Cleaner cereals without pesticides
February 01, 1999
by Teresa Acklin
Cleaner cereals without pesticides
Contributed by suppliers, technical profiles feature new technology, products, specific applications or proprietary concepts. This article was contributed by Ejner Rasmussen, export manager at Damas A/S, Faaborg, Denmark.
Higher duties on pesticides and public support for organic farming is expected to result in a general reduction of the use of pesticides and dressing materials. Subsequently, the cereal crops received by grain and seed companies may have a higher content of bacteria and mold fungi, germs, beetles, etc. Still, milling companies and malt factories demand cereal crops with the highest possible hygiene standards.
The Sigma vertical planet drum cleaner uses a powerful centrifugal force to clean and polish cereals. This process of polishing of the surface of the grain removes far more bacteria and mold fungi, micro-organisms, heavy metals, pesticides residue, beetles, toxins and germs than traditional cleaning machines.
A microbiological analysis by the Biotechnological Institute in Kolding, Denmark, concludes that centrifugal screening is more effective in removing bacteria and fungi than traditional flatbed screen or air cleaning.
This cleaning method works by drawing raw material into the center of the machine. The grain is then distributed into a number of vertical cleaning drums, which are located a set distance from the center of the machine. Each drum is fitted with scalping and bottom screens.
The drums rotate around the center of the machine as well as around their own axis in a planetary movement, in the same manner that the earth revolves around the sun.
The rapid movement of the machine produces a powerful centrifugal force, which brings the grain from the center of the machine through a rotating distributor into each cleaning drum. The same centrifugal force makes the grain stick to the inside of the screens instead of falling through the drums without being cleaned. This centrifugal force is equivalent to an artificial gravity on the grain much greater than normal gravity.
The movement of the grain, as well as the movement on the screens, polishes and grinds the individual grains. Dust bacteria that have gotten loose from the surface of the grains will partly be screened away and partly be removed by the final air separation.
Efficient surface treatment and polishing of the cereals in connection with the intake cleaning offers three advantages to the milling industry:
Increased hygiene standards from intake through to the milling process and final end product.
Quicker absorption of moisture, resulting in less time for harmful micro-organisms to develop and an enhanced end product.
The quicker absorption rate saves time and results in higher moistening capacity, depending on the size of the silo or plant.
For the malt industry, this cleaning method makes it easier to meet exacting hygiene standards. Because the harmful effects of toxins cannot be removed by heat treatment, it is important to attain the highest possible levels of hygiene from intake. Combining deculming and cleaning of malt has resulted in simpler and more cost-effective installations.
Regarding grain for seed purposes, tests have shown that germination time is reduced because of quicker absorption of moisture for grain cleaned in this manner and exposed to a suitable surface abrasion and polishing. Consequently, the cereals have a quicker start against the weed, which reduces the necessity for application of pesticides.
Reducing the amount of bacteria and fungi to a fraction may reduce the demand for using dressing materials. The consequence of this would have benefits on the aquatic environment and the food chain.