Rosemary Oil Extraction Methods, Process, Techniques

Rosemary Oil Extraction Methods, Techniques

Today, we learn Rosemary Oil Extraction Methods and Steps involved in it.

Rosemary oil extraction process, steps

Rosemary tree is an aromatic, medicinal and condiment plant that belongs to the family Labiatae. It is widely extended in Algeria and broadly used in traditional medicine. Rosemary is preferred because it is of interest as a preservative due to its antioxidative characteristics and it is used in the pharmaceutical, food and cosmetic industries. Rosemary is one of those simple herbs. It is easy to grow, easy to use and simple to preserve.

Rosemary essential oil:

Rosemary oil is extracted from Rosmarinus officinalis also known as Rosmarinus coronarium of the Labiatae family and is also called as incensier. This clean smelling Rosemary essential oil is very great for stimulating the brain, boosting the liver and gall bladder. It is used for improving hair and scalp health. Rosemary oil has a clear, powerful refreshing herbal smell, is very clear in color and watery in viscosity.

Rosemary tree is a shrubby evergreen bush that grows up to 1.5 meters or four feet high with green-gray needle-shaped leaves and pale blue or lilac flowers. What are the uses of rosemary oil? The uses of Rosemary oil are abundant, ranging from medicine and odorous to cosmetic. Its many forms consist of oils, gels, lotions, soaps, shampoos, and sprays, to name a few suggestions for homemade products.

Growing Rosemary:

Rosemary is an evergreen perennial. It likes full sun requirement and well-drained sandy soil, which means it’s not too picky and even likes its soil on the lean side. If you maintain the soil slightly moist, but not too wet (it doesn’t like wet roots), you will have guaranteed success. It grows equally well in the herb plot or in a container, but, the more room you give its roots, the bigger your plant will get.

Cultivating and harvesting Rosemary oil:

Flowering Rosemary Plant.
Flowering Rosemary Plant.

How to cultivate and harvest Rosemary oil? Rosemary is a perennial bush that often grows on the sea cliffs of Spain, Greece, France, and Italy. The leaves of the aromatic Rosemary bush have a high oil concentration, and it is an element of an aromatic family of herbs, which includes Lavender, Basil, Mint, and Oregano to name a few.

Rosemary is a hardy plant that can withstand frost, but it loves the sun and thrives in dry climates where the temperature is between 20 to 25°C (68ᵒ-77ᵒ Fahrenheit) and does not drop below -17ᵒ Celsius or 0ᵒ Fahrenheit. Though Rosemary can develop in a small pot inside a home, when grown outside, the Rosemary bush can reach a height of approximately 5 ft. Due to its adaptability to different ecological conditions, Rosemary plants can vary in appearance in terms of their colors, the sizes of their flowers, and the aromas of their essential oils. The Rosemary plant requires adequate water drainage system, as it will not grow well if it is over-irrigated or in soils with high clay content, thus it can develop in the earth that ranges in soil type from sandy to clay loam soil as long as it has a pH range of 5.0 to 6.0.

Read: Lemongrass Oil Extraction Methods.

The upper sides of Rosemary leaves are dark and the undersides are pale and covered in thick hairs. The tips of the Rosemary leaves begin to sprout small, tubular pale- to deep-blue flowers, which continue to bloom in the summer. Rosemary essential oil of the most superior quality is obtained from the flowering tops of the plant, although oils can be obtained from the stems and leaves before the plant begins to flower. Rosemary fields are generally harvested once or twice a year, depending on the geographical region of cultivation. Harvesting is most often prepared mechanically, which allows more frequent cutting due to higher yields from rapid regrowth.

Before distillation, the Rosemary leaves are dried either naturally by the heat of the sun or by using driers. Drying the leaves in the sun results in reduced quality leaves for producing oil. The ideal drying process involves the use of a forced air-flow drier, which results in better quality leaves. After the product is dried, the Rosemary leaves are further processed to have the stems removed. They are sieved to eliminate dirt.

How to dry fresh Rosemary? Fresh rosemary is easiest to use because the leaves are very soft and pliable. It’s easy to protect the flavor of the herb, but drying rosemary makes the leaves hard and woody. The procedure of how to dry rosemary can include grinding the dry needles into powder for use without the hard texture. You can just leave a stem of rosemary on the counter and it will dry, but to make sure safety and quality, a food dehydrator is useful. Dry the stems in a particular layer on the dehydrator trays. Pull off the leaves after they are dry and store rosemary ground. Other methods of how to dry rosemary can be completed by hanging on a clothes hanger or pulling off the leaves and letting them dry in a single layer on a cookie sheet. A pretty and easy method of drying rosemary is to make tied bouquets. The herb is attractive with numerous leaves and green color. When bundled and joined with a bright ribbon, the bouquet emits a fresh evergreen scent as it dries. Hang the bundles in a warm, dry region until the needles start to fall off, then remove the leaves by rubbing the stem upwards over a bowl or bag.

Treatment of the rosemary leaves:

A sample with a mass of around 40 kg was prepared. One full sunny day drying phase was implemented for the first group and two and a half day for the second groups. After completion of drying, the Rosemary leaves were re-weighed to determine any potential mass loss as an effect of the evaporation of both moisture and volatile oil components due to the drying effect.

After the moisture was removed by sun drying and air drying process Rosemary leaves were cut with scissors for the size of around 2 cm in order to raise contact areas of the leaves. 

Equipment used in the Rosemary oil extraction process:

List of machinery used in the extraction of Rosemary oil is;

The steam distillation process for the extraction of Rosemary essential oils from plant materials consists of basic parts;

  • Steam Generator or Boiler:
  • Extraction Chamber
  • Heat Exchanger
  • Separator
  • Gas chromatography-Mass spectroscopy
  • UV visible spectroscopy
  • Electric heater
  • Centrifugal separator
  • Vibro-viscometer,
  • pH meter, Oven, sieve, density separator, density bottle (pycnometer) Obscured

Rosemary oil extraction process:

Prepare the plant material:

The first thing to do is to prepare plant material. If the flowering stems that we have available come from the plants of the garden, it is good to choose the material for distillation, removing the excessively woody parts. At this position, we can reduce the size of the branches if too long, also to facilitate loading into the boiler.

It is good to remember that the Rosemary essential oil is contained in the glandular hairs there on the surface of the leaves, so it will not be necessary to chop the plant material for distillation. It is useful to keep the stems intact and not use just the leaves.  This will guarantee an improved homogeneous passage of the steam and avoid the harmful “cork effect” due to packing the leaves too tightly through distillation.

How is Rosemary oil extracted? Rosemary oil is extracted from the fresh Rosemary flowering tops by steam distillation. Methods of Rosemary essential oil production can be extracted using a variety of methods, although some are not commonly used today. The specific extraction process employed is dependent upon the plant material to be distilled and the desired end product. The essential oils from aromatic plants are for the most part volatile and thus, lend themselves to extraction methods such as steam distillation, solvent extraction, etc. 

Steam distillation

The vast majority of Rosemary essential oil is produced by steam distillation. Steam distillation is the most commonly used process for extracting essential oils. The steam distillation process is carried out in a still in which fresh or sometimes dried plant material is placed in a chamber of the still. Pressurized steam, make in a separate chamber, is then circulated through the plant material. The heat of the steam forces opens the tiny intercellular pockets in which the Rosemary essential oil is contained releasing the oils.

During steam distillation, the temperature of the steam should be moderated so that it is high enough to open the oil pouches without destroying the plants, fracturing or burning the essential oils. As the tiny droplets of essential oils are released, they evaporate and mingle with the steam, traveling during a pipe into a condenser. The steam and essential oil vapor are then condensed to a liquid mixture.

As the oil-water mixture has been created to be nearly immiscible at a lower temperature. The mixture can be separated using different gravity related techniques. Due to the immiscibility of the oil and water at low temperature, the Rosemary essential oil can be divided from the water by either decanting off the water or skimming off the oil from the top. The water obtained as a byproduct of distillation is referred to as floral water quantity or distillate and retains many of the therapeutic properties of the plant.

The extraction was carried out at different drying conditions and extraction time by maintaining an extraction temperature of 94 – 95°F to avoid thermal degradation of the essential oil components. Also, the pressure was set at the atmospheric pressure. The Rosemary leaves size is also maintained constant at 2cm. The steam distillation equipment consists of distillation stills, boiler, and condenser. The distillation still has a capability of 6kg plant material per batch. However,  1 kilogram of Rosemary leaves were tested for each experiment. Three different drying conditions such as sun-dried leaves, shade dried Rosemary leaves and fresh Rosemary leaves were tested for four different durations of 30 min, 60 min, 120 min, and 150 min, to compare their efficiency based on the oil yield and the oil composition. This time limit was completed by conducting preliminary tests on rosemary leaves using steam distillation.

The oil extraction was conducted using batch steam distillation equipment, which basically consisted of a static bed. This batch equipment possesses have advantages such as ease of operation, easy construction, and relatively low capital construction cost.

Read: Cultivation Practices of Vanilla.

Factors affecting yield and quality of rosemary essential oils

The factors affecting yield and quality of rosemary essential oils have been known to vary due to a number of factors. Such as: 

Mode of distillation

Method for the distillation must be selected on the basis of oil boiling point and nature of the herb as the heat content and temperature of steam can alter the distillation characteristics.

Proper design of equipment

Proper designing of tank, condenser, or separators can lead to loss of oils and high capital investments.

The material of construction of equipment

Essential oils which are corrosive in nature must be preferably distilled in stills made of resistant materials like Aluminum, Copper or Stainless Steel.

Nature of raw material

Raw materials like roots and seeds will not yield essential oil basically if distilled in their natural state. These raw materials have to be crushed, dried, powdered or soaked in water to expose their oil cells.

Filling of raw material or steam distribution

Improper loading of the herb can result in steam channeling causing incomplete distillation. Operating materials like steam injection rate, inlet pressure, condensate temperature. Properly manage of injection rates and pressure in the boiler-operated units are necessary to optimize the temperature of extraction and for maximal yield. The temperature of condensate must not be too high as this can result in oil loss due to evaporation.

Distillation time

Different constituents of the Rosemary essential oil get distilled in the order of their boiling points. Thus, the highest boiling fractions will be last to come over when, normally, very little oil is distilling. If the distillation is terminated too soon, the high boiling constituents will be gone.

Pre-condition of tank equipment

Tanks must be well steamed for multiple crop distillation. Tank or equipment must not be rusted for quality oil.

Chemical composition

The major chemical components of rosemary oil are a-pinene, borneol, b-pinene, camphor, bornyl acetate, camphene, 1, 8-cineole and limonene.

Cost of distillation unit and Rosemary extract:

Steam distillation unit cost approximately – Rs 8 Lakh/ Piece.

Rosemary extracts cost approximately Rs 1,200/ Kilogram.

Benefits of Rosemary oil

  • Rosemary essential oil used has a pronounced action on the brain and the central nervous system. It is used for clearing the mind and mental awareness while having superb brain stimulant properties, as well as improving memory.
  • It helps with headaches, migraines, mental fatigue and the antiseptic action of Rosemary essential oil is especially appropriate for intestinal infections and diarrhea, relieving pain associated with rheumatism, muscular pain, and gout. It helps for arteriosclerosis, palpitations, poor circulation, and varicose veins.
  • The diuretic properties of Rosemary oil are useful by reducing water retention through menstruation, and also with obesity and cellulite.
  • Rosemary increases the circulation to the scalp and is therefore also effective for promoting hair growth.
  • Boosts Immune System: When it comes to protecting the body from diseases, antioxidants are one of your biggest weapons. Rosemary oil contains myrcene, a chemical that acts as a powerful antioxidant and hunts down free radicals that can damage cells and cause a number of infections and diseases. Thus, inhaling rosemary oil on a regular basis can help boost the immune system.
  • Rosemary oil works as a powerful anti-inflammatory agent as it contains α-pinene that works to alleviate swelling and pain.
  • Works as an antidepressant: Another great method that Rosemary oil benefits mental health is by acting as an antidepressant. The carnosol and betulinic acid create in Rosemary oil have been found to create an antidepressant effect in rats. Aromatherapy using Rosemary oil helps people relax and treats symptoms of depression.

That’s all folks about Rosemary Oil Extraction Methods and Steps.

Read: How To Grow Herbs in Your Backyard.


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