Cryogenic grinding is a process in which the product temperature is reduced before or during grinding. This treatment makes the product more fragile and prone to shredding, and also protects all substances sensitive to high temperatures.
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Traditional methods of grinding generate heat, which in some cases causes the melting or evaporation of some substances or food products. Essentials, aromas and vitamins are extremely thermolabile. Too high temperature can destroy them, but also prevent the grinding of highly oily or fibrous products or with very hard texture.
During cryogenic grinding with liquid nitrogen ALIGAL™ 1 the temperature of the product is lowered (in most cases, we are talking about freezing products, sometimes it is only cooling of the product or maintaining the process temperature). A frozen or chilled product is more brittle, fragile which makes grinding easier. The freezing process prevents the loss of aroma and taste, making the final product more valuable. This cryogenic freezing technique is used to grind herbs, spices (eg. nutmeg, mustard, peper, allspice), seeds (eg. coffee), dried fruits or to reduce powder grade.
Cryogenic grinding can be carried out in two ways. The first is to freeze the product before proper grinding. For this you can use standard freezing devices:
or, for example, a screw feeder, which will ensure the freezing of the product in IQF quality.
Another method is to spray liquid nitrogen during the actual grinding process, inside the grinder. The condition is to have a mill with built-in dosing nozzles, or to have a mill resistant to low temperatures (stainless steel) on which Air Liquide will install the correct nozzles.