2.1 Raw material selection: Select corn that is free of impurities, has full particles, is free from insect infestation, and has no mold as the raw material. 2.2 Preparation of sulfurous acid: The method of burning sulfur to prepare sulfur dioxide, then dissolving it in water to prepare sulfurous acid, requires the newly prepared sulfurous acid solution to contain S020.25-0.3%. 2.3 The soaking and crushing of corn are carried out by reverse flow or diffusion methods. The newly prepared sulfite solution is pumped into groups of soaking tanks to soak the corn. The soaking solution is poured back into the tank according to the reverse flow method, and the one with the longest soaking time is moved in sequence to the one with the shorter soaking time (pouring tank). With this method, the concentration of the extract can reach 7-9%, and the steam consumption during further concentration of the extract is less than that of the static method. After soaking, the corn is subjected to secondary crushing and separation processes to completely separate the embryo from the endosperm. The soaked corn germ contains about 60% moisture and has great elasticity. At the same time, the connection between the germ, corn husk, and endosperm is weakened, and the connection between protein and starch in the corn endosperm is weakened, making it easy to separate from the corn kernel when broken. In addition, during fragmentation, the starchy portion of the endosperm is ground into granules, from which approximately 25% of the starch can be released. 2.4 Separation and Washing of Embryos: After a crushing process, most of the corn kernels are separated from the endosperm, and the embryos are separated through a floating tank before entering a secondary crushing process. After two rounds of crushing and separation, all the embryos are separated. The separated germ is subjected to continuous water spraying on a vibrating screen to wash away starch milk, gluten, and other substances adhering to the surface of the germ. It is then preliminarily dehydrated by a centrifuge to a moisture content of less than 36%. The grinding of 2Chemicalbook. 5 slurry involves crushing and separating the endosperm, which is composed of starch granules, gluten, seed coat, and endosperm fragments containing a large amount of starch. The crushed slurry needs to be finely ground through primary and secondary impact grinding to achieve finer endosperm particle size and maximize the release of starch bound to proteins and cellulose, creating conditions for the separation of the next process. 2.6 The suspension formed after sieving and washing the slag and grinding the slurry contains fine particles of free starch, gluten, and cellulose (fine and coarse slag). Separate coarse and fine slag from starch suspension using a seven stage pressure curved sieve, and wash the residue with six stages of countercurrent washing to remove the starch attached to it. 2.7 Separation of Starch and Gluten Starch and gluten separation is carried out in a disc centrifuge. Due to the larger particle size and specific gravity of starch particles compared to protein particles, their settling speed in suspension is faster than that of protein particles. Therefore, a centrifuge can efficiently separate starch and protein. 2.8 Starch washing and mechanical dehydration: To remove soluble and insoluble proteins, reduce starch acidity, and increase suspension concentration, a ten stage cyclone is used for countercurrent washing. After washing, the starch is mechanically dehydrated using a horizontal scraper centrifuge until the moisture content of the wet starch is 38-40%. 2.9 Starch drying adopts air flow drying, which is fed into the loosener by a screw conveyor according to the production requirements (depending on the moisture content of the finished starch). The wet starch that has been mechanically dehydrated is sent into the air flow drying system in the loosener, and at the same time, hot air that has been pre purified and heated to 140 ℃ is sent for drying.
