Reproducible Cannabis Extractions Require Consistent Starting Materials

 In excerpt from a forthcoming book

To perform a reproducible extraction, there must be reproducible material going into the process. For example, particle size consistency and moisture content of the starting materials are bothvital factors.

It is essential to know the plant and where the target constituents are located in the plant. For example, CBDs are concentrated in the trichomes of the plant. Even with so many different strains, varying breeds, and selective hybrids, sample preparation considerations for the extraction are the same:

  • Drying – plants are typically hung and dried in atmosphere
  • Sizing – initial sizing is performed through a sieve to separate the buds from extraneous materials
  • Aging – the presence of oxygen and UV light over time plays a factor in potential transformations of the materials
  • Shredding – hand or machine milling, what is the optimal approach for the type of plant

Cannabis must be dried before the extraction. Undried plant material can be subject to mold. Moisture content of the feed can impact quality while water in the feed can dissolve into some extraction solvents, thereby possibly reducing the extraction efficacy. Finally, heating or aging of dried leaves prior to extraction can degrade some of the non-target compounds.

How long should the plants be dried? When is the plant ready? That all depends upon the desired compound. For example, you might want CBGA as one of the components in the final mixture, in which case, you would harvest early to be able to select the component before it is extinguished or used up.

During the drying process, it is essential to analyze the percentage of water as the fewer days required to properly dry the leaves before they go to the next stage of processing impacts productivity and profitability. Regular testing should be performed daily or every other day, to know exactly where you are with each crop.

An initial and important stage in cannabis testing is grinding and homogenization of the plant. The plant sample must be made homogeneous for test results to be representative. Homogenization requires the sample to be broken down to a form that can be mixed effectively. Typically, the sample material should be ground to a size of approximately 4 mm and thoroughly mixed.

A bottleneck often occurs during the packing of the material into the extraction vessel.The packing density, or lack thereof, impacts extraction efficiency. Low packing density leads to a decrease in extraction efficiency and increases in output variability.

The starting cannabis material should be carefully loaded into the extraction vessel in 4 or 5 stages, while tamping down the material between each stage to ensure consistent density. This will help to avoid channeling of the extraction solvent and loss of efficiency during the extraction.

Once the extraction is performed, it is helpful to examine the exhaust materials to determine the efficiency of the extraction. The color of the exhaust materials provides some indication as to the quality of the extraction. Clumping of the exhaust materials may indicate channeling of the fluids during the extraction which may have caused incomplete extraction. Examination of the bio mass may also suggest changes are needed to the extraction conditions or the way in which the materials were ground.

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