The third and final installment of this series reviews how processing parameters affect yields in extraction. Operating conditions, including extraction runtime and processing parameters, have a major influence on the yield obtained from an extraction.
There are many factors influencing yields in extraction. The first article in this three-part series presented a review of starting-material influence on extraction yields: the amount of starting material added to an extraction chamber, in addition to the content of compounds of interest intrinsic to that material, are important (1). Next, part II examined the effects of material preparation: a finer particle size provides better packing efficiency, as well as greater efficiency of solvent-matrix interactions (2). Here, the final installment reviews the influence of operating conditions, elucidating how extraction runtime and processing parameters affect yields in extraction.
Effects of Extraction Runtime
An extraction operation should maximize yield while minimizing runtime and operating costs required to achieve the desired result. Consider Figure 1: as an extraction is initiated, the amount of material of interest obtained versus time sharply increases to Point Q, the maximum amount of material of interest extracted per unit time. After this point, the return of material obtained versus time gradually decreases until there is no material remaining (the extraction reaches completion). (See upper right for Figure 1, click to enlarge.)
Three additional points are noted on the graph in Figure 1. Point P, the operating break-even point, defines the moment at which the extraction has recovered enough material to cover the costs incurred to allow operation for that extraction. Point S marks the position of the operating profit line along the extraction curve. The region between Point P and Point S is the profitability region; within it, the return from the product being extracted will more-than pay for all associated costs of the extraction. To the right of Point S, the costs of operation outweigh the return from the material obtained. The undefined Point R is the ideal point to halt the extraction. The precise location of Point R changes depending on factors such as the potency of the feedstock material, whether there is a finite or infinite amount of feedstock material to be processed, and the operation costs unique to each business.
Consider the example scenario outlined in Table I. (See upper right for Table I, click to enlarge.) Because of the way the general extraction curve is shaped, the runtime required to achieve a complete extraction may conflict with the cost of running the equipment or the facility. In this hypothetical production cost-revenue analysis, a day spent performing two extractions to 100% completion would bring $8000 in revenue, whereas carrying out three extractions to 95% completion would turn a profit of $16,500.
To ensure a business is profitable, an operation will want to exceed merely breaking even. There is no magic number for the time an extraction should be allowed to proceed. Rather, runtimes and return of material should be evaluated against facility operating costs as well as those incurred in refinement (post-processing) of the extract. A longer runtime may also provide access to one or more additional components of value or, conversely, may be associated with a higher concentration of undesirable material. It is up to each organization individually to establish the extraction conditions that, for them, make the return of operation worth the effort.
Along with runtime, processing parameters have a significant effect on extraction yields. In performing an extraction, an operator must choose the parameters that result in the highest yield of desirable components and the lowest yield of undesirable components. Furthermore, coextraction of desirable and undesirable components should be minimized to reduce downstream processing. In general, parameters that may affect extraction yield include temperature, pressure, and the solvent-to-feedstock ratio.
- K. Kulczycki and A. Godin, Cannabis Science and Technology 2(2), 48–50 (2019).
- K. Kulczycki and A. Godin, Cannabis Science and Technology 2(3), 56–57 (2019).
Krista Marie Kulczycki is a technical and scientific writer with Vitalis Extraction Technology in British Columbia, Canada. Aaron Godin is an application science manager with Vitalis Extraction Technology. Direct correspondence to: [email protected]
How to Cite This Article
K. Kulczycki and A. Godin, Cannabis Science and Technology 2(4), 66–68 (2019).