The New Complete Book of Food
Preparing This Food
* * *What Happens When You Cook This Food
Heat promotes the oxidation of fats, a chemical reaction accelerated by cooking fats in iron
pots. Cooked fats are safe at normal temperatures, but when they are used over and over, they
may break down into components known as free radicals—which are suspected carcinogens.
Most fats begin to decompose well below 500°F, and they may catch fire spontane-
ously with no warning without boiling first. The point at which they decompose and burn
is called the smoking point. Vegetable shortening will burn at 375°F, vegetable oils at close
to 450°F. Safflower, soybean, cotton-seed, and corn oils have higher smoking points than
peanut and sesame oils.How Other Kinds of Processing Affect This Food
Margarine and shortening. Margarine is made of hydrogenated vegetable oils (oils to which
hydrogen atoms have been added). Adding hydrogen atoms hardens the oils into a semi-
solid material than can be molded into bars or packed in tubs as margarine or shortening.
Hydrogenation also changes the structure of some of the polyunsaturated fatty acids in the
oils from a form known as “cis fatty acids” to a form known as “trans fatty acids.” Questions
have been raised as to the safety of trans fatty acids, but there is no proof so far that they
are more likely than cis fatty acids to cause atherosclerosis. Margarines may also contain
coloring agents (to make the margarine look like butter), emulsifiers, and milk or animal fats
(including butter).
Margarine should be refrigerated, closely wrapped to keep it from picking up odors from
other foods. It will keep for about two weeks in the refrigerator before its fatty acids oxidize to
produce off odors and taste. Shortening can be stored, tightly covered, at room temperature.Medical Uses and/or Benefits
Lower risk of cardiovascular disease. A diet high in cholesterol and saturated fats increases
the amount of cholesterol circulating through your arteries and raises your risk of coronary
artery disease (heart attack). To reduce the risk of heart disease, the National Cholesterol
Education Project recommends following the Step I and Step II diets.
The Step I diet provides no more than 30 percent of total daily calories from fat, no
more than 10 percent of total daily calories from saturated fat, and no more than 300 mg
of cholesterol per day. It is designed for healthy people whose cholesterol is in the range of
200–239 mg/dL.