Introduction and state of the art
Worldwide, the food supply chain is being faced with change. On the one hand, the increasing growth of the worldwide population creates an increasing need for foodstuffs, including a supply of proteins. This increasing need cannot be covered by animal proteins/products alone, due to the land requirements of livestock. On the other hand, the growing demand by consumers for sustainable production methods must be taken into account. The criticism of the sustainability of animal products in particular is expanding: The land usage and water consumption as well as greenhouse gas emissions of these products, in comparison to those of cultivated crops, are many times higher. Alternative sources of protein are being sought, and they play an important role for meeting future population needs. In addition to plant products, mushrooms, algae or insects, can be placed in this category.
Currently, soy is the most common of the crops used as a meat substitute based on plant material. They are processed into isolates with high protein contents of > 80%. The typical method for obtaining these is wet extraction. The use of large amounts of water, chemicals and energy for drying, makes this method a laborious, complex and resource consuming process.
The solution from NETZSCH
An alternative process is dry fractionation - a process that has been used to process flour for quite some time. NETZSCH has successfully been able to carry over the experience obtained from this process to the processing requirements of crops.
The goal of the application is to achieve a protein rich fraction in which the portion of protein is considerably higher than that of the initial material, by means of grinding and subsequent separation.
Fine Grinding
Fracturing of united cell structures with the aim of separating the starch granules from the proteins. The result are singular starch and protein granules as well as cell fragments gained from protein granules that partially contain starch granules.
Classifying
Efficient separation of the starch-protein-mixture into a coarse fraction with a high starch content and a fine fraction with a high protein content.
Processing
Effective impact-grinding with the NETZSCH Classifier Mill Type CSM
The beans or grains of a chosen crop are cleaned and dehulled, and afterward passed on for dry grinding, the objective of which is to break up the cells and to separate the starch granules from the proteins and fibrous cell parts. The most energy-efficient method for achieving this, is impact grinding using the NETZSCH classifier mill type CSM.
The integrated classifier of this mill type assures that only coarse cell fragments remain in the grinding chamber until the starch particles have been separated from the cell fragments and ideally only starch and protein fragments remain. Only in this manner, can a high yield be achieved in the subsequent separation step, with an optimum amount of energy expenditure.
It is decisive for the separation step, that during the grinding process, the size difference between the protein fragments and the starch granules remain as large as possible. Depending on the type of crop, the particle size of the proteins (for example peas) range from < 3 µm, whereas the starch granules ranging from 40 µm are considerably larger. The force applied to the starch in the NETZSCH Classifier Mill, is far more gentle than that of a pin mill, whereby to the greatest possible extent, the starch particles are preserved and the protein fragments are considerably smaller. This enables highest degrees of efficiencies in the following separation.
Focus on Your Advantages
- Quick adaption to varying product characteristics
- Precious top cut for optimum fineness level of around 50 µm +/- 10 µm (d97) for legumes with minimized starch-damage due to internal classifying effect
- Axial orientation of classifier wheel and grinding disc allow equal and efficient milling properties
- Automated hull release applicable for wear-reduced running operation
Separation
Efficient separation with the NETZSCH High-Efficiency Fine Classifier Type CFS/HD-S
Separation is achieved using the NETZSCH High-Efficiency Fine Classifier CFS/HD-S.
This classifier uses a stream of air to disperse the solid particles. Only through effective dispersion is it possible to optimally separate all of the particles and classify them according to size and/or weight. For this purpose, the ground product is passed into a ring gap, charged with air. The ring gap accelerates both particles into a circulatory motion, and the additional centrifugal forces separate them from one another. The particles are separated considerably more effec-tively, and thereby higher protein values and yields achieved, as compared to other design forms of classifiers.
Depending on infeed product quality in terms of species, moisture, storage condition and protein starting level, high protein values up to 60 – 75 % for yellow peas or faba bean, respectively, are achieved.
Focus on Your Advantages
- For high protein contents up to approx. 75%
- Highest protein and starch separation performance, with special pre-dispersion unit
- Compact machine design and easy maintenance with only one classifier wheel
- Fastest and automated adjustment of protein levels for constant production quality, e.g. for downstream extrusion processes
Application example Yellow Peas
Combination of machines | Throughput | |
Mill | Classifier | [t/h] |
CSM 360 | CFS 170/HD-S | 0.5 |
CSM 560 | CFS 340/HD-S | 1.3 |
CSM 720 | CFS 510/HD-S | 2.3 |
CSM 900 | CFS 1000/HD-S | 4.5 |
SEM images
SEM image of the product at the end of grinding with the CSM classifier mill. The difference in size between the protein and starch grains is large enough to achieve maximum efficiency for the separation following the grinding step.
SEM images after the separation of starch and protein particles with the High-effciency Fine Classifier CFS/HD-S:
Summary
Therefore, dry fractionation offers possibilities for cost effective, sustainable processing of premium quality products that have a high protein content. In addition, the NETZSCH process offers the invaluable advantage of flexibility, through its ability to adapt processing parameters to the varying characteristics of raw materials and a diversity of crops.