The Problem With Large Scale Ethanol Batch Extraction: Typically, large scale ethanol extraction has a number of drawbacks. Since recycled ethanol is imperitive to low cost processing operation, the dilution of the pure ethanol becomes compromised (water keeps getting added) which results in poor extraction efficiency. In addition, ethanol has poor turpene retention (turpenes become volatile and simply evaporate). Finally, many ethanol processors who do a quick-turn extraction, end up with lots of bitter green tasting chlorophyll. To filter out that, they use activated carbon filters (referred to as carbon scrubbing), which also filter out most of the valuable components ( source: Romano LL, Hazekamp A. Cannabis Oil: chemical evaluation of an upcoming cannabis-based medicine. 2013;7(1):1-11.)
“4 pitfalls of carbon scrubbing of cannabis extract
Carbon scrubs and other filter media for cannabis oil extracts
Carbon scrubs can be used to remove color from cannabis oil extract and distillate. Other materials are also used as filter media such as diatomaceous earth, fullers earth, bentonite, kaolinite and alumina silicate.
While filter media may remove color from [weed extracts}, it may also isomerize or destroy [***] and components [used to make isolate]. It’s heartbreaking to hear stories of $10,000 of high-quality crude extract accidentally converted into low potency distillate when using filter media.”