Propylene Glycol Tobacco Extraction Method

[CAAB]

Hi 50YearsOfCigars, I have been looking for a breakdown of your PG extraction method, but haven't found it. It would be nice to learn about it. I was wondering a few things.

• If you've ever done a comparison between the 'hot bump' method you mention and just keeping the PG extract at room temperature for the duration of the extraction?

• I'm also curious what the duration of your extraction process before straining out tobacco and why?

• How do you choose your hot bump temperature and duration of hot bump?

• Shelf life of PG is typically 2 years as far as I have seen. Do you use your PG up within that period or do you freeze the extra or something?

• Have you read of the effects heat has on PG? Does it create new undesirable compounds?

• Have you experimented with methods to remove oils/waxes from PG? Can you drop things out from freeze filtering? I know we've had this conversation before, there is likely a flavor impact, I am just curious anyway...

• If you add PGA or H2O to PG, can you evaporate it out later?

I plan on comparing a few PG and VG/PGA extraction methods, both hot and cold. So hopefully I will have some results to report within 6 months or so.I am sure there will be more to report in the meantime.

[Peter_Ramish]

I was wondering a few things.

hahaha, that is 7 things ! I will respond in 7 separate REPLY posts, that way it will be more organized. But that also gives me the chance make this following:

DISCLAIMER:
Keep in mind when reading All my opinions about processes that they are directly linked and crafted to conform to my overall Goal -> I want to Always extract the broadest and most complete flavor profile from any given tobacco sample. I am not interested in making things 'lighter' or 'cleaner' or more weighted to or against 'casing or topping flavors'. - If it turns out that there are attached consequences of 'coil gunk' or other inconveniences then I accept them as a necessary part of achieving the Primary Goal. The main constraint on my goal oriented crafting of processes is that they must be a 'kitchen chemistry' plan of action (no cheating with $100K mass spectrometers).

[Peter_Ramish]

If you've ever done a comparison between the 'hot bump' method you mention and just keeping the PG extract at room temperature for the duration of the extraction?

Yes I did at least a dozen of these in my early days of extractions. I had no trouble noting from the start that in all cases the 'hot bump' was a superior technique. I abandoned total end to end cold PG extractions some time ago. I consider 'bumps' all gain and no pain. If you keep the temps at 115F and add Ultra-Sonic then you are waayyy ahead of the time lines of total Cold PG. Of course see: http://diy-tobacco-net.epizy.com/viewtopic.php?f=2&t=13

[Peter_Ramish]

CAAB wrote
I'm also curious what the duration of your extraction process before straining out tobacco and why?

This is experienced based. It is the 'art' part of the art and science of extractions. Typically the lighter Pure Leafs (various Virginia leafs) and the well fermented professional high grade cigars require the longest extractions. Sometimes the factor is orders of magnitude in time. I do not claim to understand what accounts for this wide variation but it is very real and must be given close attention.

I will adjust the over all time of infusion/extraction based on results of the 'skimming' techniques at 1 month intervals to sample the progress of the extraction. Giving it more time or calling it end of game and time for finish and filter is just a judgement call.

[Peter_Ramish]

How do you choose your hot bump temperature and duration of hot bump?

Almost same answer as 'duration of extraction'. With my standard PG extraction I have empirical evidence that temps over 115F are to be avoided. I use temps as high as 165F when exploring new territory, for example the Water Extractions, when it seems there is a good reason to go in that direction. But my 'production technique' is 115F 6-10hr Ultra-Sonic. You can't argue with results. It is experienced based.

[Peter_Ramish]

Shelf life of PG is typically 2 years as far as I have seen. Do you use your PG up within that period or do you freeze the extra or something?
-
Have you read of the effects heat has on PG? Does it create new undesirable compounds?

Well, if properly stored it is stable well beyond 2 years. At cool temperatures, propylene glycol is stable in a well-closed container, but at higher than normal storage temperatures, in the open, it may oxidize, giving rise to products such as aldehydes, propionaldehyde, lactic acid, pyruvic acid. Propylene glycol is chemically stable when mixed with high proof ethanol (+75%), glycerin, or water; aqueous solutions may be sterilized by autoclaving without harm to the molecule. See Dow Chemical PROPYLENE GLYCOLS: http://bit.ly/310ecgt

In this post we are discussing, as per the title of the post 'Extraction Methods' so we need not bother countering contrived examples that have appeared in the popular press about heating PG in contrived experiments above 300F. We can examine that in another topic post. But the short of the long of it is: that stuff is just NIH grant funding junk science.

I store reagent PG at room temps for long periods. No issues. However, all my extractions, once finished and filtered are stored in my little Sears Apartment Fridge at 40F.

[Peter_Ramish]

Have you experimented with methods to remove oils/waxes from PG? Can you drop things out from freeze filtering? I know we've had this conversation before, there is likely a flavor impact, I am just curious anyway...

Well to answer this question, I must ask another question: What waxes and oils do you have in your sample that are already "dissolved"? PG exhibits a wide range of solubility with varying waxes and oils you might find in plants. And the initial solubility is temperature dependent. Since PG is miscible with water, it will dissolve many essential volatile oils, but is immiscible with waxes and so-called 'fixed-oil', The term 'fixed oil' is apparently some term of art in the herbal and flavor extraction industry I had actually never heard it before, but since my background is in inorganic chemistry that is not surprising. Anyway they loosely define it as oil produced by plants that does not volatilize (i.e., is not aromatic). So there could be a good range of all this stuff in a tobacco leaf.

And, of course the temperature-dependent solubility of wax compounds, used to your advantage (or disadvantage) in reverse becomes what I would call 'freeze separation' and will work very well with PG. You would have to try it to see what it pulls and how it applies with the particular sample you have at any given time. The 64 dollar question is 'which of what drops out when?'. Anytime you employ a process to chemically precipitate out or employ a physical mechanical property of freezing/melting point, or take advantage of varying solubility to 'separate' things you have to realize you are doing just that. The decision to 'remove and discard' a separated component must be made very carefully, least you throw the baby out with the bathwater.


Here is an interesting article on Temperature-dependent solubility of wax compounds in ethanol.
https://naldc.nal.usda.gov/download/44460/PDF

[Peter_Ramish]

If you add PGA or H2O to PG, can you evaporate it out later?

Of course the vapor pressure of Ethyl Alcohol is very high at room temps, so it can be evaped out easily with no special techniques or equipment.

The Vapor Pressure of Water is much lower, but you can certainly remove the water from your PG, however you will need a simple vacuum dehydrator setup. These setups are really very inexpensive, and sooner or later I will knuckle under and by one as an early X-mas present (hahaha..) Besides working with your hobby of NET they are good for all sorts of important chores around the house like making your own Astronaut Ice Cream - see: https://www.youtube.com/watch?v=mlywGYcY-tA

H2O vapor pressure / temp

[CAAB]

Alrighty, that's all the info I need for now, thank you. I have a gallon of PG on the way and 10 tobaccos to extract. Will start with the procedures you outlined in your extraction method, minus the ultrasonic or ferris wheel, that's out of budget for the next year or so. Although really I could probably build the ferris wheel out of spare materials on hand for the most part. Will have to think on that one... Or I could slip into a carnival with duct tape and find a suitable ride to tape mason jars to.