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Efficient Extraction of Cannabis Plant Material

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In preparation for SFE processes, the Universal Cutting Mill PULVERISETTE 19 is utilized for the fine milling of the cannabis plant. The process of efficient and precise particle size reduction is a way to optimize oil output and formulation.


Even today, the rapidly-growing field of cannabis extraction has a number of process inefficiencies that can be easily overcome. One of the bottlenecks frequently encountered is the cannabis plant material’s packing density, or lack thereof in the extraction vessel.

A situation of low packing density creates a decrease in extraction efficiency and thus increases the variability of the output. While the packing density for non-milled cannabis plant material is generally in the range of 100-125 g/L, milled material packs have a density of 225-250 g/L.

An Efficient Tool for Comminution

An efficient tool for the quick comminution of large volumes of cannabis plant material to a precise particle size is the FRITSCH PULVERISETTE 19. Through this process, plant material is fed into the PULVERISETTE 19 through a large funnel, thus creating fast throughput.

Meanwhile, for precise particle sizing and the prevention of system clogging, the negative pressure in the milling system enables a continuous flow through the cutting rotor and the selected sieve cassette. The high throughput – up to 60 L/h – is supported by large collection vessels that have a capacity of up to 10 liters.

Further, fast processing is supported by unrestricted accessibility of the cutting chamber, by the quick removal of cutting rotor and sieve cassette, and maintaining a generally easy-to-clean grinding chamber.

The Task

This article describes the general process employed at OutCo for sample preparation in the SFE production operation. The article includes particle size distribution data as well as experimental data on extraction yield increases due to particle size reduction.

The Results

After testing, seen in Figure 1, the 2 mm screen size was chosen, since it enables a high packing density, increased extraction speed and optimized oil constitution. Further, it also allows the operator to constantly feed material directly into the mill, thus increasing work efficiency. For narrow particle size distribution, a blade speed of 300 rpm was considered optimal.

Extraction efficiency for different particle sizes. All other inputs are identical, e.g. type of material, weight of material (2.0 kg), and extraction parameters, like temperature (34 °C), pressure (124 bar), and run time (6 h).

Figure 1. Extraction efficiency for different particle sizes. All other inputs are identical, e.g. type of material, weight of material (2.0 kg), and extraction parameters, like temperature (34 ˚C), pressure (124 bar), and run time (6 h).

Further, this low blade speed can avoid thermal damage and sample loss of volatiles. It is also crucial to ensure that the moisture content of the material being milled is dry – i.e. below 15% – in the absence of which, the milling sieve will clog due to moisture. In order to prevent the buildup of chlorophyll and cannabis residue, an entire extraction load of 4.5 kg can be milled before stopping the machine to clean both the sieve and behind the milling wheel.

In the absence of a single cultivar to facilitate a full extraction run, the FRITSCH mill can be used to homogenize a blend of strains. Moreover, strains selected for a blend need to have complimentary flavor profiles and can also be chosen to enhance therapeutic effects.

Additional Applications

The other application use cases of OutCo are for sample preparation for rosin pressing as well as milling of flower for pre-roll production. In these cases, it was discovered that different particle sizes optimize draw behavior or item stability.


The FRITSCH Universal Cutting Mill PULVERISETTE 19 is a critical partner in supporting OutCo’s extraction operations by enabling the rapid milling of powders with precise particle size distribution and minimal degradation of raw material.

Source: Dr. Markus Roggen, Complex Biotech Discovery Ventures, Vancouver, Canada
Blake Grauerholz, OutCo, El Cajon, California, USA

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