Infusing an herb in oil allows its active, fat-soluble ingredients to be extracted; hot infused oils are simmered, while cold infused oils are heated naturally by the sun. Both types of oil can be used externally as massage oils or added to creams and ointments. Infused oil should not be confused with essential oil, which is an active constituent naturally present in a plant and has specific medicinal properties and a distinct aroma. Essential oil may be added to an infused oil to increase its medicinal efficacy.
Hot Infused Oils
Although hot infused oils can last up to a year, they are most potent when used fresh. If only using infused oils occasionally, make a smaller quantity than the standard amount with the same proportion of herb to oil. The wine press may be replaced with a jug—when cool enough to touch, squeeze the oil through the jelly bag as illustrated in Cold Infused Oils below.
Many herbs make effective hot infused oils, especially spicy herbs such as ginger (Zingiber officinale), cayenne (Capsicum frutescens), and pepper (Piper nigrum). These oils can be rubbed into the skin to relieve rheumatic and arthritic pain, improve local blood flow, and relax muscles. Other hot infused oils from leafy herbs, such as comfrey (Symphytum officinale), speed wound healing. Oil infused with mullein (Verbascum thapsus) is used for earache and ear infections, and chickweed (Stellaria media) ointment may be produced from a hot infused oil.
Standard Quantity (infused oils)
250 g dried or 500 g fresh herb to 3 cups (750 ml) olive, sunflower, or other good-quality vegetable oil
Store in sterilized, airtight, dark glass bottles for up to 1 year; for the best results, use within 6 months.
How to Prepare
- Stir the chopped herb and oil together in a glass bowl over a saucepan of boiling water. Cover and simmer gently for 2–3 hours.
- Remove from the heat and allow the mixture to cool, then pour into the wine press (or jug if not available) with a jelly bag in place. Collect the strained oil in a jug, pressing all the liquid out of the herb.
- Pour the infused oil into clean, dark glass bottles, using a funnel. Seal and label each bottle.
Cold Infused Oils
Making a cold infused oil is a slow process and involves leaving a jar packed with herbs and oil to stand for several weeks. Sunlight encourages the plant to release its active constituents into the oil. It is the most suitable method of oil infusion for fresh plant material, especially the more delicate parts, such as lowers.
St. John’s wort (Hypericum perforatum), calendula (Calendula officinalis), and melilot (Melilotus officinalis) are three of the most commonly produced cold infused oils. St. John’s wort oil is anti-inflammatory and analgesic, and may be applied topically or taken internally (after consulting an herbalist) for peptic ulceration. Olive oil is particularly suitable for cold infusion as it rarely turns rancid. The intensity of sunlight and length of time an herb is infused affects the concentration of its medicinal constituents. For greater strength, add the extracted oil to a fresh supply of herbs and infuse again.
How to Prepare
- Place the herb in a clear glass jar. Pour in oil until it completely covers the herb, close the jar, and shake well. Place the jar in a sunny spot, such as on a windowsill, and leave for 2–6 weeks.
- Pour the oil and herb mixture into a jelly bag, secured to the rim of a jug or bowl with string (or use a wine press as pictured above in hot infused oils). Allow the oil to filter through the bag.
- Squeeze out the remaining oil from the bag. Pour the infused oil into dark glass bottles, label, and store. Alternatively, repeat the whole process with the infused oil and fresh herbs.