Cannabis winterization equipment can be one of the most expensive parts of any cannabis extraction system. Your not only dealing with the equipment itself but also the significant amount of power consumption it can take.
- A standard -10F chest freezer.
- 10 liter Dewars for storing liquid nitrogen.
- Liquid nitrogen.
2 steps of using liquid nitrogen for the cannabis winterization process
Start by storing all solvents and material in the chest freezer, this will save on nitrogen. Buy enough liquid nitrogen to last a couple of days so it doesn’t evaporate. Storing in the freezer will help.
- When ready to run, pour the total amount of solvent plan into an adequate container and add the liquid nitrogen until it reaches the desired temperature. Typically -40F is as cold as you need. Anything below -60F is just being wasteful. 0.5 liter per gallon when the starting temp is -10 will typically do the job.
- Chill the material. Since won’t be able to pump the liquid nitrogen will need to chill your material before loading it into your machine. With the material in an adequate container, pour the liquid nitrogen directly into the material little by little and stir until the desired temperature is reached.
3 steps to winterize extracted CO2 oil
- Dilute CO2 oil in ethanol. Somewhere around 5 gallons per pound of oil should be good. Make sure the oil is fully dissolved. To ensure dissolving, it is beneficial to do this step at room temperature.
- Chill the solution. Can place the solution in your -10 chest freezer overnight to pre-chill or if in a hurry, go directly with the liquid nitrogen. Be aware that chilling 5 gallons of solution from room temp all the way to -40F may take closer to 4 liters per gallon.
- Filter out the coagulated fats and waxes
Using supercritical CO2 fractionation to skip winterization altogether
With some supercritical CO2 fractionation techniques, winterization can be avoided entirely. But there are more factors to consider than simply avoiding a process bottleneck:
- This requires uniquely high-quality feedstock. High-potency, terpene-rich cannabis feedstock will yield a crude extract containing a high cannabinoid and terpene content that may not require winterization.
- Reducing particle size will increase the mass of feedstock that can fit into a given volume and increase the extraction efficiency by reducing the distance the solvent must travel to reach the center of a particle.
However, reducing particle size ruptures plant cells and exposes their interior contents to the solvent. This increases the likelihood of coextraction of undesirables, which require removal using winterization.
- Terpenes are highly miscible under the conditions created by cold, low-pressure CO2. This is great unless the goal is cannabinoid extraction in conjunction with terpene extraction. The solubility of major cannabinoids in CO2 using these parameters is low. More solvent contact (and time) is needed if cannabinoid extraction is the goal.
So in addition to being a cost-prohibitive process, supercritical CO2 extraction with the goal of avoiding the winterization bottleneck is also a highly goal-specific approach. It is not widely deployable across the industry.
Works Cited: How to winterize an ethanol extraction without a chiller or cryo freezer Vacuum Filtration For Cannabis Winterization