Grain — a valuable raw material

by Peter Striegl
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To achieve success in the grain processing industry, it is crucial that full advantage be taken of the latest technologies for increasing the maximum outcome in processing the raw materials. The industry is demanding quantifiable value-added solutions.

Climate-induced changes such as heat, drought and other adverse weather conditions have led to unexpectedly large harvest shortfalls in various regions of the world. At the same time, demand for grain has increased because of the continuous growth of the global population paired with changes in dietary habits. Especially in emerging countries, the daily diet increasingly includes animal proteins. Bearing in mind that several kilograms of grain are required to produce 1 kilogram of meat, it is easy to see the impact that this has on the demand for grain. Moreover, the development of the ethanol industry has created an additional consumer group in the grain market.

When raw materials become scarcer and therefore more expensive, innovative technologies are required to utilize them with greater care and efficiency.

The fundamental commercial success factors and requirements for a modern grain milling business are the following:

• best possible decontamination of the raw materials;

• grading of the raw material on the

basis of quality parameters;

• consistently high end product


• higher yields of high-grade end

products;• maximized operating reliability and uptime of the production plant;

• low production costs (energy, manpower, maintenance);

• high level of automation with guaranteed traceability; and

• low plant housekeeping requirements.

The first processing stages in the grain processing industry are grain reception (intake), precleaning and cleaning.

The application of technologies in processing the raw grain in the grain receiving, precleaning and cleaning stages play an important role in maximizing processing efficiencies.


Since the situation of smaller grain harvests has also been compounded by deterioration in grain quality, lots of low-grade grain is increasingly entering the marketplace. The systematic monitoring and grading of the grain on the basis of quality parameters is a precondition for achieving end products of consistently high quality. If necessary, this will also allow complaints or claims to be addressed to the grain suppliers.

NIR online measurement instruments, such as those developed by Bühler AG, enable complete quality coverage and thus guarantee excellent checking of the incoming material by active monitoring. These advantageous attributes, combined with high-accuracy and high-performance weighing by grain scales, form the basis of a modern precleaning flow chart (see page 52).

In the cleaning section, grain passes through various processing operations. The latest technologies developed by SORTEX in the area of optical sorting technology and the resulting high capacity of the cleaning equipment open up  new approaches to grain cleaning. The SORTEX color sorter reduces energy consumption required for operation and ensures that only foreign seeds and discolored grains will be separated.

The portion of reject material is reduced to the absolute minimum. To date, such a high separating efficiency was only possible with enormous capital investments and operating expenses. Highly accurate separation of foreign seeds also enables high-grade end products to be produced with high purity and product safety, such as bright flour for specialty bakery products or fresh dough as well as whole grain products.

Gravimetric grading based on density by Buhler’s Gravomat opens up new approaches which supplement optical sorting. This technology has matured to the point that it enables plant operators to proactively control quality parameters such as falling number, gluten quality and usarium infestation at this early stage. This, in turn, allows a shift in the above-mentioned quality parameters as well as a higher raw material purity to be achieved. Shriveled, infested and diseased grains are separated in parallel with the grading discussed before. Being able to utilize grain cleaned and graded in this manner for making high grade, sanitary end products offers decisive benefits, which in turn produce monetary advantages.

There are also several grain kernel surface treatment options that can be beneficial. Scouring removes dust and loose hull particles adhering to the grain. The next and more intensive surface cleaning operation is light peeling, in which the outermost layer of the grain kernel is removed. The main goal of this is to minimize surface contamination.

The peeling process, in which a higher hulling degree is achieved, helps eliminate deeper-level contamination, caused, for example, by toxins in the environment. Another process that has become widely established is pearling in durum milling. In the pearling process, a substantial portion of the bran is ground off. In durum milling, this method has been found to be an excellent solution for increasing the quality and purity of the semolina.

A high level of automation with a high end product consistency can be attained by using electronic scales, flow balancers, flow meters and automatic moisture control systems. Accurate wheat blends and constant moisture content ahead of the first break rolls are essential if a consistently high finished product quality is to be achieved.

The tri-rotor dampener disperses the accurately dosed water homogeneously across the surface of the grain and ensures that it acts intensively upon the individual kernels. The subsequent tempering times for the different wheat varieties are optimally adjusted (first in, first out). This produces the best possible mellowing of the endosperm, which is a prerequisite for obtaining top flour quality and maximum yield.

Raw materials are the most important factors influencing the total cost of a grain milling operation. The development of the market prices over the past months is challenging millers to achieve top commercial benefits by using the newest technologies. Advanced grain cleaning technologies allow raw materials subject to quality fluctuations to be transformed into top-quality, safe food.

Peter Striegl is head of technology for Buhler AG’s grain milling business unit. He can be contacted at