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the role of oxygen in curing

pawpaw

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I just received Marijuana Botany by R.C. Clarke. I was hoping it would detail the chemistry of drying and curing. From the book:

A floral cluster is not dead after harvest anymore than an apple is. Certain
metabolic activities continue for some time. … During this time cannabinoid
acids decarboxilate into the psychoactive cannabinoids and terpenes isomerize to
create new polyterpenes with tastes and aromas different from fresh floral
clusters.
Neither decarboxilation nor isomerzaion requires oxygen. Yet the author goes on to say that the opening and closing of curing jars provides fresh air needed for curing.

One way to make sense of this is to guess that chlorophyl undergoes oxidation in the curing process. If this were the case, however, one would expect a significant lose of THC as well, unless chlorophyl was much more prone to oxidation than THC. Chlorophyl A does have a long chain extending from its main body which suggests possible greater fragility but that is hardly conclusive. A useful experiment would be to jar cure some floral clusters and place a fresh oxygen absorber packet in the jar each time it is opened during curing, and then comparatively smoke test it. Unfortunately I have no immediate prospects of being able to run such an experiment. Can anyone here per persuaded to give it a go?

Another way to make sense is to assume that anaerobic bacteria are a substantially greater problem than aerobic ones.

In either case, if you are using impermeable packaging techniques for storage, oxygen absorbers would seem worth trying if your goal is to always smoke the very best.

Decarboxylation : hxxp://en.wikipedia.org/wiki/Decarboxylation
Isomerization : hxxp://en.wikipedia.org/wiki/Isomerization
oxygen absorber source : hxxp://www.amazon.com/50-Absorbers-Dehydrated-Emergency-Storage/dp/B003F960Z2/ref=sr_1_1?ie=UTF8&qid=1310840703&sr=8-1
 

Hushpuppy

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Not to rain on yer parade brother, but I think it is much more simple than yer thinking:) Its all about moisture and its gradual removal form the bud. Think of the bud as a sponge that is just full enough with water that it isn't dripping. yu don't want to set it in the sun to dry as it will shrivel up and be no good, but yu don't want to leave any moisture that could allow mold to grow either. The key is a controlled dehydration that doesn't stress the inner chemicals that we want to keep. The first step is to qiuckly wring out most of the water(talking about the sponge...Bud don't do well with being wrung.lol) Then yu want to more slowly remove the remaining moisture so that the ouside doesn't dry up and lock moisture inside, where mold could later form.:) The reason for the jar technique is that it allows the moisture within the bud to travel to the outside of the bud(a slow process that equalizes the moisture within the bud and jar), where it is removed from the bud by evaporation. Then the jar is opened to allow the moist air to be released and have drier air to come into the jar(which creates an imballance of moisture within the jar that further leaches any moisture from the bud to reballance itself) to remove more moisture, but not so much that the outside becomes crispy before the inside can dry sufficiently. Those who have practiced this process have found that this removes the moisture and allows the natural processes to occur that contain and preserve the chemical attributes that are most wanted, ie, smell, taste, and effect.:cool: I hope this makes sense:D
 

orangesunshine

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i can vouch to smoking perfectly cured bud stored in mylar sealed bags with oxygen absorbers for 2 years that tasted as perfect as the day it was stored
 
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I'm with Hushpuppy. Simply put, we open the jars to get rid of residual moisture.
 

orangesunshine

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true that THG---residual moisture is one thing---oxygen is another when the moisture is gone---it we degenerate your prize possession in time
 

pcduck

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orangesunshine said:
true that THG---residual moisture is one thing---oxygen is another when the moisture is gone---it we degenerate your prize possession in time
That is true orange, but once the moisture level is where you want, and you do not keep opening the jar and playing with your buds it it should last a long time.ime:hubba::bolt::bong:
 

orangesunshine

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my jars do not totally seal---and---many people have worse problems than retraining the freshness of their herb---:rofl:
 

pcduck

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:rofl:

:bolt::bong:
 

pawpaw

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Thanks, As Oxygen degrades THC, my curing cabinet design includes an oxygen scrubber to remove the oxygen at the beginning of the drying phase and keep it out of the cabinet throughout the drying and curing phase. I've just been trying to establish that oxygen did not play a role. Some where on this forum I had asked someone to perform an experiment with oxygen adsorbing packets. So thanks, orangesunshine, for running the experiment before I even thought of it. :)
 

BBFan

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Hushpuppy said:
The reason for the jar technique is that it allows the moisture within the bud to travel to the outside of the bud(a slow process that equalizes the moisture within the bud and jar), where it is removed from the bud by evaporation. Then the jar is opened to allow the moist air to be released and have drier air to come into the jar(which creates an imballance of moisture within the jar that further leaches any moisture from the bud to reballance itself) to remove more moisture, but not so much that the outside becomes crispy before the inside can dry sufficiently. Those who have practiced this process have found that this removes the moisture and allows the natural processes to occur that contain and preserve the chemical attributes that are most wanted, ie, smell, taste, and effect.:cool: I hope this makes sense:D
Can you give me a reference on those statements? I always thought it was basically "wicking" or a form of capillary action. What about the breakdown of chlorophyll?

I don't think the amount of oxygen in the jar is significant enough to degrade the thc by any substantial degree. Long term storage is another issue, but Hick just showed some pics in another thread of bud that was good after 6 years with no special oxygen absorbers.
 

pawpaw

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BBFan said:
Can you give me a reference on those statements? I always thought it was basically "wicking" or a form of capillary action.
Water only wicks from a more moist area to a less moist area. And water cannot wick away from a surface. i.e. into the air. By opening the jar the humidity would be reduced (unless you were in New Orleans in August during a rain). The surface areas of the buds would then first reduce their moisture content by evaporation. After that moisture would begin to wick towards the drier srufaces areas until the entire mass eventually reached equilibrium moisture content with the air in the jar.

What about the breakdown of chlorophyll?
That's a good question. But it appears that chlorophyll is fairly fragile molecule and it might well decompose simply by the action of room temperature thermal energy. Need more info here.
I don't think the amount of oxygen in the jar is significant enough to degrade the thc by any substantial degree.
I haven't seen a redox path for the “burning” of THC but almost surely it requires only one molecule of oxygen (O2) to degrade one molecule of THC and quite possibly one half a molecule, and THC has a much higher molecular weight than O2 so it might well take much less air than you think. And we’re talking about opening the jar repeatedly as opposed to only once and leaving it tightly closed .
For your amusement: You have an 8 ounce jar that contains one ounce of bud with 17.5% THC by weight. Assuming that the jar is at sea level and that the bud displaces one half of a volumetric ounce of air and that the jar is left closed long enough for all the O2 in the air to react with the THC and that it reacts only with the THC and that all the air in the jar is completely refreshed with each opening of the jar; how many times would the jar have to be opened to reduce the THC potency of the bud by one third. You may use the www to obtain your initial values and use a calculator to get your results. You must show all of your initial values and all and every calculation. Hint: start by calculating the molecular weight of THC and O2. And no I haven't done it but if someone does I'll check their work :)
 

Hushpuppy

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BBFan said:
Can you give me a reference on those statements? I always thought it was basically "wicking" or a form of capillary action. What about the breakdown of chlorophyll?

I don't think the amount of oxygen in the jar is significant enough to degrade the thc by any substantial degree. Long term storage is another issue, but Hick just showed some pics in another thread of bud that was good after 6 years with no special oxygen absorbers.
I can't reference that information as it was pulled out of a well read but cluttered brain. But yu said it in one word "wicking" is the process that I was refering to that pulls the moisture from within the bud to the outside of the bud. PP also explained it correctly in that it is a matter of obtaining equilibrium of moisture. Evaporation is partnered with wicking in the removal of moisture from the bud....Just making an educated guess here but I would think that the breakdown of chlorophyll occurs with the drying process and possibly a certain amount of interaction with oxygen or hydrogen as those 2 are present and are the most common catalysts for chemical breakdown in the environment. :)
I would agree with yu on the oxygen degrading THC. Again, another educated guess, but I would say that during the curing process most of the oxygen in the jar gets tied up in multiple processes, and the amount is not enough to do noticable harm to the THC. Then once it is stored, any oxygen still present will quickly get locked up in any of the compounds present in the bud which effectively removes it from the jar environment. Minus any heat energy that could fuel more catalytic activity, all degradation should just about stop altogether. Again, an educated guess:)
 

pawpaw

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I would say that during the curing process most of the oxygen in the jar gets tied up in multiple processes, and the amount is not enough to do noticable harm to the THC.
Thanks, nice post.

Me:
... the THC and that it reacts only with the THC
I recognize that the above is an assumption without basis. But if the result of the calculations was more than a few openings one could discount the problem of oxygen. Basically it could only establish a basis for guessing that it was insignificant. Not that it was significant.

I will note that the flavor of dried fruits is stabilized by oxygen free storage. That is as close to hard evidence as I can get.
 

nvthis

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The process is called "gas exchange". By opening your jar, you slowly reduce the rh within. Slowly is paramount. You want to avoid moisture caused issues (mold, etc..) but allow chlorophyl to be consumed. Chlorophyl is used up by processes in the bud itself (re: OP) It is turned into simple carbohydrates and consumed. The aim of the cure, when all processes are said and done, is to eliminate as much of this chlorophyl-turned-to-sugar as possible (and, in doing so, eliminating some of the chlorophyl itself). Smoking sugar is, well, in a word.... Yucky ;)
 

pawpaw

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but allow chlorophyl to be consumed. Chlorophyl is used up by processes
in the bud itself (re: OP) It is turned into simple carbohydrates and consumed.
I have not been able to find sources that verify this assertion and I had searched for such several times before your post. I would be very greatful if you would supply one
 

BBFan

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Further reading from Clarke also includes this passage:
R.C. Clarke said:
Clusters are not sealed permanently until they have finished curing. Curing involves the presence of oxygen, and sealing floral clusters will end the free exchange of oxygen and end curing. However, oxygen also causes the slow breakdown of THC to CBN, so after the curing process is completed, the container is completely sealed. Any oxygen present in the container will be used up and no more can enter. Nitrogen has been suggested as a packing medium because it is very non-reactive and inexpensive. Jars or bags may be flooded with nitrogen to displace air and then sealed. Vacuum-sealing machines are available for Mason jars and may be modified to vacuum-sealed bags.
So attempting to totally remove oxygen during curing may produce different results than a standard cure, I don't know.

But a lot of research has also been done on the storage of MJ for long term. Most of what I have read claims 1 to 2 years is no problem if kept cool, dark, and dry. Also, as long as the trichomes remain intact, there have been several studies that say they are impervious to degradation by oxygen (but are however susceptible to degradation from heat and light). I've kept bud for a few years with no apparent degradation, though that would only be a subjective opinion.

As far as "wicking" goes, my experience is that I put an air dried bud into a jar (often times feeling crispy dry) and within 24 hours the moisture has wicked from the center of the bud to the drier outside area of the bud (the bud is no longer crispy but in fact, during the early stages of the cure, quite moist) where it evaporates into the air in the jar. Opening the jar allows the excess humidity and gases from the chlorophyll breakdown to escape and the process to begin again.
 

orangesunshine

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what up BBfan---interesting find---it has always been my impression that my jarred herb was visually getting darker and developing a brown schwagg look from the failure of jar seals---they have always been stored in a dark, room temperature cupboard---need to find a cooler location i guess
 

pawpaw

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Originally Posted by R.C. Clarke, Marijuana Botany

Clusters are not sealed permanently until they have finished curing. Curing involves the presence of oxygen,

Re my OP Clark never mentions what the actual role of the oxygen is. I'm inclined to agree with nvthis but I need sources to feel comfortable about it.

Also, as long as the trichomes remain intact...
If I ever get some I plan to store it in the freezer but I worry that will make the trichomes brittle and tend to shed off. Anyone with experience with that?
 

BBFan

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orangesunshine said:
what up BBfan---interesting find---it has always been my impression that my jarred herb was visually getting darker and developing a brown schwagg look from the failure of jar seals---they have always been stored in a dark, room temperature cupboard---need to find a cooler location i guess
Hey orangesunshine!

Here's an intersting read from a study done at the University of Mississippi back in 1999 (paid for with your tax dollars):

hxxp://www.unodc.org/unodc/en/data-and-analysis/bulletin/bulletin_1997-01-01_1_page008.html

At room temperature, there was a +/- 26% loss of thc after 1 year. After that, it leveled off to about 7% a year.

Freezing though is probably not the answer as most things I've read say it causes the trichomes to become brittle (great for bubble runs, not so much for long term storage).

Here's some more info from another study:


The stability of cannabis and its preparations on storage
Abstract:
Solutions of pure cannabinoids, nine samples of herbal and two of resin cannabis (one freshly prepared) were stored in varying conditions for up to 2 years. Exposure to light (not direct sunlight) was shown to be the greatest single factos in loss of cannabinoids especially in solutions, which should therefore be protected from light during analytical and phytochemical operations. Previous claims that solutions in ethanol were stable have not been substantiated. The effect of temperature, up to 20 degrees, was insignificant but air oxidation did lead to significant losses. These could be reduced if care was taken to minimize damage to the glands which act as "well filled, well closed containers". Loss of tetrahydrocannabinol after exposure to light does not lead to an increase in cannabinol, but air oxidation in the dark does. It is concluded that carefully prepared herbal or resin cannabis or extracts are reasonably stable for 1 to 2 years if stored in the dark at room temperature.
At 20 degrees C (68 F), this study seems slightly contradictory, though the UMiss study was done in "barrels" and does not state the barrels were air tight.
 

pawpaw

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Thanks,

BBFan said:
Here's some more info from another study:
And for those interested in sources the one for the above citatation is:


The stability of cannabis and itspreparations on storage
Fairbairn JW, Liebmann JA, Rowan MG
JPharm Pharmacol 1976 Jan;28(1):1-7
 

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