WO2020231970A1

WO2020231970A1 - Method for winterized cannabis oleoresin

Info

Publication number: WO2020231970A1
Application number: PCT/US2020/032435
Authority: WO
Inventors: Nicholas Tennant
Original assignee: Precision Extraction Solutions
Priority date: 2019-05-16
Filing date: 2020-05-12
Publication date: 2020-11-19

Abstract

A method for producing a winterized cannabis oleoresin includes providing a crude cannabis extract from cannabis bio-material by either a liquid alkane-based solvent or supercritical carbon dioxide, the crude cannabis extract contains at least cannabinoids and lipids, combining the crude cannabis extract with methanol to produce a crude winterized solution, the lipids precipitating out of the crude winterized solution, filtering the crude winterized solution to remove the lipids and produce a winterized extract solution as the filtrate, and removing the methanol from the winterized extract solution to produce a winterized cannabis oleoresin.

Description

METHOD FOR WINTERIZED CANNABIS OLEORESIN

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to United States Provisional Application No. 62/849,016 filed on May 16, 2019.

BACKGROUND

[0002] Winterization in general is a process by which a crude botanical extract is purified. More specifically, in addition to compounds of interest, such extracts contain undesired“impurity” compounds that, if not removed, may diminish the quality, utility, value, etc. of the compounds of interest. Crude cannabis extracts contain cannabinoids and other compounds of interest, as well as undesired compounds of lipids and waxes. Winterization is used in the cannabis industry to separate nonpolar compounds such as the lipids and waxes from the cannabinoids and other compounds of interest.

[0003] Winterization of cannabis crude oil can be conducted in ethanol at an extreme low temperature (e.g., -76°F) for a relatively lengthy period of time. The low temperature is necessary to cause precipitation of the lipids and waxes. The temperature processing window in which this is conducted is limited. Substantially colder temperatures may provide better precipitation but insufficient dissolution of the compounds of interest. Substantially warmer temperatures result in unacceptable dissolution of impurity compounds and poor precipitation. Therefore, the current paradigm for winterization of crude cannabis oil requires processing within a limited temperature window in order to obtain acceptable purification levels.

SUMMARY

[0004] A method for producing a winterized cannabis oleoresin according to an example of the present disclosure includes providing a crude cannabis extract from cannabis bio-material by either a liquid alkane-based solvent or supercritical carbon dioxide. The crude cannabis extract contains at least cannabinoids and lipids, combining the crude cannabis extract with methanol to produce a crude winterized solution. The lipids precipitate out of the crude winterized solution, filtering the crude winterized solution to remove the lipids and produce a winterized extract solution as the filtrate, and remove the methanol from the winterized extract solution to produce a winterized cannabis oleoresin. [0005] In a further embodiment of any of the foregoing embodiments, in the combining, the crude cannabis extract and the methanol are both at a temperature of 50°F to 90°F

[0006] In a further embodiment of any of the foregoing embodiments, the providing of the crude cannabis extract includes combining the cannabis bio-material and the liquid alkane-based solvent to provide a crude cannabis mixture, followed by removing the liquid alkane-based solvent from the crude cannabis mixture to produce the crude cannabis extract.

[0007] In a further embodiment of any of the foregoing embodiments, the liquid alkane-based solvent includes n-heptane.

[0008] In a further embodiment of any of the foregoing embodiments, the liquid alkane-based solvent consists of, by volume percentage, at least 95% of n- heptane.

[0009] The method as recited in claim 1, including maintaining the crude winterized solution at 50°F to 90°F for a dwell time of 1 minute to 24 hours, the dwell time ending at initiation of the filtering of the crude winterized solution.

[0010] In a further embodiment of any of the foregoing embodiments, the dwell time is 1 minute to about 8 hours.

[0011] In a further embodiment of any of the foregoing embodiments, the providing of the crude cannabis extract includes combining the cannabis bio-material and the supercritical carbon dioxide to provide a crude cannabis mixture, followed by removing the supercritical carbon dioxide from the crude cannabis mixture to produce the crude cannabis extract.

[0012] In a further embodiment of any of the foregoing embodiments, the crude cannabis extract has a relative concentration of chlorophyll to cannabinoids, as by units of mass per unit volume, of 0.01 or less.

[0013] In a further embodiment of any of the foregoing embodiments, the crude cannabis extract has a relative concentration of chlorophyll to cannabinoids, as by units of mass per unit volume, of 0.005 or less.

[0014] In a further embodiment of any of the foregoing embodiments, the winterized cannabis oleoresin has a relative concentration of chlorophyll to cannabinoids, as by units of mass per unit volume, of 0.01 or less.

[0015] A method for producing a winterized cannabis oleoresin according to an example of the present disclosure includes combining n-hexane and cannabis bio-material to provide a crude cannabis mixture. The n- heptane dissolves at least cannabinoids and lipids from the cannabis bio-material, removes the n-heptane from the crude cannabis mixture to produce a crude cannabis extract that contains at least the cannabinoids and lipids, and combines the crude cannabis extract with methanol to produce a crude winterized solution. The lipids precipitate out of the crude winterized solution, filtering the crude winterized solution to remove the lipids and produce a winterized extract solution as the filtrate, and removes the methanol from the winterized extract solution to produce a winterized cannabis oleoresin.

[0016] In a further embodiment of any of the foregoing embodiments, in the combining, the crude cannabis extract and the methanol are both at a temperature of 50°F to 90°F.

[0017] In a further embodiment of any of the foregoing embodiments, in the combining, the crude cannabis extract and the methanol are both at a temperature of no less than 34°F.

[0018] A composition of matter of a crude cannabis extract, or a winterized cannabis oleoresin produced from the crude cannabis extract according to an example of the present disclosure includes chlorophyll and cannabinoids, with a relative concentration of chlorophyll to cannabinoids, as by units of mass per unit volume, of 0.01 or less.

[0019] In a further embodiment of any of the foregoing embodiments, the relative concentration is 0.005 or less.

[0020] In a further embodiment of any of the foregoing embodiments, the cannabinoids are based on a combined amount of CBD, CBDA, CBGA, THC, CBC, and THCA.

DETAILED DESCRIPTION

[0021] As discussed above, practice for winterization of crude cannabis oil requires processing within a limited low temperature window in order to obtain acceptable purification levels. The method described herein, however, utilizes a different approach that permits winterization to be conducted without chilling to low temperatures. For example, winterization may be conducted at refrigeration temperatures or above, preferably at room temperature.

[0022] The method first includes providing a crude cannabis extract. The crude cannabis extract may be provided as a pre-prepared extract or by performing an extraction proximal in time to the winterizing discussed below. The crude cannabis extract is provided by an extraction from cannabis biomaterial. The cannabis biomaterial is, or is a product of, cannabis plants (also known as C. sativa). The crude cannabis extract is provided by extraction using either a liquid alkane-based solvent or supercritical carbon dioxide, both of which are nonpolar solvents. [0023] The following example extraction is based on liquid alkane-based solvent, but it is to be understood that supercritical carbon dioxide can be substituted. The extraction is performed in one or more vessels that are sized for the amount of crude cannabis extract that is to be produced. For supercritical carbon dioxide, the vessel or vessels are configured with ports or the like for introducing carbon dioxide and controlling pressure and temperature. The extraction is not particularly limited in quantity and may be scaled for the desired amount of crude cannabis extract.

[0024] The cannabis biomaterial is mixed with the liquid alkane -based solvent to provide an extraction mixture. The liquid alkane-based solvent may be liquid at the ambient conditions, or condensed and provided as a liquid. The liquid alkane-based solvent serves to dissolve nonpolar compounds from the cannabis biomaterial. The dissolved nonpolar compounds include at least cannabinoids and lipids from the cannabis biomaterial. The extraction may be conducted for a selected time period in order to extract a desired yield from the cannabis biomaterial. In general, the extraction time period is from one second to one or more days. In examples, the cannabis biomaterial is kept in contact with the extraction solvent for no more than 30 minutes, although shorter or longer soak times are effective. For the liquid alkane-based solvent no heating or chilling of the extraction mixture is required for extraction, which reduces costs and energy expenditures, although the method herein does not preclude extraction under chilled or heated conditions.

[0025] In one example, the liquid alkane-based solvent includes n-heptane. For instance, the liquid alkane-based solvent is, by volume percentage, a majority n-heptane. To avoid dissolution of undesired compounds, however, the liquid alkane-based solvent is substantially free of polar solvent. In one example, the liquid alkane-based solvent is substantially pure n-heptane, such as a liquid alkane-based solvent that has, by volume percentage, at least 95% of n-heptane. It is also contemplated that other liquid alkanes be used, either alone or in combination with n-heptane. For example, such alkanes include propane, butane, pentane, hexane, petroleum ether, octane, nonane, etc. The n-heptane is preferred due to its low vapor pressure at room temperature relative to lower molecular weight alkanes, as well as the ease of solvent recovery compared to higher molecular weight alkanes.

[0026] The degree to which the selected liquid alkane-based solvent extracts/dissolves compounds from the cannabis biomaterial may be adjusted by the extraction time and/or temperature. It is expected that there will be some variance in dissolution that is dependent on the type of cannabis biomaterial and the selected liquid alkane-based solvent, time, and temperature. Such variance will not preclude practice of the method. Given this disclosure, those of ordinary skill in the field will readily be able to optimize dissolution of their selected cannabis biomaterial with respect to selection of a liquid alkane-based solvent, time, and temperature. In general, however, heating and times longer than several minutes are not required, and it is expected that the crude cannabis solution will contain, by weight, from approximately 1% to 3% of cannabinoid.

[0027] The liquid alkane-based solvent is then removed from the extraction mixture. The technique for removal is not particularly limited and may include natural evaporation, evaporation by heating, evaporation by vacuum, or a combination of these or similar techniques. In one example, the removal is conducted in a rotary evaporator. The removal of the liquid alkane-based solvent leaves a concentrated crude oleoresin that contains at least the cannabinoids and lipids. The crude oleoresin may retain a remainder amount of the liquid alkane-based solvent. For example, the liquid alkane-based solvent is evaporated such that the crude oleoresin has the consistency of a viscous oil.

[0028] Extractions using other solvents such as ethanol are useful but extract relatively high amounts of undesired compounds from the cannabis biomaterial. One such undesired compound is chlorophyll. It has been challenging, however, to extract desired levels of cannabinoids and other compounds of interest without also extracting chlorophyll. In this regard, the liquid alkane-based solvent is more selective than ethanol and extracts cannabinoids while limiting extraction of chlorophyll. Therefore, the extract and final winterized cannabis oleoresin can be produced with higher purity than previously available by ethanol.

[0029] An experiment was conducted and demonstrates the selectivity of an exemplary liquid alkane-based solvent, n-heptane. Other liquid alkane-based solvents and supercritical carbon dioxide are expected to behave similarly. Extractions were conducted with methanol, ethanol, and n-heptane. The cannabis biomaterial used for each was of substantially equal character. For the experiment, each sample was prepared with 6oo milligrams of cannabis biomass that was suspended in 4.2 mL solvent and placed in a room temperature sonicating bath for 10 minutes. The suspensions were then filtered through 0.2 um syringe filters and the solvent was replaced with ethanol for acquiring the UV/Vis spectrum data to determine the amounts of chlorophyll that were extracted. The cannabinoid content was taken by high performance liquid chromatography and was based on the combined amount of cannabidiol (CBD), cannabidiolic acid (CBDA), cannabigerolic acid (CBGA), tetrahydrocannabinol (THC), cannabichromine (CBC), and tetrahydrocannabinolic acid (THCA). A selectivity factor was then determined as a ratio of cannabinoid to chlorophyll (based on units of nanograms per microliter or equivalent units). The methanol extraction yielded a selectivity factor of 14; the ethanol extraction yielded a selectivity factor of 26; and the n-heptane yielded a selectivity factor of 377. The results indicate that n-heptane has a strong selectivity for cannabinoids over chlorophyll. Moreover, the n-heptane extracted a lower gross amount of chlorophyll by a factor of more than 25X based on unit volume of extracted crude cannabis oil in comparison to methanol and ethanol.

[0030] The inverse of the selectivity factor represents the relative concentration between the chlorophyll and the cannabinoids in the crude cannabis extract (and thus also in the winterized cannabis oleoresin). In examples herein, the relative concentration is 0.01 or less. In further examples, the relative concentration is 0.005 or less, for example 0.003 or less. Total elimination of chlorophyll is not expected, and the relative concentration therefore may be limited to approximately 0.001.

[0031] The next step in the method is a winterization step. The winterization is the removal of lipids, waxes, and other nonpolar compounds from the crude cannabis extract. The winterization is conducted by combining the crude cannabis extract with methanol to produce a crude winterized emulsion. The combining is performed in one or more vessels that are sized for the amount of crude cannabis extract that is being processed. The methanol causes the lipids, waxes, and other nonpolar compounds to precipitate out of the crude winterized emulsion as solids or semi-solids. The crude winterized emulsion may be agitated, such as by stirring, to facilitate precipitation.

[0032] The precipitation occurs relatively rapidly. Therefore, the winterizing step can be conducted with a short dwell time before the next step of filtering. For example, the crude winterized emulsion is maintained for a dwell time of approximately 1 minute to 24 hours (as measured from the combining of the crude cannabis extract up to initiation of filtering of the crude winterized solution). In further examples, a dwell time of 1 minute to 8 hours may be useful. Dwell times of even longer than 24 could be used, although there may be diminishing precipitation.

[0033] Unlike prior processes that require chilling to deep-freeze temperatures, the winterization of the present method does not require deep-freezing temperatures. For example the crude cannabis extract and methanol are at refrigeration temperatures or above, which herein is considered to be above 34°F. More typically, however, the temperatures of the crude cannabis extract and the methanol are above 50°F, for example from 55°F to 90°F. As no heating or chilling is required, implementation of the present process may facilitate reductions in costs and energy expenditures in comparison to methods that require chilling or heating. [0034] The crude winterized emulsion is then filtered to remove the precipitated lipids, waxes, and other nonpolar compounds to thereby produce a winterized extract emulsion as the filtrate. The filtering is not particularly limited. For example the filtering is performed by vacuum filtration through 8 um filter paper in a Buchner funnel. Filtration through industrial apparatuses such as candle filters or filter presses are also effective.

After filtering, the methanol is removed from the winterized extract emulsion to produce a winterized cannabis oleoresin. As above, the technique for removal is not particularly limited and may include natural evaporation, evaporation by heating, evaporation by vacuum, or a combination of these or similar techniques. In one example, the removal is conducted in a rotary evaporator. The following example demonstrates further non-limiting aspects of the disclosure.

[0035] EXAMPLE:

[0036] Hemp was extracted with n-heptane using a closed loop extraction system (X10 MSE, Precision Extraction Solutions). The miscella was reduced to a thick oleoresin via rotary evaporation. The oleoresin was mixed with methanol in a round bottom flask, and the resulting mixture was stirred until a uniform emulsion formed. At this point the stir bar was removed and the emulsion was separated via vacuum filtration. The weight of the solids collected represented 11% of the mass of oleoresin which was winterized.

[0037] Although a combination of features is shown in the illustrated examples, not all of them need to be combined to realize the benefits of various embodiments of this disclosure. In other words, a system designed according to an embodiment of this disclosure will not necessarily include all of the features shown in any one of the Figures or all of the portions schematically shown in the Figures. Moreover, selected features of one example embodiment may be combined with selected features of other example embodiments.

[0038] The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from this disclosure. The scope of legal protection given to this disclosure can only be determined by studying the following claims.

Claims

CLAIMS What is claimed is:

1. A method for producing a winterized cannabis oleoresin, comprising:

providing a crude cannabis extract from cannabis bio-material by either a liquid alkane- based solvent or supercritical carbon dioxide, the crude cannabis extract contains at least cannabinoids and lipids;

combining the crude cannabis extract with methanol to produce a crude winterized solution, the lipids precipitating out of the crude winterized solution;

filtering the crude winterized solution to remove the lipids and produce a winterized extract solution as the filtrate; and

removing the methanol from the winterized extract solution to produce a winterized cannabis oleoresin.

2. The method as recited in claim 1, wherein in the combining, the crude cannabis extract and the methanol are both at a temperature of 50°F to 90°F

3. The method as recited in claim 1, wherein the providing of the crude cannabis extract includes combining the cannabis bio-material and the liquid alkane-based solvent to provide a crude cannabis mixture, followed by removing the liquid alkane-based solvent from the crude cannabis mixture to produce the crude cannabis extract.

4. The method as recited in claim 3, wherein the liquid alkane-based solvent includes n- heptane.

5. The method as recited in claim 4, wherein the liquid alkane -based solvent consists of, by volume percentage, at least 95% of n- heptane.

6. The method as recited in claim 1, including maintaining the crude winterized solution at 50°F to 90°F for a dwell time of 1 minute to 24 hours, the dwell time ending at initiation of the filtering of the crude winterized solution.

7. The method as recited in claim 6, wherein the dwell time is 1 minute to about 8 hours.

8. The method as recited in claim 1, wherein the providing of the crude cannabis extract includes combining the cannabis bio-material and the supercritical carbon dioxide to provide a crude cannabis mixture, followed by removing the supercritical carbon dioxide from the crude cannabis mixture to produce the crude cannabis extract.

9. The method as recited in claim 1, wherein the crude cannabis extract has a relative concentration of chlorophyll to cannabinoids, as by units of mass per unit volume, of 0.01 or less.

10. The method as recited in claim 1, wherein the crude cannabis extract has a relative concentration of chlorophyll to cannabinoids, as by units of mass per unit volume, of 0.005 or less.

11. The winterized cannabis oleoresin as produced from the method of claim 1 , and having a relative concentration of chlorophyll to cannabinoids, as by units of mass per unit volume, of 0.01 or less.

12. A method for producing a winterized cannabis oleoresin, comprising: combining n-hexane and cannabis bio-material to provide a crude cannabis mixture, the n- heptane dissolving at least cannabinoids and lipids from the cannabis bio-material;

removing the n-heptane from the crude cannabis mixture to produce a crude cannabis extract that contains at least the cannabinoids and lipids;

13. The method as recited in claim 9, wherein in the combining, the crude cannabis extract and the methanol are both at a temperature of 50°F to 90°F.

14. The method as recited in claim 9, wherein in the combining, the crude cannabis extract and the methanol are both at a temperature of no less than 34°F.

15. A composition of matter of a crude cannabis extract, or a winterized cannabis oleoresin produced from the crude cannabis extract, including chlorophyll and cannabinoids, with a relative concentration of chlorophyll to cannabinoids, as by units of mass per unit volume, of 0.01 or less.

16. The composition of matter as recited in claim 15, wherein the relative concentration is 0.005 or less.

17. The composition of matter as recited in claim 15, wherein the cannabinoids are based on a combined amount of CBD, CBDA, CBGA, THC, CBC, and THCA.