Methods of Maize (Corn) Degerming


Satake Maize Degerming Process


Satake has long been involved in removing bran and germ from rice and we are always looking for ways to apply this knowledge and experience to the processing of other grains. During the past few years, we have used the experience and knowledge in removing bran and germ from wheat and have now applied this technology in over twenty wheat mills throughout the world.


As we look for other industries, which might benefit from debranning technology, our focus has turned naturally toward the maize processors, because conventional maize milling already attempts to remove the germ from the maize kernel prior to reduction. We believed that a more efficient and less destructive method of bran and germ removal could lead to overall improvements in the process of milling maize.

Benefits of Satake’s Maize Degermination Process

When we examine applications for our technology, we always seek four essential benefits for our customers: 

  • We wish to increase the yield of primary product
    In this case, our system improves the yield of “yellow” products, with a significant increase in the yield of high value flaking grits.

  • We wish to improve the quality of that product
    Our new system offers higher yield of low-fat endosperm, and lower levels of fragment, microbial and trace element contamination. 

  • We seek to provide a shorter process
    Because it produces such high yields of relatively pure endosperm, our degermination system shortens both the purification and reduction processes normally associated.

  • We hope to provide a system with lower costs of operation
    The shorter system does fulfil this requirement.

The new Satake Maize Degermination Process enhances the efficiency of all of the areas normally associated with dry maize milling, from the production of low fat flaking grits to high quality corn flour to corn starch and ethanol.

Note: By convention, starch and flour produced by means of wet processes are called corn starch and corn flour respectively to differentiate them from the less pure products available from a dry process.


It is important to remember that we do not consider the removal of bran and germ to be a single step in milling, but a process of several steps, each of which should be tailored to maximise the efficiency of its particular task.


We have found that bran and germ removal can best be accomplished by first pre-conditioning the maize kernels, then removing their bran and germ, and finally separating the endosperm from the resulting bran and germ fractions.

 

 

The Satake Hydratorwpe35.jpg (8303 bytes)

Although the efficient removal of bran and germ is accomplished in a process, and not in a single machine, there are three key units involved that provide the desired efficiency and product quality. The first of these is the Hydrator, which applies moisture uniformly to each maize kernel while keeping the grain moving.

The Hydrator, by means of its slow moving mixing paddles and vibrating housing, combines the benefits of a grain-tempering mixer with the accelerated penetration of moisture through the bran skin and into the germ.

By controlling the quantity of moisture added to the grain and the retention time of the grain in the hydrating cylinder, efficient pre-conditioning can be accomplished in less time than is possible using other more conventional methods.

Automating the process to optimise the water addition and retention allows us to take advantage of the phenomena, whereby the maize and germ can be encouraged to naturally separate from the core endosperm of the kernel.


The Satake VBF Maize Degerminator
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The VBF Degerminator differs from all previous machines by having a vertical configuration, which is the key to its uniform and even action on the grain being processed.

It provides an aggressive rubbing action that simultaneously removes both bran and germ from individual maize kernels, while at the same time controlling breakage to produce a maximum number of large pieces of pure endosperm and limiting fines to a minimum.

In the degerminator, maize enters the annulus formed by a multiple sided perforated screen and an eccentric shaped rotor. As the rotor turns, the clearance between the rotor and the screen is constantly changing, causing the grain within the annulus to experience alternate periods of compression and relaxation.

This produces a very efficient rubbing action, in which bran layers are removed by rubbing grain against grain. In combination with abrasive action resulting from the grain moving across specially designed textured surfaces, this rubbing action simultaneously removes bran and germ from the kernel. The object is for bran and germ to exit the chamber through the perforations in the screen, leaving the clean endosperm to exit at the discharge of the machine.

A weighted discharge gate, which can be set manually or automated, is used to regulate the work done and thus the degree of bran and germ removal.

Because the clearance between rotor and screen is constantly changing with each rotation, a cyclic compression and relaxation occurs in the grain bed. This produces both the effective rubbing action and the pressure necessary for efficient removal of bran and germ.

As mentioned earlier, the VBF's unique vertical configuration allows for uniform loading of grain within the milling chamber. This maximises power efficiency and produces highly uniform bran and germ removal among individual maize kernels.


The Satake KB Grain Polisher
kb_maize.gif (32622 bytes)

The third key piece of core equipment in our new degermination process is the KB Grain Polisher.

Like the VBF, the KB uses an eccentric rotor in a polygonal screen to produce cyclic compression and relaxation. Its long milling chamber, however, allows it to use lower pressures than does the VBF.

In addition, its horizontal configuration facilitates movement of individual kernels relative to one another. This makes it an ideal polishing machine.

The KB is ideal for the removal of bran only, as is the case when recovery of large germ particles is desired. It is also most suitable for secondary polishing of recovered endosperm.

The new degerminating process will produce much higher yields than has been the case using previous, conventional technology.

In addition, it allows the possible production of value added products, because the flaking grits produced will have very low fat contents and levels of contaminants, such as insect fragments, microbial activity, insecticide and fertiliser residues.

 


Colour Sorting
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However efficient the cleaning and degerming system there is always a risk of discoloured kernels giving grits which show up as imperfections in the final corn flakes.

The Scanmaster colour sorter will act as a final check and ensures the finished product meets the highest standards of food purity.

What are the benefits of this system?

Through the use of this new technology, we believe that the maize miller can achieve product differentiation through increased purity, and more importantly, can increase profitability through increased yields with a shorter process.

As mentioned earlier, maize varieties and even kernels within a variety, are more varied than in, say, wheat. We have therefore trialed the system on all the major types, including:-

        White maize in Southern Africa
        U.S. yellow maize in Venezuela and N. America
        African yellow maize in Asia

Over 100 units are now in commercial service.


Comparison of Samples

 

# 5 Over (4,000 micron) # 6 Over (3,330 micron) #18 Over (1,000 micron
Existing Decorticator wpe30.jpg (6748 bytes) wpe31.jpg (7271 bytes) wpe32.jpg (7275 bytes)
Satake Maize Degermer VBF 10A wpe33.jpg (6591 bytes) wpe34.jpg (6945 bytes) wpe35.jpg (7696 bytes)

wpe1.jpg (915 bytes) Download Full Maize Degerming Presentation (1.9 MB)

 

 

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