At a glance, modern extraction machines can seem a little mysterious: plant material is added to an extraction chamber, processing parameters are chosen, the extraction process is carried out, and an output of material is collected. Part I of this series examines the two main biologically-inherent starting-material influences. These include total mass of material loaded in the extraction chamber at the start of an extraction and the component makeup of the material with regards to content of compounds of interest. An extensive review of percent extraction efficiency calculations is also presented.
An extraction’s yield, that is, the amount of components of interest obtained from an extraction’s output, has three main areas of dependency. Spread across a three-part series, these will be discussed as follows. Here, in Part I, we discuss the influence of the starting material, performing extraction calculations and examine the two main biologically-inherent starting-material influences: the total mass of input feedstock to be extracted and the component makeup of that material. An extensive review of percent extraction efficiency calculations is also presented. In Part II, we will examine the impact of material preparation and consider the impact of physical preparation of the feedstock material. Finally, in Part III, we will discuss optimizing an extraction and the associated processing parameters. We will also investigate the impact of conditions of operation: total extraction time and processing parameters.
Influence of the Starting Material
Mass of Starting Material
The most intuitive variable with regards to yield is the mass of input material available for extraction. For example, given identical feedstock and extraction parameters, 100 kg of plant matter would be expected to yield around twice as much extract as the same extraction performed on only 50 kg of material.
This parameter is instinctive, but it is important to realize that starting-material-influence does not stop there.
Makeup of the Starting Material
A further major influence of the starting material on yields is the makeup of the material itself. To best explain what is meant here, consider the cannabis flower.
Components of Interest in Cannabis Flower
Suppose a recipe for a bulk batch of baked goods calls for the cannabinoids extracted from 100 kg of flower. This is a bit of an ambiguous recipe: what mass of cannabinoids can be obtained from this mass of starting material? Intuitively, there is an understanding that it is not 100 kg.
This understanding stems from basic knowledge of plant anatomy (Figure 1). For simplicity, the cannabis flower is divided into three contingents: the lipids, chlorophylls, and cannabinoids. This multicomponent nature is the first layer of the starting-material-makeup factor. If, say, the cannabinoids make up 20% of the flower’s mass, then the maximum possible mass that may be obtained from 100 kg of flower can be calculated to be 20 kg:
total mass × fraction of mass due to component of interest = total mass of component of interest 
total mass of flower × fraction of flower mass due to cannabinoids = total mass of cannabinoids 
100 kg × 0.20 = 20 kg 
It follows, then, that a 100%-efficient extraction would recover 20 kg of these desirables from the extraction process. If no other material were coextracted, a test of the material remaining in the extractor would see a total of 80 kg of residual composed of lipids and chlorophyll, with no trace of cannabinoids remaining.
Example Extraction Calculations
Calculating the percent extraction efficiency (%EE) is the best standard against which to evaluate the success of any extraction. There are two variations of the calculation that can be carried out (Figure 2). The theoretical %EE calculation assumes all mass of the component of interest extracted appears in the extract, with no loss; it is a measure of the mass of component of interest removed from the feedstock. The actual %EE calculation measures the mass of the component of interest present in the extract.
To verify comprehension of this calculation, consider following through the example extraction presented in Figure 2; 100 kg of cannabis flower composed of 20% cannabinoids and 80% lipids and chlorophylls is loaded into the extraction chamber (Figure 2a). At the end of the extraction, 40 kg of material composed of 5% cannabinoids and 95% lipids and chlorophylls remains in the extractor (Figure 2b); 60 kg of material composed of 30% cannabinoids and 70% lipids and chlorophylls is found in the collection vessel (Figure 2c).
In this example, no material is lost in the extraction process, and the results of the theoretical and actual %EE calculations match, at 90%. In cases where loss of material would occur (for example, small amounts of residual left in the extraction equipment), the actual %EE will fall below the theoretical %EE.
These calculations are important in evaluating the success of an extraction. They are, however, not trivial. The next portion of this section reviews several misconceptions commonly encountered when performing %EE calculations.