Proteins are the building blocks of living organisms. Together with carbohydrates and fats, they are our main nutrients and indispensable for both human and animal nutrition.

Modern protein concentrate technology focuses on vegetable-origin proteins because there are many different sources that are widely available. At the same time, animal proteins now carry many negative associations, such as BSE and antibiotic residues.

Process engineering makes it possible to produce protein concentrates economically from sustainable crop sources and thus contributes to meeting the growing demand for high-quality protein ingredients. Depending on the crop used, protein levels can be raised to between 40 and 70 percent protein. This enables foodstuffs and animal feed ingredients to be attuned to market demands, while at the same time minimising anti-nutritive factors, such as phytates in soya grits. Table 1 shows the plants most often used for producing protein concentrates. Particle size can range from a few microns down to the nanosize scale.








Soya and rapeseed focus

From the standpoint of economics, soya (de-oiled soya grits) is the most often used raw material although de-oiled rapeseed grits are becoming significant in Europe. In both cases, the protein concentrate is produced from the end product of the oil extraction process. But many carbohydraterich plants are also used for the manufacture of protein concentrates.

The Hosokawa protein shifting process has been used for the last 30 years to produce specialty flour from a wheat flour base, produced specifically for certain bakery applications. Many large and small, national and international flour millers employ this process for wheat flour and Hosokawa`s protein concentrate process is built on this practical experience.

Two different processes are available. The lower energy standard process is preferred for manufacturing protein concentrate from starchy crops, where the end products need to meet minimum market requirements.





To meet maximum requirements, in terms of both quality and quantity, a highprecision process, which uses more energy, is available.


Pea protein concentrate

The mechanical production of protein concentrates involves the disintegration of the core conglomerate into its individual components. In the case of peas, there are two main components. Assuming that the shell and thus the fibres have been removed, what remains is protein (23%) and starch (55%). This material is fed into an Alpine Zirkoplex classifier mill, which grinds it to a clearly defined particle size. After the grinding process, the components thus liberated are separated in a downstream air classifier. The various constituents are dispersed as a function of their density in the airflow and routed to the classifying wheel.

The classifier yields two end products, the fine fraction with a high proportion of protein, and a coarse fraction with a high proportion of starch and a strongly depleted residual protein content. Depending on the degree of material disintegration, up to 70 percent of the protein portion can be routed to the fine fraction.

After protein separation, the concentrated starchy raw materials in the coarse fraction can be employed for industrial applications in new markets.


Protein concentrates from oilseeds

A similar process is used to concentrate protein from oilseeds after oil extraction. The grits, comprising mainly fibres and proteins, are fed to a grinding step that is usually combined with drying. The two raw materials are again separated in the downstream air classification process, as a function of the different densities, into two fractions, coarse material and fine material. Protein enrichment of up to 70 percent can be achieved with this process using soya grits. Amino acid composition can be optimised by processing different raw materials together.

The Hosokawa process for manufacturing protein concentrates not only opens up new markets but also enables the processor to tailor products to market requirements. This economic process is built on 30 years of specialised experience in the flour industry.



Acknowledgement

We greatly thank the kind collaboration of Perendale Publishers (UK), whose contribution of technical articles appeared on their magazines AQUAFEED and GRAIN & FEED MILLING TECHNOLOGY is deeply appreciated by Engormix.com and its community members.