(This article is part of an ongoing series on extraction techniques. Join us at monthly meetings in Los Angeles, for tips and traps on extraction, new techniques, how to increase yields, and lessons from the experts. It’s ALL ABOUT EXTRACTION!)
Four temperatures parameters.
Terpenes are a valuable product captured the extraction process. Not controlling temperatures through the extraction will cause you to lose terpenes. There are four temperature parameters that need to be controlled in live resin extractions – fresh plant materials, butane, column, and purging temperatures.
Freezing live plant materials under inert conditions.
Live resin requires low temperatures to extract cannabinoids and terpenes and leave behind water and plant waxes. Since dry ice and ethanol are required for almost every step, it makes sense to use it for flash freezing the plant material. This is done by filling vacuum bags with fresh plant material in a way that maximizes surface area. Once filled with plant material, the bags are filled with dried CO2 gas to purge out the humidity from the room. The bags are vacuum sealed, dipped into a dry ice bath until fully frozen, and are then made ready to fill into a prechilled column.
There are many ways to freeze plant material. Choose the one that works best for you.
Cooling your butane with a condensing coil.
Control your butane temperature before it comes in contact with the plant material. If you don’t, your freshly frozen plant materials will thaw from the warm butane, and start to release plant lipids. Pass your butane through a condensing coil that is submerged in a dry ice/ethanol bath – on average, the dry ice bath will cool the butane down anywhere from -20C to -50C. The cooling capacity, or rate of cooling, is dependent on the size of the bath and the amount of dry ice added to it. Once cooled down, the liquid butane passes into your packed column and the extraction begins.
Temperature control at the column is key to long soak times.
A commonly missed point is that the column must be frozen in the freezer prior to extraction. Do this, and you’re one step ahead of the game.
A problem with long soak times is that the frozen plant material can be warmed up if the column temperature is not controlled. This causes the water that’s locked up in the solid phase (i.e. ice) from plant cells to release water, water-soluble phytochemicals, and plant lipids/waxes.
After the cooling coil, butane temperature needs to be controlled at the column. Keeping the column at a temperature less than -20C (optimally -30C to -40C) ensures water and waxes do not contaminate the extract. The column temperature can be controlled by a dry ice/ethanol bath; it can be connected to a cryogenic pump or just be an open sleeve/cylinder filled dry ice and ethanol. If dry ice isn’t available, an ice bath will improve your extractions.
Transferring to thin film and purging.
You’ve finally got your live resin extract in the collection chamber of your extractor. Live resin extracts are low viscosity – the additional terpenes decrease the internal friction of the liquid. Pour the extract onto silicon mats, then scrape out the collection chamber with a silicon spatula and transfer it onto a second mat. You’re now ready to purge.
Live resin purging – temperature and time.
Two important components in any chemical reaction are temperature and time. Higher temperatures cause loss of terpenes, but decrease the purging times to boil off all the butane. Keep your purging conditions below room temperature and not much below 5C. This preserves terpenes, but is still above the boiling point of butane. To make up for the lower temperature, increase the amount of time spent purging to 5 days. This is the simplest process to preserve your terpenes, and make your live resin runs worthwhile.
General purging tips.
A favored way of purging is to heat the extract up to it’s purging temperature for 30 minutes without pulling a vacuum. Once the oil is up to your desired purging temperature, you can pull a full vacuum. Purging times vary from strain to strain, but you can follow the bubbles to see when your extract is purged. The purging has nearly completed when the major bubbles of butane stop forming – those bubbles are typically large and burst when they reach their maximum size. You’re looking for the point when the bubbling slows down and only small bubbles form. At this point, you can dial in your process with residual solvent testing at your local laboratory to confirm when your extract is fully purged.
Properly controlling temperatures of fresh plant materials, butane, column, and purging will improve your process. There are multiple benefits at each step, that when combined create perfect conditions for preserving the essence of the fresh plant – the terpenes. Not all starting materials are worthy of making live resin. When you do have good starting materials, you will be rewarded with knockout flavor and taste that would have otherwise been lost to the atmosphere. Follow these steps and enjoy the experience.
(This article originally appeared on Hemphacker.com About the author: Andrew Samaan is President of Orion GMP, which helps companies through the process of meeting international GMP Standards, by Design, and builds processes from the ground up to meet GMP standards and integrate lean manufacturing into businesses. For more information, please visit: http://oriongmp.com/)