Flour milling predates agricultural production and is the oldest of the fully automated food processes.
Vacuuming wheat from hull of the ship
NAMILCO imports wheat from the United States of America. It arrives in Guyana by ship or barge and is off-loaded at the mill’s jetty at Agricola on the east bank of the Demerara River. The wheat is vacuumed (photo at right) from the cargo hold of the vessel and then transferred via a conveyor belt to the flour mill’s storage silos (photo immediately below). Before the milling process begins the wheat is cleaned, scoured and tempered.
In the Tempering Process the moisture content of the wheat is increased to the optimum condition for milling. After the wheat has been in the tempering bins for up to 24 hours (depending upon variety), the milling process begins.
As it enters the mill, wheat first enters the Break System. This consists of a series of corrugated steel break rollers, which crush the wheat and gradually scrape the endosperm from the bran resulting in Middlings. The finer fractions of the middlings are graded in the sifting process by size and are sent on to the Purification System.
Here machines called Purifiers take out as much of the bran particles as possible in the interest of producing the whitest flour. The results are then fed to the Reduction System. This contains a series of smooth steel rollers through which the purified middlings are fed, according to their particle size and purity. After each reduction passage the resulting flour is removed by sifting in the final stage of the process called the Dressing Process
Flour Dressing System
In this system the ground stocks are separated on finely-woven nylon seives in machines called Plansifiers. Any material not fine enough to sift through as flour is sent back to the appropriate part of the system for further processing. The whitest flours are made from the purest stocks of the early passages through the reduction system.
Because white flour is required by the baking industry it is common practice to bleach the flour immediately after it comes from the mill. This is done by the addition of a gas or powder which oxidizes the carotene pigment. White refined flour is also enriched with iron, folic acid, niacin, thiamine and riboflavin which were partially lost with the removal of the bran in the refining process.
Approximately 75% of the wheat is recovered as flour. The by-products of milling process are called Millfeeds. They are used as animal food. Another by-product is wheat germ-the embryo of the wheat seed, which is often produced for human consumption. It is rich in B vitamins, vitamin E and protein.
See a step-by-step diagram of the flour milling process (1.2MB, prints on Letter-size paper) – Click HERE.