Cannabis Extraction Industry Blog

Cannabis Winterization & the Extraction of Ethanol

January 9, 2020

A temperature-based cannabis refinement process

Cannabis Winterization

Winterization – not to be confused with parkas and snowplows – also called ‘de-waxing’, is a key step in the purification of cannabis concentrates. After the extraction phase, cannabis resin remains in a “crude” format, not sufficiently free of unwanted organic compounds to be developed into products like tinctures and edibles.  Two of the compounds still present are plant lipids (fatty acids) and waxes. Unless removed, their presence can lead to products with a muddied appearance, less amenable for the end-user; waxes can make edibles difficult to digest, and, along with lipids, can leave residues and unpleasant tastes when vapourized. At MediPharm Labs, where our aim is a product of the highest quality and purity, winterization to remove fats and waxes is crucial. 

Ethanol Extraction System

During the winterization process, crude cannabis extract is first diluted with ethanol. The mixture is then placed in a freezer set at a very low temperature – hence the term “winterization”.

In grade school science class, we learned that different substances stay soluble at different temperatures. For example, when a cook cools freshly-made soup, fats break out of the soup solution, rise to the surface and solidify in the colder temperatures, at which point the cook can skim them off. Winterization is not all that different. The lipids and waxes turn to solids in the freezer’s cold temperature, separate out and sink to the bottom. Meanwhile, the dissolved crude extract and the ethanol stay in liquid solution and rise to the top. Much like a skilled chef, the production technician can now filter out the lipids and waxes with the help of a cellulose filter liner and a vacuum-pumped filtration device. From here, the extraction technician removes the ethanol, using a machine called a rotary evaporator, leaving a highly concentrated resin, with a consistency something like molasses.

Crude Cannabis Extract

To learn more about our processes, please check out our article “Supercritical CO2 Extraction Explained: What’s so super about supercritical CO2 extraction?”

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