Popcorn

Popcorn or Popping Corn is a type of corn which explodes from the kernel and puffs up when heated. Special varieties are grown to give improved popping yield. Some wild types will pop, but the cultivated strain is Zea mays subsp. mays, which is a special kind of flint corn. Popcorn was first formally discovered by Native Americans thousands of years ago.

History
In 1948, ears and kernels of an early corn variety capable of being popped were found in an archaeological dig in a New Mexico rock shelter known as "Bat Cave". These finds are widely reported as being the oldest ears of popcorn ever found; such reports often say they are dated to be 4000–5000 years old, or more. The actual facts about the Bat Cave corn are less clear. While initial reports dated the corn to be 4000–5000 years old, in 1967 the same researchers revealed data from more specifically targeted dating: a sample consisting only of cobs was dated to be 1,752 years old, and a sample of cobs and nearby wood 2,249 years. These dates have been called into question as well: Michael S. Berry, after a study of the Bat Cave procedures, wrote it "was a poorly excavated site that can be interpreted nearly any way one pleases by juggling the data."

Popcorn was very popular in the 1890s, until the Great Depression. As corn crops became more depleted during the Great Depression, nuts were used instead of corn. During the Depression, popcorn was a luxury at 5-10 cents a bag. When some of the other businesses failed, the popcorn business thrived. An example is "an Oklahoma banker who went broke when his bank failed bought a popcorn machine and started a business in a small store near a theater. After a couple of years, his popcorn business made enough money to buy back three of the farms he'd lost." In the time of World War II, Americans ate three times more popcorn than they had before because of the sugar that was going over seas.

At least five localities (all in the United States of America) claim to be the "Popcorn Capital of the World": Valparaiso, Indiana; Van Buren, Indiana; Marion, Ohio; Ridgway, Illinois; Schaller, Iowa; and North Loup, Nebraska. According to the USDA, most of the maize used for popcorn production is specifically planted for this purpose; most is grown in Nebraska and Indiana with increasing area in Texas.

As the result of an elementary school project, popcorn became the official state snack food of Illinois.

How popcorn pops
As with all cereal grains, each kernel of popcorn contains a certain amount of moisture and oil in its starchy endosperm. Unlike most other grains, the outer hull, or pericarp, of the popcorn kernel is both strong and impervious to moisture, and the starch inside consists almost entirely of a hard, dense type.

As the oil and the water are heated past the boiling point, they turn the moisture in the kernel into a superheated pressurized steam, contained within the moisture-proof hull. Under these conditions, the starch inside the kernel gelatinizes, softening and becoming pliable. The pressure continues to increase until the breaking point of the hull is reached: a pressure of about 135 psi (9.1 atm) and a temperature of 180°C. The hull ruptures rapidly, 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 an airy foam. As the foam rapidly cools, the starch and protein polymers set into the familiar crispy puff.

Expansion and yield


Popping results are sensitive to the rate at which the kernels are heated. If heated too quickly, the steam in the outer layers of the kernel can reach high pressures and rupture the hull before the starch in the center of the kernel can fully gelatinize, leading to partially popped kernels with hard centers. Heating too slowly leads to entirely unpopped kernels: the tip of the kernel, where it attached to the cob, is not entirely moisture-proof, and when heated slowly, the steam can leak out of the tip fast enough to keep the pressure from rising sufficiently to break the hull and cause the pop.

Producers and sellers of popcorn consider two major factors in evaluating the quality of popcorn: what percentage of the kernels will pop, and how much each popped kernel expands. Expansion is an important factor to both the consumer and vendor. For the consumer, larger pieces of popcorn tend to be more tender and are associated with higher quality. For the grower, distributor, and vendor, expansion is closely correlated with profit: vendors such as theaters buy popcorn by weight and sell it by volume. For both these reasons, higher-expansion popcorn fetches a higher profit per unit weight.

Popcorn will pop when freshly harvested, but not well: its high moisture content leads to poor expansion and chewy pieces of popcorn. Kernels with a high moisture content are also susceptible to mold when stored. For these reasons, popcorn growers and distributors dry the kernels until they reach the moisture level at which they expand the most. This differs by variety and conditions, but is generally in the range of 14–15% moisture by weight. If the kernels are over-dried, the expansion rate will suffer and the percentage of kernels that pop at all will decline. Over-dried popcorn can be rehydrated by introducing some water into the storage environment (consumers can do this at home as well), but the expansion rate will be less than it would have been had they not been over-dried in the first place.

Two explanations exist for kernels which do not pop at proper temperatures, known in the popcorn industry as "old maids". The first is that unpopped kernels do not have enough moisture to create enough steam for an explosion. The second explanation, according to research led by Dr. Bruce Hamaker of Purdue University, is that the unpopped kernel may have a leaky hull.

Types


Popcorn varieties are broadly categorized by the shape of the kernels, the color of the kernels, or the shape of the popped corn. While the kernels may come in a variety of colors, the popped corn is always white as it is only the hull (or pericarp) that is colored. "Rice" type popcorns have a long kernel pointed at both ends; "pearl" type kernels are rounded at the top. Commercial popcorn production has moved mostly to pearl types. Historically, pearl popcorns were usually yellow and rice popcorns usually white. Today both shapes are available in both colors, as well as others including black, red, and variegated. Commercial production is dominated by white and yellow.



In popcorn jargon, a popped kernel of corn is known as a "flake". Two shapes of flakes are commercially important. "Butterfly" flakes are irregular in shape and have a number of protruding "wings". "Mushroom" flakes are largely ball-shaped, with few wings. Butterfly flakes are regarded as having better mouthfeel, with greater tenderness and less noticeable hulls. Mushroom flakes are less fragile than butterfly flakes and are therefore often used for packaged popcorn or confectionery, such as caramel corn. The kernels from a single cob of popcorn may form both butterfly and mushroom flakes; hybrids that produce 100% butterfly flakes or 100% mushroom flakes exist, the latter developed only as recently as 1998. Growing conditions and popping environment can also affect the butterfly-to-mushroom ratio.

As a food
Popcorn is usually served salted or sweetened. In North America, it is traditionally served salted, although a sweetened version, generally called caramel corn, is also commonly available. Popcorn is a popular snack at sporting events and in cinemas, where it has been served since 1912. Although small quantities can be popped in a kettle in a home kitchen, commercial sale of freshly popped popcorn is done with the help of specially designed popcorn machines, which were originally invented in Chicago, Illinois by Charles Cretors in 1885. Cretors successfully introduced his invention at the Chicago's Columbian Exposition in 1893. At this same world's fair, F.W. Rueckheim introduced the first caramel corn; his brother, Louis, slightly altered the recipe and introduced it as Cracker Jack popcorn in 1896.

Cretors' invention introduced the first patented steam-driven popcorn machine that popped corn in oil. Previously, vendors popped corn by holding a wire basket over an open flame. At best, the result was a hot, dry, unevenly cooked confection. The Cretors' machine popped corn in a mixture of one-third clarified butter, two-thirds lard and salt. This mixture could withstand the 450 degree temperature needed to pop corn and it did without producing much smoke. A fire under a boiler created steam that drove a small engine; that engine drove the gears, shaft, and agitator that stirred the corn and also powered the attention-attracting clown – the Toasty Roasty Man. 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 hollow pan below the corn storage bin and kept freshly popped corn uniformly warm for the first time ever.

The Boy Scouts of America sell popcorn door-to-door as a primary fund-raiser, similar to Girl Scout cookies.

Other uses
Popcorn, threaded onto a string, is used as a wall or Christmas tree decoration in some parts of North America, as well as on the Balkan peninsula.

Some shipping companies have experimented with using popcorn as a biodegradable replacement for expanded polystyrene packing material. However, popcorn has numerous undesirable properties as a packing material, including attractiveness to pests, flammability, higher cost and greater density than expanded polystyrene. A more processed form of expanded corn foam has been developed to overcome some of these limitations.

The world's largest popcorn ball was unveiled in October 2006 in Lake Forest, Illinois. It weighed 3,415 pounds (1550 kilograms), measured 8 feet (2.4 m) in diameter and had a circumference of 24.6 feet (8 m).

Nutritional Value
Air-popped popcorn is naturally high in fiber, low in calories and fat, contains no sodium, and is sugar free, which makes it an attractive snack unless one is limiting carbohydrates. The actual fat, sugar, and sodium content depends on how the popcorn is prepared though and a naturally healthy snack can quickly become unhealthy.

Popcorn is included on the list of foods that the American Academy of Pediatrics recommends not serving to children under four, because of the risk of choking. It is one of the top causes for children choking to death (along with hotdogs and balloons). Special "hulless" popcorn has been developed that offers an alternative for small children and for people with braces or other dental problems who may otherwise need to avoid popcorn.