Understanding the Solvent-to-Flower Ratio in Hydrocarbon Extraction
Mastering the solvent-to-flower ratio in hydrocarbon extraction is definitely a challenge for many cannabis companies. Too much solvent can lead to unnecessary processing time and increased costs, while too little may result in incomplete extraction, impacting the quality of the end-product.
So, how do you achieve that perfect balance?
Truthfully, experimentation is a huge part of discovering the right ratio for the type of products you’re producing. However, understanding the factors that influence the ratio makes experimentation easier.
Factors That Influence the Solvent-to-Flower Ratio
Quality & Type of Cannabis
The potency, freshness, and purity of the cannabis material affect how much solvent is needed for extraction. High-quality, well-cured cannabis with a rich cannabinoid and terpene profile may require less solvent to extract these compounds efficiently. Comparatively, older or lower-quality materials with less bioavailable compounds will need a higher solvent volume to achieve similar yields. Contaminants and/or excess moisture will also impact the effectiveness of the solvent.
Additionally, the specific strain and its inherent characteristics will impact the ratio. Indica, Sativa, and hybrid strains have varying densities, resin content, and trichome distributions, all of which impact the extraction process. So, denser buds typically found in Indica strains may require a higher solvent ratio to penetrate the material thoroughly, while Sativa strains, which are less dense, may require a lower volume.
To make matters even more challenging, the part of the cannabis plant you process will also affect the ratio. Flower buds contain high concentrations of cannabinoids and terpenes compared to leaves or trims. Buds may extract more efficiently at lower solvent ratios, while less potent trim may need higher solvent ratios to pull out all available cannabinoids.
Like we said, it’s all about experimentation.
Target End-Product
The most common question we often ask cannabis companies is—what products are you trying to make? This is arguably one of the most critical factors not just for optimizing the solvent-to-flower ratio but also when selecting equipment and deciding which extraction process to use.
So, if you’re using hydrocarbon extraction, you’re most likely creating shatter, wax, budder, live resin, or terp sauce rather than tinctures, distillates, and edibles.
Out of these four end-products, which ones are you going to produce more of? Each type of extract has specific requirements. For example, high-purity extracts like shatter or crystals need a lower solvent-to-flower ratio. This lower ratio can provide a more controlled process that targets only the most soluble and desirable compounds, minimizing the extraction of waxes and lipids.
In contrast, full-spectrum extracts like live resin should capture a broader range of cannabinoids and terpenes to reflect the original profile of the plant, so a slightly higher solvent-to-flower ratio would be used to ensure more of the delicate terpenes and minor cannabinoids are dissolved and preserved in the final extract.
Then, you have waxes and budders with creamy, whipped consistencies. With these end-products, a higher solvent ratio can sometimes help in the agitation processes that result in these solid but malleable consistencies.
Solvent Type
Three primary solvents are commonly used in hydrocarbon extraction: butane, propane, and isobutane.
Butane typically requires a lower solvent-to-flower ratio because of its high solvency power, meaning that it can extract a significant amount of active compounds, even when used at lower volumes.
Propane is similar to butane but has a lower boiling point, which can lead to a faster recovery time. Propane is effective at extracting certain terpenes, which may volatilize at the higher temperatures used in butane extraction. Because of this, propane might be used in a slightly higher ratio compared to butane, especially if the goal is to maximize terpene preservation in the extract.
Lastly, isobutane can be used in ratios similar to butane but may be adjusted based on the specific extraction goals related to the purity and type of the targeted cannabinoids and terpenes.
Targeted Terpenes & Cannabinoids
Cannabinoids like THC and CBD have specific solubility thresholds in different solvents. If your primary target is a highly soluble cannabinoid, a lower solvent-to-flower ratio may be OK for extraction, but if you want to extract cannabinoids with lower solubility, a higher ratio may be needed.
Terpenes are more difficult to calculate in the ratio because they are more volatile than cannabinoids and can be lost if not carefully extracted. Because of this, solvents must be managed carefully both in terms of quantity and extraction conditions (like temperature) to prevent degradation or evaporation. Unfortunately, quite a bit of experimentation is needed to determine the right ratio. When experimenting, consider the volatility and solubility of the specific targeted terpenes and go from there.
Extraction Goals
Lastly, what are your goals? To scale production? To improve yield? We’ve highlighted some general tips for common goals below:
- Extraction Efficiency: Higher ratios might be used to gauge the maximum potential yield but may need to be adjusted to reduce solvent use without compromising the output. It really is a balance of getting the most out of each extraction without wasting solvent. Incorporating an automated solvent recovery system can also prevent wasted solvent.
- Product Quality: A lower ratio could be used here to minimize the extraction of unwanted compounds that could compromise the purity and taste of certain extracts.
- Scaling Production: In these situations, it’s important to optimize the ratio not just for yield but also for operational feasibility. Like we’ve already mentioned, you don’t want to waste precious solvent. When experimenting with the ratio, take into account the increased homogeneity of mixing and solvent contact with the plant material.
- Fast Production: An increased solvent-to-flower ratio can accelerate the process, but will also use more solvent. Consider how important speed actually is and if it’s worth the extra cost of using more solvent.
Challenges With the Solvent-to-Flower Ratio
As if the solvent-to-flower ratio wasn’t already complex, several challenges can be hard to overcome, including material inconsistencies, solvent inefficiencies, temperature and pressure control, and equipment capabilities.
Material Inconsistencies
Plant material can vary significantly in terms of cannabinoid and terpene profile, moisture content, and biomass density, and these variations affect how the solvent interacts with the plant material. The only way to really overcome this is to have stringent material assessment and pre-processing standards to ensure you’re continually working with consistent plant material, along with partnering with growers you can trust.
Solvent Inefficiencies
Solvents can degrade or become contaminated over time, reducing their effectiveness, which will impact how much solvent needs to be used in the extraction process. Because of this, you should regularly test solvent quality, replace degraded or contaminated solvents when needed, and implement solvent recovery systems.
Temperature & Pressure Control
Temperature and pressure are two extremely important variables in extraction. These variables also need to be optimized based on the targeted compounds. Fluctuations in these parameters can lead to inconsistencies, which is why many cannabis companies are looking toward advanced automation and real-time monitoring systems that can maintain these conditions consistently.
Equipment Capabilities
If you’re an up-and-coming cannabis company, do yourself a favor and invest in the right equipment first. The investment can initially seem significant, but you will see a cost recovery over time. With the right equipment, your process will become more efficient, and you won’t have to worry about potential operator errors.
Investing in the right equipment can also potentially help you in the future when federal regulations become more stringent. We won’t get into this here, but you can read more about our insights in this article. Ultimately, invest in equipment that you know will use solvent efficiently and provide consistent heating and pressure management, and be sure to look for UL and ASME ratings.
Measuring & Adjusting the Ratio
Once you find the optimal ratio, the extraction process becomes much easier, but finding that ratio, as we’ve already established, can be challenging.
Here are our recommendations for getting started:
- Start by running several test extractions under controlled conditions to establish a baseline ratio that works generally well for your typical batch of material. You can use analytical tools like HPLC to analyze cannabinoid and terpene profiles to ensure you’re effectively capturing the compounds you want.
- Run controlled experiments to observe how different ratios impact yield and quality. Make sure you keep the other variables (temperature, pressure, type of solvent used, material type, etc.) constant, and always document any output changes to better understand what ratios work and which don’t.
- If you want to scale your operations, you’ll need to do more testing because what works on a small scale might not necessarily work in larger batches due to differences in mixing efficiency and solvent contact time. In this situation, perform pilot runs on the larger batch and adjust the ratio as needed based on the results.
You may encounter several issues during your tests, like low yield and inconsistent quality.
If yields are consistently lower than expected, check for solvent quality degradation or contamination that might affect its efficacy first. If it seems fine, increase the solvent-to-flower ratio incrementally to see if it improves. If your end-products are inconsistent, especially in terms of cannabinoid and terpene profiles, adjust the extraction temperature and time along with the solvent-to-flower ratio, using finer temperature and pressure control to maintain the integrity of volatile terpenes if it’s a priority for your end-products.
How MACH Technologies Can Help
At MACH Technologies, we understand the challenges cannabis companies currently face. If you need help optimizing your existing processes, get in touch with our team today.
As a turnkey specialty equipment manufacturer, we can not only help you find the best equipment but also provide implementation assistance, training, and ongoing support. If you already use the hydrocarbon extraction process, our MHES unit (with ASME-stamped vessels) provides a consistent, industry-leading 10:1 solvent-to-flower ratio, up to 95% extraction efficiency, and can run 100% propane, butane, or a blend.
Please contact us today to learn more about these units or to get general advice for your existing process.