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Supercritical 101
Traditional Supercritical Fluid Extraction (SFE)
Supercritical fluid extraction (SFE) is the most prolific use of supercritical fluids today. For almost 30 years
supercritical fluids (typically CO2) have been utilized as a replacement for conventional extractions of
oilseeds and natural feedstocks to produce high value oils and extracts for the foods and nutraceutical
markets. SFE has also become a standard method in the decaffeination of coffee and tea, hops
extraction for the beer industry, and a host of other products including spices, cosmetics, and
nutraceuticals.
SFE has several advantages over hexane and mechanical extraction methods:
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Simple solvent removal. No effort is necessary to remove residual solvent left in the products
after extraction, as the CO2 simply returns to its natural gas state. In contrast, a solvent
extraction plant requires a rather large and energy-intensive step to remove residual solvents.
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Safe and efficient. CO2 is a benign and safe solvent. Other solvent plants require great amounts
of safety control measures and over-design.
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Faster extraction rates. Supercritical fluids have the diffusivity of gases, but the density of liquids.
With near-zero surface tension and very low viscosities, SFs can permeate quickly into products.
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Broad range of dissolving power. Unlike conventional solvents, SFs have a broad range of
dissolving power under different operating conditions (ie, temperatures and pressures). This
property allows for very selective extractions and separations, and properly designed systems
can produce highly-refined products.
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Product integrity. Products extracted retain their natural aromas and flavors because the volatile
compounds are not removed as they are with solvent extraction.
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Decreased degradation by heat and moisture. SFE requires less exposure to heat and moisture,
which means less degradation of sensitive components in the extract and residual meal.
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Decreased oxidation. No oxygen in the process means there is less oxidation of the oil or extract.
Despite its clear advantages and popular use in food products, conventional SFE has not made
the transition to the larger-volume oilseeds, primarily due to operating costs in comparison to
commercial-scale solvent extraction plants. See our Technology section
for on how MOR has developed systems that change economics of SFE, allowing the oilseed
extraction industry to reap these benefits on commodity products.
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