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Water Today Title July 18, 2019

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Update 2019/3/28
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MICROWAVE EXTRACTION -Q&A Dr. Jocelyn Paré



In September 2017, Organigram, an Atlantic Canada licensed producer of medical cannabis, entered into a memorandum of understanding with the New Brunswick Innovation Research Chair in Medical Technologies (NBIRC), to jointly develop an industry leading method of microwave extraction of cannabinoid extracts from marijuana plants. The project is headed by Dr. Jocelyn Paré, a researcher at the Atlantic Cancer Research Institute (ACRI) whose current focus is in the use of microwaves for the selective ablation of tumours. WT sent Dr. Paré a series of questions, our questions and his answers can be found below.

Q&A



WT - Can you elaborate on the work you are doing with OrganiGram to develop an industry leading method of microwave extraction of cannabinoid extracts from marijuana plants. What are the advantages of this process as compared to others? Is the microwave method still in R&D?

Dr. Paré - First, let me clarify that I cannot refer to anything that is specific to OrganiGram's activities, whether R&D or industrial. You should direct those questions to them.

I can, however, comment over the rationale for anyone to look into microwave-assisted extraction as a technique for the production of cannabinoid extracts. Microwave-assisted extraction was originally developed back in 1986 in the laboratories of Agriculture Canada (now called Agriculture and Agri-Food Canada). I had the privilege of heading these activities that led to a number of patents that served as the basis of numerous applications. I was the main inventor on these patents and developed a number of applications that are still widely used today, principally in the laboratory.

In basically all applications developers to date - literally more than 100 feedstock - microwave-assisted extraction offered unparalleled advantages in terms of extraction efficiency, selectivity, energy reduction, solvent usage reduction, etc. These advantages still apply today and there is no reason to believe that it would not apply to cannabis as a feedstock. The real challenge was and remain the lack of critical mass in terms of experts in that area. Experts than can do the extrapolation from the laboratory-scale to multi-ton per hour operations.

Radient Technologies has in its portfolio of processing equipment a unit that I designed for them a few years ago and that can process a few tons of slurry materials per day. To the best of my knowledge this is still the largest microwave-assisted extraction unit in the world.

It is relatively simple to scale-up procedures. The challenges remain the subsequent design of the extraction chamber - the so called microwave applicator - to be used to process the materials. That chamber is material-specific and this is what many parties failed to understand and thus failed to be successful. A faulty design and poorly thought extraction cavities cannot lead to economically viable use of the technology.

WT - Most extraction companies in Canada have opted for Supercritical CO2 extraction. Why do you prefer microwave extraction? Are the end products aimed at different markets?

Dr. Paré -Supercritical fluid extraction (SFE) is capital and operational cost intensive. This is especially true if one uses CO2 as the solvent. It is used almost exclusively for high value-added feedstock. Cannabis biomass certainly meets that requirement. Alternative extraction technologies used in the past included hydrocarbons as solvent - mostly propane and butane - and ethanol.

Without presuming about the reasons for this one can safely think that the historical illicit nature of the activities until the decriminalization of cannabis contributed to looking for techniques that used readily materials (like propane and butane) with associated simple technology to control and dispense such materials. Further, extraction was strictly a batch process unit operation and the volumes being treated per batch relatively small.

Under the large volumes to be extracted under the current market demands one can easily see that the risks associated with using these materials - highly flammable and under some pressure bring about new considerations.

SFE with CO2 has advantages in terms of reduced risks in terms of flammability. Higher pressure requirements pose a greater risk but the technology has been around for a long time and the engineering solutions are well known and controlled.

SFE offers advantages to those with less practical experience in terms of ease of removing the solvent, thus ensuring low or no-residual solvent - a definite marketing benefit. However, obtaining selective extracts from SFE is not that straightforward and can prove costly and time-consuming.

Microwave-assisted extraction on the other hand offers unparalleled selectivity. A selectivity that can be obtained very easily, reproducibly and with very little time to establish the conditions. And what is best, some of these extracts can prove unique to the technology thus lending a leading advantage to the manufacturer. With edibles coming inline soon, uniqueness of products will definitely be a major asset in terms of competitiveness in the market.

Finally, the basic patent rights to the microwave-extraction rights have expired thus opening the door to numerous applications. There may be selected applications that may benefit from continued patent protection, but there is ample room to freely use the technology in this area when basing the procedures on the original patents filed back in 1989.

Furthermore, nothing precludes the hyphenation of SFE and microwave-assisted extraction (SFE-MAE). In fact we presented such data back in the early 2000's - not on cannabis as a feedstock however. The economic viability of this approach would need to be assessed against the target products to be obtained from such a hyphenated technology and the value added brought about to the cannabis extracts. It must be noted that the microwave hardware technology has evolved drastically since our original work of 1986. Sairem SAS in France has patented a novel applicator that would lend itself very well to the special requirement associated with using flow through closed-vessel, high-pressure conditions such as SFE-MAE.

WT - As the publisher of watertoday.ca, I am interested in the use of water in any process. Is there any usage of water in this method? Is it a more sustainable usage than in other methods?

Dr. Paré -This is a more complicated question to answer because to do it justice one must do whole-life cycle analysis. Water is a resource used in basically all unit operations and comparing the use of water is highly dependent on the specific steps and tools used by the various users.
There is no direct use of water in the microwave-assisted extraction operational unit itself. There can be use of water as cooling medium but a properly designed closed-loop cooling unit can be used and little to no water is consumed.

WT - Is microwave extraction aimed at industrial production only or could this method be used by smaller cannabis producers? What equipment is involved and how costly is it as compared to other methods?

Dr. Paré -This is a very interesting question. There is no limit as to the volume of biomass to be treated. There are engineering requirements to ensure that this operation is efficient and cost-effective. In many applications, the time required to perform the extraction is within second to few minutes - as opposed to hours in other technologies. Hence it is possible to design a smaller volume unit that has the same daily capacity.
This approach offers the net advantage that a producer could opt to offer a variety of distinct unique extracts to its consumers. And this can be achieve using a single production unit and produce a variety of extracts basically on a daily basis. Other technologies usually require significant amount of time to switch from one extract to another one thus limiting the possibility of offering "just-in-time" products.

WT- Is the procedure similar to the one you use in your cancer research and how does it differ from ultrasound?

Dr. Paré -To a certain extent it is the same objective, namely a selective heating of targeted materials. In our cancer-related work we aim at selectively heating diseased tissue and limiting any collateral damages to non-diseased tissue. In extraction one aims at extracting the targeted components and leave behind as much as possible of the less desirable components. Less desirable can be because of colour, taste, and else... I am not qualifying the components by themselves. Some components can be valuable in a target applications and less so in others. The main difference between "cancer" and extraction and any other microwave application for that matter, is the "applicator". As expressed before, each applicator is application-specific and even materials-specific. Microwave is very different form ultrasound. The former is an electromagnetic wave, whereas the latter is mechanical. They differ in frequency, thus in wavelength. Hence their impact on surrounding materials is different. So is their interaction - physical interaction - with the materials to be processed.

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