opcorn (also called popped corn, popcorns, or pop-corn) is a variety of corn kernel which expands
and puffs up when heated. The term also refers to the snack food produced by the expansion. It is one
of the oldest snacks, with evidence of popcorn dating back thousands of years in the Americas. It is
commonly eaten salted, sweetened, or with artificial flavorings.
A popcorn kernel's strong hull contains the seed's hard, starchy shell endosperm with 14–20%
moisture, which turns to steam as the kernel is heated. Pressure from the steam continues to build
until the hull ruptures, allowing the kernel to forcefully expand, to 20 to 50 times its original size, and
then cool.[1]
Some strains of corn (taxonomized as Zea mays) are cultivated specifically as popping corns. The Zea
mays variety everta, a special kind of flint corn, is the most common of these. Popcorn is one of six
major types of corn, which includes dent corn, flint corn, pod corn, flour corn, and sweet corn.[2]
History
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Corn was domesticated about 10,000 years ago, in what is now Mexico.[3] Archaeologists discovered
that people have known about popcorn for thousands of years. Fossil evidence from Peru suggests
that corn was present there as early as 4700 BCE, and popped there over 1000 years ago.[4][5]
[6] Between 2007 and 2011, evidence, as early as 4700 BCE, for popping corn, as macrofossil cobs,
were discovered at the Paredones and Huaca Prieta archaeological sites on the northern coast of Peru.
[7] In 1948 and 1950, evidence, as early as 3600 BCE, for popping corn, as ears of popcorn, were
discovered by Harvard anthropology graduate student Herbert W. Dick [8] and Harvard botany graduate
student Claude Earle Smith, Junior (1922–1987),[9][10] in a complex of rock shelters, dubbed the "Bat
Cave", in Catron County,[11] west-central New Mexico, and attributed to the Ancestral
Puebloan peoples, who maintained trade networks with peoples in tropical Mexico. [4][12][13][14][15][16][17]
[18]
Through the 19th century, popping of the kernels was achieved by hand, on stove tops over flame.
Kernels were sold on the East Coast of the United States under names such as Pearls or Nonpareil. The
term popped corn first appeared in John Russell Bartlett's 1848 Dictionary of Americanisms.[19]
[20] Popcorn is an ingredient in Cracker Jack and, in the early years of the product, it was popped by
hand.[19]
An early popcorn machine in a street cart,
invented in the 1880s by Charles Cretors in Chicago.
Popcorn's accessibility increased rapidly in the 1890s with Charles Cretors' invention of the popcorn
maker. Cretors, a Chicago candy store owner, had created a number of steam-powered machines for
roasting nuts and applied the technology to the corn kernels.
By the turn of the century, Cretors had created and deployed street carts equipped with steam-
powered popcorn makers.[21]
Specimen of Zea mays everta
During the Great Depression, popcorn was fairly inexpensive at 5–10 cents a bag and became popular.
Thus, while other businesses failed, the popcorn business thrived and became a source of income for
many struggling farmers and entrepreneurs, including the Redenbacher family, namesake of
the Orville Redenbacher's popcorn brand. During World War II,
sugar rations diminished candy production, and Americans compensated by eating three times as
much popcorn as they had before.[22] The snack was popular at theaters, much to the initial
displeasure of many of the theater owners, who thought it distracted from the films. Their minds
eventually changed, however, and in 1938 a Midwestern theater owner named Glen W. Dickinson Sr.
installed popcorn machines in the lobbies of his Dickinson theaters. Popcorn was more profitable than
theater tickets, and at the suggestion of his production consultant, R. Ray Aden, Dickinson purchased
popcorn farms and was able to keep ticket prices down. The venture was a success, and popcorn soon
spread.[19] The rise of television in the 1940s brought lower popcorn consumption as theater
attendance fell. The Popcorn Institute (a trade association of popcorn processors) promoted popcorn
consumption at home, bringing it back to previous levels.[23]
An ear of popcorn grown in
an Oklahoma organic garden
In 1970, Orville Redenbacher's namesake brand of popcorn was launched. In 1981, General
Mills received the first patent for a microwave oven popcorn bag; popcorn consumption saw an
increase.[21]
At least six localities (all in the Midwestern United States) claim to be the "Popcorn Capital of the
World;": Ridgway, Illinois; Valparaiso, Indiana; Van Buren, Indiana; Schaller, Iowa; Marion, Ohio;
and North Loup, Nebraska. According to the USDA, specific corn for popcorn is grown mostly
in Nebraska and Indiana, and increasingly in Texas.[24][25] As the result of an elementary
school project, popcorn became the official state snack food of Illinois.[26]
Popping mechanism
Each kernel of popcorn contains moisture and oil. Unlike most other grains, the outer hull of the
popcorn kernel is strong and impervious to moisture, and the starch inside consists almost entirely of a
hard type.[27]
The sequence of a kernel
popping
As the oil and water in the kernel are heated, they turn into steam. Under these conditions, the starch
inside the kernel gelatinizes and softens. The steam pressure increases until the breaking point of the
hull is reached; a pressure of approximately 930 kPa (135 psi)[1][27] and a temperature of 180 °C
(356 °F). The hull ruptures, causing a sudden drop in pressure inside the kernel and a corresponding
rapid expansion of the steam, which expands the starch and proteins of the endosperm into airy foam.
As the foam rapidly cools, the starch and protein polymers set into the familiar crispy puff.[27]
Special varieties are grown to improve popping yield. Though the kernels of some other types will pop,
the cultivated strain for popcorn is Zea mays everta, which is a variety of flint corn.[citation needed]
Cooking methods
An in-home hot-air popcorn maker
A commercial pop corn making machine
Popcorn can be cooked with butter or oil. Although small quantities can be popped in a stove-
top kettle or pot in a home kitchen, commercial sale employs specially designed popcorn machines,
which were invented in Chicago, Illinois, by Charles Cretors in 1885. Cretors introduced his invention at
the Columbian Exposition in 1893. At that fair, F. W. Rueckheim introduced a molasses-flavored
"Candied Popcorn", the first caramel corn; his brother, Louis Ruekheim, slightly altered the recipe and
introduced it as Cracker Jack in 1896.[28]
Popcorn being cooked in a pan
Cretors's invention was the first patented steam-driven machine that popped corn in oil. Previously,
vendors popped corn by holding a wire basket over an open flame. At best, the result was hot, dry,
and unevenly cooked. Cretors's machine popped corn in a mixture of one-third clarified butter, two-
thirds lard, and salt. This mixture can withstand the 232 °C (450 °F) temperature needed to pop corn
and produces little smoke. A fire under a boiler created steam that drove a small engine to drive
gears, shaft, and the agitator that stirred the corn, and also powered a small puppet, "The Toasty
Roasty Man", an attention-getting amusement to attract business. A wire connected to the top of the
cooking pan allowed the operator to disengage the drive mechanism, lift the cover, and dump popped
corn into the storage bin beneath. Exhaust from the steam engine was piped to a pan below the corn
storage bin and kept freshly popped corn warm. Excess steam was also used to operate a small, shrill
whistle to attract attention.[29]
