Maize kernels are classified into the following nine types according to their morphology, the structure of the endosperm and the availability of the glumes.
1. hard grain type also known as flint type. Seeds are mostly square and round, the top and around the endosperm are horny, only the center of the near-embryo part of the powder, so the appearance of translucent glossy, hard and full. The color of the grain is mostly yellow, or by, red, purple and other colors. Seed quality is good, is China's long-term cultivation of more types, mainly for food grain.
2. Horse-tooth shape is also called horse teeth type. Seeds flat rectangular, because the top of the powder than the sides of the horny dry faster, so the top of the center concave, shaped like a horse's teeth, so the name. Seed skin wrinkles rough opaque, mostly yellow, white, a few purple or red, poor eating quality. It is the most cultivated type in the world and in China, suitable for the manufacture of starch and alcohol or as fodder.
3. Semi-horse-tooth type is also called intermediate type. It is from the hard grain type and horse tooth type corn hybrid. The top of the kernel depression is shallower than the horse-toothed type, and some are not depressed but only white speckled. The powdery endosperm at the top is less than the horse-toothed type but more than the hard-grain type, the quality is better than the horse-toothed type, more cultivated in China.
4. Powdery type is also known as soft type. The endosperm is all powdery, and the seeds are milky white and lusterless. Can only be used as raw materials for starch, rarely cultivated in China.
5. sweet type also known as sweet corn. The endosperm is mostly horny, containing more sugar, containing starch is low, because of the evaporation of water during maturity so that the surface of the grain wrinkled, translucent. Mostly used as a vegetable, China's planting is not much.
6. sweet powder type, the upper part of the seed for the horny endosperm; the lower part of the powder endosperm. China is rarely cultivated.
7. Waxy type, also known as glutinous type. The endosperm of the seeds is all horny but opaque and waxy, and the endosperm is almost entirely composed of branched-chain starch. Eating properties like glutinous rice, sticky soft and palatable. China only sporadic cultivation.
8. popping type, smaller seeds, rice-shaped or pearl-shaped, endosperm is almost entirely horny, hard and transparent texture, the seed coat is mostly white or red. Especially suitable for processing popcorn and other puffed food. China has sporadic cultivation.
9. lemma type, the seed is longer lemma shell package, the kernel hard, difficult to threshing, is a primitive type, no cultivation value.
China's national standard of corn quality, according to the corn grain color and grain quality is divided into four categories:
Yellow corn: corn with yellow seed coat.
White corn: corn with white seed coat.
Glutinous corn: corn rich in viscosity.
Mixed Corn: Corn that has more than 5.0% of corn other than this category mixed in with the above three categories.
History of corn cultivation and utilization
I. History of cultivation
Corn, also known as "corn", "grain", "bun Lu", "Pearl rice" and so on. According to evidence, corn is native to South America. 7000 years ago, the American Indians have begun to plant corn. Because corn is suitable for dryland cultivation, Western European colonists invaded the Americas and brought corn seeds back to Europe, after which it was widely planted in Asia and Europe. Around the middle of the sixteenth century, corn was introduced to China and then to India in the eighteenth century. So far, corn is grown on all continents of the world, with North and Central America having the largest area of corn cultivation.
Second, corn classification
There are two main ways to classify corn: according to the color of the seed coat classification and quality classification. Specifically as follows:
1, China's newly revised national standards and U.S. standards are based on the color of the seed coat will be divided into yellow corn, white corn and mixed corn.
Yellow corn. The seed coat is yellow and includes slightly reddish yellow corn. The U.S. standard specifies that yellow corn contain no more than 5.0 percent of any other color corn.
White Corn. Corn that has a white seed coat and includes a slight yellowish or pinkish color. The U.S. standard describes yellowish as light straw-colored and states that white corn shall not contain more than 2.0 percent of other-colored corn.
Mixed corn. China's national standard is defined as corn mixed with more than 5.0% of corn other than this category. Expressed in the U.S. standard as having a color that meets neither the color requirements for yellow corn nor the color requirements for white corn and containing white-topped yellow corn.
2, according to the quality classification, corn can be divided into conventional corn and special corn. The so-called special corn, refers to a variety of types of corn in addition to conventional corn. Traditional special corn has sweet corn, glutinous corn and popping corn, the newly developed special corn has high quality protein corn (high lysine corn), high oil corn and high straight chain starch corn. Because of special corn than ordinary corn has a higher technical content and greater economic value, foreign countries call them "high value corn".
Sweet corn. Usually divided into ordinary sweet corn, enhanced sweet corn and super sweet corn. Sweet corn on the production technology and harvesting requirements are more stringent, and short shelf life. China has now mastered a full set of breeding technology and accumulated some germplasm resources, domestic breeding of various sweet corn types can basically meet market demand.
Glutinous corn. Its production technology is much simpler than that of sweet corn, and there are almost no special requirements compared with ordinary corn, the harvest period is more flexible, the shelf life is also longer, and does not require special storage and processing conditions. Glutinous corn in addition to fresh food, or starch processing industry is an important raw material. China's glutinous corn breeding and production development is very fast.
Bursting corn.
High oil corn. Higher oil content, especially in which the content of unsaturated fatty acids such as linoleic acid and oleic acid reaches 80%, which has the effect of lowering serum cholesterol and softening blood vessels. In addition, high oil corn than ordinary corn protein is 10-12% higher, lysine is 20% higher, vitamin content is also higher, is food, feeding, oil three multi-functional corn.
Quality protein corn (high lysine corn). The yield is not less than ordinary corn, while the whole seed lysine content is 80-100% higher than ordinary corn, in some areas of China, has realized the combination of high yield and high quality.
Purple corn. Is a very rare corn varieties, for China's specialty, because the grain shape like a pearl, there is a "black pearl". Purple corn quality is excellent and special, but the stick is small, fewer grains, mu yield is only about 50 kilograms.
Other special corn and variety improvement corn. Including high starch special corn, silage corn, edible corn hybrid varieties.
Three, the history of utilization
1, corn utilization overview
On the use of corn, roughly experienced as human rations, livestock feed and raw materials for industrial production of the three stages.
Ration consumption accounts for the proportion of total corn consumption is about 5%, but with the development of the times, this proportion has a tendency to gradually reduce. Corn is one of the three major food varieties, to solve the problem of human sustenance play a great role. To date, corn is still an indispensable food on the table of people all over the world: in the "hometown of corn" Mexico, "national dish" tortilla annual consumption of 12 million tons of people, whether rich or poor, noble or lowly are very like to eat; in the developed countries and regions, corn has also been used as the basis for the development of the food industry, but also as the basis for the development of the food industry. Developed countries and regions, corn is also necessary as a supplement to the human body, iron, magnesium and other minerals for people to eat a wide range of sources; in some poor countries and regions, maize is still people's cheap things to wrap their stomachs.
Feed consumption is the most important consumption channel for corn, accounting for about 70% of total consumption. The consumption can be seen as a function of the standard of living and population size over time: in the early stages of people's living standards, Engel's coefficient is high, people on meat, eggs, poultry, milk, strong demand for animal husbandry and feed industry to pull the development of the big, leading to a substantial increase in demand for feed corn, corn production has become the main driving force; in the life of a certain level, Engel's coefficient declines, meat, eggs, poultry, milk, etc. demand will remain stable. Milk and other needs will remain stable, at this time the consumption of feed corn will only be proportional to the number of population.
The use of industrial raw materials is also the main channel of corn consumption. Corn is not only the "king of feed", but also food crops in the most widely used, can develop the most products, the largest amount of industrial raw materials. Corn as raw material for the production of starch, can get the best chemical composition, the lowest cost products, added value over the original value of corn dozens of times, widely used in paper, food, textiles, medicine and other industries. Corn starch as raw material for the production of alcohol is a clean "green" fuel, may be in the 21st century to replace the traditional fuel and is widely used.
Stocks are also a form of corn demand. For food security reasons, countries always need to stockpile some food. World corn stocks generally account for about 20% of the proportion of consumption. In recent years, China's corn stocks of about 6 to 7 million tons.
2, the world corn utilization status quo
The general situation of corn utilization is used as a large proportion of feed in industrially developed countries, and in developing countries used as a large proportion of food rations.
With the great development of the world's livestock industry, the feed industry can be the rapid development of the world's demand for corn for feed shows a growing trend. In developing countries for industrial feed consumption of corn increased, while the traditional way of feeding livestock and poultry feed corn consumption is also increasing. In developed countries and regions to show that a large number of corn grains are processed into industrial feed.
From the world's consumption of corn trends, in the past 15 years, both developing and developed countries as feed corn are increasing year by year, as the number of food rations in the decrease, as industrial raw materials and food processing of corn in the increase. To China, for example: the early 90s, the feed industry and the rapid development of animal husbandry, in 1993, the consumption of feed corn reached 62 million tons, accounting for 67% of the total consumption of maize, in 1995, the indicator quickly reached 77% of the total consumption of maize, maize consumption incremental increase almost entirely by the incremental increase in the consumption of feed corn embodied.
Worldwide, 264 million tons of corn were used as industrial feed in the 1980s, 66 million tons of corn were used as food rations, and 0.44 billion tons of corn were used as industrial raw materials. Into the 1990s, the above three indicators were 352 million tons, 59 million tons and 56 million tons, respectively.
In 1996, the United States production of industrial feed consumed 127 million tons of corn, accounting for 53% of total corn production. The European region consumes 66 million tons of feed corn, China produces 34.98 million tons of industrial feed consumption of corn, Japan consumes 16.62 million tons of corn, Brazil produces 15.2 million tons of feed consumption of corn, France 13.26 million tons of feed corn, South Korea 8.52 million tons of feed corn.
The United States corn production accounted for 40% of the world's total output. Throughout the decades the United States corn market consumption trends can be seen, the United States in the 50's corn products used as feed accounted for 85.7%, industrial raw materials, food accounted for 8.08%, exports accounted for 5.17%; 60's corn for feed accounted for 81.76%, industrial raw materials, food accounted for 8.23%, exports accounted for 12.38%; feed accounted for 66.02% in the 70's, industrial raw materials, food accounted for 8.77%, exports accounted for 25.21%; 80's to the early 90's, corn used as feed accounted for 59.36% (122.37 million tons), used as industrial raw materials, food accounted for 11.65% (24.01 million tons), exports accounted for 28.63% (59.02 million tons). It can be seen that in the United States, although the proportion of corn used as feed is declining, but the feed is still the most corn-consuming industry, exports are increasing rapidly, used as industrial raw materials and food processing corn consumption is relatively stable.
China's reform and opening up with the great development of animal husbandry, people's living standards, the development of the corn industry, corn has become a food, feed, industrial raw materials and export commodities, multi-purpose crops.
China's corn consumption is the proportion of rations in the 80s accounted for 38%, consuming 25.88 million tons of corn, corn for feed accounted for 48% (industrial feed and traditional feed), consuming 32.69 million tons of corn, exports accounted for 11%, exporting 7.49 million tons of corn, industrial raw materials and food processing accounted for 3%, consuming about 2.05 million tons of corn.
Entering the 1990s, the proportion of corn consumed directly by people is declining. National ration consumption of corn accounts for about 19% of the total corn production, consumption of corn amounted to about 18.7 million tons; corn as feed consumption in our country there are two kinds of situations. One is the processing and production of compound feed. China in recent years with the feed production of about 48 million tons, according to 60% rate of conversion, the annual consumption of 28.8 million tons of corn. Second, the traditional corn directly for feed consumption. In the countryside, mainly corn directly as feed for large livestock, pigs and poultry. According to expert estimates, this traditional feeding method is estimated to consume about 35 million tons of corn per year, these two annual consumption of corn about 63.8 million tons, accounting for 68% of the total corn production.
Corn is an important industrial raw material, can also be processed into refined corn food. China is currently used for industrial raw materials and food industry corn accounted for about 5% of the total corn production, annual consumption of about 2.5 million tons of corn. China's average export of corn from 1990 to 1994 8.2 million tons, accounting for about 8% of total corn production. 1995 and then turned to a large number of imported corn. In the past 10 years, China's corn consumption trend is used in the production of corn with the number of feed soared, used for rations of corn decreased year by year, used as industrial raw materials and food processing of corn growth is slow, from corn exporters to corn importers.
3, China's new trend in the use of corn
Since the 80s, China began to pay attention to and the development of corn processing industry, has introduced technology and equipment, built a number of production scale in more than 100,000 tons of corn deep processing enterprises. Jilin Province, the implementation of the "million tons of corn deep processing project", the corn deep processing industry as a pillar industry. Jifa Group and Hong Kong businessmen to establish a joint venture of the company's annual processing capacity of corn has reached 400,000 tons, becoming Asia's largest corn processing enterprises. Although China's corn deep processing industry has made initial progress, but compared to the world's advanced countries, there is still a big gap. Jilin Province, for example: 1979 to 1998, Jilin Province, the amount of food processing and conversion from 1.59 million tons to 6 million tons (including livestock and feed processing 4.4 million tons of grain), an average annual growth of 230,000 tons, during the same period, the main production of corn in Jilin Province, but from 9.03 million tons to 2.506 million tons, an average annual growth of 840,000 tons. Comparison of the two, the former is only 28% of the latter, production is much larger than consumption. With the United States and other countries of corn deep processing products have reached more than 4,000 kinds of products, the output value of hundreds of billions of dollars compared to the gap is obvious. China's modified starch, fructose syrup and other production has just started, alcohol production is not high, corn deep processing prospects are very broad.