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Decarboxylation (decarb) 101: Basic understanding and at home method comparison

ichibancrafter

By Troy Ivan
ibc@ichibancrafter.com

Like most people, when I first heard ‘DECARBOXYLATION,’ I had no idea what it meant, and the word itself confused me, but the sound of science grabbed my attention. I had to know more.  I was relieved to learn that a short form of the big word existed and is commonly called ‘decarb.’  The more I researched, the more confusing the concept and process became. Everyone had different stories, experiences, opinions, and references to various conflicting recommended temperature and time combinations.  Some people even claimed decarbing was a myth and completely unnecessary.  Most of the available information was unorganized and unreliable, stoking my motivation to work on this experiment to clarify different open decarb methods.  There are far too many methods and time/temp combinations, so I compared a few of the easiest to perform in a typical home kitchen.  Before we get too far ahead of ourselves, let’s better familiarize ourselves with the different essential aspects and implications of performing decarb.

BASIC SCIENCE OF DECARB

Being familiar with the basic science involved with decarboxylation can be very helpful in sorting through all the internet noise surrounding the topic.  Let’s start with the natural form of tetrahydrocannabinol (THC) that develops in the trichomes of the cannabis plant as it grows and matures, THC-A.  Many people will refer to THC-A as the “acid form of THC,” meaning it has an extra carboxyl group that differentiates it from THC.  Notice that the word ‘carboxyl’ is the root of “decarboxylation,” which simply means to remove the carbolic acid group.  When the carboxyl group breaks away, carbon dioxide (CO2) is given off, and the molecular mass of THC-A reduces by about 12%, becoming the smaller molecule known as THC. This size relationship can be seen in one of the most common equations for measuring total potential THC in a cannabis sample [THCtotal = (THCA x 0.877) + THC].

The change from THC-A to THC is a natural process that begins immediately when the plant is harvested and continues very slowly over years, depending on how well the cannabis is prepared and stored.  The process can be accelerated by soaking cannabis in a solvent like ethanol, completing the conversion in 6-8 months, or hyper-accelerating with heat application.  Decarb is influenced by three specific variables: temperature, time, and environment.  Changing any one of the three variables will affect the extent of decarb achieved.  By applying varying degrees of heat, you can fully decarb cannabis at different rates. Low heat will take longer, high heat works faster, and the temperatures used for smoking or vaping cause instantaneous conversion. As time passes, decarb continues, so with the comparison of any two periods of time, with everything else equal, the longer period will always result in a higher degree of decarb. Environment is a more opaque and less concise consideration but very important.  Open air, ambient temperature, and exposure to sunlight will cause oxidation, conversion, and degradation of both THC-A and THC.  The environmental influence on the cannabis I used in this exercise had already taken place before it came into my possession, making it a fixed variable across all the samples used for each method.  Therefore, I will treat the environment as a constant, remove it from the discussion by comparing the different methods in this exercise, and concentrate on temperature and time.

Every day, I see people obsessing over the simple science of decarbing and meticulously analyzing every factor for fear of ruining their cannabis if they make an error.  Simple decarb questions in some groups often break out into internet brawls.  If you take a step back and think about it, you can see there is very little precision happening in your kitchen compared to a lab, so it might be best to treat the decarb process less like a lab procedure and more like a kitchen activity. If the starting material came from a source other than your own grow, you have no real idea how it was stored, how long it’s been out, how much sunlight it’s taken on, and the actual state of decarb that’s already taken place (environment factor).  Even if you did grow, cure, and store it yourself, it would be difficult to know precisely in most cases.  Furthermore, controlling the temperature of your appliances, especially cheap appliances, will be far from laboratory specifications but will be good enough to do what we need.  So, my general advice is to relax a little bit, take what I’ve written here under advisement, give it a little thought, take your best shot, believe in chaos theory, stay lifted, and move on.

COSTS ASSOCIATED WITH DECARB

The quality of terpenes and the amount of decarb present in the cannabis you consume depend on the same three variables (temp, time, environment) but are at odds and inversely correlated.  This means any factor that furthers decarb comes at the expense of terpenes.  The loss of terpenes during open decarb is a concern for most people, but it’s not an easy problem to solve since anything that facilitates decarb degrades terpene quality.  Maintaining low processing temperatures can help preserve some of the most volatile terpenes to a minor degree, and decarbing with a containment that traps them can also provide a small degree of salvation. For the most part, though, you must accept that when you choose to decarb, you will have substantial terpene conversion and loss.  Luckily, one of the most exciting recent developments in the cannabis industry is the availability of isolated terpenes and terpene profiles that can be reintroduced to a decarbed concentrate to make up for any loss and, in some cases, make the concentrate better than it would have been originally.

Another cost of decarb that causes concern is the conversion of THC to CBN.  Only a small amount of elevated CBN can cause a difference in the psychoactive effects of cannabis.  CBN conversion takes a bit of effort, and you have to overprocess a decarb by a decent margin, but the good news is, even if it happens, it’s not the end of the world.  People often mistake the effects of CBN for an elevated degree of being ‘high,’ when in reality, it’s not more ‘high’ but more sedated.  In fact, many people who need a very strong ‘chill’ factor or heavy sleep aid seek the help of the CBN component.

The following linked study is incredibly well done and interesting in many ways. If you have a chance to chew on it a bit, I highly recommend it.  It discusses the science of many aspects of the process, including the nullification of CBN development under vacuum, temp/time combinations for both THC and CBD, and other exciting stuff.  Decarboxylation Study of Acidic Cannabinoids: A Novel Approach Using Ultra-High-Performance Supercritical Fluid Chromatography/Photodiode Array-Mass Spectrometry.

WHY DO PEOPLE DECARB, DO I NEED TO?

To determine if decarbing is necessary for your intended use and needs, decide if you require the benefits of THC-A, THC, or both.  To begin exploring this, let’s look at the difference in the psychotropic effects and the potential benefits of using THC-A and THC.  The most apparent difference between the two is that THC-A does not induce psychotropic effects, the feeling of being “high,” while THC does when ingested orally or inhaled.  THC-A has become very important as an anticonvulsant, controlling and stopping many forms of seizures, anti-inflammation, pain relief, nausea, depression, and overall well-being, and has shown positive signs in prostate cancer treatment. It can do all of this without making people feel high.

On the other hand, THC has strong psychotropic effects that some people love, and others have difficulty with.  The difference in psychotropic effect is a result of the smaller relative molecular size of THC compared to THC-A.  The smaller molecular size allows THC to pass through the blood-brain barrier and attach to the cannabinoid receptors in the brain, creating the ‘high.’  The smaller THC molecule has been demonstrated to have an increased ability to kill cancer cells, work as an anticonvulsant, bronchodilator, appetite stimulant, strong pain reliever, soothe nausea, help with PTSD, induce sleep when nothing else works, along with a number other general health benefits.

The choice between using THC-A or THC is pretty clear-cut, but I’d like to include a couple of brief comments that might be helpful on how that choice relates to the various modes of consumption like oral ingestion, suppositories, topicals, smoking, and vaping. The decision to decarb for oral ingestion typically hinges on two considerations: desired benefits and one’s tolerance for psychotropic effects. Suppositories generally are understood to have no psychotropic effects if used correctly, so either THC-A or THC can be used.  Having said that, suppository effectiveness is hotly debated, and I recommend reading my post “The Cannabis Oil Suppository Debate: Personal Testing & Results” for more information.  Topicals are not directly ingested into the body orally, nor through the lungs, so either THC-A or THC can be used without psychotropic effects.

When it comes to smoking or vaping, there’s an interesting consideration concerning conversion efficiency and bioavailability.  In most cases, the rule of thumb for cannabis that will be smoked or vaped is that decarbing before consuming is unnecessary because it occurs automatically when combusted or vaped.  With combustion and smoking of flower, high heat is applied, and the desired constituents are able to be consumed, making prior decarbing mostly unnecessary.  Vaping and dabbing with quality equipment allows for precise temperature control to target cannabinoid and terpene components, attain very high conversion, and dial in desired effects, using temps to control the intensity of the high delivered. With higher quality controllable vaping equipment, decarbing is also usually considered unnecessary because you can preserve all the terpenes in your concentrate with high cannabinoid conversion efficiency. 

On the other hand, some people like to do low-temp dabs to enjoy rich flavors and avoid the possible adverse health issues associated with high-temp dabbing. In this case, it’s possible to lose a good percentage of cannabinoids to low conversion.  The low conversion problem can be solved by decarbing the material before and adding back terps to replace those lost while decarbing, creating a high cannabinoid conversion and high terpene dab.  Likewise, many people use vape cartridges with low-power batteries that operate at low temps and don’t provide reliable THC conversion, hence much weaker effects than desired.  To ensure a more potent delivery of THC, some people use decarbed oil and added terpenes to make vape cartridges. For this case, a much better option called Jar Tech Decarb saves the terpenes in the decarb process. The details are in the post Jar Tech Decarb to Keep the Terpenes: Real FECO, Carts, and Terpy Deliciousness.

To recap, there are just a few considerations when deciding if you need decarb.  First, determine if you desire THC-A, THC, or a combination.  Second, consider your form of consumption and if higher conversion is necessary.  Third, for your use, are the costs of decarbing worth the benefit?  Lastly, can the risk of potential terpene loss be mitigated by adding terpenes back later?

 

METHOD COMPARISONS

 PREPARATION

For this exercise, I prepared some outdoor GSC flower broken up by hand and separated into 7g bags for a control sample and each test.  I chose a 7g sample size because it represents what many people may decarb at home for personal use, and the results will be consistent with the larger volumes when executed properly.  When processing larger amounts, you must ensure the cannabis is not in a thick or compressed layer that would hinder heat transfer and cause unequal and incomplete decarb.

NOTES ON USING AN OVEN FOR DECARBING

Ovens are notoriously unreliable for temperature accuracy, and to my disbelief, during this exercise, I found my Across International vacuum oven was off by nearly 30°F. In contrast, the oven in my kitchen was spot on.  Here are some things you can do to make using the oven more reliable for decarbing:

COMPARED METHODS

I chose to compare methods that range from the traditional use of an oven, a couple of gadgets, and a couple of methods I worked up myself.  First, we’ll look at using the oven with foil tents, sealed canning jars, and vacuum packs, then the sous vide, steaming, and the Ardent Nova.  In comparing each method and the respective results, I was looking for high THC conversion, low CBN conversion, possible terpene preservation advantages, ease of use, odor, and general advantages or disadvantages of each.

Oven – Foil Tent

This is a simple method: just put the cannabis on some foil and fold it loosely like a tent, then fold over the ends to completely seal.  The folded shape doesn’t help control the odor much, but it does prevent the cannabis from getting overly toasted as it would without the foil protection.  This was the easiest of all methods, and both samples were effectively fully decarbed.  The only real downside to this method is there is a decent amount of odor; there will be no secrets about what you are doing.

Oven – Vacuum sealed pack

After doing the foil tent, I thought a vacuum-sealed pack would perform the same function but better. I had never seen nor heard of this being done, so I wasn’t sure if the plastic would melt and ruin the cannabis. I had only one way to find out!  A Food Saver unit vacuum-sealed the cannabis in the bag and it was ready. When the oven and cookie sheet were up to temp, the vacuum-packed cannabis went in.  After the time was complete, the CO2 release from the process made the bag puff up a little, and there was moisture in the pack that wasn’t there to start.  The pack worked as planned and trapped anything that had evaporated, then condensed on the cannabis or the pack’s surface as it cooled.  It wasn’t odor-proof, but a lot less than the foil tent.

A significant advantage of this method is capturing the vapor and everything remaining in the pack. When making butter, an infusion, or an extraction, I would be sure to gather whatever was collected on the surface of the bag by using the pack to do part of the infusion or ethanol wash for extraction. I liked this method. It seemed to work very well and achieved full decarb.

Oven – Mason Jar

I’ve been developing a feel for decarbing with sealed mason jars for a while.  Like the vacuum pack, evaporated terpenes are trapped in the jar and later condense on the glass surface if you don’t open the jar until it’s thoroughly cooled.  Then, you can use the jar to do your infusion or extraction and collect all the desirables that would have otherwise been lost.  After the jar cools, I put it into the freezer and use the same jar for doing frozen QWET (Cannabis Oil QWET Extraction Battle of the Wash: Dry Ice vs. Freezer).  The big bonus to this method is the smell is completely contained in the jar.

This process has a couple operational considerations that require attention.  First, a cool jar will require ramping time and uncertain heating, so it’s important to pre-heat the jar.  The jar can be brought up to temp along with preheating the oven.  When it’s time to put the cannabis in the oven, remove the pre-heated jar from the oven, quickly load the cannabis into the jar, secure the lid on the jar, and place it back in the oven.  This process also provides the added advantage of creating a natural vacuum seal later when it cools and before going into the freezer.  Second, the jar shouldn’t be filled too much. It’s best to leave quite a bit of headroom to allow even heating of the material.  I usually don’t fill the jar more than 1/3 full at most.  If I put more in, I rotate the jar halfway through the process to ensure even heating and add a few minutes to the total time to make up for opening the oven and losing some heat.  Third, I lay the jar on its side to expose as much surface area as possible.  Lastly, glass in a dry heat environment requires caution, and you must use your own judgment to determine if it is safe or not.  I have not had a single failure, but it’s essential to understand the possible risks of breaking glass due to temperature changes before trying for yourself.

Sous Vide (gadget) – Vacuum Pack

I was really looking forward to using the sous vide. Regrettably, it ended up being a failure, but not by fault of the process.  I believe the process is sound and will work great at lower elevations.  The sous vide claimed a range up to 199°F, which seemed achievable because water here at 5,000 feet boils at 203°F. However, it failed to heat above 191°F on its own.  I added boiling water, and then 194°F was maintained for the remaining time.  The original plan was to perform both 90-minute and 120-minute tests, but with the low-temperature limitation, I did only the 120-minute.  I’ve heard numerous great reports about this technique, and I believe if I were at a lower elevation where water boiled at a higher temperature, it would have achieved full decarb.  This assumption is supported by the results of the following method, steaming, and the temperatures used there.

The operational considerations are limited with this method.  The only difficulty was keeping the pack submerged as it to bloated.  Magnets were able to hold it down, but any form of weight would work.  There is one functional concern with this method.  When the packs are vacuum sealed, small stems can puncture the plastic and the contents will be compromised and not protected from the water.  The leaks don’t appear immediately but slowly over time. So with this method, prepare the vacuum sealed packs in advance and let it set overnight to confirm the vacuum seal is sound or you may end up with a water logged problem.

Steaming – Vacuum Pack

When I started seeing the sous vide used for decarb, I thought, why not steam a vacuum-sealed pack?  The steam temperature is at least that of boiling water, and maybe just a degree or two higher with the lid in place to create a minor amount of back pressure.  As already mentioned, at 5,000 feet elevation, water boils at about 203°F, so I hoped this temperature would perform better and overcome the difficulties I had with the low sous vide temps.  I was thrilled with this process; there was a slight odor, and it was no more hassle than the sous vide but required no costly gadget.  Like the sous vide, if I lived at a lower elevation where water boiled around 212°F, I’m sure this would have been a blinding success.

Instant Pot

This section doesn’t have testing results because it has been added after the original post was written. Since then, I and many others have found the Instant Pot a great option as a heat source. For the vacuum pack or sealed mason jars, this is perfect. The different Instant Pots have different settings, so the approximate temps can be found in the user manuals. Those temps can be combined with times comparable to the above examples. A great advantage here is that while decarb isn’t affected by pressure, the boiling point of terpenes are, so if you decarb in an Instant Pot under positive pressure, in some case, it can help preserve more terpenes.

Ardent Nova (gadget)

1 cycle – 100% THC conversion, slight elevation of CBN .09 to 0.15

I’ve been experimenting with the Ardent Nova, trying to understand this gadget’s claims for over a year now.  I’ve run it with many samples, and I’ve even taken it apart to examine the components and structure, and it seems to be pretty much the same tech as a rice cooker.  It has two temperature sensors that run against a timed algorithm and appear to be its extent.  It’s simply a heated cylinder; however, the claims I’ve seen are extensive: 1) decarb THC with precision, 2) decarb CBD with precision by running two complete cycles, 3) decarb plant material as well as oil, 4) use it for infusion.

These claims appear to be overstated, misleading the average consumer into believing it does more than I think.  I mentioned earlier that decarbing with absolute precision in the kitchen is quite difficult for several reasons, and the Ardent might solve only one of the difficulties.  It appears to provide a reliable and consistent heat, so if that’s what they mean by ‘precision’, great.  However, treating different cannabinoids like THC and CBD and different forms like cannabis flower and concentrates all with the same decarbing method is wrong.  Each of them has their own considerations and different processing requirements.  For that reason, any claim of precision is ultimately not reasonable, in my opinion. Looking back at the Decarboxylation Study of Acidic Cannabinoids you can see the difference in the curves used at low-temperature decarbing.  The Ardent uses a low temp for a long time, which as you can see from the graphs, conversion flattens with longer times at lower temps.  While it might be ‘good enough’ I don’t consider it to be precision, and it’s certainly a result that can be replicated for free using other methods. Another problem with the claim of precision is the inability of the unit to differentiate between the amount of mass or density of material loaded into it. It can’t tell if there is a little or a lot loaded, which should be accounted for by the temp ramping algorithm but doesn’t seem to change in the operation when I run a ¼ ounce or more.  On that same point, the inability to distinguish between plant material and oil mass has its own problems with precision. The inability to observe the oil or stir it during the process builds in conversion inefficiency and ignores the fact that the oil may have already sustained ample decarb during extraction, depending on what equipment and process was used.  Therefore, I think this gadget can be used for all the claimed applications. However, the ‘precision’ is only in the ability to hold a constant temp and not precision processing, which I find to be terribly misleading in their marketing. Lastly, the suggestion to use the appliance as an infusion appliance as well as for decarb is kind of funny; it’s obviously not designed to be both.

The processing time for 7 g was about 2 hours. It was 2 hours where I didn’t have to worry about monitoring and paying attention to it; that was very easy and worry-free.  In fact, after about 1 hour 45 minutes, I just went to bed because I was tired of waiting for it to finish.  This method provided the most toasted sample in this exercise and showed signs of being over-processed with a not-so-pleasant aroma.  This was the only method I tested here with a capacity limitation.

Some people love this gadget for its ability to push the button and walk away without monitoring or considering whether they are getting the best result possible.  With a bit of thought and minimal effort, you can achieve the best possible outcome without spending this kind of money and having volume restrictions.  I’ve tested this gadget thoroughly, and it’s my least favorite of all the methods presented here. The Instant Pot is a MUCH better option.

CONCLUSION

I’m so happy to have had the opportunity to do all of these tests side-by-side and present them together. I’ve been wanting to do this for a long time.  It’s clear to me that every one of these methods provides nearly the same outcome with some minor differences, and I think this shows that at home, decarb is a lot more forgiving and robust of a process than it’s usually recognized as.  These techniques can easily provide full decarb and require minimal effort.  The methods employing water for the heat source do not appear suitable for higher elevations.

To choose the method that best suits your needs, think about what tools you already have at your disposal, processing volume needs, how much time you have, if the odor is a factor, if you want to try to recover what terpenes may be present, your value of convenience, and your budget for unnecessary but convenient gadgets.  The pre-heated jar method was a clear winner for me, but everyone will have their favorite process, and I’m confident that whichever one you choose, you will achieve great results, so stop worrying about it and enjoy a stress-free decarb.

APPENDIX:  DECARBING OIL

The chemical behavior of decarbing and converting THC-A to THC is the same with cannabis plant material and processed oil or finished concentrates.  Applying heat to instigate the breaking off of a carboxyl group is the same for both.  I focused on decarbing plant material in this post but often prefer decarb concentrates and oil.  There are two ways to decarb processed oil and concentrates: an open or closed process. 

For the open process, place the oil or concentrate in an appropriate container and apply heat between 220°F-260°F until the bubbles stop forming.  There are a few things to be aware of when working with this.  First, be careful when heating a concentrate because it will become the viscosity of a runny liquid, so it must be contained, or it will run off any mat or flat surface and make a terrible mess.  Second, as decarb begins to happen, tiny CO2 bubbles will appear and can expand rapidly, so make sure there is A LOT of room for expansion.  Third, stirring the oil throughout the process can help facilitate an even decarb and knock down the expanding bubbles.  Lastly, once the CO2 bubbles stop forming, the decarb is complete.  I prefer to work with a magnetic stir plate with an integrated thermocouple when I use this process.  That way, the heat is accurately maintained, and the contents are constantly stirred.

Left to right: Decarb in full action, almost done, done

For the closed process, I have developed a technique called Jar Tech Decarb.  The main advantage of this process is that it’s the single way to achieve decarb and maintain the terpene profile.  All the information for this process is in the Jar Tech Decarb to Keep the Terpenes: Real FECO, Carts, and Terpy Deliciousness post.

Now I’m out….Stay lifted my friends!

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