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Old 03-04-2018, 02:10 AM #21
Junkyard Frog
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I usually only lurk and learn in this section but I believe I can add value to your search.

Freeze drying may your best bet. I have tried the inexpensive method (dry ice) in small amounts with great results. A vacuum chamber and pump at low pressure placed inside a freezer (chamber only) could facilitate curing larger quantities, but I have not tested that option.

You dry the sample for few days then freeze and place it in the chamber or container with dry ice (sample goes above the ice and a hole should be in the top of the container). Continue to freeze with low vacuum running or co2 gently pulls the moisture out of the sample.

The vacuum method would work best at ideal temp + pressure.
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Old 03-04-2018, 10:02 AM #22
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Not trying to win a pissing contest here but...
Freeze drying is a very efficient, fast, and gentle method for drying stuff which greatly reduces any chemical or biological reaction during the process. Usually, the samples aren't pre-dried and that results in physical/structural changes of the sample. Unless you cure fist and then use freeze drying only to speed up the final drying step.
Usually, freeze drying is used to remove any residual water (moisture content below 5%) whereas cannabis should still contain a certain amount of residual moisture or it won't burn nicely. Freeze drying makes it hard to stop early enough without repeated thawing-weighing-refreezing cycles (which BTW will accelerate sample degradation and reduce shelf life). Please be advised that poor/unprofessional or overly long freeze drying will remove essential oils quite efficiently and rupture the trichome heads.
That said, freeze drying is exactly the opposite of curing and hence your worst bet .

If you still want to try freeze drying: Do not add dry ice INTO the vacuum chamber or it will break the vacuum by quickly evaporating and hence you'll be either freezing or drying/vacuuming but not both at the same time. Put the dry ice around a "vacuum vessel" and the ice will also last way longer and this time, there will be a real vacuum. Besides, the aim of freeze drying isn't to "pull the moisture out of the sample" with CO2 gas. The correct term here is "sublimation" and that works better the stronger the vacuum is (or the lower the pressure).
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Old 03-04-2018, 02:29 PM #23
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The Biochemistry of Chlorophyll Degradation in Senescing Leaves


Protein mobilization in senescence is regulated by a network of processes (Dangl et al., 2000; Hörtensteiner and Feller, 2002; Thomas and Donnison, 2000), among which the induction of chlorophyll degradation is an early and, for plastid membrane polypeptides, essential event (Thomas et al., 2002). Net loss of chlorophyll from green tissues during senescence and other terminal developmental events culminates in the accumulation of colorless products (nonfluorescent chlorophyll catabolites, or NCCs) (Mühlecker and Kräutler, 1996). The enzymic pathway of NCC formation from chlorophyll (Hörtensteiner, 2004) commences with chlorophyllase, which dephytylates chlorophyll a. Magnesium (Mg) is removed from chlorophyllide a by a dechelatase activity. The tetrapyrrole macrocycle of the product of Mg removal is opened oxygenolytically by pheophorbide a oxygenase (PaO), producing a red bilin, RCC. A reductase immediately converts RCC into a colorless fluorescent product, FCC. Further enzymic and nonenzymic reactions metabolize FCC to NCCs in a species-specific manner (Hörtensteiner and Feller, 2002; Thomas et al., 2001). Catabolites of chlorophyll b are not normally observed in senescing tissues, leading to the notion that there is interconversion between chlorophyll(ide) a and b and catabolism exclusively by the a-specific pathway. An enzymic activity capable of converting chlorophyllide b to a has been shown to become elevated during senescence (Scheumann et al., 1999). Terminal catabolites are sequestered in the cell vacuole. There is no evidence that the N of the chlorophyll ring is exported from the cell during senescence. Chlorophyll catabolism is summarized in Fig. 1.


https://www.sciencedirect.com/topics...chlorophyllase
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Old 03-04-2018, 02:31 PM #24
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Role of chlorophyllase in chlorophyll breakdown


Of high importance to all photosynthetic organisms is chlorophyll, and so, its synthesis and breakdown are closely regulated throughout the entire life cycle of the plant. Chlorophyll breakdown is most evident in seasonal changes as the plants lose their green color in the autumn; it is also evident in fruit ripening, leaf senescence and flowering. In this first step, chlorophyllase initiates the catabolism of chlorophyll to form chlorophyllide. Chlorophyll degradation occurs in the turnover of chlorophyll, as well as in the event of cell death caused by injuries, pathogenic attack, and other external factors.

Chlorophyllase’s role is two-fold as it functions in both de-greening processes, such as autumnal coloration, and is also thought to be involved in turnover and homeostasis of chlorophylls. Chlorophyllase catalysis of the initial step of chlorophyll breakdown is important for plant development and survival. The breakdown serves as a prerequisite in the detoxification of the potentially phototoxic chlorophyll and chlorophyll intermediates as it accompanies leaf senescence to non-fluorescent catabolites. Rapid degradation of chlorophyll and its intermediates is therefore necessary to prevent cell damage due to the potential phototoxicity of chlorophyll.[5][6][7]

Reaction and mechanism catalyzed by chlorophyllase
Chlorophyllase catalyzes the hydrolysis of ester bond to yield chlorophyllide and phytol. It reacts via tranesterification or hydrolysis of a carboxylic ester in which its natural substrates are 13-OH-chlorophyll a, bacteriochlorophyll and chlorophyll a.


Hydrolysis of chlorophyll starts with the attack of a carbonyl group of chlorophyll by the oxygen of the hydroxyl group of the crucial serine residue of the chlorophyllase. This attack forms a tetrahedral transition state. The double bond of the attacked carbonyl reforms and the serine is then esterified to chlorophyllide. The phytol group consequently leaves the compound and replaces the serine residue on the chlorophyllase enzyme. The addition of water to the reaction cleaves the phytol off the enzyme. Next, through the reverse reaction, the oxygen on the hydroxy group from the water in the previous step attacks the carbonyl of the intermediate in order to form another tetrahedral transition state. The double bond of the carbonyl forms again and the serine residue returns to chlorophyllase and the ester of the chlorophyll is now a carboxylic acid. This product is chlorophyllide.[8]

Chlorophyllide is then broken down to Pheophorbide A. After Pheophorbide a is formed, the poryphin ring is cleaved by Pheophorbide an oxide to form RCC causing the plant to lose its green color. RCC is then broken down into pFCC.

Regulation
Posttranslational Regulation
Citrus sinesis and Chenopodium album were the first plants from which the genes encoding chlorophyllase were isolated. These experiments revealed an uncharacteristic encoded sequence (21 amino acids in Citrus sinensis and 30 amino acids in Chenopodium album) located on the N-terminal that was absent from the mature protein. The chlorophyllase enzyme is a smart choice as the rate limiting enzyme of the catabolic pathway since degreening and the expression of chlorophyllase is induced in ethylene-treated Citrus. Recent data, however, suggests that chlorophyllase is expressed at low levels during natural fruit development, when chlorophyll catabolism usually takes place. Also, some data suggests that chlorophyllase activity is not consistent with degreening during natural senescence. Finally, there is evidence that chlorophyllase has been found in the inner envelope membrane of chloroplast where it does not come in contact with chlorophyll. Recent studies inspired by inconsistent data revealed that chlorophyllase in Citrus lacking the 21 amino sequence on the N-terminal results in extensive chlorophyll breakdown and the degreening effect that should occur in vivo. This cleavage occurs in the chloroplast membrane fraction. Both the full chlorophyllase and the cleaved, mature chlorophyllase, however, experienced similar levels of activity in an in vitro assay. This data suggests that the mature protein comes in contact with its substrate more readily because of the N-terminal sequence and some natural regulation occurs that directly affects enzyme activity. Another possibility is that the suborganelle compartments breaking down allowing a greater amount of enzyme activity.[9]

Other forms of regulation
Chlorophyllide, the product of the reaction catalyzed by chlorophyllase, spontaneously combines with plant lipids such as phosphatidylcholine liposomes along with sulfoquinovosyl diacylglycerol. These two lipids cooperatively inhibit the activity of chlorophyllase, but this inhibition can be reversed by the presence of Mg++, a divalent cation.[10] The activity of chlorophyllase also depends on the pH and ionic content of the medium. The values of kcat and kcat/Km of chlorophyllase in the presence of chlorophyll showed pKa values of 6.3 and 6.7, respectively. Temperature also affects chlorophyllase activity. Wheat chlorophyllase is active from 25 to 75 °C. The enzyme is inactivated at temperatures above 85 °C. Wheat chlorophyllase is stable 20 °C higher than other chlorophyllases. These other chlorophyllases can stay active at temperatures up to 55 °C.[11]

Ethylene induces the synthesis of chlorophyllase and promotes the degreening of citrus fruits. Chlorophyllase was detected in protein extracts of ethylene treated fruit. Ethylene treated fruits had chlorophyllase activity increased by 5 fold in 24 hours. Ethylene, more specifically, induces increased rates of transcription of the chlorophyllase gene.[12][13]

There is also evidence of a highly conserved serine lipase domain in the chlorophyllase enzyme that contains a serine residue that is essential for enzyme activity. Histidne and aspartic acid residues are also a part of the catalytic triad of chlorophyllase as a serine hydrolase. Specific inhibitors for the serine hydrolase mechanism, therefore, effectively inhibit the chlorophyllase enzyme. Also, mutations at these specific amino acid residues causes complete loss of function since the mutations change the catalytic site of the chlorophyllase enzyme.[8]

https://en.wikipedia.org/wiki/Chlorophyllase
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Old 03-04-2018, 02:40 PM #25
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Chlorophyllase Is a Rate-Limiting Enzyme in Chlorophyll Catabolism and Is Posttranslationally Regulated

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1867358/
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Old 03-04-2018, 04:53 PM #26
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Curing and subsequent aging allow for the slow oxidation and degradation of carotenoids in the tobacco leaf. This produces various compounds in the tobacco leaves that give cured tobacco its sweet hay, tea, rose oil, or fruity aromatic flavor that contributes to the "smoothness" of the consumed product. Non-aged or low quality tobacco is often artificially flavored with these otherwise naturally occurring compounds. Tobacco flavoring is a significant source of revenue for the international multimillion-dollar flavor and fragrance industry.[1]

The aging process continues for a period of months and often extends into the post-curing harvest process.


Carotenoids (/kəˈrɒtɪnɔɪd/), also called tetraterpenoids, are organic pigments that are produced by plants and algae, as well as several bacteria and fungi. Carotenoids can be produced from fats and other basic organic metabolic building blocks by all these organisms. The only animals known to produce carotenoids are aphids and spider mites, which acquired the ability and genes from fungi[1][2][3] or it is produced by endosymbiotic bacteria in whiteflies.[4] Carotenoids from the diet are stored in the fatty tissues of animals, and exclusively carnivorous animals obtain the compounds from animal fat.

There are over 600 known carotenoids; they are split into two classes, xanthophylls (which contain oxygen) and carotenes (which are purely hydrocarbons, and contain no oxygen). All are derivatives of tetraterpenes, meaning that they are produced from 8 isoprene molecules and contain 40 carbon atoms. In general, carotenoids absorb wavelengths ranging from 400–550 nanometers (violet to green light). This causes the compounds to be deeply colored yellow, orange, or red. Carotenoids are the dominant pigment in autumn leaf coloration of about 15-30% of tree species, but many plant colors, especially reds and purples, are due to other classes of chemicals.


Aroma chemicals

Products of carotenoid degradation such as ionones, damascones and damascenones are also important fragrance chemicals that are used extensively in the perfumes and fragrance industry. Both β-damascenone and β-ionone although low in concentration in rose distillates are the key odor-contributing compounds in flowers. In fact, the sweet floral smells present in black tea, aged tobacco, grape, and many fruits are due to the aromatic compounds resulting from carotenoid breakdown.

https://en.wikipedia.org/wiki/Carotenoid
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Old 03-04-2018, 09:53 PM #27
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Again: as long as the buds are still green there's considerable amounts of chlorophyll present (if not even most of it).
Me too, I was wondering if and/or to what extent carotenoid breakdown products contribute to the smell and aroma of cannabis. At least in tobacco high carotenoid content correlates with dark brown to red colours whereas progressive carotenoid degradation leads to paler shades like yellow and beige. These colours aren't as good an approximation of carotenoid content as green goes along with chlorophyll, though.
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Old 03-05-2018, 12:49 AM #28
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I guess a lot of it boils down to personal preference. The closest thing you are going to get to the original "flavor" of the living plant would be to freeze it fresh then vaporize it. Actually smoking cured flower seems like your going to get a much more degraded monoterpene effect with the carotenoids playing a stronger role in the experience.


Ornamental- from how you understand these enzymatic processes, are they oxygen dependent? One thought I has was co2 or nitrogen curing to slow the oxidization of monoterpenes down.
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Old 03-05-2018, 10:00 AM #29
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Quote:
Originally Posted by coldcanna View Post
...
Ornamental- from how you understand these enzymatic processes, are they oxygen dependent? One thought I has was co2 or nitrogen curing to slow the oxidization of monoterpenes down.
Not all but many of these require oxygen. CO2 is not inert and will affect or even induce physical and chemical changes. Nitrogen seems perfect but without a bottle of nitrogen gas...
See also THIS thread.
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Old 03-06-2018, 12:14 AM #30
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Interesting read, I think our curiosity is in the same place. I could prob have access to nitrogen but my company doesn't have a GC-MS so unfortunately I can't give any proof on essential oils beyond my own senses.
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