Natural raw materials are often altered to prepare them for consumption. A standard process in the food industry is extraction with the aim of increasing the concentration of components in the starting material. Extraction is the isolation of pure substances from a material mix of substances using a suitable solvent. As a rule, organic solvents with a low boiling point such as methanol, ethanol, dichloromethane etc. are used. As some of these materials are toxic, their use today is avoided where possible.
The alternative to organic solvents is high pressure extraction with compressed gases. Particularly in the supercritical state (having both gaseous and liquid properties) some gases exhibit excellent solvent characteristics, for example:
- High diffusion capacity
- Low viscosity
- Almost zero surface tension
- High dissolving power
Supercritical carbon dioxide (CO2) has proven to be extremely suitable for applications in natural product extraction. The low critical temperature of 31°C allows for a particularly gentle extraction treatment of the natural products present.
Decaffeinating coffee represents the opposite requirement: in this case, the extract is the caffeine, which is dissolved out by means of water and CO2.
- Dry, solvent-free products, concentrates and essences
- Gentle treatment of temperature sensitive substances
- Natural materials isolated without loss of aroma
- Selective material separation through variation in pressure and temperature
- Simple recovery of the extraction medium
Messer develops and optimises high pressure extraction plants for individual requirements.