Solvent-
There are essentially 3 classes of solvents being marketed for botanical extraction-
- Light Hydrocarbons (Butane, Propane, or a blend)
- Ethanol
- Supercritical CO2
All of the above will successfully separate the soluble oils from the insoluble plant matter, with varying degrees of success. We chose propane as our solvent of choice in 1996. We chose this knowing that our objective was foods, nutraceuticals, and cosmetics. This was our second plant, having built and run a hexane plant previously. We chose propane for many reasons including quality, safety, cost, and yield. Although the primary reason was yield. Propane produces the highest yields at intermediate cost without sacrificing quality.
Yield – Propane – 99% +
Super Critical CO2 – 80-85% est.
Ethanol – 80-85% est.
When you are working with a high value product, a 10-15% yield is significant.
Cost – Comparing the capital and operating costs of these 3 solvents technologies, and without getting into too much detail, the most expensive by far is Super Critical CO2. Propane and ethanol are a distant second and third.
Safety – In a properly designed plant with trained personnel, all 3 are safe. CO2 operates at extreme pressures with a major failure risking suffocation. Propane and ethanol are both flammable although propane dissipates very rapidly.
Quality –
Super Critical CO2 – The main advantage of this process is the ability in certain areas for selective extraction. However, the same post-extraction separations are needed as with the others in the market.
Ethanol – This system will also remove chlorophyll which then must be removed.
Propane – Propane is a non-toxic food safe ingredient that is approved by the FDA. And due to it being normally gaseous, it evaporates easily. It is approved in the EU as a food solvent.