Cannabis vs. Coffee

In their work, Dr. Roggen, Blake Grauerholz, and colleagues first set out to study the impact of particle size and consistency of the starting material on recovery yields of cannabinoids and terpenes. In a first set of experiments, a homogenous mixture of whole plant material was ground into multiple samples ranging from 1 mm to 10 mm using a FRITSCH PULVERISETTE P-19 Milling System. In parallel, a mixed particle size sample produced using a food processor as well as an un-ground sample were analyzed. The RPM of the milling system was also varied during testing, in order to determine if there was any thermal degradation of compounds resulting from increased rotor speed. Lab testing was performed on pre- and post-milled material to determine recovery yields of terpenes and cannabinoids. Results indicated that recovery yields of cannabinoids and terpenes increased as the size of the milled particles decreased. Furthermore, milling RPM of the P-19 had minimal effects on decarboxylation or thermal degradation of compounds. This is consistent with the engineering and operational functionality of this device and the focus on heat load and temperature mitigation.

The act of coffee grinding provides access to internal compounds within the cavities of the beans. The resulting exposure of increased surface area within the beans promotes extraction of the compounds. The size and the consistency of the coffee grinds, as well as the duration and precision of the process, have significant bearing on the success of extraction. Smaller size particles slow down the flow of water and increase contact time between the grinds and the water.
Higher particle consistency results in better integrity of the extraction vessel, less channelling, and other effects. Whether pour over, flow, or pressurized extraction, the extraction efficiency is paramount in attaining that perfect cup of brew.
A further set of experiments by Dr. Roggen’s group focused on the impacts of particle size and consistency on cannabis extraction efficiency. A select range of particle sizes (2 mm, 6 mm, and 10 mm, along with controls) were used for CO₂ extraction under typical production parameters. The effects of milling were determined by analysis of cannabis oil yield and composition.
Results indicated that finer, more uniform particle sizes provided better precision in extraction. Furthermore, smaller particle sizes resulted in higher quality and purity of cannabinoid fractions in the extracted product. Un-ground samples, on the other hand, offered minimal precision and demonstrated greatly reduced extraction yields compared with milled samples. Espresso beans are typically ground to a fine consistency and packed tightly for extraction. Rapid extraction with hot, pressurized water gives rise to a highly concentrated, strong “shot” of coffee. In theory a tight, uniform particle size distribution should allow more cannabis material to be packed in an extraction column. This is turn should lead to increase sin extraction yield.
To test this, the output of the PULVERISETTE 19 milling system was examined, and the particle size distribution was measured using the FRITSCH Laser Particle Sizer ANALYSETTE 22 NeXT. Results showed a sharp peak at 1 mm, with minimal secondary peaks, indicative of a tight size distribution. Further investigations of milled and un-milled cannabis within the extractor vessel demonstrated that indeed the packing density has a significant effect on total recovery.