Sweet Mary’s terpenes, terpenoids, and cannabinoids dissolve readily in fats and oils, allowing us to use them (fats and oils) for both extraction, or simply as a menstruum for delivery.
Animal fats like butter and lard work, as well as vegetable and nut oils. The following is a non-exclusive list, of just the ones that we’ve tried:
Hemp Seed Oil
The vegetable and nut oils are non-polar and non-water soluble, so aren’t prone to pick up water, water solubles, or polar elements like the anthocyanin plant pigments/glucosides, or chlorophyll.
Like any solvent there are limits to how much of a given solute they can hold in solution and in a perfect world or heaven it might be higher, but 30% saturation is probably a reasonable average here on planet Earth. As they can’t be subsequently distilled off at a temperature that isn’t destructive to the concentrate, that saturation level is about all you can expect when using them for extraction.
On the other hand, the oils will mix at any ratio with cannabis essential oils, if you heat them both to molten state and simply mix them together.
The difference is that as a solvent becomes more saturated, it loses its solvent properties, and so things slow to a crawl long before stopping altogether.
Another attendant issue is that the undissolved material interfacing with the solvent is also losing purity, so that the boundary layer between the material and solvent becomes a highly saturated solvent in contact with partially dissolved material, slowing or halting the process even before average saturation is achieved, unless you constantly remove those boundary layers.
Shaking, stirring, or vibration are examples of methods typically used to keep the boundary layers in check.
Some higher potency is achievable by cascading, which means taking the oil from the first extraction and using it to extract more fresh material. It won’t do a good job of extracting it, so it will require follow up extraction to glean the balance, but it will increase the concentration in the solvent some.
Here is the smoke point of some of the different oils:
|No||Fats & Oils||Smoke Point||Ratio Omega-6/Omega-3|
|1||Unrefined flaxseed oil||107°C||225°F||1:4|
|2||Unrefined safflower oil||107°C||225°F||133:1|
|3||Unrefined sunflower oil||107°C||225°F||40:1|
|4||Unrefined corn oil||160°C||320°F||83:1|
|5||Unrefined high-oleic sunflower oil||160°C||320°F||40:1|
|6||Extra virgin olive oil||160°C||320°F||73% monounsaturated, high in Omega 9|
|7||Unrefined peanut oil||160°C||320°F||32:1|
|8||Semirefined safflower oil||160°C||320°F||133:1|
|9||Unrefined soy oil||160°C||320°F||8:1|
|10||Unrefined walnut oil||160°C||320°F||5:1|
|11||Hemp seed oil||165°C||330°F||3:1|
|13||Semirefined canola oil||177°C||350°F||2:1|
|14||Coconut oil||177°C||350°F||86% healthy saturated, lauric acid 66% medium chain triglycerides (MCTs).|
|15||Unrefined sesame oil||177°C||350°F||138:1|
|16||Semirefined soy oil||177°C||350°F||8:1|
|17||Vegetable shortening||182°C||360°F||mostly unhealthy saturated, Trans Fat|
|18||Lard||182°C||370°F||mostly unhealthy saturated|
|19||Macadamia nut oil||199°C||390°F||1:1|
|20||Canola oil (Expeller Pressed)||200°C||400°F||2:1|
|21||Refined canola oil||204°C||400°F||3:1,|
|22||Semirefined walnut oil||204°C||400°F||5:1|
|23||High quality (low acidity) extra virgin olive oil||207°C||405°F||13:1|
|27||Virgin olive oil||216°C||420°F||13:1|
|28||Almond oil||216°C||420°F||Omega-6 only|
|29||Hazelnut oil||221°C||430°F||75% monosaturated (no Omega 3, 78% Omega 9)|
|32||Refined corn oil||232°C||450°F||83:1|
|34||Palm kernel oil||232°C||450°F||82% saturated (No Omega 3)|
|35||Refined high-oleic sunflower oil||232°C||450°F||39:1|
|36||Refined peanut oil||232°C||450°F||32:1|
|36||Semirefined sesame oil||232°C||450°F||138:1|
|38||Refined soy oil||232°C||450°F||8:1|
|39||Semirefined sunflower oil||232°C||450°F||40:1|
|40||Olive pomace oil||238°C||460°F||74% monosaturated, high in Omega 9|
|41||Extra light olive oil||242°C||468°F||74% monosaturated, high in Omega 9|
|42||Ghee (Clarified Butter)||252°C||485°F||0:0, 62% saturated fat|
|43||Rice Bran Oil||254°C||490°F||21:1|
|44||Refined Safflower oil||266°C||510°F||133:1|
Besides smoke point and Omega ratios, there is also the important issue of personal taste. I suggest that you try a dropper of each of the oils that you are considering, to see how you like them.
After selecting an oil, the next step is to prepare the material for extraction by removing most of the moisture. We like to strip the fan leaves and hang the plant 5 to 7 days, or until the small stems will just snap. About 15 to 25% moisture content.
New material will have more residual monoterpenes and therefore the most flavor. Old desiccated material loses its floral undertones and eventually tastes like the remaining diterpenoids. Some folks prefer the hashy phenolic diterpenoid flavor, and in those cases older material works fine.
You can’t make chicken salad out of chicken manure, and what you end up is heavily influenced by what you start with, so as you might expect, oil extractions from prime bud are tastier than that from trim, and both are tastier than oil from fan leaves.
We made most of our oil from sugar trim leaves, which we processed as was, without further breaking them up, as they offered good access to their surfaces by the hot oil when stirred.
Once the hanging plants small stems can be snapped, if we coveted “whole plant” processing, we processed buds and sugar trim together, discarding only the fan leaves and stems.
As the buds don’t provide good access to the solvent, we either broke small volumes up into <1/2” chunks by hand, or larger amounts using a bud buster.
Once any sizing is done, we pack the material into a suitable container and cover it with about an inch of oil, with enough room left over for stirring without making a mess.
A suitable container can vary as to purpose, so for small batches that I make for myself, I use a stainless bain marie, in conjunction with a a Cuisinart electric fondue pot, as it has better low-end temperature control than a fry cooker like a Fry Daddy. I like using hot oil because there is no steam or water to replenish, and I can later decarboxylate the finished oil at 122C/250F in the same device.
Stainless bain marie container sitting in Cuisinart electric fondue pot
66C/150F is low enough to use canning jars as the suitable container and water as the heating medium, so conventional pots or canning pots can be used on stove tops as well.
Pan on stovetop
When using jars, after lightly capping them, we set them into an water or oil bath and bring the temperature up to 66C/150F. Setting a room temperature jar directly into a 150F hot oil bath, may induce cracking from thermal shock, especially if there are any hairline scratches on the glass.
Leave the lid off the boiling pot if you use water, so as to not force steam into the jar headspace. When I say lightly capped, I mean loose enough to vent excess pressure, but tight enough to build some pressure and to keep the water out.
We stir regularly with a wooden spoon as we bring it up to temperature. I mention wooden spoon because a metal one leaves microgrooves in the glass, which act as stress risers for thermal stresses to break.
After reaching temperature, we lightly cap and cook for about 6 hours, stirring about each thirty minutes.
We discussed boundary layers above, and keeping them removed maximizes dissolution rates, but allowing the material to soak and soften the remaining some first, shortens the time at temperature, because you will have the freshest solvent interfacing with the most concentrated solute.
There is also a line of thought that some of Sweet Mary’s goodness comes from within, vis a vis strictly all from her trichomes, so there are at least those two thoughts on where to proceed from here.
In both scenarios we remove the jars from the hot oil or water and in in the first we press the material to separate the oil from the solids, and in the second we allow it to cool to room temperature for further heat cycling and cooking to remove any further goodness.
To heat cycle in scenario two, allow the jar of material to cool to room temperature and soak overnight, before again bringing it up to temperature while stirring and processing another six to eight hours, with one cool, soak, and reheat in the middle.
At the end of the cook cycle, we press the hot material to separate the oil from the plant material using either a press, or a commercial potato ricer.
Commercial Potato Ricer
Ricer lined with 200 thread count material
Dump Jar into Ricer
Pressing out the oil
Decarboxylation. The oil is now ready to decarboxylate by placing it in a hot oil bath or oven and bringing it up to 122C/250F.
The carboxylic acids decarboxylate naturally with age and drying, and even young plants have a combination of THC-a and THC from natural decarboxylation. For that reason, we can never know the exact state of decarboxylation of the plant material.
In addition, decarboxylating the plant material itself before extraction in an oven, melts the trichomes and smears them over the plant material, where they are harder to dissolve later.
We prefer to decarboxylate oil tinctures after extraction, and use the CO2 bubble production from decarboxylation to identify our actual state of decarboxylation.
The decarboxylation process removes a COOH link from the THC-a molecule, which turns into CO2 and H2O. The CO2 is released in fine fizzy bubbles that reveal exactly what is going on at two points in the process.
One is at 70% decarboxylation, which is where the extraction curves peak and drop off from there, as does the peak THC levels obtained. See following two graphs:
Decarboxylation graph from Journal of Chromatography
The peaks on this graph are around 70% decarboxylation, and are readily identifiable on the 145C/293F and the 122C/252F peaks when watching bobble production .
When you hit the 70% peak at 145C/293F, bubble production abruptly falls off and is easy to see if you keep your oil stirred so that the bubbles break rather than float around on the surface.
When you approach the 70% peak on the 122C/252F curve, bubble production begins to rapidly fall off before peaking and then drops abruptly.
At 100% decarboxylation, there is zero bubble production and the product is less heady and more sedative than that remaining at 70% decarboxylation, but with peak (maximum) THC content.
The same heat that decarbs the carboxylic acids, degrades them to lower rotating groups ending in CBN. The total THC and CBD are actually less at 100% than 70% decarboxylation, because they break down into those lower groups with the added heat at a faster rate than they are replenished by decarboxylating the remaining carboxylic acids.
Read 10.1.1 Decarboxylation of Tetrahydrocannabinolic acid (THCA) to active THC article for a more complete discussion of decarboxylation.
Examples of assorted oil extractions
Student sample station from one of our 2013 classes
How to and why make Ghee instead of using butter?
Both the why and how to are straightforward. Reducing the polar elements from the butter before extracting, reduces the amount of polar elements like chlorophyll and water soluble elements that the extraction picks up from the plant matter.
Chlorophyll adds a greeeeeeeeeeeeeeeeeeeen taste, and some of the water soluble salts are bitter, so we avoid any process that extracts them.
As far as how, easy peasy. Simply melt the butter and skim off the stuff that floats to the top, leaving only the clear Ghee.