Winterization

Winterization is a refining step that chills a crude extract dissolved in a solvent so that waxes, lipids and other fats solidify and can be filtered out.

Crude hemp extract, particularly from carbon dioxide extraction, carries plant waxes and fats that make it cloudy, thick and prone to separating. Dissolving the extract in ethanol and holding it well below freezing for a day or more causes those materials to precipitate, after which the liquid is filtered and the ethanol removed. The result is a cleaner extract with higher cannabinoid concentration.

The step affects texture, clarity and stability more than cannabinoid identity, though some terpenes are lost along the way. Because ethanol is introduced, winterized extracts are subject to residual solvent testing even when the original extraction used carbon dioxide. On a certificate of analysis the process leaves no direct trace; its effects are seen indirectly in a higher potency percentage and, when done well, an ethanol result below the reporting limit.