. When a fat has
such a low melting point that it is liquid at room temperature, it is called an
oil. Among these are olive oil, canola oil, and cod liver oil.
Human body fat contains from 70 to 80 percent olein, and therefore has a
melting point below normal body temperature. As a result, simple body fats are
found in the form of droplets of oil in body cells. In addition, nearly all
body cells contain at least some body fat.
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