Hi Cannabis extraction experts,
Our company located in Canada are working to implement a complete centrifuge cold ethanol extraction line. Some vendors told us that the quality of the terpenes from ethanol extraction is not as good as the terpenes coming from a CO2 extract.
May I have your input on this claim please ?
Regards
What are your end products ?
With co2 one can extract and refine terpenes on their own
Wich is hard if not impossible with ethanol
As for extraction power both solvents can extract them all
As an additional benefit co2 rigs can be used with a 10% ethanol co solvent making it a more terpene versatile unit
BUT CO2. Takes a lot more time for the same volume and upfront investment
The primary difference lies in the ability to extract terpenes with pure CO2 and avoiding the introduction of ethanol until cannabinoid extraction. One can extract, separate, and collect terpenes from your biomass, then introduce the ethanol via co solvent pump to dramatically increase extraction speeds.
Ethanol and many terpenes have similar boiling points, so when you extract with ethanol, then rotovap the ethanol from the crude solution, a bunch of the terps go too. This leaves you with āterp shineā instead of those terps being in your product.
Thank you for your reply, we will offer different products to our customers, crude oil (60%+ potency average), Distillate (90%+ potency average) and CBD Isolates.
The terpenes part is important for the vape cartridges we are looking to market.
If with ethanol is impossible to extract terpenes with our distillation machine what type of terpenes extraction we should do. CO2 subcritical extraction (terpenes run) prior to centrifuge ethanol extraction ?
Regards
Thank you for your reply, based on your comment, what happen with high pressure in CO2 extraction vessel. I assume the temperature will dramatically increase with the pressure. We donāt lose terpenes there ?
No, the terpenes will extract at lower pressures and fall in your collection vessel. Having multiple collection vessels allows you to do the entire run without multiple collections and get better separations.
The extraction should be done in stages, increasing pressure over time.
to @Roguelabs point, the challenge is solvent removal
purging your terpenes of co2 - not so hard
but how do you separate your terpenes from your ethanol? 
Great thanks for the advice. So if we are going with cold ethanol extraction process, you recommend to do a terpenes run with CO2 before the centrifuge extraction process I assume ?
Or do you have a better approach for terpenes extraction combined with cold ethanol extraction process ?
For solvent removal we will go with a falling film evaporator after rotovap and finalize with a decarb reactor.
For the terpenes part, we will do three passes with our distillation machine. During the passes we will recoup our terpenes ? Do you think my understanding is wrong ?
If I had a solution to that delimma I might be quite rich by now, haha.
There is no great scalable terpene extraction technique yet. For carts i would recommend just buying terps and reintroducing them after distillation
couple things on that
so basically - a lot of your terps will be āstuckā in your ethanol, and any terps you separate with practically any application of heat will cause them to degrade, and smell like shit. if you dont believe me, go smell a cold trap 
Great advice, Iāll need to evaluate the legality with Health Canada as Iāll become a licensed producer shortly.
Great advice, where did you learn all that ? Do you have a great book on the topic to recommend ?
Based on your comments, what do you think will be the best approach to extract the terpenes with less damage ?
Something to also consider is that terpenes recaptured during distillation will almost always smell terrible. As @YeahBet said, many of these compounds are very delicate and exposure to oxygen/UV in the presence of high heat and vacuum will convert them into very undesirable smelling compounds.
I would also agree with what @ExTek90 said, if there was an easy foolproof method to extract terpenes with CO2 then easily transition the material into a cryo-ethanol extraction process EVERYONE would be doing it. CO2 extraction provides the most pure and representative terpene profiles from flower, and ethanol provides the fastest and most efficient cannabinoid extraction.
The easiest way to accomplish CO2 terpenes ā cryo-ethanol is run your material for terps in a CO2 extraction machine, remove biomass, then run it through your cryo setup. This is pretty labor heavy for the relatively small amount of terpenes you will extract (typically 1-2% depending on starting biomass), however finding ways to speed up the loading/unloading of the CO2 vessel will help.
I wish I had a book to recommend on canna-chemistry, but unfortunately this is a new field and good books take a long time.
Me personally, I paid some fine folks at a private university way way too much money to teach me forensic science, which led me to chemistry itself, and finally organic chemistry. community college is what the smart people do 
co2 will extract your compounds of interest, and a skilled operator on a good co2 system will know how to keep it from extracting things you dont want, or be able to separate impurities with ease. no worries about solvent either.
-80C with propane at a 1:2 biomass to solvent ratio
microwave assisted for terps separation + cryo ethanol extraction is the key for a TRUE whole plant extract