Are we prechilling our biomass correctly and at the right temps?

Hey Gang,
Looking for advice on how we are currently winterizing our biomass and if the temps need to be lower.

Our current process to Winterize our biomass is as follows:

  1. Mill the biomass and place it in ethanol extraction bags and on a stainless steel racks and roll them into our walk-in freezer. Material remains in the deep freezer for 12+ hours at a temperature of -28.
  2. After 12 hours we load the extraction sacks into our Cryo-ethanol extraction vessels and let them soak for 8- 12 minutes at -40.

Thoughts on the temps or the overall process, looking for improvement or confirmation that we are doing it right.

Thanks for the advice.

This would not be considered winterizing in the common form. its more prep for cold extraction.

Winterization is the step you use to remove wax, lipids and fats.

I’ll let someone with more cold extraction experience answer your question though.


Thank you.
Hoping to hear from others.

I do know this much, at -40 you will still pull some fats and waxes. Usually extracting at -60 to -80 is the range where you can skip the winterization step altogether.

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I agree with @thesk8nmidget. The process you are describing is that of cold extraction, not winterization. Biomass cannot be winterized; crude oleoresin is what is typically winterized.

The process you describe above could use a bit of refining, and once that is complete, the process of winterization can be implemented should it be needed for your desired end product/processes.

The biomass does not need to be frozen, and doing so may be inhibiting your process more than helping it. Your milled biomass is mostly air, which carries very little thermal mass. It should not be detrimental to your process to have it at room temperature, especially with your process being conducted in a controlled -40 environment.

Freezing your biomass can cause ice crystals to form around the trichome heads, making it impossible to extract all of the cannabinoids present. If you see freezerburn, you’re fighting a losing battle. Flash freezing is the easiest way to prevent the residual moisture in the cannabis from becoming problematic, and this is really only something that needs to be done when working with fresh frozen material being extracted with hydrocarbons. Alcohol at -40 will not melt ice. Try not to shoot yourself in the foot before you even start.

If you do not have in-house analytics or are sending out samples of your post-extraction biomass for testing, you have no idea what your extraction efficiency is. This will largely be based on the mill and density of your biomass coupled with the pores size of the extraction bags, temperature of solvent, whether there is agitation to assist with saturation, and the duration of which the biomass is in direct contact with the solvent. You have a lot of variables at play, and depending on your end goal, you may be doing fine. Problem is we don’t have enough information to provide you with what appears to be the answer you seek.

Winterization is a process by which an increased concentration of cannabinoids in tincture (compared to that at the time of extraction) coupled with cold (as cold or colder than one’s cold extraction) and time causes lipids to crash from solution, where they can then be filtered our or decanted and left behind. -67C is the temperature at which lipids will not be pulled into solution. I have run plenty of unwinterized crude to distillate that was extracted at around -40C with zero issue, but whether you require it for your process is up to whole host of details that we frankly do not have.

It seems to me based on your questions and understanding of the terminology that you may greatly benefit from a consult and/or a lot more reading here on this site. All of the information you seek is here and free, but as you seem to be extracting already, you may want to spend a bit to expedite the process.

Hope this helps.


See: Winterization

8-12 min “soak” without flow or agitation is almost certainly leaving a lot of the goods behind.

How do you get your solvent off the biomass? Is there a centrifuge involved? How much solvent (tincture with cannabinoids!) are you leaving behind? (I suggest weighing your bags post extraction).

I agree with @Akoyeh that paying someone to get you up to speed might be a good move…

investing in In House analytics early rather than late is also a pro move.

Have you got any analytics back on your current process? What is your extraction efficiency? (Follow the cannabinoids. How much did you start with. Where are they when you’re done?!?)


Hello Cyclopath,

Thanks for the reply and advice!

We use a closed loop cryo-ethanol extraction system built by Pinnacle Stainless out of Colorado. The system does have continuous flow and agitation. We also use a 1,400 lb centrifuse to flush out the remaining oils and solvent.
If I am understanding what most are saying is that we should not freeze the material prior to running it through our cryo-ethanol, correct?

@cyclopath has mentored and trained me for years, as has @Photon_noir. Is my advice not valid or trusted?

Edit: I have also run a lab that utilized nearly every piece of equipment Pinnacle makes, and I was thoroughly unimpressed with all of it. Their system is not closed loop, as it requires being left open to atmosphere. It also never even achieved the advertised 85% efficiency or maintained remotely near to the advertised temperatures with sustained use.

at -40C, your process doesn’t technically qualify as “cryogenic”, but in this industry misusing terms is par for the course…so that’s not particularly relevant.

with appropriate packing, the Pinnacle system should get decent extraction efficiencies, without follow up in a centrifuge, you’re going to lose solvent, or tincture. if you lose tincture, you’re losing cannabinoids. the only Pinnacle system I’ve seen in action was set up in a shipping container in such a fashion to be almost unusable (not enough over head room to load or unload efficiently).

The lab in question purchased a centrifuge to get more solvent out of their biomass, but purchased a fuge that wouldn’t take the bags their Pinnacle used. they also shot themselves in the foot by chilling their solvent to -40C, then running it through 100+’ of 1.5" stainless tube that actually passed through their boiler room!!

when you say 1400lb centrifuge, what exactly does that weight signify? eg: I ran a 900lb centrifuge that processes 10lb of biomass at a time: Cold ethanol pumps - #11 by cyclopath

do you have pictures? IMO extracting in the centrifuge makes way more sense than loading and unloading bags from the pinnacle then loading and unloading them from the centrifuge.

but then I’m biased…


Thank you for your reply and advice!

We just bought an entire HLPC testing lab and will have it installed and calibrated in our facility this Friday.

I have enclosed our company overview with actual pictures of our facility and labs.

Kind Roots Botanicals Company Overview.pdf (3.9 MB)

We were told by our manufacturer of the extraction equipment that the biomass needed to be frozen prior to being placed in our extraction vessels. So many points of view.

Once we have the HPLC up and running we can get a better idea of the remaining compounds in the spent material and our crude.

Thanks for your help!


You’re welcome. Sorry if that last comment came off as a bit salty. I can tell you from personal experience that while many of Pinnacle’s employees are super nice, pleasant people to be around, they do not know what they are talking about. They designed an outrageously priced, super inefficient system. I spent a lot of time on the phone and in person troubleshooting their systems and correcting the misinformation they were dolling out.

Those in-house analytics will help significantly! Glad you have them on their way!


We can run 200LBS. per run. I agree with you on using the centrifuge as the main extractor. It agitates and is connected directly into our whole system. You can see in the pictures in our overview.

Kind Roots Botanicals Company Overview.pdf (3.9 MB)

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looks like an expensive build out. glad you’ve got analytics on the way.

I’ve frozen a lot of biomass. When I first started, it was about keeping whatever scraps of decent material I got in the best shape possible while I accumulated enough to run single strain BHO. Later it became about “fresh frozen”, again for BHO.

as @Akoyeh points out, done wrong, freezing your biomass can actually reduce your yields by coating your trichomes in an impermeable layer of ice. vacuum sealing before freezing helps.

I’ve visited a lab that ground and bagged their biomass, then stored it in a walk-in freezer for days before extraction. they did not have in-house analytics, so I have no data on how that practice was affecting their yields, but such a strategy would not work in the Willamette Valley except during July-October.

the need to verify everything your equipment manufacturer tells you is an unfortunate fact of life in this business.


Thanks for the feedback, it’s always good to hear direct users opinions.

I’d love to chat with you direct if possible. Would be good to chat through some of the prior experiences you have had and if the team has taken any measures to correct or help with those issues.

I will dm you my direct number, looking forward to chatting.



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That is a rather impressive facility, @RossK! You can definitely count on the advice from @Akoyeh & @cyclopath in general, and @thesk8nmidget has presented good information here, as well!

I will say that -40°C/F is a reasonable temperature for achieving decent selectivity with 190 proof potable ethanol. As long as your comminution (aka: milling, grinding, shredding, etc.) does NOT cut open too many plant cells, you actually maintain -40° at all times when plant matter (even sediment) is in contact with solvent, and you keep the solvent residence time on your biomass to a minimum (less than 15 minutes, total), your extracted tincture (ethanol:resin solution) should only require 3 or 4 stages of filtration to remove unwanted solids and solutes. While that temperature will exclude (from dissolution) all epicuticular wax and the vast majority of triglycerides (vegetable oil), there will be some free fatty acids (FFAs) and phosphatides (e.g. lecithin) that dissolve along with the resin, as well as chlorophyll and other pigments. The -67°C mentioned is the temperature at which chlorophyll, FFAs and phosphatides are almost completely excluded from solution, as well.

I will not reiterate what the others have said already regarding pre-chilling biomass, because their information is quite accurate. I will add that the condensed surface water that clings to cold biomass can also have the counterintuitive effect of warming your extraction solution! As @Akoyeh nearly mentioned when he wrote of heat capacity, water has a LOT more heat capacity than the dry cellulosic biomass! In other words, for every 1°C of temperature in every 1 gram of that superficial water mass (including all the water vapor from the air that condenses on the biomass as you move it from the freezer to the extraction chamber), the solid ice which must melt contains 2.1 joules & liquid water contains 4.2 joules of energy, while each gram of dry biomass has perhaps 1.5 to 1.8 joules per °C. Unlike water’s fairly constant heat capacity within its state, pure liquid ethanol’s heat capacity falls as it cools, and is less than 2J/g°C at -40°, although that is still higher than that of dry biomass, with at least 5% water in 190 proof, that water heat capacity exists in addition to the ethanol’s, keeping its total likely just above 2J/g°C.
Since it requires about 8 kg of -40° ethanol (-40° density is about 1.05X room temperature density) to cover every 1 kg of dry biomass, you can begin to see why it is only water’s high heat capacity that will be able to significantly impact the overall extraction temperature. Water will dissolve into ethanol almost instantly, distributing its heat energy much more quickly than solid biomass, and that excess water content, with its higher heat capacity, also makes it harder to cool the ethanol back down; not to mention the deleterious effect that excess water has upon the resin extraction efficiency of the solvent!

The short & sweet solution to heat capacity is thus; DRY your biomass as completely as possible without overheating it. “Superdrying” is accomplished by storage of biomass inside a sealed room with dehumidifiers, plumbed (air filtered and condensate-pumped to minimize & blow out dust) through smooth (non-corrugated) lines to drain outside the room, set to their lowest possible settings (30-40% RH); oscillating fans circulating the air continuously; air conditioned to remain below 85°F; biomass OFF the floor on wire/slat/perforated racks, stored in mesh bags no more than 2-3 feet deep, at least 6 inches apart. Add at least 2 extra days of drying time for every foot (12") depth of traditionally cured (67% RH) biomass in a single container. THAT is your ideal storage room for Cannabis to be extracted by any solvent, and especially alcohol.

As much as I have said here about so very little, it is important to understand that almost every single aspect of extraction warrants this same depth of investigation if one wishes to achieve the greatest possible efficacy, efficiency and economy.

Best of luck to you, @RossK!