Freeze Dryer Terpene extraction


Hi all,
So I haven’t seen anybody mention on here about using a freeze dryer to pull the terpenes out of cured or fresh bud. Does anybody have any experience with this? Any ideas about how complete the extraction would be, what kind if any terpenes would be left behind? My facility uses Harvest Right freeze dryers to remove terpenes from really sugary trim and re add them later to preserve them since we only can use ethanol for extraction. Any thoughts? I haven’t found anything on here already which makes worry a little bit. haha


Do you have any more details on your procedure. Do you use the stock pump? Have you measured yields? What do you use for a cold trap?

I have a medium sized harvest right that I have shelved b/c it pulls so many terps despite trying various temperatures and times. I have recently started doing some cryo ethanol extractions and would like to pull terps first as you describe.


We normally are freeze drying high quality trim, on average, for every 1000g of dried trim, freeze drying removes around 90-110mL of water/terpenes. then this you can use a seperatory funnel to separate the terp layer from the water layer. The terp layer is normally 5-10mL depending on the strain. The only issue with this method is that there are some water soluble terpenes that are being left in the water portion and discarded, maybe there is a way to evaporate of the water and leave the terps behind, but i find that the terpenes that are not soluble in water that you collect from the terp layer are really nice, and are the most common and fragrant.

All in all I think that if you have the harvest right, and you are going for cryo ethanol, might as well freeze dry first, and reintroduce the terps later if you choose.


Maybe you could add anhydrous magnesium sulfate or really any desiccant at all until there is no water and then extract with a low boiling polar solvent like dimethyl ether? @G_Boe

Edit: Turns out MgSO4 dissolves in ether and may or may not dissolve in dimethyl ether so tiny 3Å mol sieve beads would be a better choice as the dessicant.


Interesting, How long does it typically take (machine run time) in the harvest right freeze dryer to collect said 90-110ml/kg of terps/water?

1-2 days I imagine


@ScoobyDoobie Thats an interesting idea, but unfortunately in my state we are only medical with pretty strict limits on solvents we can use. Right now we can only use ethanol, isopropanol, water and CO2. Hopefully changing in the future.

1 freeze dry run takes about 24- 30 hours.



Are you just collecting the hydrosol that deposits on the inner frozen steel drum upon defrost, or do you use a cold trap inline? I think many of the terpenes make it past the frozen drum in the drying process.
I’ve thought about using one of those bvv buckets traps but the harvest right uses a unique threaded vacuum port that doesn’t seem compatible?


How would adding ethanol to the hydrosol assist in separation? Wouldn’t the terpenes and water just dissolve in your ethanol leaving with a hard to separate mixture?


We don’t use a cold trap, just the inside of the drum. I agree, there are probably terps making it into the vac, we have vacuum filters we run the vacuum pump oil through to clean up the oil a bit, but it still slowly absorbs terpenes.
From my companies perspective, they are just focused on getting some terps to add to shatter/wax/distillate/co2 oil, since we freeze dry everything before hand. Definitely not the most ideal way to get terps, but it works well enough for us.


Forgive my ignorance…
With the IC links, this link, and with most teks I see, why is everyone freezing/deep freezing this stuff beforehand? If we’re using nitrogen and deep vacuum, can’t we just do this at room temp? Or at the very least just slightly cold?

Is the freezing/thawing actually doing anything? Does it destroy the cell wall allowing for better evap? Can that just be handled by pulverising the material?


What do you mean using nitrogen and a deep vacuum, sorry I don’t quite follow. I am using the freeze dryer to remove terpenes and water from the plant material before I do a cold ethanol wash. We cant use hydrocarbons, so removing the terps before extracting with ethanol helps to save our ethanol so we can re use it. It also allows us to re add the terps to the finished oil, so they degrade much less.


Sorry, meant in reference to @cyclopath link.
But even in reference to your freeze drying…
Why is it being frozen?

If we’re running under deep vacuum the water+terps boil off at a set temperature based on a combination of boiling point + vacuum. If it wasn’t frozen beforehand why does it make a difference?

The tagged nitrogen process is a (potential) refinement of the freeze drying with; either a quick flood or slow stream of warmed nitrogen (inert gas) to add thermal + mechanical energy into the system, then using vacuum to “sweep” the molecules out, then condense them onto a trap.

The question I had is… Why is “freeze” necessary in any of this when we’re simply “boiling” off these molecules under vacuum.


Ah, I see, when freeze drying, the whole chamber is first frozen, then, a deep vacuum is pulled. then only the inner portion of the freezer, the shelves holding the trim, is slowly heated. the outside part of the freeze dryer stays frozen so as the terpenes get enough energy they release into the freeze dryer and (hopefully) freeze on the frozen outside of the container. It really isnt the most efficient way to extract terpenes, that is for sure, but I think that it is still a really good EASY option for extracting terpenes from plant material. I am interested in figuring out what terpenes im missing, whether I am missing an entire terpene, or if Im still getting the full spectrum of terpenes just leaving some of each behind.


The freezing/thawing under vacuum is specifically to cause the water to sublimate rsther than just evaporate.


Ok… But I’m still curious… Why is that important?


As far as seeing what terpenes you’re searching for. You just need to see/test what remains in the ethanol post extraction. Then compare the data to what you pull freeze dried. (If you do this please let me know, you’ll save me $$. Infact I’ll probably give you $$ if you have this data lol)

Every extract methadology loses terps along the way. We’re simply trying to find how little we can use while using ethanol as a primary solvent.


I dont know enough to give you anything but a weak observation.

It looks like the way those harvest right machines work is they just freeze the water inside the material and bring it outside of the cell walls to be more easily evaporated. I dont think this is reslly sublimstion because sublimation is when a solid is skipping the liquid phase and going straight to a gas.

I dont know why the terpenes from the freeze dry procedure are any different from any other cold trap terps except that they smell the most like a natural bouquet still.

As far as how they are removed by the frweze drying or if its more effective to just nitro sweep warm like youre saying, i dont know. I think its just simple evaporation under vacuum.


Have you compared and noticed the difference between the two?

All I can think of is the rapid freezing can blow up the cell wall to release more water and aromatics; but still; it seems like a problem that can be tackled mechanically with less energy input.


I can see the gradual warming helping to negate issues arising from over-riding the condenser.

I’ve been trying to figure out for a few months though. Why make it cold? If you can capture the water and turps, just make sure you catch it all.

The temperature difference is increased by running it under warmer temps compared to the (likely) -40 to -60c of your cold trap. So it would conceptually be more efficient with a warmer temp pull over a colder?