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PHOTO BY JOSIE DALTON ESPLIN
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Julia Child reserved
margarine only for her
enemies. "If you're afraid of butter, as many people are nowadays,"
she said on her television cooking show, "just put in cream!" But
Child was bucking a national trend. A few years before her inaugural
show aired in 1963, U.S. households started for the first time
to consume more margarine than butter. Today, the average American
eats almost two times as much margarine as butter.
Margarine wouldn't exist without butter, of course. From its
inception, margarine was an attempt to mimic the taste and texture
of butter. In the 1860s, Emperor Napoleon III offered a prize
to the person who could produce an edible fat substitute for butter.
Hippolyte Mege-Mouries, a French chemist, created oleomargarine,
a combination of clarified beef fat, water, and a bit of tributyrin--a
milk fat--to give it a buttery taste.
Mege-Mouries called it oleomargarine after the fatty acid then
called margaric acid. It turns out that margaric acid (named after
the Greek word for pearl--margarites--for its pearl-like luster)
is actually a combination of stearic and palmitic acids, fatty
acids often found in animal fats.
It would be hard to find beef fat or other solid animal fats
in today's margarines. Soybean oil is the most common base in
U.S. margarines; manufacturers also use sunflower, corn, palm,
safflower, cottonseed, peanut, and canola oils. But they can do
so only because about a century ago, French and German chemists
figured out how to convert liquid vegetable oils into a semisolid
product.
Butter
owes its semisolid state to the saturation of its fatty acids.
Fatty acids are the building blocks of fats and oils. A fatty
acid molecule has a long, unsubstituted carbon chain with a carboxylic
acid group at one end. Many fatty acid chains in butter (palmitic,
stearic, and myristic, for example) are saturated with hydrogens;
they contain no double bonds. These unvarying chains pack together
nicely, and it takes more heat than is available at room temperature
to get them to loosen to a liquid.
Fatty acids in oils, on the other hand, are mostly monounsaturated
or polyunsaturated. Oleic and linoleic acids, for example, have
one or more double (olefin) bonds along the fatty acid chain.
Because natural double bonds usually assume the cis configuration,
where the olefin hydrogens are located on the same side of the
chain, these fatty acids contain a bend of about 30°. Fatty
acids with cis double bonds don't pack well and are liquid at
room temperature.
French and German chemists learned how to solidify liquid oil
through hydrogenation. They heated the oil in the presence of
a metal catalyst and pressurized hydrogen gas, causing hydrogen
atoms to add randomly to the double bonds. Complete hydrogenation
saturates all double bonds. Partial hydrogenation saturates some
and converts others from cis to trans. In a trans double bond,
the hydrogens are kitty-corner, which allows for compact packing
of the fatty acid chains. The more complete the hydrogenation,
the firmer the oil becomes--and the longer the shelf life. Oils
turn rancid as double bonds oxidize in air.
Over the past century, margarine makers have favored partially
hydrogenated oils--ones that remain soft enough for spreading
on toast. To that semisolid fat base, they add a butter flavoring
(buttermilk, whey, or a nondairy substitute), salt, emulsifiers
(such as soy lecithin), a preservative like sodium benzoate or
citric acid, some vitamin A to give it the nutritional value of
butter, and a dash of yellow color (often ß-carotene).
In margarine's early days, its main selling point was its low
cost. A strong dairy lobby, however, supported the Margarine Act
passed by Congress in 1886, which added a two-cent tax to margarine
and required expensive licenses to make or sell it. Most states
also passed laws forbidding margarine manufacturers to add yellow
coloring to the naturally pale spread. Not until 1967 did the
last state, Wisconsin, repeal its coloring ban. By law, regular
stick margarine must be 80% fat and 20% water or milk (with added
vitamin A). Reduced-fat margarines and spreads, however, can range
from 60% fat all the way to fat-free.
Margarine got a boost in the 1970s when studies came out indicating
that dietary cholesterol and saturated fat raise LDL (low-density
lipoprotein) cholesterol levels in the blood and increase the
incidence of heart disease. Made with vegetable oils, margarine
has no cholesterol and less saturated fat than butter. Naturally,
margarine advertisers began to trumpet the health benefits of
eating margarine.
However, further research on the trans fatty acids found in
partially hydrogenated oils took many by surprise (C&EN,
Sept. 22, 2003, page 33). Trans fatty acids, though unsaturated,
were found to also increase LDL ("bad" cholesterol) levels in
the blood.
In the U.S., the Food & Drug
Administration will require labeling of trans fats on all
products by 2006. In anticipation of the U.S. regulation, many
margarine makers have found alternative fats and oils or alternative
forms of hydrogenation that minimize the creation of trans fatty
acids.
Grocery store shelves now hold a dizzying variety of margarines:
Soft or hard. Made from safflower or soybean oil. Partially hydrogenated,
saturated, or polyunsaturated. Made with yogurt. Made with olive
oil. Some are even mixtures of butter and margarine.
Today, nutritionists say to go easy on both butter (high in
saturated fat) and margarine (high in trans fatty acids). The
American Heart Association
still recommends margarine over butter but also advises consumers
to choose the soft liquid or tub varieties. Look at the ingredients
and nutrition facts, AHA says, and buy the variety with no more
than 2 g of saturated fat per tablespoon and with liquid vegetable
oil (not hydrogenated) as the first ingredient.
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