Decarboxylation the process of activating cannabinoids

Decarboxylation is the process of converting cannabinoid acids like THCA into the neutral or "activated" cannabinoids like THC. In the case of THCA and THC it is the decarboxylation process that makes it psychoactive as THCA does not pass the blood brain barrier and does not activate the primary cannabinoid receptors, CB1 and CB2. The "high" effect of THC is a result of THC entering the brain and activating CB1 receptors. As THCA is not capable of passing the blood brain barrier or activating the CB1 receptor, it is not capable of causing psychoactive effects observed with THC.
Decarboxylation is a result of a combination of heat and time. Most of the cannabinoids on the plant while it is still growing are cannabinoid acids. As cannabis is dried and cured decarboxylation occurs at a relatively slow rate. Increases in heat can increase the rate of decarboxylation and cooking cannabis or exposing it to high heat can decrease the time required to complete full decarboxylation. For example, cooking cannabis at between 106 and 130 degrees Celsius will likely cause decarboxylation to be fully completed with in an hour. Heating cannabis to the temperatures sufficient to vaporise the cannabinoids will cause instant decarboxylation as will the heat involved in smoking it, although the extreme heats involved in smoking cannabis will also burn many of the cannabinoids and essentially destroy them through combustion.
The reason why the most efficient methods for completing full decarboxylation are considered to be either vaporisation or cooking for an hour at between 106 and 130 degrees Celsius is because other factors, like degradation, or even combustion at extreme temperatures, can also come into play. For example, while heat and time can cause decarboxylation which converts cannabinoid acids like THCA into neutral cannabinoids like THC, heat and time can also cause THC to degrade to another cannabinoid called CBN.
In laboratory experiments looking at different times and temperatures involved in decarboxylation it was observed that above 140 degrees Celsius decarboxylation was achieved very quickly with approximately 70% of the THCA converted to THC in under 7 minutes, however after 7 minutes THC began to degrade to CBN at a faster rate than the remaining THCA converted to THC. This meant that the 70% decarboxylation represented the highest potency of THC achievable at that temperature and THC quantity then rapidly decreased as it degraded to CBN at a faster rate than the remaining THCA was able to convert to THC.
A similar problem is observed with lower temperatures for longer time periods and as a result the optimum temperatures recommended for cooking cannabis is between 110 and 130 degrees Celsius. Producing cannabis extracts through vaporisation is even more efficient as decarboxylation occurs instantly with virtually no degradation or combustion, however use of such techniques are difficult for most people to achieve in large quantities.
At any consistent temperature decarboxylation above 70% with out causing degradation to CBN is very difficult to achieve and higher percentages usually required multiple stages of cooking. More efficient decarboxylation has been achieved through cooking initially at between 90 and 100 degrees Celsius for approximately 30 minutes followed by an additional 30 minutes at between 120 and 130 degrees Celsius. Different variants of this method and different times and temperatures have been tried and tested also.
The problem with such precise decarboxylation is that other factors also come into play. For example already extracted oils decarboxylate at different rates than plant material. How much decarboxylation has already occurred prior to cooking, like during drying or even in some cases prior to drying, can also influence the time and temperature required to complete full decarboxylation.
Extreme precision would require laboratory testing prior to the process, during the process and obviously post decarboxylation to test your results. So in the absence of such testing, the general rule of thumb for people who wish to complete full decarboxylation in the most efficient manner possible would be to cook it for between 30 minutes and an hour at temperatures ranging between 110 and 130 degrees Celsius.
Although many oil makers do cook plant material to achieve full decarboxylation prior to extracting oil from the plant material, there is advantages to cooking after oil has been extracted. The main advantage to decarboxylation after extracting oil is that you can observe the decarboxylation in the form of tiny bubbles and pin prick pops on the surface of the oil. At temperatures above 106 degrees Celsius the decarboxylation "activity" is easily observable and obvious and when this activity subsides you can be sure that the decarboxylation is complete.
There are also advantages to cooking plant material prior to extracting oil as well, primarily that the cannabinoids extract easier if the plant material is dryer. A very popular method is to cook plant material enough to dry out the plant material and partially decarboxylate the cannabis prior to extraction and then cook the oil after extraction to finish decarboxylation. This way you are getting the best of both worlds and the final decarboxylation process will also help to purge remaining traces of solvents from the oil, which is especially important when using toxic solvents like Naptha, butane or Isopropyl alcohol.
It is also worth noting that different extraction processes will cause different levels of decarboxylation. Depending on other factors, like the amount of material you are working with, which would influence the amount of solvent required, there is also a big difference between how much decarboxylation is achieved during the actual extraction process.
For example, the methods popularised by people like Rick Simpson, which involves the use of petro chemical solvents like Naptha or Isopropyl alcohol, require heat to boil off the solvent. The heat and time involved will cause at least a partial decarboxylation of the cannabis, so is unsuitable for people who wish to avoid decarboxylation for the purpose of creating raw oils or extracts. Alcohol, for example, boils at just over 80 degrees Celsius which is hot enough to cause some measurable level of decarboxylation, though depending on how long these temperatures are applied, which itself will depend on how much solvent you are boiling off, the amount of decarboxylation achieved will vary. Other methods like infusing with Olive oil require much less heat so much less decarboxylation will occur with out additional cooking. Butane extraction (BHO - Butane Honey Oil) require very little heat so virtually no decarboxylation is likely to occur and subsequent extract will be virtually completely raw.
It is worth noting that even hot extraction processes like the Rick Simpson method only partially cook the oil and additional heat is required to finish the decarboxylation process. Rick Simpson's protocol does recommend the use of a gentle heating device like a coffee warmer to "finish" the oil, which can complete decarboxylation if applied for long enough. However the coffee warmer is only used as an example of a "gentle heating device" and is portrayed as simply a step to help evaporate last traces of solvent and water with out burning the oil. It is not articulated what the heat and time required actually is and his video guide fails to mention decarboxylation in anyway and fails to mention the need for minimum temperatures during this process.
It is actually possible to complete full decarboxylation in the rice cooker but this would require you to allow the temperature to rise after the solvent is boiled off, which is actually contrary to what is advised in Rick Simpson's video guides, like the guide found on his documentary "Run from the Cure". If you are using Isopropyl alcohol, or other forms of alcohol, to extract the cannabis oil then the rice cooker will not heat the oil solvent solution beyond the boiling temperature of the solvent until the solvent is virtually all gone. In the case of alcohol the temperature will remain just above 80 degrees Celsius through out the cook off and while some partial decarboxylation will occur during this process additional cooking will be required to complete this. Recently added to Rick Simpson's website as an alternative to the coffee warmer is the recommendation of placing oil in an oven for an hour at 130 degrees Celsius, though previously recommended temperature was 110c. Though both are viable options the coffee warmer will only heat to about 60 degrees Celsius so cooking at the higher temperatures of 110 to 130c is considered a far more efficient method of decarboxylation.
In addition to the desired decarboxylation, heating at lower temperatures for longer time periods or cooking at temperatures above the optimum recommended temperatures can also degrade the THC to CBN. Also, in addition to losing cannabinoid acids through conversion to neutral cannabinoids, full decarboxylation will inevitably cause a loss of terpenoids which will evaporate during the cooking process.
At the end of the day the it is important to understand decarboxylation and how it is achieved. If you are wanting to utilise the medicinal benefits of raw cannabinoid acids, like THCA, with out the psychoactive effects of THC then you will need to avoid any heat. Extraction process will need to stay below 50c and oil will need to be refrigerated to prevent gradual decarboxylation which can occur at room temperature. However if you are treating something like cancer then you will require maximum THC or CBD potency, which will require full decarboxylation. For full decarboxylation you will need to cook your cannabis at temperatures ranging from 110 to 130 degrees Celsius. Full decarboxylation will result in a loss of terpenoids which will evaporate as it is cooked, and of course a complete loss of cannabinoid acids as they are converted to neutral cannabinoids, but for cancer it is the neutral cannabinoids that are most effective. For some conditions a combination of raw and decarboxylated cannabinoids, along with terpenoids, may be preferred. For this reason many people prefer to intentionally cook their oil to the point of partial decarboxylation. Partial decarboxylation does give a larger range of cannabinoids, cannabinoid acids and terpendoids but accurate doses are harder to gage so combining fully cooked oils with completely raw oils is often better from a dosing point of view.

Often confused with decarboxylation, oxidisation is actually a slightly different process. Decarboxylation is the loss of carbon(Co2) which converts cannabinoid acids like THCA to the neutral or "activated" cannabinoids like THC. Oxidisation is the loss of hydrogen, which converts THC to CBN, or THCA to CBNA if decarboxylation has not already occurred.
Both decarboxylation and oxidisation can be achieved through a combination of heat and time. For example, during the process of drying or "curing" cannabis decarboxylation will occur at a very slow rate, often taking many weeks, even months, to be fully completed. This same process also causes oxidisation and the longer cannabis is left to dry the more likely oxidisation will occur, which will degrade cannabinoids like THC to lesser cannabinoids like CBN.
Generally speaking decarboxylation occurs before oxidisation. Both drying and cooking cannabis will cause decarboxylation which converts cannabinoid acids to neutral cannabinoids, then additional cooking or drying will then cause the neutral cannabinoids to degrade to the lesser cannabinoids, this is often referred to as aging cannabis.
To use the THC journey as an example, the acidic precursor to THC is THCA. THCA converts to THC through decarboxylation, which is caused by a combination of heat and time. THC then converts or degrades to CBN through oxidisation, which is caused by additional heat and time. This is the most common journey to CBN.
However it is possible to oxidise cannabinoid acids with out causing decarboxylation. In the case of THCA, oxidisation with out decarboxylation will cause the THCA to degrade directly to CBNA, with out converting to THC. CBNA can then be converted to CBN through decarboxylation. UV exposure and oxygen can cause oxidisation to occur before decarboxylation. This is why it is recommended to dry cannabis in the dark as decarboxylation can occur but oxidisation is minimised if it is not exposed to excessive light.
Generally speaking oxidisation is an unwanted consequence of drying or cooking cannabis but as uses for degraded cannabinoids like CBN become more sought after for their medical applications, methods of intentionally oxidising cannabis are becoming of interest. Very old cannabis is often much higher in CBN and cannabis that has been overcooked is also likely to be higher in CBN. CBN is a sedative and people who consume old or overcooked cannabis, which is high in CBN, find that it is more useful for aiding sleep.

The optimum cooking times and temperatures for decarboxylation are considered to be between 110 and 130 degrees Celsius for between 30 minutes and an hour. Decarboxylation can be completed at much lower temperatures, as low as 60 degrees Celsius, and at higher temperatures but outside of the optimum range oxidisation is more likely to occur. Low temperatures take so long to complete full decarboxylation that by the time the decarb is complete a measureable amount of oxidisation will also occur. In addition to this, high temperatures can cause an undesirable amount of oxidisation. THC does not actually vaporise until temperature reaches 157 degrees Celsius, however temperatures above 140 degrees Celsius can degrade THC to CBN with out actually vaporising it. It depends on the time involved but one experiment that monitored decarboxylation at temperatures of 145 degrees Celsius observed that decarboxylation was quickly achieved with approximately 70% of the THCA converting to THC with in 7 minutes, however after this time the THC levels dramatically dropped as THC began to degrade to CBN at a faster rate than the remaining THCA could convert to THC (as mentioned in the decarboxylation section). So unless you intentionally want your cannabis to be high in CBN you want to avoid such high temperatures. Low temperatures have a similar problem and temperatures below 80 degrees Celsius take so long to complete decarboxylation that oxidisation is often unavoidable. This is why 110 to 130 degrees Celsius is considered the optimum range and 30 minutes to an hour is the likely time period.
Even with in the optimum range 100% decarboxylation with zero oxidisation is near impossible to achieve at a set temperature and it seems that breaking the cooking up into two stages, applying a lower temperature of between 100 to 110 degrees Celsius followed by a higher temperature ranging between 120 and 130 degrees Celsius, can optimise the decarboxylation and minimise the oxidisation. Experiments on this have come back with differing recommendations for exact times and temperatures and other factors also effect this, like how much decarboxylation is achieved prior to cooking either from the drying of the cannabis or the extraction process. For example, cannabis oil made using a cold extraction method like BHO (Butane extraction - Butane Honey Oil) would be almost completely raw with no decarboxylation achieved prior to cooking, where as hot extraction methods like RSO (Rick Simpson Oil), which involve heat to boil off the solvent, will cause some partial decarboxylation. So the optimum cooking temperatures and times required to complete decarboxylation would differ depending on how much decarboxylation had already been achieved.
Essentially, when it comes to decarboxylation and oxidisation, cannabinoids are broken down into 3 categories. Raw cannabinoid acids like CBGA, THCA, CBDA and CBCA represent the main components of raw cannabis. "Activated" cannabinoids like CBG, THC, CBD and CBC are the main components of heated/cooked cannabis and are the result of decarboxylation. Degraded cannabinoids like CBN and CBL represent aged cannabis and are the result of oxidisation. As previously mentioned it is possible to oxidise cannabinoid acids with out causing decarboxylation. Cannabinoids like CBNA and CBLA are degraded cannabinoids but have remained acidic as they have not gone through decarboxylation so would technically be classed as "aged" or degraded cannabinoids despite not being activated by decarboxylation. But generally speaking the most common pathway is for cannabinoid acids to convert to activated cannabinoids through decarboxylation and then degrade to "aged" cannabinoids through oxidisation.
After CBGA has converted, through enzymes, to THCA, decarboxylation would convert it to THC and oxidisation would then convert the THC to CBN. If CBGA is converted, through enzymes in the plant, to CBCA then decarboxylation would then convert the CBCA to CBC and then oxidisation would then convert the CBC to CBL. Just as THCA can oxidise directly to CBNA, with out converting to THC, CBCA can degrade directly to CBLA, by passing CBC. The journey to "aged"/degraded cannabinoids like CBN or CBL are a result of both decarboxylation and oxidisation regardless of which is achieved first. If only decarboxylation is achieved then cannabinoid acids like THCA will convert to THC and CBCA will convert to CBC. If only oxidisation is achieved, with out decarboxylation, then THCA will degrade to CBNA and CBCA will degrade to CBLA (by passing the activated cannabinoids THC and CBC). A simple way of thinking about it is to think of decarboxylation as losing the "A" (though in actuality you are losing Co2). Decarboxylation converts THCA to THC, CBDA to CBD, CBCA to CBC and CBGA to CBG. Decarboxylation also converts degraded cannabinoid acids (which have already gone through oxidisation) like CBNA to CBN and CBLA to CBL.