Production processes at Kräuter Mix
Grinding spices and other natural products is one of the most challenging tasks for mechanical comminution technology. Materials that start out as larger pieces are processed into a powder or grainy end product. Each grinding process is different and depends on the various properties of the products and the customer specifications. Products may vary in terms of their hardness, size, oil content, sheer strength and toughness. These properties determine which grinding process is used. Essential oil content, in particular, plays a key role in this. This determines the subsequent market value of the product, as well as its aromatic intensity in its end use as a food product or herbal medicine.
Preservation of the ingredients
The temperature during the grinding process is a key factor in determining the quality. Because the essential oils, which give the natural product its distinctive flavour or active ingredient, are slightly volatile, the substances should not be heated too strongly in the grinder. This is the only way to ensure that the characteristic properties, such as the components that give off the spiciness or seasoning qualities, remain consistent and effective. This is why spices such as pepper, coriander, nutmeg, ginger and other roots must be ground very gently. But dried medicinal herbs, dried vegetables and ingredients for herbal and fruit teas should also be processed in such a way as to ensure the ingredients’ properties are not wasted. One tried and tested method is cold grinding with nitrogen.
Kräuter Mix has five modern, high-performance manufacturing plants for powder production that are constructed in very different ways. Two of these are for inert grinding, two for cold grinding and one can carry out both processes. In order to set the various grain sizes of the ground product, the plants use a number of different sifters. These can produce grains of between 0.2 and 1 mm, depending on what the customer needs.
Cold grinding with nitrogen
With inert grinding in a fine impact mill, the product remains in the milling chamber until the grain size corresponds to the sifter that has been used. With cold grinding in a pin mill, the product is ground down between the pin grinders working in opposite directions. The speed determines how fine the product will be. All of Kräuter Mix’s cold grinding plants are laid out in such a way that the supply of refrigerated liquid nitrogen injected into the cooling spiral is precisely coordinated with the controlled flow of coolant.
Liquid nitrogen with a temperature of -196°C in a closed plant system creates the perfect conditions for this process. It reduces the heat produced by friction as this snap-frozen product is mechanically processed, thus improving its quality by reducing or completely eliminating damage caused by excess heat. The ground product is immersed in liquid nitrogen, which transforms into gas at the same moment. The goods are transported into the milling chamber through a spiral conveyor. Specific amounts of nitrogen are continuously introduced into the cooling cycle to maintain the necessary temperature for the specific product.
Increasing process reliability
The products undergo a drastic cooling process to bring them to the specific processing temperature for that product, which causes the goods to become brittle and then break into smaller pieces on impact inside the grinder. These are then ground into a fine powder in the pin grinder without much mechanical force being applied. This prevents products with high oil or fat content from sticking together, because the fats dry out during the cooling process. In addition, this enables sensitive products to be ground more finely without changing their properties, such as through oxidation processes or browning. The ground product can still be poured.
Not only does Kräuter Mix use nitrogen for its cold grinding, but it also uses it for inert grinding to make the process safer by using the principle of inerting to displace the remaining oxygen in the plant, thus reducing the risk of dust explosion. At the same time, the cooling effect of the nitrogen enables the material to be ground in a temperature-controlled environment.
GMP production
Kräuter Mix uses four qualified grinding plants to produce its powders through both inert gas and cold grinding processes in accordance with GMP certification standards, which require the highest levels of hygiene and safety. In this way, we ensure our active ingredients and medicinal products are manufactured according to Good Manufacturing Practice (GMP) guidelines. This goes hand in hand with other specific requirements such as validated processes, comprehensive manufacturing and auditing documentation, and staff trained in accordance with GMP.
Flyer on the production process
Process description with flow charts of the grinding systems