By-product processing
In the process of producing corn starch, intermediate products such as corn pulp, germ, residue and protein water can be obtained, all of which can be utilized as by-products if processed. The main maize by-products processing methods are as follows.
(1) corn pulp: soak corn with sulfur dioxide solution counter-current, and finally pump out the soaking water containing 6-7% dry matter, which can be evaporated using a three-effect vacuum to concentrate it to a thick liquid containing 50% dry matter, called corn pulp. According to the chemical composition of corn pulp determination results are as follows: moisture 48 ~ 50% reducing sugar more than 5.5% ammonia content of more than 3.6%
Inorganic matter more than 10% Ammonia nitrogen more than 0.9% Lactic acid more than 9-12%
In addition to being used as a raw material for the cultivation of yeast and antimicrobial nutrients and the manufacture of fermen and inositol, corn pulp is also a good animal feed when mixed with recovered corn protein and coarse and fine residues.
(2) Corn germ: the germ cleaned from the sieving section contains about 50-60% moisture, and it can be dried to a moisture content of 4% by a drum dryer or boiling machine. Usually three stages of drying are used, the first stage is dried until the germ contains about 35% moisture; the second stage is 10%; the third stage reaches the moisture content specified for the germ.
The dried germ contains 45 to 50% oil. It has a higher oil content than soybeans (soybeans contain about 20% oil), so it is a very good oilseed. The crude corn oil obtained by the oil press is yellow in color and contains free fatty acids, which is then refined to obtain refined corn oil that can be consumed, and the oil cake can be used as feed.