Process description

Liquid CO₂ from the storage is pressurized, heated and transferred to the extractor, where it gets loaded according to adjusted conditions. A change of these conditions (pressure, temperature) causes precipitation of the dissolved substances in the separation vessels. The now gaseous CO₂ is condensed, intermediately stored and recycled again.

Process principles

Gases in fluid condition (above the critical pressure and the critical temperature) dissolve larger quantities of substances than the partial pressure of the substance in the solvent normally permits
CO₂ is an UNPOLAR solvent, which results in a high solubility for non polar and low polar substances up to a molecular weight of 250
Solubility decreases with increasing polarity
High polar substances are insoluble
The raw material is exposed to the fluid and soluble substances are transferred into it
Separation is achieved by change of parameters or adsorption

Supercritical fluid extraction plant
for solid-liquid extraction

Please click here for an animation of the process

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Thin-film extraction plant for viscous raw material
and liquid-liquid column

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Advantages

CO₂ is inexpensive, not combustible, not explosive, germicidal, free of bacteria, selective and mobile
Heat sensitive materials are gently treated
Products and residues are solvent-free
Fragrances and aromas remain unchanged
An excellent flavour profile is achieved
Pure extracts are produced by few process steps
The solvating power can be changed (conditions, modifiers)
Selective extraction and fractionated separation is possible
CO₂ is recycled within the plant, is physiologically harmless and does not cause environmental problems like some conventional solvents

Disadvantage

High capital investment

Solubility of substances in CO₂

Easily soluble	Reduced solubility	Unsoluble
esters, alcohols aldehydes, ketones volatile oils aromas mono- and sesquiterpenes	edible oil from oilseeds waxes polyphenols	sugars fruit acids starch proteins mineral salts glycosides

Supercritical fluid extraction plants

Supercritical fluid extraction technology

Powder generation plants

Powder generation technology