Why make an oily maceration?
Oily maceration is effective for retaining essential oils, waxes and resins. In addition to these specialist compounds, it is also effective for several vitamins (in a similar way to alcohol) and certain phenolic compounds such as flavonoids and pigments (but the latter are also soluble in alcohol and vinegar). Making an oily macerate yields a good aromatic and therapeutic oil that can be used directly externally, or as the primary component of an ointment or cream. In short, why use a simple oil when you can use an oil “pimped” with active plant ingredients?
Principles of oily maceration
We use an oil that’s stable enough (i.e. doesn’t go rancid too quickly) to extract certain active principles from a plant.
As with all liquid concentrates, we encourage contact between the solvent and the plant:
Oily maceration and liquid concentrate: are they the same thing?
In theory, an oily macerate is a liquid concentrate whose solvent is oil. However, we rarely see the term “liquid oil concentrate”, but rather “maceration” or “oily macerate”.
| Solvent | Specific name of liquid concentrate |
| Water | Infusion and decoction |
| Alcohol | Dyeing (see liquid concentrate processing) |
| Vinegar | Liquid vinegar concentrate or vinegar… |
| Oil | Oily macerate or maceration |
| Glycerine | Glycerate |
| Honey | Medicinal honey or honey from … plant name |
Is oil a good solvent?
Oil dissolves fewer active elements than alcohol or even water. It is effective for waxes, oils (fatty acids, polyines), essential oils (terpenes) and resins. It is also effective with flavonoids, pigments and certain vitamins (A, D, E, K).
A maceration will therefore be ineffective if a plant is of interest for its alkaloids (many nervous system applications), bitter principles (digestive plants) or saponins. But as oil macerations are made for external use, either directly as oil (e.g. massage oil or liniment) or in ointments or creams, there are still many interesting applications for macerations in cosmetics, massage oils and for use on the integumentary and locomotor systems. For a recipe idea, see liniment after exercise.
Proportion of plant in a maceration
A simple traditional method is to pack the plants into a jar, then fill it with oil.
Many recipes call for a ratio of 1 part plant to 2 parts oil (1:2).
For greater repeatability, weight can be used; it is important that the quantity of oil covers the plant.
| Plant weight | |
| Weight of fresh plants / liter of olive oil | Between 140g and 180g |
| Weight of dried plants / liter of olive oil | Between 60g and 120g |
Increase the concentration of our oily maceration
Can plants be combined during oil maceration?
It is possible to mix the dried plants during maceration. This saves time if you know in advance what you want to use your maceration for. On the other hand, I recommend making one maceration per plant. With single-component macerations, you can better adapt to new problems, and you’re more flexible. What’s more, a maceration is a delicate product that can easily go bad… making several small pots of macerations reduces the risk of loss if one pot goes rancid more quickly.
How to make an oily maceration…
…from cold-dried plants?
- Select quality dried plants (of the year, well-preserved and clean);
- Finely chop (or grind) the part of the plant used;
- Mix the plant and oil in a jar (see Good Tools for the right type of container). Stir the mixture slowly to remove air bubbles;
- Identify the macerate: name of plant, name of oil, date maceration began, date filtered;
- During the maceration period, stir the jar frequently (at least twice a week). Cold maceration takes place in a fairly warm environment, between 22°C and 35°C, for example above your plant dryer or water heater. I use the same heat mats I use for my seedlings, to give gentle heat to my macerations while covering them with an opaque blanket;
- Once the maceration period is over, filter the macerate a first time through a fine sieve or cheesecloth and squeeze firmly to obtain as much liquid as possible. For this stage, I like to use a potato press, which allows me to recover as much of the precious oil as possible;
- Leave to settle for 1 to 2 weeks, then filter again through an unbleached coffee filter;
- Check that no solid particles remain in the mixture (if so, repeat step 6);
- Sterilize bottles;
- Bottle;
- Identify each bottle: name of plant, name of oil used, bottling date, expiration date, dosage and (optional): plant/solvent ratio used.
…from fresh (and cold) plants?
For fresh plants, a few extra precautions are necessary. With fresh plants, we’re more concerned about mildew and rancidity of the oil… in general, look and smell the mixture for fungi or odors.
In line with this risk, certain steps will be more elaborate:
… hot (from fresh or dried plant)?
There are 2 main reasons for hot maceration:
This technique is widely used; personally, I find it less gentle, heavier in a way… but so effective.
For hot maceration, the best technique is to use a large Crock-pot; fill it halfway with water and place the glass bottles with a breathable fabric stopper attached with an elastic band.
Select the heat setting: warm (do not cook).
Add water to the Crock-pot when necessary and stir your pots regularly.
Maceration time
| Method | Duration |
| Dried plant – cold maceration | 6 to 12 weeks |
| Fresh plant – cold maceration | 2 to 5 weeks |
| Hot maceration | 1 to 1.5 weeks |
Express method: if you don’t have a maceration for a pressing use, it’s possible to heat plants with oil over low heat for 30 minutes, but the result isn’t as interesting.
Shelf life and storage of oily macerations
Shelf life varies greatly from one product to another. Here are the influencing factors:
Under the right conditions, maceration can be kept for much longer than a year. But as these products are by nature more fragile, don’t hesitate to smell and inspect your products before each use. The presence of foam on the surface or a sort of veil in the maceration are very bad signs.
For your own good …
Danger of botulism
Because oil macerations are made with gentle heat in an anaerobic environment, they should not be used internally, as there is a danger of botulism. As a reminder, botulism is caused by a neurotoxic bacterium that becomes very dangerous (even lethal) if it develops in an anaerobic environment. Use externally; if Clostridium botulinum were present, it would be neutralized by contact with air. For uses that are a little borderline between external and internal – here we’re thinking of open wounds, oils in the ear (when the eardrum is not pierced) – take no chances and add vinegar at the rate of 60 ml per liter of oil. The addition of vinegar acidifies the maceration to destroy the bacteria.
Many flavored oils can be found in delicatessens; you can see the beautiful bottles, often with the herbs still in the bottle. Often, the concentrations are much lower than those suggested in this article, but they have been processed and are safe with regard to the danger of botulism.
Alternatively, instead of consuming macerations, you can make your own vinegars with your medicinal plants; in many cases, vinegar is a better solvent than oil, and cider vinegars are tasty, whether diluted in a glass of water or mixed with the oil in a salad dressing. However, check the dosage: some medicinal plants should be taken in moderation.
Choice of ingredients
Choice of oils (solvent)
The oils most often chosen are olive oil and sunflower oil. Available in organic versions at reasonable prices, they are versatile and pleasant on the skin, with excellent shelf life.
If you use hot maceration, the butters, which should be liquid during maceration, will take on a solid form for use… This can be interesting for their stability, but also for making an ointment. On the other hand, it will be difficult to apply a thick layer afterwards, and their use in ointments will reduce their fluidity.
Alternatively, grapeseed oil is interesting for its neutral scent and good skin penetration. Avocado oil and white sesame oil are interesting for their moisturizing power, although they are more fragile than olive oil.
Finally, to benefit from both the fine oil and the herbs, a good alternative is sometimes to make the maceration with olive oil, but add a little fine oil to the ointment or cream. There are, of course, other preservative options (see article on ointments for more information) that can be added to finished products.
Are fresh plants preferable to dried plants for oily macerates?
There is no universal answer to this question.
Generally dried plants are generally preferred. When we use fresh plants, we add a lot of water to the mixture, and since water is the source of life, a maceration made from fresh plants is more likely to go bad or go rancid… For successful maceration of fresh plants, we often use gentle heat, for example above the plant dryer or in a Crock-pot filled with water on the stove (see hot maceration), which accelerates evaporation of the water in the plant and reduces maceration time.
If you’re using fresh plants for your macerations, it’s essential to allow the water to evaporate, for example by replacing the jar stopper with a piece of cloth.
For many plants, I prefer macerations from dried plants, but there are a few plants for which fresh plants give much better results. Here are the plants for which I prefer fresh plants for oily maceration:
FE: Leaf, FL: Flower, SF: Flowering top
The right tools
Containers
As we have seen, exposure to light and air will reduce the shelf life of macerations. On the other hand, translucent glass containers are required to check for the formation of substances with a consistency other than maceration, which would render the latter unsuitable.
For storage: choose bottles with the same volume as the quantity produced (and relatively small), slender in shape and made of tinted glass.
As I store my macerations in the fridge, i.e. at a temperature when the olive oil is solid, I prefer the 250 ml Mason jars. Their wide opening exposes the macerations to more air, but allows me to use a spoon to scoop out small quantities of my products; furthermore, the format is practical, allowing me to collect all my macerations in one corner of the fridge; and finally, the ring on the lids is ideal for holding the cloth over the jar while macerating fresh plants.
Cutting tools
For an oily maceration, cut the plants by hand. In the case of dried ingredients, especially if they are solid, it is possible to grind them (in a clean coffee grinder). In this case, it’s not a good idea to use the food processor with the plant in the oil, as this process will bring in a lot of air, which will accelerate the rancidity of the preparation.
Filtering tools
Filtering macerates is more difficult than vinegar and alcohol concentrates, as the oil is more viscous.
Start by filtering the solids through a slightly coarser filter, and for the 2nd filter, through a coffee filter; you can heat the macerate (up to 35°C) to reduce the oil’s viscosity. Hang the filter with the oil and take your time.
Using a potato press is a good way of recovering most of this precious oil. The oil caught in the plant fibers is often the one most loaded with active principles, so it would be a shame to throw it away.
Photo credit:
Title photo: Trevor Leyenhorst
In order of appearance: Vratsagirl, Audray Pepin