Corn, a cereal originating from Mexico, is very present in the food of the entire American continent and in Africa but much less in Europe. It is an herbaceous plant which has a variable-sized stem growing leaves and flowers grouped in spikes which, at maturity, become grains. The most cultivated cereal in the world, in front of rice and wheat, corn is also very much used to feed animals.
History of corn
Corn originates from Meso-America (Mexico, Guatemala). It would have been domesticated a few millennia before our era, possibly in two distinct places, either in Mexico and in the highlands of Peru, where very different types of each other have emerged and evolved, which explains why there is such a variety in modern forms. We speculated a lot about its wild ancestor, which we never found in nature, until an American geneticist announced in 2004 it came probably from a spontaneous crossing between two very close plants, the teosinte, considered until then as the most plausible, and another grass belonging to the genus Tripsacum.
Corn will only reach North America much later, about 1 000 years before our era, but it is then adopted by all Amerindian peoples. When Jacques Cartier landed in the Gaspé Peninsula and the St. Lawrence Valley in the sixteenth century, he found that Hurons and Iroquois cultivate at least one variety, and when he went up the river to Hochelaga (Montreal), he saw big and beautiful fields of corn.
While the Amerindians of the south and north devoted corn, without exception, a quasi religious cult and regard it as the mother of all food, the Spanish conquerors will not be interested in it and will be content to give it to the farmed animals, preferring to cultivate the wheat, which they brought in their luggage. This bad reputation will follow this vegetable in its travels across Europe where it was not popular in human food, except for northern Italy, the Basque region and certain parts of central Europe were happy to adopt corn.
On the other hand, in Africa, where the Portuguese introduced it, it will become a staple food, supplanting in the twentieth century sorghum and millet and, to a lower extent, tubers and roots previously constituted the main food. Under the British Empire, it will be the main food of the black miners and, in the United States, which slaves brought back from Africa. It will also play an important role in the diet of Indonesians and inhabitants of some remote areas of China, where rice grows poorly.
Of the three most important cereals on the globe (wheat, rice, corn), it is the only one not to be grown primarily to feed human beings. Only one fifth of the world’s production is destined for them, while two thirds are going to feed the animals and about a tenth to the production of industrial products: plastic, ethanol, germ-derived oil, starch, sweeteners (syrup, fructose, dextrose, etc.), pharmaceuticals (vitamins C and E, amino acids, organic acids, antibiotics), etc.
The genus Zea includes only a few species, including Zea mays, the most important. Researchers have selected thousands of varieties for this species, which are grouped into three categories according to the employment to which they are intended, namely: grain corn, mainly grown as fodder and silage intended for animal feed and incidental to the production of flour and semolina intended for human consumption; sweet corn and puffing corn, mostly consumed in the United States and Canada.
Corn is a cereal from America, sometimes used as a vegetable. Although it’s part of the traditional Aboriginal diet throughout the Americas, it’s less popular in Europe where it is more livestock-only. We know mostly about yellow corn, but in the last few years we have started to see products made of “blue” or “purple” corn. Very versatile, corn comes in a thousand and one forms: it can be tasted on the cob, frozen, canned or blown. We also know its derivatives such as flour, semolina, oil, bran, starch and corn syrup, which can be found in a multitude of foods, from breakfast to dessert.
Active ingredients and properties
For cereal products in general
Cereal products are of great importance in our diet. One of health authorities recommendations for the health of people is to give “the largest share of cereals, breads and other cereal products and vegetables and fruits”. The Food Guide to healthy eating takes this recommendation into account and stresses the choice of whole or enriched grain cereal products. The American authorities, on the other hand, recommend at least half of the cereal products should be consumed entirely.
These recommendations are based on the results of epidemiological studies demonstrating that whole-grain consumption would be related to a lower risk of cardiovascular disease and diabetes, some cancers, and obsity. These beneficial effects would be linked to the synergy between many compounds contained in whole grain cereal products, such as fibers, antioxidants, vitamins and minerals. Since the majority of these compounds are contained in sound and seed, cereals have the advantage of being consumed as little as possible.
Antioxidants. Antioxidants are compounds protecting the body’s cells from damage caused by free radicals. The latter are highly reactive molecules and would be involved in the development of cardiovascular diseases, certain cancers and other diseases related to aging. A study comparing the antioxidant activity of four cereal grains (corn, wheat, oats, rice) showed corn was the one with the highest activity. Other researchers observed the total antioxidant activity of corn increased when it was cooked, probably as a result of the release of some antioxidant compounds under the heat effect.
Phenolic compounds. Corn contains antioxidant phenolic acids, one of the main of which is férulique acid: corn bran would be one of the foods containing the most. However, it was observed among animals that only a very small proportion of phenolic acids in corn bran was absorbed by the digestive system. However, these researchers believe different treatments, such as heat, could make these phenolic acids more accessible to the boedy, thereby improving their bio-availability. Other researchers have discovered in purple corn a derivative of quercetin, another type of phenolic compound, which has demonstrated a strong antimutagenic in vitro potential. However, it is not known whether these effects can also be applied to humans.
Lutein and zeaxanthin. Corn contains lutein and zeaxanthin, two antioxidant compounds of the carotenoides family. According to health authority’s nutrient, an ear of corn contains 745 μg of lutein and zeaxanthin. As a comparison, 250 ml (1 cup) of raw spinach, a very rich vegetable of lutein and zeaxanthin, contains 3 867 μg. On the other hand, researchers observed corn baking made these two compounds more bio-available, which is, more apt to be well absorbed by the body. Lutein and zeaxanthin accumulate in the macula and retina of the eye, thus protecting it from oxidative stress which could cause damage. Moreover, data from a scientific literature journal indicate a steady intake of lutein and zeaxanthin is associated with a lower risk of macular cataract degeneration, two eye diseases. In addition, it is believed that these compounds could help prevent certain cancers, especially those of the breast and lung, and contribute to the prevention of cardiovascular diseases. It should be noted, however, studies on the cardiovascular level are still limited and sometimes contradictory.
Anthocyanins (blue or purple maize). Anthocyanins, antioxidant pigments such as cyanidin and pelargonidine, are responsible for the particular color of certain corn varieties19. The anthocyanins of purple maize showed antimutagenic in vitro properties. Among animals, the consumption of anthocyanins from purple maize has provided some protection against colon cancer and has counteracted the detrimental effects of a fat-rich diet (e.g., removal of fat accumulation in tissues and normalization of blood sugar levels). Other studies are necessary, however, to check whether these properties can also be observed among humans.
Tocopherols (corn oil). Corn oil contains antioxidants belonging to the family of tocopherols (vitamin E). It is particularly rich in one of these compounds called gamma-tocopherol. It has been demonstrated among humans the blood concentration of gamma-tocopherol increases when corn oil is added to the normal diet, and that the tocopherols of corn oil have an antioxidant activity in the humain body. Another clinical study among humans showed corn oil, through gamma-tocopherol, provided protection against DNA damage from certain blood cells, an aspect which could be favorable for cancer prevention.
Cardiovascular disease. Some studies have looked at the potential effects of corn derived foods related to cardiovascular health.
Corn oil. In a study among humans, the addition of corn oil to a normal and balanced diet resulted in a decrease in blood LDL cholesterol (“bad” cholesterol). The researchers indicate this effect could be attributed to several compounds. They include polyunsaturated fats, which are the main fats present in corn oil. Phytosterols may also contribute to these benefits: they are cholesterol-related compounds, but rather promising for health. Corn oil would be one of the best sources. In addition, another human clinical study showed phytosterols of corn oil were the main compounds responsible for a decrease in cholesterol absorption by the body.
• Ear of corn. A study conducted among hypercholesterolemic men (too high blood cholesterol) showed the addition of finely ground corn to low-fat diets had more effect on the decrease in blood cholesterol than the low fat diet only. However, these researchers were unable to explain the mechanism by which the ear of corn exercised this benefit.
Also known as gluten intolerance, or gluten enteropathy, celiac disease affects about 4 people out of 1 000 in North America. People with a permanent intolerance to gluten a protein found in the grain of several cereals. This protein is toxic to people celiac and its consumption can lead to intestinal symptoms such as bas food absorption of several nutrients. The treatment of this disease is to totally exclude gluten from food. Since corn does not contain gluten, the people affected can consume it.
Compounds are both harmful and beneficial in cereals
Cereal grains contain phytochemicals such as phytic acid, one of the most abundant micro constituents of grain. Corn contains more phytic acid than rice or wheat28. This compound, which is found in greater quantity in the outer shell of the grain and the germ, has the ability to bind certain minerals (calcium, magnesium, iron, zinc) and thus reduce their absorption in the intestine. However, researchers agree in a North American context where there is food abundance and diversity and where nutritional deficiency is rather rare, this effect has little impact on health. In addition, some domestic processes (e.g. soaking in water, cooking) eliminate a portion of the phytic acid from corn, making minerals more absorbable. The consumption of phytic acid (or phytate) would have even a beneficial side since it acts as an antioxidant in the body. However, the potential benefits of phytic acid have not yet been validated among humans, since they have been observed only in animals and in vitro.
Choice, conservation and culinary uses
Cooking corn grains
Whole grains require a few hours soaking (all night if possible) and a long cooking in water with added soda, in order to eliminate their skin. It is possible to omit the soda, but the grains will be less digestible. They can be cooked in an electric slow cooker, which allows very slow cooking without the risk of burning or getting the food attached.
Corn on the cob (sweet corn): it is offered in North American supermarkets throughout the summer. Although after the harvest its sugar is transformed less rapidly into starch than grain corn, it still loses its taste qualities over time. It is recommended to buy it as fresh as possible, preferably directly from the producer or the market, and to consume it immediately. The leaves must be green and smooth, and the grains bulged.
Grain corn: it is usually found in the form of flour, flakes, oatmeal and semolina, which unfortunately underwent a process of transformation aimed at eliminating the bran and the germ in order to increase the shelf life. Some rare flour mills offer whole grain-based products; make sure they are freshly prepared, at the risk of being rancid. Some companies also sell the whole grain, not processed.
Tortillas: the products of the trade are usually made from corn flour with white grains or wheat flour, although consumers begin to find products based on yellow, red or blue grains. Preferably buy refrigerated or frozen products, which contain fewer preservatives.
A large part of the “Mexican” products (tortillas, tacos and chips) are found in grocery stores and are made with corn flour from genetically modified grain varieties. Note these products do not come from Mexico, a country which does not cultivate any genetically modified corn varieties, but rather the United States, the world’s largest producer of GM (genetically modified) plants.
Products based on cornstarch, Dextrose and maltose are also produced in the majority with GMO corn, although it is not necessarily traceable in the foodstuffs containing them, as they are purified substances.
Morning cereal based on corn flakes can be made with transgenic corn.
In Canada, the cultivation of genetically modified fresh corn is not permitted, while it is the case in the United States.
By choosing varieties maturing at different times (early and late) and by planting successive seedlings until July, fresh corn can be collected throughout the season. Serious enthusiasts who want to grow grain corn or to blow it should be careful to isolate these types of fresh corn varieties, at the risk of changing the sugar content of the latter. Sow these varieties as soon as possible in season, as the grain takes a long time to ripen. To germinate, corn requires temperatures above 13 °C.
It is a demanding plant in fertilizer. Bury manure or compost in the previous fall or grow it as a result of a legume.
In order to promote pollination and to obtain well supplied grains, preferably in blocks of four short rows rather than a single row will be sown. Space seeds from 22 cm to 30 cm in row and rows from 70 cm to 85 cm.
Irrigation: water in case of drought, especially when the spikes and bristles emerge, and the maturation of the spikes.
Insect control: it will be possible to exert some control over the borer by spraying a solution of BT (Bacillus thurigensis).The small immature spikes are plucked only a few days after the formation of the bristles, the fresh, but not mature ears, about twenty days later, when the tips of the bristles begin to brown and dry.
Ecology and environment
Larvae of two insects, the borer and the rootworm of the roots, result in losses of several hundred million dollars per year for corn producers. This is why, over the past ten years, the areas dedicated to transgenic corn, which is resistant to these two insects, have increased significantly in North and South America.
However, transgenesis remains a controversial technique within the scientific community and some researchers prefer to explore the classic breeding and crossing tracks, which do not use genes from organisms outside the plant. As a result, an American geneticist has recently created hybrid varieties showing an astonishing resistance to these two insects, as well as the tomato moth, which also attacks corn. It’s by crossing corn with the tripsacum, one of its wild ancestors, it has obtained these varieties.
According to this researcher, only a better knowledge of corn genetics and the traditional uses which have been made by the populations in the past will create sustainable modern agricultural applications. To do this, it is necessary to preserve the genetic capital of corn, because among the old varieties may be the solution to the present and future problems. However, this capital is currently under threat because of the exponential increase in genetically modified corn crops, which are likely to contaminate the old varieties of corn and teosinte. The threat also comes from the current economic expansion, which pushes the Mexican peasants to leave their farms or turn to commercial agriculture and abandon the varieties they sowed for generations.
To counter this threat, the International Maize and Wheat Improvement Center (CIMMYT) have set up a comprehensive program to preserve corn diversity. This program is based on a close collaboration between scientists and farmers, the latter being holders of ancestral knowledge often eludes the former.