One of the most critical steps in terms of making a clean cannabis product is CBD winterization. If you’ve ever wondered what that means, click to learn more! Winterization is an important step in oil purification, including cannabis extracts, that allows for the removal of inactive compounds.
What is CBD winterization?
There are many steps to processing hemp into a consumer-level product. One of the most critical, in terms of making a clean product, is winterization. No, this isn’t what your dad does to the lawnmower every fall. Winterization is a process that removes undesirable elements extracted from hemp, for example, fats, waxes, and lipids leaving behind clean, consumable CBD oil. Without CBD winterization, these unwanted materials would cause the final product to be cloudy, darker, and have an unpleasant taste.
What steps come before the winterization of oil?
The winterization process starts with raw extract straight from our CO2 machine (see photo below). This CBD crude oil contains all the essential parts of the hemp plant except for the actual plant material itself. CBD, minor cannabinoids, terpenes, fats, waxes, and lipids are all part of this viscous liquid. Crude oil extracted from a CO2 machine will have an attractive, light color to it, especially compared to alcohol extracted oil, which will have a dark, sludge-like appearance.
What is CBD Winterization?
The CBD crude oil is combined with 200 proof alcohol and stirred vigorously until completely mixed. The alcohol is used to thin the crude oil out, as the desirable parts of crude will go into solution with the alcohol while the undesirable parts will coagulate and freeze allowing them to be filtered out. The mixture is then placed in a deep freezer at below-zero temperatures. Once it has time to freeze it looks cloudy and is ready for filtration. The next step is to place the mixture in vessels that use paper filters to remove the frozen fats, waxes and lipids. The actual CBD oil remains with the alcohol solution and passes through the filter while the frozen undesirable parts are caught by it. The photo below shows what a filter will look like after the solution passes through it. When properly winterized, the filters will catch all of the frozen plant waxes from the oil, leaving them sitting on top. Once the pass is complete, the filters and waxes are discarded. The clean oil flows through the filter into a collection vessel where it is refrozen for more passes. We winterize multiple times just to make sure that our oil is 100 percent clean!
So wait, even though the winterized oil is CO2 extracted, it will still contain alcohol?
Nope! The alcohol is just used to thin the CBD oil in order to properly filter it. Once it’s been filtered and the undesirable elements have been removed, it’s time to remove the alcohol. This is done with a piece of equipment called a rotary evaporator (rotovap). This is CEO Craig Henderson, who started refining hemp from the garage of his home, using a rotovap in the early days of Extract Labs. This bad boy is an efficient way to quickly distill the alcohol out of the solution. The bulb spins in a hot water bath while the system is under vacuum, allowing the alcohol to evaporate out while leaving the winterized oil spinning in the bulb. The alcohol vapors then travel up to the chiller coils where they condense into a liquid and drip down for collection. The alcohol is then recycled into our process. Once the rotovap is done with a work order, the spinning bulb will contain only clean winterized CBD oil. The winterized CBD is then ready to move on to the next phase of the process. From here, the winterized oil will be formulated into tinctures or it will move to our distillation department for further refinement.
Cannabis / Hemp Winterization
Winterization is an important step in the purification of oils-including cannabis extracts-that allows for the removal of inactive compounds like fats, waxes, and lipids.
Precipitation of inactive compounds
Removal of unwanted compounds and refinement of cannabis extract
Reclaim solvent to perform further extractions, winterization, or other post-processing techniques
Polish and activate crude oil for further refinement
Purification into a highly concentrated and refined cannabinoid oil
CBD isolate is used for herbal supplement and end-product applications
THC, heavy metal, pesticide, and color remediation
Preparation into tinctures, topicals, vaporizer cartridges, water-solubles, and other consumer focused end-products
Crude oil is extracted directly from plant material
Buchner Funnel Kit
Our Buchner Funnel Kit helps you effectively perform vacuum filtration at a small scale. The kit includes a Duran Filter Flask, a Porcelain Buchner Funnel, and a full Filter Adapter Set for creating a vacuum-tight seal.
The kits are available in four different flask sizes; 5L, 10L, and 20L.
5L, 10L, 20L, 20L Multi-Funnel
Duran Filter Flask, Porcelain Buchner Funnel, Filter Papers
M.W. Watermark Filter Press
Dramatically improve your filtering process while increasing capacity with these large-scale filter presses.
We carry a selection of industrial plate filter dimension sizes and a range of capacities, to fit the ever-changing needs of our customers.
- FP-320 – (12.5″ x 12.5″) (Min. 2.8L to Max. 14L)
- FP-470 – (18″ x 18″) (Min. 14.2L to Max. 113L)
- FP-630 – (24″ x 24″) (Min. 57L to Max 342L)
Multi-plate Positive Pressure Filtration
Air-driven Diaphragm Pump
The Importance of Winterization
Winterization is a vital step in the purification of oils, including cannabis extracts. Winterization allows for the removal of inactive compounds like fats, waxes, and lipids. This process can be performed in a few different ways but what each has in common is the use of cold temperatures to facilitate precipitation of the undesired compounds. The resulting solids are then removed via filtration.
Winterization is most commonly performed as a post-processing step, but there are other techniques that can also be used to keep cannabis extracts free from undesired compounds. Below, we will expand upon winterization in cannabis processing and its effects on end product creation.
Winterization is a key step in the chain of cannabis processing. It creates clean crude extracts that are free of fats, waxes, lipids, and other inactive compounds. Those compounds contribute a poor flavor and aroma to end products and can also cause potential health risks from ingesting them. Winterized extracts are more sought after by the market, and while they take a few extra steps and pieces of equipment, they will provide you with higher-quality products to bring to market.
Winterization In Post Processing
Winterization is performed after the initial extraction process. The crude extract is dissolved in a solvent, commonly ethanol, and the solution is placed in a freezer. The colder the temperature, the faster fats, waxes, lipids, and other inactive compounds will precipitate from the solution.
Freezer, Chest Style
Low-Temperature Freezer, Chest Style
Upright Freezer (-40°C)
Ultra Low, Upright Freezer (-40°C to -85°C)
Lab Freezer, Upright Style (-15ºC to -30ºC)
Ultra Low Freezer, Chest Style (-40°C to -85°C)
The precipitate will flocculate together and form a large, fatty-looking mass suspended within the solution. The solution must then be passed through a filter to remove the solidified fats and waxes. For small-scale processing, filtration is easily accomplished with a vacuum-assisted Buchner Funnel. At larger pilot-and-industrial scales, Filter Presses, Lenticular Filters, Bag Filters, or other methods may be used.
Buchner Funnel Kit
FP1 Filter Press
4 Stage Lenticular Filter Skid
The freezing and filtration steps are often repeated multiple times to fully remove all inactive compounds. After the undesired components are fully removed, the crude extract must be separated from the solvent by evaporation. This may be performed in rotary evaporators, falling film evaporators, recovery membranes, and more. This process creates a clean and appealing crude extract that can be turned into many marketable end products such as high-quality distillate, isolate, edibles, and topicals.
Inline Winterization & Alternatives
While not technically winterization, there are other methods for keeping extracts clean from waxes, fats, and lipids. These may be performed through control of variables, inline with extraction, through specialized membranes, or by introducing additives to induce precipitation.
In closed-loop hydrocarbon extraction systems, solvent is often injected into the system at an ultra-low temperature. As the solvent washes over the cannabis plant material, it does not extract the unwanted inactive compounds due to the effect of cold temperatures on solubility. This reduces post-processing steps and allows the extraction process to create a desirable end product without additional equipment for winterization.
Some closed-loop extraction systems also have a secondary column that performs inline winterization. The secondary column holds only the crude extract solution, which is then chilled to an ultra-low temperature. This is followed by a stack of filters that remove any precipitated fats and waxes. While this is inline winterization, it is often referred to as “dewaxing”.
The same temperature dependence on the solubility of a solvent also applies to ethanol extraction. When the ethanol solvent is properly chilled prior to the extraction, it will not dissolve fats, waxes, and lipids from the plant material due to the extremely cold temperature. Similar to the secondary column in the closed-loop example above, winterization may also be performed inline immediately following ethanol extraction by channeling the crude extract solution into a secondary vessel that chills to an ultra-low temperature.
After chilling, the solution is forced through an inline filtration system to remove the precipitated compounds. This reduces possible contamination by never exposing the solution to the atmosphere.
Membrane filtration is another method of dewaxing and an alternative to winterization. This method removes fats, waxes, and lipids from the solution but does not require ultra-low temperatures. In fact, this method can be done at room temperature in most cases. Membrane filtration is achieved by permeation of the solution through the membrane and is often much faster than standard filtration styles due to the shape of the membrane and backpressure of the solution.
Why Choose Lab Society?
We’ve been at the forefront of the cannabis processing industry for many years now. And we’ve helped countless businesses and labs just like yours grow and become profitable. Let us create a tailored solution to fit your processing needs. When it comes to winterization, we have the expertise and equipment selection you need to consistently produce cannabis oil at any scale, with any budget, and for any operational capacity.