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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.
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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.
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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. Call us with your specific needs and we will prepare a custom quote.

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