Corn starch processing process(3)

When the corn in the steel plate silo needs to be processed, the valve is opened, it is sent to the cleaning tank in the workshop through a sc*r and elevator, and then it is hydraulically transported to the soaking tank, where sulfite is added for soaking.

Soaking is a key process in corn starch production, and the quality of soaking directly affects the yield of flour and the quality of starch. The purpose of soaking is to change the structure of the endosperm and its physico-chemical properties, weaken starch bonds, reduce the strength of the corn kernels, leach out soluble substances, and inhibit the growth of microorganisms.

Soaking is carried out in an aqueous sulfite solution, usually using a semi-continuous process. During soaking, the corn remains still in the soaking tank, and the soaking liquid flows from one side to the other in the tank. During the soaking process, always keep the newly added sulfite solution in contact with the corn with the longest soaking time (the soaking is about to end), while the newly added corn is in contact with the soaking liquid that is about to be drained, so as to maintain the best soaking effect. The soaking temperature is (50±2) ℃, the soaking sulfite concentration is 0.2%~0.25%, and the soaking time is 48~60 hours. After soaking, the dry matter content of the thin corn syrup is 5% to 9%, the pH value is 3.9 to 4.1, and then sent to the evaporation process to be concentrated into a corn syrup with a dry matter content of more than 40%. At the end of soaking, the moisture content of the corn is 40% to 46%, and the soluble matter does not exceed 2.5%. The moisture can be squeezed out by hand and the germ is completely separated.