Maize starch processMaize can be used to produce starch, sugar syrups and oil. The commercial separation of pure starch from maize is achieved by a wet milling process which is generally considered to be an efficient process. The process is operated as an enclosed system in which process water is reused in a closed circuit. The addition of fresh water is limited to one point in the production process.
The raw material is cleaned using aspiration and screening to remove dust, chaff, broken grain, cobs and other extraneous material. The maize is soaked in water with sulphur dioxide or sodium bisulphite (NaHSO3), for around 36 hours, in a process known as steeping. This removes solubles in the maize, softens the kernel to improve separation of the various components and reduces microbial activity. After steeping, the maize is passed through several grinding and separation operations until only starch and gluten remain. The grain is first ground coarsely and the germs removed from the coarse gristAfter removing the germ, the grist is finely ground and fibre is removed through a screening operation. Starch and gluten are separated, typically using centrifugal methods. The starch is washed, dewatered and dried. The gluten, and fibre are collected separately as co-products.
The process is operated as an enclosed system in which process water is re-used in a closed circuit. The addition of fresh water is limited to one point in the production process.