Maize flour can be divided yellow and while. It contains lecithin, VE, fiber with the function to decrease blood pressure, blood fat and prevent cancer. It is also healthcare for diabetes patient.
There are two main milling technologies: one in which the grain is directly ground without any pre-processing and one in which the grain undergoes a number of pre-processing stages prior to milling. The former milling technology yields whole meal which contains both the bran and germ, while the latter one yields a large range of products including partly or fully de-germed meals called respectively bolted and super-sifted meals.
The second maize milling technology is used in roller mills where the maize undergoes a series of pre-processing stages which include cleaning, tempering, de-germing, sifting, reduction, etc. These mills yield a number of maize products for various food preparations. The composition of some of these products and the milling yields are shown in table IV.2. The range of products generally varies from one mill to another depending on market requirements. The extraction rate of the dry milled products is approximately 80 per cent. In general, the majority of the output comprises prime quality grits or meals with a fat content of less than 1.0 per cent. A small proportion of the output is made up of lower quality fines or flour with a fat content of 1.0 to 2.0 per cent. The by-products make up the remaining 20 per cent of the grain input. The germ is generally further processed for the extraction of oil while the bran is used for animal feed.
The maize goes into hulling chamber of maize grinder machine and moves to the outlet as the pusher pushes. Particles become closer and closer as the room in the chamber reduces and resistance increases. Friction strengthens while the cylinder rolls and pushes, which makes the maize shelled. The hulled maize enters grinding system and they are graded during this process. Finished products are got after dedusting.