[CannaChemist]

Hi everyone,

I am currently running CO2 extractions and winterizing the crude material with 200 proof ethanol at -20oC for 12-24 hours. I am interested in speeding this process up by performing the winterization in a -80oC freezer. Does anyone have any experience with this? Does it speed up the process? I would think that cooling faster would speed up the precipitation of the lipids, but I also know that precipitation/crystallizations are hampered by increased viscosity, and that larger crystals form at a lower viscosity.

Another potential scenario is to use the -80oC freezer to increase the cooling rate, but then filter in stages in order to pull out precipitated lipids, reduce the viscosity of the mixture, and allow the next stage of precipitation to happen more efficiently.

Any insight is appreciated.

Cheers!

[Gray Wolf]

Originally Posted by CannaChemist

Hi everyone,

I am currently running CO2 extractions and winterizing the crude material with 200 proof ethanol at -20oC for 12-24 hours. I am interested in speeding this process up by performing the winterization in a -80oC freezer. Does anyone have any experience with this? Does it speed up the process? I would think that cooling faster would speed up the precipitation of the lipids, but I also know that precipitation/crystallizations are hampered by increased viscosity, and that larger crystals form at a lower viscosity.

Another potential scenario is to use the -80oC freezer to increase the cooling rate, but then filter in stages in order to pull out precipitated lipids, reduce the viscosity of the mixture, and allow the next stage of precipitation to happen more efficiently.

Any insight is appreciated.

Cheers!

We haven't tried a -80C cooler, but have shortened the time using dry ice, so it should work.

[PDX Dopesmoker]

I think I remember reading someone saying that they tried winterizing at too low a temperature and substantial THC crystalized out of the solution along with the lipids. Don't remember exactly what temperature that was at though, but if its a problem at -80º then maybe it would still work if you used more solvent.

[Dr.Terp]

Ive found a stepwise gradient in temp drop is best, especially if going to -80C (many of the cryo freezers can be programmed to follow specified temp/time gradient) Going too low, too fast does indeed make a mess of your solution and not recommended. Depending on your mixture (poopsoup? Terpy-coldrun-BHO? Apeks-SFE? Hemp? Heady-Hemp?), you may or may not need to perform filtrations between different stages of the temp drop curve. Does the -80C perform better than dry ice? Im not sure, but I do know that -80C isnt
a complete necessity for winterizations. CannaChemist you seem to be on track. This is a big bottleneck for many operations. I am not claiming to have it optimized for all mixtures... My goal is to get it down to less than an hr if possible. Ill report in this thread our progress.

[flatusm]

I've looked at a lot of info and the best I found was -50C for 90 minutes was the sweet spot.
Dry ice around an open stainless column with ball bearings can do that easy. If you go below -50 you risk freezing THC--BUT--if the temp of the ethanol goes up for even a moment before the filter, that THC and waxes will melt right out.

So like, maybe put it in the freezer an hour or until it's at -60, remove it and vacuum filter it when it gets to -40? With gloves, obviously.

[Shortburner]

I have one. It works great. But keep in mind cryo freezers arent really freezers they are cold storage. My service tech says what we do with it will burn it out quickly.

Btw it beats the dry ice bill!!

[Shortburner]

-74c pours thick but leaves almost no lipid for the second winterization

[BlackestofOps]

I use a -40C freezer for 120 minutes. Works great.

[CannaChemist]

Originally Posted by Dr.Terp

Ive found a stepwise gradient in temp drop is best, especially if going to -80C (many of the cryo freezers can be programmed to follow specified temp/time gradient) Going too low, too fast does indeed make a mess of your solution and not recommended. Depending on your mixture (poopsoup? Terpy-coldrun-BHO? Apeks-SFE? Hemp? Heady-Hemp?), you may or may not need to perform filtrations between different stages of the temp drop curve. Does the -80C perform better than dry ice? Im not sure, but I do know that -80C isnt
a complete necessity for winterizations. CannaChemist you seem to be on track. This is a big bottleneck for many operations. I am not claiming to have it optimized for all mixtures... My goal is to get it down to less than an hr if possible. Ill report in this thread our progress.

Hey man, thanks for the feedback. Our mixture is like the poopsoup (lol) you mentioned. My oil is all used for edible-type products (capsules, carrier oil tinctures, etc.) so we decarb the plant material before running a supercritical CO2 method (5000 psi/60oC) to pull off over 90% of the cannabinoids. This method extracts a lot of wax which we use for creams and balms.

We ended up buying the -80 freezer and developed a method that works pretty well. We started with a 5:1 ethanol (vol.) to crude (mass) ratio which we used when winterizing at -20, but realized that a 10:1 ratio was better (reduces viscosity and solubility which allows lipids to precipitate more readily). We found that filtering in stages produces the best results. The protocol was to store at -80 for 1 hr and then filter. This process was repeated 3 times until no more wax was collected on the filter paper. So total winterization time of 3 hours with filtrations after each hour. We also stepped down the pore size of the filter paper with each filtration.

We've found you tend to use more ethanol when filtering since you're doing it in stages, so that is one downside (we use 200 proof ethanol, which in Canada is not cheap). We also noticed a change in the solubility of the winterized extract in some of our carrier oils. I'm hypothesizing that the cryo temps might be precipitating smaller chain lipids that are not precipitated at -20. I think this because we found the solubility was most reduced in carrier oils that contain smaller length fats (and like dissolves in like - I know that's for polarity but it's just a hypothesis). We're going to test extracts winterized to a certain end point (yet to be determined) at -20 and -80 and determine the fatty acid profiles using GC-MS. I'll report back with some findings!

[CannaChemist]

Originally Posted by Shortburner

I have one. It works great. But keep in mind cryo freezers arent really freezers they are cold storage. My service tech says what we do with it will burn it out quickly.

Btw it beats the dry ice bill!!

Man, you're not wrong. One of the compressors on the freezer went already (6 months of use). I literally have a technician coming in tomorrow to fix it. They definitely don't like when you're opening and closing the door every hour during 9-5 five days a week lol.

We have bulk tanks for LN2 and LCO2 on site, so we're going to hook our -80 up to one of those lines to help the compressors.