How are medicinal properties from plants extracted?

For thousands of years plants were the primary source of medicine, with widespread knowledge of the healing properties of specific plants recorded in ancient civilisations. Until the mid 1800’s the medicinal properties of plants were the main healing treatments available & today many of the drugs developed & used are derived from these natural sources. There are about 390,000 known species of plants & it is estimated between 35,000 - 70,000 have been screened for medicinal use. The contribution plants have made to medicine is enormous both as a source of pharmacologically active compounds as well as providing chemical models or templates for the design & synthesis of new drugs, with many of the core structures or architecture of synthetic drugs based on natural plant chemistry. Plant derived compounds have a long history of medicinal use, with patient tolerance & acceptance because of time tested use & efficacy, and provide almost unlimited leads in the search for new drugs because of their unmatched chemical diversity.

What is plant extraction?

All plants produce chemical compounds known as phytochemicals. Some have natural therapeutical or medicinal properties and the process of selectively separating these constituents from the plant is known as extraction and there are a number of ways to do this.

Traditionally used methods include Maceration, Infusion, Percolation, Decoction, Distilation & Cold Pressing.

Maceration is a very simple extraction process of softening & breaking down material by soaking in a liquid & is most commonly associated with the process of wine making where grapes are burst releasing the juices to soak in a large vat.

The classical method is grape stomping or pigeage where the grapes are crushed in big vats by barefoot workers.  Maceration helps bring out flavours, colours & complexity but with disadvantage of a long extraction time and low extraction efficiency.

Infusion is the process whereby a compound or flavour is released from plant material by suspending the material in a solvent such as water, oil or alcohol. An infusion is the resulting liquid. An example is the cup of tea using a tea bag. To extract valuable compounds from the Kūmarahou plant, we steep the leaves in cold water for a full week before straining & gently heating the resulting infusion.

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Percolation is done by passing a solvent liquid through plant material & most people would be familiar with the use of coffee percolators where hot water (solvent) is passed through ground coffee beans. 

Decoction achieves extraction by first mashing plant material to break it down & then boiling it in water to make tisanes and tinctures & other solutions. The higher temperatures & differing preparation from the process of Infusions, may result in different properties being released, especially in the extraction of the more oil soluble constituents. Like Infusion & Percolation, Decoction can be used where a more liquid product may be better suited for some applications.

Distilation. Steam distillation is a very effective method to extract pure essential oils from plant material such as Mānuka. A large container or Still is filled with the plant material & steam is injected,  gently releasing the plants essential oils from the leaf sacs in the form of vaporised compounds. These then travel through a condenser which cool the vapour back into liquid form. As water & oil do not mix, a Separator removes the water from the essential oils leaving a very pure and concentrated product. 

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Cold Pressing is often used to extract oils from seeds such as Harakeke. Historically it was done by hand but today often done mechanically & literally involves the application of pressure, pressing or squeezing the oil from the seed pods. Since no heat or solvent is involved, there is little change in the composition of the oil compounds. Heat increases the yield but may degrade the product in certain instances. An example is Cold Pressed Olive Oil where the addition of heat in the process of extraction could degrade the flavour. 

At Aotea, we use several of these extraction methods in the formation of our natural products.

We have built our own Steam Distillery on Aotea & use this in the production of our high grade Mānuka Oil. We take care to use relatively low temperatures to avoid degradation of potent enzymes in the extraction process, resulting in a kiri (skin) care product which is deeply nourishing & anti bacterial & helps maintain the skin’s natural PH balance.

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To make our Kawakawa Balm we start with a cold infusion process, suspending the Kawakawa in ‘sweet almond’ oil. After 3 weeks, we apply gentle heat to the infusion to extract the higher active compounds, strain out the fibrous matter & then mix the concentrate with our own Mānuka oil & beeswax to form a wonderful soothing balm. 

We extract the seed oil for our Harakeke Seed Oil Night Cream which is packed with nourishing Omega 3 & 6 and antioxidants, through the process of Cold Pressing before adding shea butter, coconut and kānuka water.

Lastly, our all natural Kūmarahou & Mānuka Hand and Body Wash is made using a combination of Infusion for the Kūmarahou & Steam Distillation for the Mānuka Oil from our Distillery.  The Kūmarahou leaves are steeped in cold water for a full week before being gently heated & strained & combined with the Mānuka Oil.

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