SUPERCRITICAL FLUID AND HIGH PRESSURE SOLVENT EXTRACTION

High pressure extraction is the most effective and efficient way to extract valuable constituents from botanicals. The simplest way to explain this process is that you take the plant material and put it in a pressure vessel and pump a particular liquefied gas or liquid solvent through it at a specific pressure and temperature.

The pressure forces the solvent into the cell walls of the botanical and separates the desired constituent rapidly. The process of separating the extract from the solvent varies from one solvent to another.Eden Labs has conducted in depth studies and trials with all the most important solvents and designed equipment which can utilize all of them. Here is our summary of findings. Following the summary you will find starting prices for units that will utilize the solvents of your choice. Keep in mind that we can design units that utilize a variety of solvents if you choose that option. Eden Labs can provide consulting and sampling to help you. Carbon Dioxide CO2- Carbon Dioxide is the king of extraction solvents for botanicals.  It is an all natural product which leaves no toxic residues behind.   Its extraction properties can be widely and precisely manipulated with subtle changes in pressure and temperature.

 It is inexpensive and widely available. The capability of processing botanicals skillfully with CO2 gives a company an added edge of status and prestige.

There are two basic types of CO2 extraction. Low pressure cold extraction involves chilling CO2 to between 35-55 degrees F and pumping it through the plant material at between 800-1,500 psi. Supercritical Fluid extraction involves heating the CO2 to above 87F and pumping it above 1,100 psi. Usually this work is done between 6,000-10,000 psi. Supercritical Fluid CO2 can best be described as a dense fog whereas the first method described uses the CO2 in a dense liquid state.

Low pressure CO2 is often the best method for producing high quality botanical extracts. CO2 has a high loading rate in this state meaning that you will have to pump many volumes of CO2 through a given volume of botanical. The loading rate is typically 10-40 volumes. For this reason, it is important to have a high flow pump and a CO2 recycle system unless wasting high volumes of CO2 is not a concern.

Supercritical CO2 has a much faster loading rate 2-10 volumes and a wide range of uses. The downside is that some extracts can be damaged by either the high pressure breaking molecular ring structures or the fact that moisture in the botanicals can react with the CO2 and form carbonic acid which can turn some oils rancid. Following proper procedures can avoid these problems.

Eden Labs has pioneered a method of fractionating supercritical extracts so that constituents with different molecular weights fall out in to different separators during extraction. Below is a picture of a supercritical unit with this feature we manufactured at a research lab at Loyalist College in Belleville, Ontario.

Ethyl Alcohol or Ethanol- The majority of extracts are made with ethanol and it is the most widely accepted method in use. There are many ways of extracting with alcohol but high pressure is the best. It is faster, does a more thorough job and requires less alcohol per volume of herb than other methods. It is a good idea to purchase vacuum distillation equipment with your high pressure alcohol extractor so that you can remove alcohol from the extract. High pressure alcohol equipment can also utilize compressed water which is very effective in many cases.

Propane- There is a little known school of thought in the natural products industry which believes that propane is the ultimate solvent for extracting botanicals. Eden Labs has tested this theory thoroughly and we have come to the conclusion that there is something to it. Although propane cannot be as widely manipulated through temp. and pressure as CO2, it produces very similar results, sometimes better. It has an amazingly small loading ratio 1-4 volumes and it can be recovered quickly. This means much faster production times. It leaves no toxic residues and it is an all natural, organic solvent. The material data safety sheet, MSDS, says it is harmless except for the fact that is flammable. Because it works at relatively low pressures, 80-150 psi, the technology costs much less than a full supercritical CO2 system and can be very competitive in terms of quality and speed of production.

The downsides to propane is that it is highly flammable so precautions such as sparkless rooms with powerful ventilation are a must. The fact that is is not widely understood or accepted can also be an issue.

Butane/IsoButane- In some cases where propane doesn't do the job, butane works better. It has all the pros and cons of propane and requires identical equipment for utilization.

Dimethyl Ether- This is the ultimate extraction solvent.  It strips everything out of plant material almost instantly.  All of the same equipment and precautions as propane should be used as it is also highly flammable.  Has a vapor pressure slightly above propane.

R134a and other refrigerant gases- There has been a lot of talk in recent years about using R134a and related gases in natural product isolation. Our experience has shown that R134a has similar extraction properties to low pressure CO2. It works better than anything for isolating fragrance and perfume essences.

The downsides are that it becomes highly toxic if overheated and there a number of conflicting patent and intellectual property claims regarding its use.

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