White Paper · 8 min read
Cold Ethanol Extraction: Process Guide
Cold ethanol extraction pulls cannabinoids and terpenes into chilled ethanol while keeping the solvent cold enough to limit co-extraction of unwanted plant lipids and waxes — the colder the ethanol, the more selective the wash. Decimal's centrifuge-based systems run this process at temperatures down to -40°C with cycle times of roughly 15 to 20 minutes. This guide covers how the process works, what temperature control actually buys you, and a pre-run checklist for consistent results.
How Cold Ethanol Extraction Works
Biomass is washed with chilled ethanol, which dissolves cannabinoids and terpenes while staying cold enough to limit how much plant fat and wax dissolve along with them. A centrifuge-based system like the 20.EX or 40.EX spins the biomass and solvent together, using centrifugal force to separate spent material from the ethanol solution far faster than a static soak.
The result is a crude ethanol extract that still needs winterization (a longer cold soak to precipitate remaining lipids and waxes), filtration, and solvent recovery before it's ready for distillation or further refinement.
Temperature Control and Cycle Times
Both the 20.EX and 40.EX are rated to run as cold as -40°C, with cycle times of roughly 15 to 20 minutes. Running colder generally improves selectivity — less fat and wax pulled into solution — at the cost of slightly longer chill-down time between runs. The right operating temperature for your process depends on your biomass condition and how much post-processing capacity you have downstream.
Cold ethanol is still a flammable solvent: Follow your facility's solvent-handling procedures and equipment manual for safe operation, storage, and recovery regardless of operating temperature. Cold ethanol reduces vapor pressure; it does not eliminate flammability.
Pre-Run Checklist
- Confirm the target run temperature and that the system has fully reached it before introducing biomass.
- Verify biomass is properly dried and free of foreign material that could affect centrifuge balance.
- Check that downstream winterization and filtration capacity can keep pace with your planned run rate.
- Confirm solvent recovery equipment is staged and ready before you generate crude extract that needs to wait.
- Log run temperature, cycle time, and batch weight for each run as part of your facility's process documentation.
20.EX vs. 40.EX at a Glance
| Spec | 20.EX | 40.EX |
|---|---|---|
| Batch size | Up to 20 lbs. per cycle | 40-lb. batches |
| Cycle time | 15–20 minutes | Roughly 15–20 minutes |
| Minimum rated temperature | -40°C | -40°C |
| EU-GMP design intent | Yes | Not currently flagged |
After Extraction: Winterization and Solvent Recovery
Crude ethanol extract still carries dissolved lipids and waxes that need to precipitate out before filtration. For the winterization and filtration equipment that fits into this step, see our winterization and filtration strategy guide.
Common Mistakes and Quality Risks
- Loading biomass before the system has actually reached its target temperature, which reduces selectivity for that run.
- Treating winterization as optional for a "cold enough" ethanol wash — cold extraction reduces co-extracted fats and waxes, it doesn't eliminate them.
- Running biomass with inconsistent moisture content, which throws off centrifuge balance and extraction consistency between batches.
- Skipping per-run temperature and cycle-time logging, which makes it much harder to diagnose a quality drift later.
Topics covered
- ethanol
- cold extraction
- centrifuge
- GMP extraction lab
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Frequently Asked Questions
Why does temperature matter so much in ethanol extraction?
Colder ethanol is more selective — it dissolves cannabinoids and terpenes while limiting how much plant fat and wax comes along with them. Running warmer generally pulls more unwanted material into the crude extract, which means more work at the winterization and filtration stage.
What's the difference between the 20.EX and the 40.EX?
Both are centrifuge-based ethanol extractors rated to -40°C with cycle times of roughly 15 to 20 minutes. The main difference is batch size: the 20.EX processes up to 20 lbs. per cycle, and the 40.EX handles 40-lb. batches.
Is cold ethanol extraction GMP-compliant?
GMP is a facility and process standard rather than a property of the extraction method itself. The 20.EX is designed to support EU-GMP facility compliance; whether your specific facility meets GMP or EU-GMP requirements depends on your full quality system, documentation, and room design.
Do I still need to winterize after cold ethanol extraction?
Yes. Cold extraction reduces how much lipid and wax co-extracts, but a dedicated winterization step is still standard practice for producing a clean crude extract ready for filtration and distillation.
See the winterization and filtration guide
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