The present invention relates to a process for substantially deodorising tea tree oil and deodorised tea tree oil. BACKGROUND ART

Tea tree oil is an essential oil extracted from trees of the species Melaleuca alternifolia (commonly known as "tea trees").

The leaves of tea trees are known to contain germicidal properties and this feature was known to Australian aborigines in regions of upper New South Wales where tea trees grow in significant numbers. Such aborigines used a poultice of tea tree leaves and mud to heal wounds, burns and other skin ailments.

Tea tree oil is also known to have significant germicidal properties. In particular, tea tree oil has been used for cleaning and treating wounds, sore throats, skin infections, acne, tinea, rough or cracked feet, dermatitis, eczema, fungal infections, burns, sunburn, insect bites and perionychia. It had also been used as a vaginal douche, as a deodorant, for dissolving pus and as an ingredient in antiseptics and soaps.

Tea tree oil is also non-toxic and generally does not irritate human skin.

There are three chemical variants of oil obtained from Melaleuca alternifolia grouped as low, intermediate and high cineole forms. The pharmaceutical use of only the low cineole variant has been emphasised, as high cineole levels have been claimed to irritate mucus membranes. Terpinene-4-ol is the main germicidal ingredient of tea tree oil, although other ingredients are believed to contribute to the germicidal action. The Australian standard for tea tree oil, AS2782, stipulates a minimum of 30% terpinene-4-ol, and a maximum of 15 cineole.

Accordingly, tea tree oil has already been used to a substantial extent as a natural germicide for certain conditions such as those referred to above.

One of the factors presently inhibiting the market potential of tea tree oil is its taste and/or odour, which many people regard as somewhat pungent or unpleasant. Accordingly, there has been an adverse reaction to proposals for using tea tree oil as an ingredient in substances for use in the oral cavity and on other parts of the body, such as mouth washes and skin ointments, or creams and preservatives.

Attempts have been made to mask the rather unpleasant odour of tea tree oil by adding perfume substances. This increases the cost of such products, and has the further

disadvantage that the added perfume(s) may have an adverse effect (such as irritation) on the skin of the user or the user may have an allergic reaction to any such perfume(s).

With the above problems in mind, the present invention is directed towards a process for deodorising tea tree oil.

SUMMARY OF THE INVENTION

According to this invention there is provided a process for substantially deodorising tea tree oil including the step of sparging a gas containing at least one of steam, nitrogen, carbon dioxide or air through the oil. It is preferred that a super-heated gas is sparged through the oil at a temperature of about 175°C until the oil reaches a temperature of about 100°C. The preferred gas for sparging through the oil is steam.

The invention further provides a process for substantially deodorising tea tree oil including the step of heating the oil to a temperature of up to about 100°C.

The process may further include the step of allowing the heated oil to cool for at least 24 hours. Generally, the greater the cooling period, the greater the degree of deodorisation achieved. It is preferred that the cooling be done in an open topped vessel.

Preferably, the oil is left open to air for 7 days or more. It is further preferred that the airing occurs in a substantially dust proof room, with a slightly positive air pressure to inhibit dust infiltration.

The invention also provides a process for substantially deodorising tea tree oil including the step of filtering the oil through an activated carbon, cotton or paper filter.Two or more such filters may be used in the process.

The invention also provides a process for substantially deodorising tea tree oil including the step of exposing the oil to activated carbon. The activated carbon may be in powdered or paniculate form which is mixed or suspended in the oil. Alternatively, the activated carbon may be a filter (as mentioned above).

It is preferred that the exposing of the oil to activated carbon is by passing the oil through one or more activated carbon filters.

It has been found that each of these processes is effective in substantially deodorising tea tree oil. Accordingly, one or more of the above processes may be used, in combination, as separate steps in a deodorisation process. In particular, it has been discovered that a particularly advantageous process includes the steps of sparging the oil with a gas, filtering the oil through one or more activated carbon filters, and subsequently airing the resultant oil in an open topped vessel for at least one day.

Without intending in any way to limit the scope of the invention, it is presently believed that the deodorisation process involves the release from the oil of nitrogenous and/or sulphurous compounds that previously would have entered the oil during the distillation process. These compounds are dissolved in the oil in very minute quantities and have proven to be difficult to identify and remove. It is believed that these nitrogenous and/or sulphurous compounds contribute significantly to the unpleasant odour and/or taste of tea tree oil.

DETAILED DESCRIPTION OF PROCESSES EMBODYING INVENTION

Without limiting the scope of the invention described above, processes embodying the invention will now be described by way of example only, with respect to the following examples:

EXAMPLE 1:

It has been found that a particularly effective process for deodorising tea tree oil includes the following steps:

1. Collect the oil in a stainless steel batching tank from a separator discharge.

2 Super heated steam at a temperature of about 175°C is sparged through the designated batching tank until the oil reaches a temperature of about 100°C.

3. The heated oil is allowed to cool for at least 20 hours or longer. The longer the cooling period, the better the result.

4. The oil is then passed through one or more cotton and/or activated carbon filters.

5. The oil is then transferred into at least one open storage vessel.

6. The oil is allowed to air for about 7 days by leaving the vessel(s) uncapped. It is preferred that the airing step is performed in a substantially dust proof room with slight positive air pressure.

EXAMPLE 2:

The process of this example includes the following steps:

1. The oil/water condensate from the condenser is heated to about 55-60 degrees Celsius (or more) from which it passes to the stainless steel separator for separation.

2. From each of the separators the separated oil passes into a primary holding tank , measuring about 30cm in diameter and about 60cm in height, where the oil is allowed to settle and breath for not less than one hour.

3. Following this settling and breathing period the oil is released with a 316*1/2*800*WOG quick release gate valve through a 60cm length of 12mm diameter stainless steel pipe.

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4. By gravity feed, the oil then flows into a 30mm mainline and thence into an underground secondary storage tank in a separate, sealed room where further settling occurs for a duration of not less than 10 minutes.

5. By using a stainless steel pump, the oil is then transferred from the secondary storage tank into a stainless steel outlet pipe of 30mm diameter, through a gate valve, and into a special in-line sparging cylinder.

6. The sparging cylinder is a 60mm diameter stainless steel housing holding a cylindrical gauze havinghundreds of small apertures through which food-grade nitrogen gas is passed from a satellite cylinder at not less than 10 psi pressure causing thousands of bubbles of nitrogen gas to pass through the oil. Oil flow through the sparging cylinder is continuous, with the flow rate being preferably in the range 5-20 litres per second.

7. Flow from the sparging cylinder continues in a 30mm stainless steel pipe for a distance of approximately 6 metres to allow gas/liquid separation and then into a stainless steel storage vat. Significant separation of the gas and liquid occurs in the 6 metre pipe. The entry into the vat is at its base. Further separation occurs in the vat as the gas bubbles through the liquid.

8. The storage vat is nitrogen charged to expel all air. A release valve to the atmosphere is at the top of the storage vat. The oil is held in the vat for a period of not less than 24 hours. Following this further period of settling, the oil is transferred into stainless steel batching tanks through a 30mm stainless steel pipe.

9. From the batching tank the oil passes through a second sparging cylinder before being passed through an activated carbon filter for removal of any remaining odiforous or dissolved oxygen particles for final cleansing before being passed to transportable containers, in the form of stainless steel drums.

10. Stainless steel drums are filled with nitrogen with oil passing through a special fitting to fill the drum from the bottom, thus gradually replacing the nitrogen in the drum until the desired fill level is achieved. The drum is then sealed, trapping nitrogen in the head space. The oil is therefore stored for shipping under a nitrogen blanket.

Some modifications using a heat, sparging and activated carbon filtration combination may occur to fine-tune the process. The result of the process is that the odiforous molecules (thought to be nitrogen and sulphur based) are released from the oil into the atmosphere as a result of the application of heat combined with sparging and a period of airing.

The activated carbon filter collects substantially all remaining offending molecules leaving the oil with a relatively low odour. The process uses nitrogen to attract oxygen dissolved in

the oil thus removing a source of future oxidisation and discolouration. This attraction of oxygen molecules also collects the other odiforous compounds referred to above for subsequent discharge to the atmosphere or by collection in the filter.

It will be appreciated that the object of this invention may be achieved without adhering rigidly to the process described above. For example, the order of performing the various steps may be able to be re-arranged whilst still achieving an acceptable degree of deodorisation of the oil.

Furthermore, it will be readily understood by persons skilled in the art that the above process may well have application in relation to essential oils other than tea tree oil.