Color remediation of extracts can be accomplished with different techniques often referred to as polishing or scrubbing. Chromatography appears to be the most effective, versatile technology for this (and any) purification purpose. That said, chromatographic color remediation is not without its controversy.
Extractors working with hydrocarbon and ethanol solvents may be familiar with the color remediation column (CRC), which is an additional inline column packed with filtration media (e.g., silica, activated bleaching earth, etc.) that target dark colors. Some filtration media strip out cannabinoids in addition to color. Increased residence time, therefore, creates a tradeoff – do you want to remove pigmentation at the expense of cannabinoids?
GW Pharmaceuticals holds a US patent for “preparing cannabinoids in substantially pure form starting from plant material” that relies on chromatography for purification and quantification to produce “clear colourless solutions” of cannabinoids. As one specific example, the inventors mention that cannabidiolic acid (CBDA) should be a pale yellow crystal; extracts should undergo column chromatography then flash chromatography for additional purification as needed.
Orochem Technologies, Inc. also holds a US patent for the purification of cannabinoids from “dried hemp and cannabis leaves.” The invention is a “novel chromatographic scheme” relying on simulated moving bed technology with multiple columns and inlets/outlets that allow for continuous purification. A zone is dedicated to decolorization in the model.
The legitimate extractor employs purification technology to make products safer and better for the consumer. However, extract color is traditionally associated with quality; putrid green does not befit shatter, for example. Unscrupulous operators might convert old, brown cannabis into translucent, desirable gold extract and vend it as a top-shelf product. This represents an act of deception towards the consumer. Further, the ability to remediate color alone to confer the appearance of quality is dangerous.
Other interesting concerns include residual adsorbents; should we be testing for them? Should we indicate that a product has undergone color remediation to the consumer? Should such products, like refurbished computers, be available but discounted? The technology marches on. Testing and transparency remain key tools for brand trust.