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What to Consider When Selecting Biomass for Extraction, a Q&A With Lydia Abernethy

By Leo Bear-McGuinness

Published: Apr 29, 2021   
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When discussing cannabis/CBD extraction, a lot of attention is rightly given to the techniques and tools used during the actual extraction process. But let’s wind back a bit. What about the very first step? What factors should an extractor consider when selecting the plant material they’ll extract from?

Well, Analytical Cannabis asked Lydia Abernethy, former senior science consultant at Steep Hill Labs and current testing and regulatory compliance expert at Trace Trust, just that.

Lydia Abernethy (LA): So, what an extractor should be looking for in their material and what to avoid… Well, we're looking for clear guidelines for how to pass state regulations to get product into market, which obviously is completely different with extracts than what we see with flower just due to the co-illusion of pesticides with cannabinoids and the concern about heavy metals within the vaporizer, heating coils, and things of that nature.

So, the steps that I would go through would be: number one, check the state regulations. Just like you said with the hemp Farm Bill, we have allowed for the cultivation and extraction of hemp-based cannabinoids, which includes CBD and CBDA as well as a lot of other things, as long as it’s not the Δ-9-THC that the federal government is concerned about. We see a lot of Δ-8-THC – not all too different from Δ-9 except for the fact that it’s not federally scheduled. So, the thing I would do would be to check the state regulations, and they’re going to be different for hemp and cannabis because cannabis is more regulated than hemp is at this time. But if we are trying to prepare for the eventual federal legalization of cannabis, it’s best to identify the state regs where your extraction facility is, and then also to maintain awareness of where the strictest regulations are.

So, my number one [piece of advice] is to check your state regulations. Two would be to identify your extraction method, that includes whatever solvent you’re using or if it’s solventless. And also, it includes what kind of product you’re trying to make at the end. So what's the cannabinoid profile? What's the terpene profile of the extract or concentrate that you're that you're attempting to make?

After that, number three would be to develop your extraction methods. So, if it’s a supercritical CO2 and you’re going to mix back in your terpenes, what’s the start time for that to be homogenous? What it is that you’re needing to do on a step-by-step to get your end product from your bulk biomass? Because all these things are going to make a difference in the way that you're going to approach the prescreen testing.

It’s a lot rougher on the smaller companies; they don't have as much access to money. And so being able to test appropriately throughout the production process, it’s more difficult for them to bear because of the price of testing, [for] one. And then, two, if they have a recall situation, where they choose to buy dirty biomass, it can be infinitely more harmful to their business if they can’t survive a couple of months without being able to produce product that can go to market. Whereas one of these larger companies, if they mess up a few times they still have that money in the bank to keep them from folding. So that would be my starting place there.

Leo Bear-McGuinness: That’s definitely a good start. What about the biomass itself? What should extractors know about their source material?

LA: So, okay, after you’ve dubbed your extraction method, my recommendation would be to identify your source material. Most people are using trim, right, they’re using the spent leaves and stocks and material that would not be appropriate for market. Most people, when they say biomass, is they mean all this leaf matter that’s not being used. There are people that do extractions with flower. But, for the most part, people are using trim. And then the other thing is, most people are using fresh frozen material when they’re trying to produce extracts. They’re not going through the drying and curing process. And then there’s this other group of people where they’re using cultivars and genetic specific extracts. So, there are some products where it’s just, indica or sativa, or a blend. So, there’s multiple different strains or genetics and a single product. And then there are some more high-end artisanal extracts, where they’re strain specific. And again, the reason why it’s important to know is it helps [an extractor] understand from a testing perspective. If you're going to have five different cannabis strains, for example, in a singular extraction batch, you would want to test all five of the strains either, ideally, separately or mix them all together and try to take a representative sample to the best of your ability.

The other thing I really, really encourage people to do, is take a farm tour. Then [you] can review the cultivation site, understand the integrated pest management strategy, whether the facility is actively spraying pesticides, what pesticides they’re using, or if they’re using beneficial organisms, mites and kind of predatory parasitoid insects to be able to keep down pest populations. And when we go into that portion of it, you’re looking for any kind of contaminant that could possibly be entered into the cultivation stream, which is the growing medium. And then you’re looking at pesticides and water, and these are really the places within the cultivation site that could essentially lead to a problem downstream when it comes to processing because of the different contaminant types that are being tested for in the industry.

So, the ones that are of major concern for extraction is pesticides. Depending on the extraction method, and what you know what your end product and cannabinoid percentages and terpene percentages, you may have a greater likelihood to pull out certain pesticides that were perhaps introduced either on purpose or by accident through the cultivation process. And so the best decision would be to set up a micro extraction, and that can be done with ethanol, methanol, acetone, it just depends. Ideally, you want to keep this micro extraction or this biomass pre-screen testing. We do it this way because it's a quick and easy low-tech method. And it's cheaper than liquid chromatography or gas chromatography.

But the disadvantage potentially with using a micro extraction to do this biomass pre-screen is that, again, these pesticides have different relative solubility. So certain pesticides are going to dissolve better in ethanol versus acetone, so it’s worthwhile to have a conversation with your lab partner, to ask them what their limits of detection and limits of quantification are.

If you have a lab that has perhaps more sensitive instrumentation than you are preparing yourself for, then you might have a problem. And, on the back end, when it comes to bringing your market-ready product for testing, find the lab partner and have clear conversations with them about what you know you are doing as an extractor, so that they can assist you to the best of their ability. The kind of the behavior that we've heard all about for years is ‘lab shopping’ within the industry. I don't necessarily mind people trying out different labs to see which one works for them, is the most cost efficient, whatever. But you don’t want to keep changing it around; you want to use the same people, ideally, indefinitely or until another player in the game comes in and they're better. But you don't want to be bouncing around.

At Steep Hill, we would have a lot of people do their pre-testing or pre-screening or whatever, before their product was for final market ready state, they would send this into some other laboratory and they would get back the results. And they’re like, ‘Okay, great, we can go ahead and process all of this biomass that we have in house, we're ready to go,’ And then they take their product over to our lab, and our instruments were more sensitive. It was something fairly common that we saw at the beginning of the Californian legal industry. People would engage in this behavior, then the state would fail them against being tested at our lab because our methods were more sensitive. And so that is not an ideal place to be, especially when you're not expecting it to happen to you.

So, a lot of these things mirror the current good manufacturing processes that we see in pharmaceuticals, cosmetics, food, and we just want to establish that within cannabis. Because what we care about for the biomass is potency, which is cannabinoids and terpenes, pesticides, and heavy metals. Those are the major categories of concern when it comes to extraction. Microbiological contamination is basically a non-issue. For a lot of solvent-based extractions, it’s just not going to be a thing. The presence of mycotoxins is concerning in any cannabis product. But if you don't have the Aspergillus niger, Aspergillus terreus, if you don't have these specific species of Aspergillus detected in your product, it's very unlikely that you're going to have mycotoxins developing in storage. It’s not that it doesn't happen, but it's very, very rare.

So, the major ones to test for when purchasing biomass and talking to a cultivation site would be the cannabinoids and terpenes, pesticides, and heavy metals.

LBM: Are there any more practical considerations to have in mind? If you’re running an extraction facility, for example, should you try and match your milling machines to the type of biomass your receiving?

LA: Yeah, like you said, there’s absolutely a market where they’re grinding up biomass, and they're providing it powdered in cylinders, ready to go through CO2 extraction. And sometimes it’s been cut down and harvested but hasn’t been dried and cured. Again, it’s just making sure that the relationship between the extractor/processor and wholesaler or distributor is clear – that they are doing this pretesting and that they have a certified legal relationship with this company. And so, if they receive this product in a form that would be completely ridiculous for the processor to try to do a prescreen testing on, that they have those relationships set up.

Additionally, the extraction process itself, they can be processing like hundreds to thousands of pounds of cannabis in a day. And if that is all going into a single batch, or even in multiple batches of extracts, you want to make sure that that is has all been mixed really, really well, that it’s homogenous. Because if it's not properly purged and homogenized, then you can have huge spikes and residual solvents in your sample material or in products that go out to the consumer. And that's the same thing with pesticides, it’s the same thing with cannabinoids, heavy metals, any of that. So testing throughout your extraction process – taking samples of crude and seeing if your laboratory can test them before you go further downstream through your extraction process – might be a method of dealing with if you’re a very large company and you have the capacity to purchase LCMSs and GCMSs and do this more advanced pesticide prescreening.

But there’s people that receive their biomass in trash bags. And everything’s fine with the biomass until they put them into trash bags and the trash bags happen to be scented or happen to have certain chemicals in them that could potentially cause a problem downstream. I’ve seen that type of behavior as well. We didn’t even know that that was going to be a thing in California until it started popping up in the tests. And the cultivators were like, ‘We did not spray anything. We did not put this adulterant in there. This is not coming from us.’ And we realized in the end it came from the trash bags they had put the product in. So, understanding how it’s moving, understanding how you’re going to get your product and how it’s been treated prior would be especially important when it comes from a state regulatory testing standpoint.

Lydia Abernathy, former senior science consultant at Steep Hill Labs, was speaking to Leo Bear-McGuinness. Questions and responses have been edited for clarity. 

This article originally appeared in Analytical Cannabis' Advances in Cannabis Extraction and Processing eBook in March 2021. 

Leo Bear-McGuinness

Science Writer & Editor

Leo joined Analytical Cannabis in 2019. From research to regulations and analysis to agriculture, his writing covers all the need-to-know news for the cannabis industry. He holds a Bachelor's in Biology from Newcastle University and a Master's in Science Communication from the University of Edinburgh.


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