Protein Shifting and Enrichment with Dry Grinding and Classifying
The global food supply chain is undergoing significant changes. With the world’s population growing, the demand for food, especially proteins, is increasing. This demand cannot be met solely by animal proteins due to the extensive land required for livestock and water usage. Additionally, consumers are increasingly demanding sustainable production methods. Therefore, alternative protein sources obtained from plants, mushrooms, insects as well algae or bacteria fermented biomass are crucial for future needs and are intensively investigated nowadays.
A well-established source are plant-based proteins. Focusing on the production of meat alternatives, protein isolates from soy with a protein content > 80 % are the means of choice as major ingredient therefore – mostly obtained through diverse wet extraction methods.
But due to ongoing developments in dry fractionation technologies and seed breeding, the process has become an energy-efficient method to produce high-quality protein concentrates with significant lower plant investment as wet technologies. The goal is to achieve a protein-rich fraction with a significantly higher protein content than the original material through dry grinding and air classification.
Starting mostly from dehulled pea, mung or faba bean, the resulting protein fractions are achieving protein concentration generally between 55 and 70% - just mechanical treated with full functionality and native state of the protein. Without question, an economical yield of the fraction of 25 – 40% (dm) should be generally achieved. Main influencing factors are species, moisture and protein starting level of each legume.
To understand the main principle of the protein shifting process, we must look on the kotyledone of a suitable legume, like pea: The size difference between big, elastic starch bodies (40 µm) and small protein granules (3 -10 µm) is the essential condition of the raw material.
Processing step 1 – Production of fine flour
The process starts after the cleaning and dehulling step of the legumes. The milling disaggregates the relatively large starch bodies from the smaller protein parts. Furthermore, the damage of starch should be avoided to keep its quality. The most effective and gentle way to achieve this is through impact grinding in a NETZSCH Classifier Mill CSM. A fineness of around 40 – 60 µm (d90) of the obtained flour is ideal.
Processing step 2 – Efficient separation
Using a high-efficiency classifier, the flour from step 1 is then separated into the high-protein and low-protein fraction (“starch fraction”), respectively. As this fineness range brings conventional flour sifters to their limits, separation is carried out by dynamic air classifiers. The NETZSCH High-efficiency Fine Classifier CFS/HD-S is used to achieve highest yields with a minimal loss of protein in the starch fraction. For this purpose, the ground product is passed into a ring gap, charged with air for optimum dispersion. The ring gap accelerates the particles into a circulatory motion and the additional centrifugal forces separate them from one another. The particles are separated considerably more effectively, compared to conventional types of classifiers.
In March 2024, ANDRITZ and NETZSCH formed a strategic partnership to serving the alternative protein market with innovative technologies. Their collaboration combines NETZSCH’s expertise in fine grinding and subsequent classifying to extract a protein-rich fraction, with ANDRITZ’s comprehensive process knowledge of conditioning, extraction, dewatering, drying, extrusion or pelleting – followed by offering tailor-made solutions for turn-key plants or conceptual designs and of course testing possibilities.
