The corn, also named Maize, originate from central and south America’s tropic and subtropical plateau mountain area around Mexico and Guatemala. After Columbs discovered the new world, he brought the corn to Spain. Along with the development of world navigation, the corn were spread to European, Asia and Africa quickly.
The corn initially enter human society as main grain. The corn contents high starch, which can supply energy for human body. With the social development and progress of technology, basing on meet human survival, the corn are used to produce beverage and other deep processing. Therefore, it greatly promotes the development of world corn. At present, the corn is not only one of three main grains, the output production is also the first place:
Unit: thousand ton
America is the biggest country of corn production in the world. In 2007, all over the world produce 703.45 million ton corn. Among, the America produce 38% corn of the world’s total production. China is second, 20% of the world’s total production. China and America together take more than half of the world’s corn total production.
2. Wet milling
Starch producing have more than 2000 years history. In 17 century, European have produced potato starch. In middle of 18 century, all of European can produced potato starch. In 1842, the corn starch producing was born. In 1861, potato starch can be used to produce sugar. In the beginning of 19 century, the wet milling to produce corn starch was found.
Wet milling, just as its name implies, grind under wet situation. The purpose of corn starch production is as much as possible to extract pure starch and byproducts, such as starch, fat, gluten, fiber, various soluble substance. These substances exist in different section of corn, for example, corn starch mainly exist in farinaceous endosperm, gluten mainly exist in cutin endosperm and germ, fat mainly exist in germ, fiber mainly exit in root cap and skin of corn, other soluble substances, such as pentose, various mineral substance and vitamin, exist in all sections. As above composition, we know from corn we can not only get much starch, but also other nutrient substances: gluten, fat, fiber.
To make pure corn starch, it need separate all compositions, extract soluble substances, fat, fiber and gluten. At same time should note, each of the corn’s composition are mainly one chemical composition, but also content little other substance. So refining starch is difficult.
Wet milling basic process are one steeping, two milling, three separating. One steeping means using H2SO3 solution to steep corn. Two milling means the germ mill and fiber mill, germ mill refer to degerminator to separate the germ, fiber mill refer to pin mill to separate the fiber. Three separating means separating germ, fiber and gluten. After the degerminator and pin mill, the germ and fiber are extracted, then use disc separator to separate gluten from starch milk. Finally, the starch use 12 stages hydrycyclone to refine and use peeler centrifuge to dewater. At last, dewatered starch use air dryer to dry. The brief flow chart are as below: