fats and oils group of organic substances that form an important part of the diet and also are useful in many industries. The fats are usually solid, the oils generally liquid at ordinary room temperatures. Some tropical products, liquids in their sites of origin, become solids in cooler climates; in commerce these often retain the name originally given, e.g., palm oil and coconut oil. Chemically fats and oils are either simple or mixed glyceryl esters of organic acids belonging to the fatty-acid series (see triglycerides ; fatty acids ). Fats and oils are derived from both plant and animal sources.

Commercial Processing of Fats

Among the vegetable oils of greatest commercial importance are cottonseed, linseed, olive, palm, corn, peanut, soybean, and castor oils. The method of obtaining the oils is similar for all: the fruits or seeds after being cleaned are crushed and pressed cold to obtain the highest grade of oil and then pressed warm, yielding a grade suitable for industrial use. Sometimes solvents are used to remove the remaining oil from the crushed mass. Edible oils are those used in foods, and for these the highest grade is utilized; these must be pale in color, free from disagreeable odor and taste, and wholesome. The lower grades are suitable for making soap and for other industrial purposes. The chemical property that makes fats solid and oils liquid is the amount of saturation in the ester (see saturated fats ). Animal fats are esters of saturated fatty acids; vegetable oils are esters of unsaturated fatty acids.

Conversion of liquid vegetable oils into solid fats is an important chemical industry. This process, sometimes called hardening, involves hydrogenation of the unsaturated fatty-acid portion of the oil molecule by heating the oil with hydrogen in the presence of a metal catalyst; by controlling the extent of hydrogenation, various products can be obtained. For example, controlled hydrogenation of cottonseed oil produces a solid vegetable cooking fat. Most fats become rancid upon standing; since a major factor leading to rancidity is air oxidation of double bonds (to form foul-smelling aldehydes ), saturated fats are much more resistant to rancidity than unsaturated fats.

Fats as Food

Animal fats used in foods include butter, lard, chicken fat, and suet. Cod-liver oil and some other fish oils are used therapeutically as sources of vitamins A and D. Nutritionally fats and oils are valued as a source of energy. Because they contain less oxygen than other nutrients, they oxidize more readily and release more energy. Fats are digested in the human body chiefly by the enzyme lipase (in the pancreatic juice) aided by the bile. There are several theories to explain the method of absorption of fats; favored by many is the view that they are absorbed by the epithelial cells of the lining of the small intestine in the form of the fatty acids and glycerol into which they are split by digestion and that a recombination to re-form the fat occurs within the cells. Most of the fat then enters the lymphatic system through the villi in the lining of the small intestine, although some is probably absorbed directly by the blood vessels of the villi. Medical research indicates the possibility that saturated fats in the diet contribute to the incidence of arteriosclerosis ; such fats may raise the blood's level of cholesterol, which is deposited in the arteries.

See oils ; petroleum .

SIC 2079
SHORTENING, TABLE OILS, MARGARINE, AND OTHER EDIBLE FATS AND OILS, NOT ELSEWHERE CLASSIFIED

This category covers establishments primarily involved in manufacturing shortening, table oils, margarine, and other edible fats and oils that are not elsewhere classified. Companies primarily engaged in producing corn oil are discussed in SIC 2046: Wet Corn Milling.

NAICS Code(s)

311225 (Fats and Oils Refining and Blending)

311222 (Soybean Processing)

311223 (Other Oilseed Processing)

Many of the goods classified in this industry are long-time staples of the American kitchen. Commonly utilized for cooking and baking purposes, products such as shortening, vegetable oil, and margarine have become established presences in the marketplace. The market in the late 1990s and early 2000s was dominated by shortenings and cooking oils.

Margarine is a key product in this industry. Invented in France in 1869, margarine's introduction to the United States was initially impeded by low quality and the

efforts of a powerful butter lobby, which led to discriminatory taxes. With technical improvements and altered legislation, margarine enjoyed increased acceptance. It came to be largely regarded as a healthier and cheaper alternative to butter. By the mid-1990s, however, the $1.5 billion margarine industry began to falter while butter increased its market share. Many consumers who switched from butter to margarine for health reasons became disillusioned after learning that vegetable shortenings might also raise the risk of cardiovascular disease. Of particular concern to many health practitioners was the presence of trans fatty acids (TFAs) in margarine. In 2003, the U.S. Food and Drug Administration announced its intent to mandate the labeling of all products containing TFAs as of January 2006.

Due to the negative publicity related to TFAs, the production of margarine had started slowly declining in the late 1990s. Per capita margarine consumption declined from 10 pounds in the mid-1990s to 8.5 pounds in the early 2000s. Margarine sales declined from 1.3 billion pounds in 1998 to 1.1 billion pounds in 2003, while butter sales increased from 398.1 million pounds to 452.1 million pounds over the same time period. However, margarine sales continued to outstrip butter sales as of 2003 due to margarine's considerably lower price. Between 1998 and 2003, butter prices ranged from $2.51 to $3.17 per pound. Although margarine prices increased from 96 cents per pound to $1.08 per pound during this five-year span, margarine remained roughly two-thirds cheaper than butter.

The fastest growing segment of the industry in the early 2000s was the specialty oils market, which included blended oils such as canola/corn oil, corn/palm oil, olive/canola oil, and peanut/sesame oil, as well as flavored cooking oils that infused herbs and other seasonings, including garlic. Newer contenders like canola and olive oil had grabbed the attention of increasingly health-conscious consumers by the late 1990s. Physicians were impressed by reports that stated that the rate of heart disease in certain regions of the Mediterranean—where olive is the principal oil consumed—was relatively low, and that dietary monounsaturated fat was capable of lowering total cholesterol.

U.S. imports of olive oil during 2000 totaled 203,833 tons, a substantial increase from 1998 imports of 164,972 tons. Spain and Italy are the leaders in world olive oil production.

Further Reading

Global Information Inc. "Butter and Margarine–U.S." November 2003. Available from www.the-infoshop.com/study/mt17178_butter_margarine.html.

U.S. Department of Agriculture, National Agricultural Statistics Service. "Statistics of Oilseeds, Fats, and Oils." Washington, DC: 2003. Available from www.usda.gov/nass/pubs/agr03/03_ch3.pdf.

fat Semi-solid organic substance made and used by plants and animals to store energy. Fats dissolve in organic solvents such as ether, carbon tetrachloride, chloroform and benzene. Most common fats are triglycerides: esters in which one molecule of glycerol is bound to three molecules of fatty acids, each having 12 to 18 carbon atoms. Animal fats are esters of saturated fatty acids. Vegetable oils are esters of unsaturated fatty acids, that is, they have a higher proportion of molecules with double carbon–carbon bonds in the chain. In animals, fat resides in the subcutaneous layer beneath the skin and deep within the body as a specialized adipose tissue. It serves as an insulator and protects internal organs. Research indicates that the consumption of high levels of saturated fat can increase the risk of heart disease. Foods high in fat include butter, margarine, and most oils. Almost all fats found in plant sources are unsaturated. See also lipid