Corn processing and starch extraction process
1. smash
The main purpose of crushing is to break the soaked corn into more than 10 small pieces in order to separate the germ. Disc crushers are mostly used for corn coarse crushing. Coarse crushing can be done in two steps. For the first time, the corn is broken into 4 to 6 pieces for germ separation; for the second time, the corn is broken into more than 10 pieces so that all the germs fall off and the germ is separated for the second time.
2. Germ separation
At present, domestic germ separation mainly uses germ separation tanks. The advantage is that the operation is relatively stable, but the disadvantages are that it occupies a large area, consumes a lot of steel, and has low separation efficiency, generally no more than 80%.
3. Grind
For efficient corn grinding, secondary grinding is often used. For the first time, a hammer mill is used for grinding and the starch milk is screened; for the second time, a sand disc starch mill is used for grinding. Some use a universal grinder for the first grinding, and after screening the starch milk, use a stone mill for the second grinding.
4. Starch screening
After grinding the corn pieces, corn paste is obtained, and the starch and coarse and fine residue can be separated by screening. Commonly used screening equipment includes hexagonal screens, flat shaking screens, curved screens, centrifugal screens, etc. The screen holes for screening starch should be determined according to the type of screening equipment and starch quality requirements.
The diameter of the sieve hole of the hexagonal screen for cleaning coarse residue is 0.6 mm, and the diameter of the sieve hole of fine residue is 0.12 mm. The amount of clean water required to screen coarse and fine residue is calculated based on 100 kg of dry matter. It takes 230 to 250 liters to screen coarse residue and fine residue. It requires 10 to 130 liters, the water temperature is 45 to 55°C, contains 0.05% sulfur dioxide, and the pH is about 4.3 to 4.5.
In addition to starch, the dry matter in starch milk is mainly protein and water-soluble substances, so protein separation and starch cleaning must be carried out.
Proteins are generally separated by flow channels. Due to the large area and low separation efficiency, centrifuges are gradually used for separation. However, it is required that the starch milk contains less residue to prevent the nozzle in the disc from clogging and causing mechanical vibration.
The starch milk coming out of the hydrocyclone contains 78% moisture. If the starch workshop and the starch sugar workshop are combined, it can be directly sent to the starch sugar workshop for use. It is not necessary to dehydrate and dry the starch milk. However, the starch milk obtained from the cleaning bucket contains water and must be dehydrated.

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