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Particle size reduction technologies for selected foods and food additives

In the food, luxury food or food additive sector, micronization is one of the most important processing steps. For that unit operation, NETZSCH Food & Confectionery offers advanced processing technologies to reduce particle sizes. Examples are natural food colorants, diverse hydrocolloids, fibres, sugar and sweeteners, but also nut and oil seed pastes, cocoa and chocolate related products.

In the specific field of dry milling and classifying, a wide range of machines are available. This includes flexible fine impact mills, as well as classifier and jet mills for fineness below 20 µm. For fibrous products like cellulose or carob, fine-cutting mills are installed. The machines and systems must meet highest requirements regarding safety, hygienic design and disinfectability, which makes NETZSCH a proven and reliable partner for processing of high quality food and food additives by dry-milling.

In addition to this, one can also depend on NETZSCH´s experience and expertise as a worldwide leading company in the area of wet-grinding and dispersing. With innovative dry and wet processing technology, an economical solution that suits your requirements is always found.

Application example: Protein Shifting and Enrichment with the use of Dry Grinding and Classifying

The worldwide nutritional demand for plant-based proteins is increasing enormously. The main sources are soybeans, wheat or peas. More often, regional crops such as faba beans are being taken into consideration. Semi manufactured products are amongst others protein-enriched flours or high-protein containing isolates using wet processes. The use of large amounts of water, chemicals and energy for drying makes isolate production a laborious, complex and resource consuming process.

NETZSCH focuses itself on protein shifting by dry grinding. This process, taken from classical flour production, is being used successfully to process legumes such as yellow peas, faba beans, mung beans or chickpeas. The aim of the process is to gain a protein-rich fraction by fine-grinding and classifying, in which the amount of protein is considerably higher than in the original product.


Processing step 1 – Production of refined flour

Ideally, the cleaned legumes are dehulled prior to the protein shifting process to a residual portion of < 1 %. The refining serves to break the cell structure and to isolate the relatively large starch granules from the smaller protein granules. Depending on the product, the proteins have a particle size of < 3 µm, whereas the starch granules range from 3 to 40 µm.

Most important for the subsequent separation is that during grinding, the difference in size between the protein and starch granules remains as large as possible. Care must be taken not to damage the starch granules in the process. The most effective and gentle way to achieve this is through impact grinding in a NETZSCH Classifier Mill, model CSM.


Processing step 2 – Efficient separation using a high-efficiency classifier, model CFS/HD-S

The resulting refined flour, which has to be separated into a high-protein and low-protein fraction, has a particle size between 40 and 70 µm. This is a range that brings conventional sifting to its limits. For this reason, fractionation with dynamic air classifiers has become widely accepted.

The NETZSCH High-Efficiency Fine Classifier, model CFS/HD-S achieves the highest yields with a minimal loss of protein in the high-starch fraction. In contrast to conventional classifiers, this classifier is highly compact and is equipped with a guide vane cage for most efficient dispersion and separation – the decisive advantages when viewing the economics of protein enrichment. Dependent on raw materials, protein values > 60 % in the protein rich fraction are obtainable!

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