Technical field of the invention

The present invention relates to a method for extracting cannabinoids from cannabis plant material using an extractor with super critical carbon dioxide.

Background of the invention

Biodynamic growth of Cannabis Sativa is of increased interest. Parts of the plant are already being used commercially. The seeds are used for dietary

supplements, either as oil or as peeled off seeds. The stems that consist of fibers are used for paper or ropes.

Cannabinoids are unique molecules that can only be found in subspecies of hemp (cannabis). Cannabis (hemp), together with the genus Humulus (hops), belongs to the family of Cannabinaceae, with hops, for instance, not containing any cannabinoids. The cannabinoids are divided into three groups:

endocannabinoids that are naturally produced within our body,

phytocannabinoids that are found in cannabis, and synthetic cannabinoids.

There is currently an increasing interest to utilize the cannabinoids for purposes such as antibiotics, anti-inflammatory drugs, analgesics, and antispasticity drugs.

The leaves of cannabis furthermore comprise a unique composition of proteins, which contain all the essential amino acids for humans as well as for e.g. pigs.

The cannabis leaves are also known to stimulate appetite. Hence, there is a possibility of utilizing hemp leaves for dietary supplements and/or animal feed. However, the presence of the cannabinoids in the leaves is blocking this possibility. Summary of the invention

This invention provides a method for extracting cannabinoids from cannabis plant material. The present invention allows for complete extraction of

cannabinoids from cannabis plant material, thereby making it possible to utilize e.g. hemp leaves for dietary supplements and/or animal feed.

A first aspect relates to a process for extracting cannabinoids from cannabis plant material comprising the steps of:

a) providing a cannabis plant material, such as leaves and/or flowers, with a water content of at most 60% w/w, preferably at most 10% w/w;

b) in a pressure tank, subjecting the cannabis plant material to a first extraction step with a one-phase solvent system comprising supercritical carbon dioxide and optionally a non-polar co-solvent, and performed at a temperature of about 10-70 degrees Celsius;

c) collecting a first liquid extract from the pressure tank;

d) collecting/removing a solid product from the pressure tank comprising a cannabis plant fiber material with a reduced content of cannabinoids;

e) dissolving the first liquid extract from the pressure tank in ethanol, subjecting the solution to a temperature of -20 degrees Celsius or lower, filtrating the solution to remove precipitated matter, and removing the ethanol to collect a second liquid extract;

f) optionally, heat treating the second liquid extract at 100-150 degrees Celsius, preferably in an inert atmosphere, to decarboxylate any acid form of the cannabinoids to the neutral form of the cannabinoids;

g) dissolving the second liquid extract, optionally heat treated, in a non-polar solvent;

h) extracting the solubilized second liquid extract with an aqueous basic solution; and collecting the non-polar solvent phase as a third liquid extract; and i) optionally, removing the non-polar solvent to collect the neutral form of the cannabinoids. A second aspect relates to a cannabis plant fiber material with a reduced content of cannabinoids produced by the process according to the present invention, wherein the cannabinoid content, such as the tetrahydrocannabinol content, is 0.05% at the most, and wherein the pressure within the pressure tank during the extraction steps are at least 400 bar.

A third aspect relates to a cannabis plant fiber material with a reduced content of cannabinoids produced by the process according to the present invention, wherein the cannabinoid content, such as the tetrahydrocannabinol content, is

0.05% at the most, and wherein the pressure within the pressure tank during the extraction steps are at most 400 bar.

A fourth aspect relates to a process for extracting cannabinoids from cannabis plant material comprising the steps of:

a) providing a cannabis plant material, such as leaves and/or flowers, with a water content of at most 60% w/w, preferably at most 10% w/w;

b) in a pressure tank, subjecting the cannabis plant material to a first extraction step with a one-phase solvent system comprising supercritical carbon dioxide and optionally a non-polar co-solvent, and performed at a temperature of about

10-70 degrees Celsius;

c) collecting a first liquid extract from the pressure tank;

d) collecting/removing a solid product from the pressure tank comprising a cannabis plant fiber material with a reduced content of cannabinoids;

e) dissolving the first liquid extract from the pressure tank in ethanol, subjecting the solution to a winterization step, filtrating the solution to remove precipitated matter, and removing the ethanol to collect a second liquid extract;

f) optionally, heat treating the second liquid extract at 100-150 degrees Celsius, preferably in an inert atmosphere, to decarboxylate any acid form of the cannabinoids to the neutral form of the cannabinoids;

g) dissolving the second liquid extract, optionally heat treated, in a non-polar solvent selected from pentane, hexane, and mixtures thereof;

h) extracting the solubilized second liquid extract with an aqueous basic solution; and collecting the non-polar solvent phase as a third liquid extract; and i) optionally, removing the non-polar solvent to collect the neutral form of the cannabinoids.

Detailed description of the invention

Hemp is the commonly used name for plants of the cannabis genus. Several subspecies exist, but they are often all mentioned as Cannabis Sativa L, where L is short for Linnaeus, who was the first man to name the species. The two commonly known subspecies are Cannabis Sativa subsp. Sativa and Cannabis Sativa subsp. Indica.

The subspecies Sativa has an origin north of latitude 30° N and is primarily a fiber type and Indica has the origin south of 30° N and is primarily a drug type.

The chemical and morphological properties of the subspecies of Cannabis Sativa are environmentally modifiable and can vary depending on the conditions and location, which is why Cannabis Sativa normally refers to all subspecies. So far, 70 different cannabinoids have been identified. The cannabinoids can be divided into the following subclasses:

• Cannabigerol type (CBG)

• Canabichromene type (CBC)

· Cannabidiol type (CBD)

• Tetrahydrocannabinol type (THC)

• Cannabicyclol type (CBL)

• Cannabielsoin type (CBE)

• Cannabinol type (CBN)

· Cannabinodiol type (CBND)

• Cannabitriol type (CBT) • Miscellaneous types

Depending on the composition of cannabinoids, Cannabis Sativa can be categorized as either a fiber type/industrial or a drug type. The content of CBD is in inverse proportions to the content of THC, and depending on the content of these, the type of Cannabis Sativa can be determined.

There are two ways to distinguish between the types; one way based on the proportions of CBD and THC and the other is based on the content of THC in the sample. The industrial type is defined as having a content of THC at maximum 0.2 % in Europe and 0.3 % in Canada. The low content of THC in industrial

Cannabis Sativa makes it impossible to get high from eating or smoking it and it is therefore considered safe. However, pigs may still respond to such

concentrations.

To obtain the label "Industrial Cannabis Sativa", the type has to be analyzed several times with acceptable results to get on the list of approved types. Another way to distinguish the types is to determine the relationship between the two main psychoactive components and CBD as shown below.

X = : ; (1 )

If X is below one, the sample is categorized as a fiber type and if it is above one it is considered a drug type. To determine X either the concentrations or the area in a chromatogram e.g. from HPLC or GC can be used. A first aspect relates to a process for extracting cannabinoids from cannabis plant material comprising the steps of:

a) providing a cannabis plant material, preferably leaves and/or flowers, with a water content of at most 60% w/w, preferably at most 10% w/w;

b) in a pressure tank, subjecting the cannabis plant material to a first extraction step with a one-phase solvent system comprising supercritical carbon dioxide and optionally a non-polar co-solvent, and performed at a temperature of about 10-70 degrees Celsius;

c) collecting a first liquid extract from the pressure tank;

d) collecting/removing a solid product from the pressure tank comprising a cannabis plant fiber material with a reduced content of cannabinoids;

e) dissolving the first liquid extract from the pressure tank in ethanol, subjecting the solution to a temperature of -20 degrees Celsius or lower, filtrating the solution to remove precipitated matter, and removing the ethanol to collect a second liquid extract;

f) optionally, heat treating the second liquid extract at 100-150 degrees Celsius, preferably in an inert atmosphere, to decarboxylate any acid form of the cannabinoids to the neutral form of the cannabinoids;

g) dissolving the second liquid extract, optionally heat treated, in a non-polar solvent;

h) extracting the solubilized second liquid extract with an aqueous basic solution; and collecting the non-polar solvent phase as a third liquid extract; and i) optionally, removing the non-polar solvent to collect the neutral form of the cannabinoids.

A fourth aspect relates to a process for extracting cannabinoids from cannabis plant material comprising the steps of:

a) providing a cannabis plant material, such as leaves and/or flowers, with a water content of at most 60% w/w, preferably at most 10% w/w;

b) in a pressure tank, subjecting the cannabis plant material to a first extraction step with a one-phase solvent system comprising supercritical carbon dioxide and optionally a non-polar co-solvent, and performed at a temperature of about

10-70 degrees Celsius;

c) collecting a first liquid extract from the pressure tank;

d) collecting/removing a solid product from the pressure tank comprising a cannabis plant fiber material with a reduced content of cannabinoids;

e) dissolving the first liquid extract from the pressure tank in ethanol, subjecting the solution to a winterization step, filtrating the solution to remove precipitated matter, and removing the ethanol to collect a second liquid extract;

f) optionally, heat treating the second liquid extract at 100-150 degrees Celsius, preferably in an inert atmosphere, to decarboxylate any acid form of the cannabinoids to the neutral form of the cannabinoids;

g) dissolving the second liquid extract, optionally heat treated, in a non-polar solvent;

h) extracting the solubilized second liquid extract with an aqueous basic solution; and collecting the non-polar solvent phase as a third liquid extract; and i) optionally, removing the non-polar solvent to collect the neutral form of the cannabinoids.

The term "winterization" as used herein refers to a process which involves the chilling of the first liquid extract from the pressure tank in ethanol at temperatures below 0 degrees Celsius, such as -1 12 to -5 degrees Celsius, for removal of amongst others fats and waxes, optionally combined with filtration and/or centrifugation. The first liquid extract is subjected to an ethanolic precipitation to remove a substantial proportion of non-cannabinoid materials, e.g. waxes, wax esters and glycerides, unsaturated fatty acid residues, terpenes, carotenes, and flavonoids. The precipitation is preferably performed at low temperatures of -20 degrees Celsius or lower, such as within the range of -1 12 to -20 degrees

Celsius, e.g. within the range of -1 10 to -25 degrees Celsius, such as within the range of -105 to -30 degrees Celsius, e.g. within the range of -100 to -35 degrees Celsius, such as within the range of -95 to -40 degrees Celsius, e.g. within the range of -90 to -45 degrees Celsius, such as within the range of -85 to -50 degrees Celsius, e.g. within the range of -80 to -55 degrees Celsius, such as within the range of -75 to -60 degrees Celsius, e.g. within the range of -70 to -65 degrees Celsius. The solution is then filtrated to remove precipitated matter, and ethanol is subsequently removed to collect a second liquid extract. The inventors have found that impurities are still present after cold filtration.

Some of the impurities are identified by the inventors as omega-3 and omega-6 fatty acids (GC retention time = 9.82 minutes), and homogentisic acid (GC retention time = 1 1 .64 minutes). The latter one can be potentially dangerous for humans if consumed in large quantities. Hence, if the cannabinoids are to be used for medicinal purposes, a further purification is necessary. Therefore, the inventors have developed a further purification step suitable for large scale production of cannabinoids for medicinal purposes. The second liquid extract is optionally heat treated (1 -2 hours at 1 15-125 degrees Celsius, or at 135-145 degrees Celsius, depending on the cannabis origin/species) to secure that all the cannabinoids are decarboxylated. The second liquid extract is then solubilized in a non-polar solvent; and extracted with an aqueous basic solution. Thereby, the impurities are degraded into water soluble components and will thus be removed from the non-polar solvent phase. The neutral form of the cannabinoids is not susceptible to degradation by this method. The non-polar solvent phase is then collected, and the non-polar solvent is removed (e.g. by evaporation under reduced pressure) to collect the purified neutral form of the cannabinoids.

The term "non-polar" as used herein, represents a solvent, which is relatively inert to proton activity, i.e., not acting as a proton donor. Preferably, the non- polar solvent is selected from the group of saturated hydrocarbons. In the present context, the term "saturated hydrocarbon" refers to any hydrocarbon, which does not contain any carbon-to-carbon double bonds or carbon-to-carbon triple bonds. Examples of saturated hydrocarbons include, but are not limited to pentanes (isopentane, n-pentane, cyclopentane), hexanes (n-hexane, cyclohexane), heptanes (n-heptane, cycloheptane), octanes (n-octane, isooctane), nonanes (n-nonane), decanes, and mixtures thereof. Preferably, the saturated hydrocarbons have a boiling point within the range of 30-180 degrees Celsius, and even more preferably within the range of 30-120 degrees Celsius. In one or more embodiments, the non-polar solvent is selected from the group consisting of isopentane, n-pentane, cyclopentane, n-hexane, cyclohexane, n- heptane, cycloheptane, n-octane, isooctane, and mixtures thereof. Living cannabis leaves contain about 80% w/w water. To perform an efficient extraction, the leaves should be dried, e.g. at 90-105 degrees Celsius, to reduce their water content, since the cannabinoids are not soluble in water. Hence, any water present in the leaves will complicate the extraction process.

In one or more embodiments, the cannabis plant material for use in the present invention should have a water content of at most 60% w/w, such as within the range of 0-55% w/w, e.g. within the range of 1 -50% w/w, such as within the range of 2-45% w/w, e.g. within the range of 3-40% w/w, such as within the range of 4-35% w/w, e.g. within the range of 5-30% w/w, such as within the range of 10-25% w/w, e.g. within the range of 10-20% w/w, preferably at most 10% w/w.

The drying process may to some extend result in decarboxylation of the acid form of the cannabinoids to the neutral form of the cannabinoids.

In one or more embodiments, the cannabis plant material for use in the present invention are subjected to a decarboxylation process prior to the extraction process. A decarboxylation process may comprise the step of heating the cannabis plant material for about 30 minutes at 1 15-125 degrees Celsius, or for about 15 minutes at 135-145 degrees Celsius, depending on the cannabis origin/species. It is crucial that the heating temperature and time is controlled, since the cannabinoids may risk degradation.

Preferably, the cannabis plant material may be triturated/shred/grinded prior to the extraction process to increase the penetration rate of the one-phase solvent system.

There has been an increasing interest for SCF's (Super Critical Fluids) as solvents for a wide variety of processes, due to the ability of using

environmentally friendly solvents and being able to design more selective processes than possible with the use of traditional solvents. SFC's add a new dimension to the process because of their density being easily manipulated, where traditional solvents do not have that possibility. With changes in

temperature, pressure, and composition, the density of the system can be altered. The solvent can therefore have its abilities designed and changed for a given purpose. Supercritical carbon dioxide is mixable with compounds having up to 10 carbon atoms. Compounds with polar groups complicates the process, and it might not be possible at all to extract these compounds with pure carbon dioxide. Often the extraction will take a lot of time, and not all the compounds will be removed. SCF's can be divided into low Tc fluids and high Tc fluids.

Condensable gasses and compounds with low critical temperature are

considered as low Tc fluids; and alcohols, higher alkanes and water are considered as high Tc fluids. An overview of some of the most used SCF's and their critical data is shown in the below table.

The first three in the table are considered as low Tc fluids and the last four are high Tc fluids. There are strong differences in solvent power and selectivity between the two groups. To decide which SCF to use for extraction of cannabinoids from plant material, such as leaf or flowers, of Cannabis Sativa, the nature of the cannabinoids needed to be evaluated.

Cannabis Sativa of the type Fedora 17 has been used for extraction, which is a type that contains a maximum of 0.2 % w/w HTC and then the inverse proportion of CBD (5% w/w). Other cannabinoids are only present in trace amounts. Both THC and CBD are aromatic compounds that consist of carbon, hydrogen and oxygen. Both have the empiric formula C21 H30O2. They are capable of making hydrogen bonds. Carbon dioxide is one of the most used SCF's for extraction. It can be used for non-polar components alone or for polar components with a co-solvent. Carbon dioxide is stabile even at high pressures and temperatures and is rarely reacting with the component that is being extracted. Furthermore, it is easy to recover carbon dioxide at ambient conditions, since it will be in its gas state. Most other solvents will need some kind of unit operation to be recovered, which makes the process much costlier.

Carbon dioxide in supercritical fluid form is used in the present invention, optionally together with a co-solvent, for the extraction of cannabinoids from the cannabis plant material. The co-solvent must be miscible with the supercritical fluid to form a one-phase solvent system. The density of the one-phase solvent system is dependent on the temperature and the pressure within the pressure tank. The correct pressure may be solely obtained by pressurized carbon dioxide, or may partly be adjusted by inert pressurized gasses, such as nitrogen, helium, and argon. In order to obtain total extraction of the cannabinoids from the cannabis plant material, the inventors have found that the optimal density of the one-phase solvent system is at least 750 kg per cubic meter. The temperature should be within the range of 30-60 degrees Celsius to avoid degradation of the cannabinoids during the extraction process.

In one or more embodiments, the extraction step is performed at a temperature of about 10-70 degrees Celsius, such as within the range of 15-65 degrees Celsius, e.g. within the range of 20-60 degrees Celsius, such as within the range of 25-55 degrees Celsius, e.g. within the range of 30-50 degrees Celsius, such as within the range of 35-45 degrees Celsius, e.g. within the range of 40-45 degrees Celsius. In one or more embodiments, the extraction step is performed at a temperature of about 30-60 degrees Celsius, such as within the range of 32-58 degrees Celsius, e.g. within the range of 34-56 degrees Celsius, such as within the range of 36-54 degrees Celsius, e.g. within the range of 38-52 degrees Celsius, such as within the range of 40-50 degrees Celsius, e.g. within the range of 42-48 degrees Celsius, such as within the range of 44-46 degrees Celsius.

In one or more embodiments, the pressure within the pressure tank during the extraction steps are at least 74 bar, such as within the range of 75-1000 bar, e.g with n the range of 80-995 bar, such as within the range of 90-990 bar, e.g. with n the range of 100-985 bar, such as within the range of 1 10-980 bar, e g- with n the range of 120-975 bar, such as within the range of 130-970 bar, e g- with n the range of 140-965 bar, such as within the range of 150-960 bar, e g- with n the range of 160-955 bar, such as within the range of 170-950 bar, e g- with n the range of 180-925 bar, such as within the range of 190-900 bar, e g- with n the range of 200-875 bar, such as within the range of 225-850 bar, e g- with n the range of 250-825 bar, such as within the range of 275-800 bar, e g- with n the range of 300-750 bar, such as within the range of 325-700 bar, e g- with n the range of 350-650 bar, such as within the range of 375-600 bar, e g- with n the range of 400-550 bar, such as within the range of 425-525 bar, e g- with n the range of 450-500 bar.

In one or more embodiments, the pressure within the pressure tank during the extraction steps are at least 400 bar. Such pressure will result in denaturation of the proteins within the plant material, such as the leaves.

In one or more embodiments, the pressure within the pressure tank during the extraction steps are at most 400 bar. Such pressure will avoid denaturation of the proteins within the plant material, such as the leaves. In one or more embodiments, the density of the one-phase solvent system is within the range of 750-1000 kg per cubic meter, e.g. within the range of 765-985 kg per cubic meter, such as within the range of 790-970 kg per cubic meter, e.g. within the range of 805-955 kg per cubic meter, such as within the range of 820- 940 kg per cubic meter, e.g. within the range of 835-905 kg per cubic meter, such as within the range of 850-890 kg per cubic meter, e.g. within the range of 865-875 kg per cubic meter.

In one or more embodiments, the process further comprises the steps of:

b2a) injecting a one-phase solvent system comprising supercritical carbon dioxide and optionally a non-polar co-solvent into the pressure tank, and subjecting the cannabis plant material to a second extraction step at a

temperature of about 30-60 degrees Celsius; or

b2b) in situ forming a one-phase solvent system within the pressure tank by injecting carbon dioxide and a co-solvent into the pressure tank; and subjecting the cannabis plant material to a second extraction step at a temperature of about 30-60 degrees Celsius

c2) collecting/removing a secondary first liquid extract from the pressure tank; c3) optionally, repeating steps b2) to c2).

In one or more embodiments, the first and/or second and/or further extraction step is performed for at least 30 minutes before collecting/removing a liquid extract from the pressure tank. In one or more embodiments, after performing the first extraction step, the injection of the carbon dioxide and optionally the co-solvent into the pressure tank is performed simultaneously with collecting/removing a liquid extract from the pressure tank. In one or more embodiments, the injection of the carbon dioxide and optionally the co-solvent is performed into the bottom of the pressure tank, while the collection/removal of a liquid extract is performed in the top of the pressure tank.

In one or more embodiments, the co-solvent is present in an amount of from about 0 to 20 weight % of the total weight of the one-phase solvent system being used, such as within the range of 1 -18 wt.%, e.g. within the range of 2-16 wt.%, such as within the range of 3-14 wt.%, e.g. within the range of 4-12 wt.%, such as within the range of 5-10 wt.%, e.g. within the range of 6-9 wt.%, such as within the range of 7-8 wt.% of the total weight of the one-phase solvent system being used.

In one or more embodiments, the one-phase solvent system further comprises a co-solvent selected from the group consisting of pentane, cyclopentane, hexane, cyclohexane, heptane, octane, benzene, toluene, and mixtures thereof. A second aspect relates to a cannabis plant material fiber material with a reduced content of cannabinoids produced by the process according to the present invention, wherein the tetrahydrocannabinol content is 0.05% w/w at the most. A second aspect relates to a cannabis plant fiber material with a reduced content of cannabinoids produced by the process according to the present invention, wherein the cannabinoid content, such as the tetrahydrocannabinol content, is 0.05% at the most, and wherein the pressure within the pressure tank during the extraction steps are at least 400 bar. Such pressure will result in denaturation of the proteins within the plant material, such as the leaves, and make the proteins more prone to enzymatic degradation.

A third aspect relates to a cannabis plant fiber material with a reduced content of cannabinoids produced by the process according to the present invention, wherein the cannabinoid content, such as the tetrahydrocannabinol content, is

0.05% at the most, and wherein the pressure within the pressure tank during the extraction steps are at most 400 bar. Such pressure will avoid denaturation of the proteins within the plant material, such as the leaves, and make the proteins more resistant to enzymatic degradation (increased shelf life). In one or more embodiments, the tetrahydrocannabinol content is within the range of 0-0.05% w/w, e.g. within the range of 0.001 -0.045% w/w, such as within the range of 0.002-0.040% w/w, e.g. within the range of 0.003-0.035% w/w, such as within the range of 0.004-0.030% w/w, e.g. within the range of 0.005-0.025% w/w, such as within the range of 0.010-0.020% w/w, preferably within the range of 0-0.010 % w/w.

In one or more embodiments, the cannabinoid content is within the range of 0- 0.05% w/w, e.g. within the range of 0.001 -0.045% w/w, such as within the range of 0.002-0.040% w/w, e.g. within the range of 0.003-0.035% w/w, such as within the range of 0.004-0.030% w/w, e.g. within the range of 0.005-0.025% w/w, such as within the range of 0.010-0.020% w/w, preferably within the range of 0-0.010 % w/w.

It should be noted that embodiments and features described in the context of one of the aspects of the present invention also apply to the other aspects of the invention.

The invention will now be described in further details in the following non-limiting examples.

Examples

Proof of concept

The process starts from the CO2 bottle 1 (Figure 1 ) with a dip tube, ensuring that the CO2 drawn will be in liquid state. There is an emergency cut off valve 2 in front of the CO2, which can be used to switch the liquid flow on and off instantly. After the cut off valve 2, the liquid CO2 flows into a pump 3, which pressurizes the liquid CO2 to the desired pressure. A pressure sensor 10 is installed in the pump to indicate to which pressure the liquid has been pressurized to.

After the pump, the fluid then flows through a valve 4, which can be used to isolate the extraction unit 5 from the pump.

The extraction unit 5 is a steel vessel of known volume, which is filled with ground cannabis plant material. A heating jacket 6 is positioned around the extraction unit 5 to turn the liquid CO2 into a supercritical fluid (SC-CO2), and use its unique properties in order to extract the cannabinoids from the cannabis plant material. A thermocouple 1 1 is inserted into the wall of the extraction unit 5 in order to monitor the temperature inside of the steel vessel. A pressure relieve valve 7 is connected to the extraction unit 5 to be able to degas the unit. No extract collection is carried out with this valve.

The saturated SC-CO2 flows out of the extraction unit 5 into a heater 8 and through a glove valve 9 into a collection vessel (not shown). The heater 8 is used to counter the Joule-Thompson expansion effect, which would turn the SC-CO2 solid upon expansion to atmospheric pressure. A thermocouple 12 monitors the temperature of the heater 8. A volumetric flowmeter 13 monitors the CO2 flow, from which it's possible to determine the flow rate of CO2.

Purification Process

After the extraction, the steel vessel is emptied, and the cannabis plant fiber material with a reduced content of cannabinoids is removed. The extract

(preferably heated to 30-50 degrees Celsius) is dissolved in ethanol and cooled to about 4 degrees Celsius for about 12 hours to let the insoluble part of the extract precipitate. The extract is then filtrated, and the liquid part is collected and cooled to about -20 degrees Celsius. The reason for cooling in two steps, is to avoid solidification of the extract at such low temperatures. Most of the extract consists of linoleic acids, which freeze at about -5 degrees Celsius. At about -90 degrees Celsius, the solubility of linoleic acid in ethanol is zero. Hence, one way of purification of the extract is to use extreme winterization. If this method is to be used, the lower the final temperature is, the more winterization steps need to be undertaken.

After the 2nd winterization step, the ethanol is removed from the extract by evaporation. At this stage the cannabinoid concentration in the extract is about

30-40% w/w.

After evaporation, the extract is heat treated (e.g. oil bath) to 1 10-140 degrees Celsius, preferably in an inert atmosphere, in order for the cannabinoids to decarboxylate. The extract is then cooled, and subsequently mixed with a short- chain saturated hydrocarbon, i.e. pentane. The final mixture is arranged to contain about 6-10% w/w of extract in pentane.

An aqueous solution of NaOH is prepared. The concentration shall be

somewhere in between 0.25 and 0.3 mol/L; however, the method is not limited to these concentrations. Lower concentrations decrease the saponification efficiency, and with concentrations higher than about 0.6 mol/L, the cannabinoid will degrade.

The extract solution and the aqueous NaOH solutions are mixed together in a 50:50 proportion together, and shaken rigorously for 2 minutes. The mixture is then centrifuged in order to separate the polar from non-polar phases.

Depending on the outcome of the centrifugation, sometimes the non-polar solution might have some of the saponified fatty acids in the non-polar phase. This problem can be solved by using a solution of NaCI in water. The non-polar and polar phases are mixed and separated. The separation process is quite efficient and can be done via a separation funnel, however for complete separation of phases centrifugation is still recommended.

After the phases have been separated, the non-polar phase can be heated up to remove the solvent. The resulting product should have a concentration of cannabinoid of about 85-90%, with the remaining lipids constituting no more than 10% of the product.