Ann Marie Overby, age 13, of Keen, N.H., for her question:
WHERE DO WE GET VEGETABLE OIL?
Vegetable oil is a fatty material obtained from certain plants. Most vegetable oils are liquids but several, such as coconut oil, palm oil and cocoa butter, are solids at temperatures below about 75 degrees Fahrenheit. Production of vegetable oils begins with their extraction from fruit or seeds. Many oils are simply squeezed out.
Seeds provide oils from soybeans, coconuts, cottonseeds, safflower, peanuts and linseed. Oils extracted from fruit include olive and palm oil.
The chief vegetable oils used in the United States and Canada are corn, cottonseed and soybean oil. People use these oils, as well as olive and peanut oil, in frying food and as salad oil.
Processors use a powerful machine called a high pressure press to squeeze out coconut and palm oil and some cottonseed oil. This procedure removes nearly all the oil from the fruit or seeds. But the high pressure heats the oil, which develops a dark color and a strong flavor as a result.
Oil also may be squeezed out under low pressure in a process called cold pressing. This process, which does not heat the oil, results in a light colored, mild flavored product.
But low pressure extraction does not remove all the oil from the plant. Manufacturers use cold pressing chiefly to obtain olive oil.
A process known as solvent extraction is sometimes used. In this process, the manufacturer soaks the fruit or seeds in a liquid called a solvent that dissolves oil. A mixture of plant material, solvent and oil results. Machines then remove the plant material and evaporate the solvent to obtain the oil. Most soybean oil is produced by solvent extraction.
Oils obtained by high pressure or solvent extraction are bleached, deodorized and purified to produce a high quality product. Cold pressed oils require no further processing.
Vegetable oils are used mainly in producing or cooking many kinds of foods. These oils consist almost entirely of fat, an essential part of a healthful diet.
Most salad dressings that you buy today include soybean oil. Margarine and other solid shortenings are made from corn, cottonseed, palm, safflower or soybean oil.
Cocoa butter, coconut oil and palm kernel oil are used extensively by the candy manufacturer.
Many nonfood products also contain vegetable oil. As an example, manufacturers make cosmetics, shampoos and soaps from coconut, palm and palm kernel oil. Some medicines contain cocoa butter or castor, olive or wheat germ oil.
Many paints and varnishes include a drying oil, such as linseed, soybean or tung oil. Drying oils combine with oxygen from the air to form a tough coating.