WO2015184494A1

WO2015184494A1 - Process for preparation of caffeine extract

Info

Publication number: WO2015184494A1
Application number: PCT/AU2015/000340
Authority: WO
Inventors: Hendrik Emanuel TAIT
Original assignee: Abroad Promotions Pty Ltd
Priority date: 2014-06-05
Filing date: 2015-06-05
Publication date: 2015-12-10
Also published as: AU2014203077B2; AU2014203077A1

Abstract

A process for obtaining a caffeine extract from coffee beans using a glycerol and water solvent system. The caffeine extract is isolated by filtration of the extraction mixture and removal of solvent under reduced pressure. The isolated caffeine extract thus produced has a high caffeine content and good shelf stability. In particular the caffeine extract is easy to incorporate into emulsion formulations and finds application in the field of personal care products such as cosmetic, hair care and skin care preparations.

Description

PROCESS FOR PREPARATION OF CAFFEINE EXTRACT

FIELD OF INVENTION

The present invention relates to a process for extracting caffeine from coffee beans. In particular, the invention relates to a process for preparing a caffeine extract. More particularly the invention relates to a process for extraction of caffeine that is in a form of a caffeine extract that is easy to incorporate into cosmetic formulations. BACKGROUND OF THE INVENTION

Caffeine is a xanthine alkaloid found in a variety of plants such as tea and coffee plants. Caffeine is present at levels of approximately 1.2% to 2.2% in raw coffee beans. Isolated caffeine is an odourless white crystalline solid.

Caffeine has several pharmacological effects on the human body. In particular, when ingested caffeine can act as a stimulant on the human central nervous system and metabolism and is used worldwide to reduce fatigue and restore alertness. Accordingly, caffeine containing beverages such as coffee, tea, cola, cocoa and energy drinks are consumed widely. Caffeine may also be taken in the form of a caffeine tablet.

Caffeine is also known to have biological activity when applied to the skin.

Personal care products such as skin care, hair care and cosmetic products containing caffeine are known. These personal care formulations are reported to contain up to 3% caffeine. When applied to the skin, caffeine is believed to have anti-inflammatory and antioxidant properties [see, for example, Herman et al, Skin Pharmacol. Physiol., 2013, 26(1 ):8-14]. For example, a caffeine preparation applied under the eye can help reduce puffiness and dark circles caused by inflammation and poor circulation. Caffeine containing face creams are also believed to minimise blood vessels thus reducing redness and firming of the facial skin.

Commercially available caffeine is usually produced as a by-product of the process used to decaffeinate coffee. Typically caffeine is removed from green (unroasted) coffee beans by extraction using a solvent. Solvents used in early decaffeination processes included benzene, and chlorinated solvents such as chloroform or trichloroethylene. These solvents were considered to be too toxic, or had a high environmental impact. Dichloromethane is considered to be a less toxic solvent, but it is believed to be a potential carcinogen.

Ethyl acetate can be used as a solvent in the caffeine extraction process. It is considered to be of low toxicity and a less harmful solvent. A direct extraction method for decaffeinating coffee generally involves steaming the green (raw) coffee beans for 30 minutes and repeatedly rinsing with fresh portions of ethyl acetate for approximately 10 hours to wash the caffeine from the beans. Caffeine is obtained by evaporation of the solvent from the washings.

An indirect extraction method involves soaking the green coffee beans in hot water for several hours to extract caffeine into the water. The beans are removed from the water, and the caffeine is then extracted from the water by repeated washing with a suitable solvent such as ethyl acetate or dichloromethane. Evaporation of the solvent gives caffeine.

Other currently used methods of decaffeinating coffee include the use of supercritical fluid carbon dioxide. The coffee beans are steamed before being soaked in supercritical fluid carbon dioxide in a pressure chamber for approximately 10 hours during which time the carbon dioxide extracts caffeine from the beans. The supercritical carbon dioxide solution of caffeine is removed from the pressure chamber and exposed to standard pressure, the carbon dioxide evaporates to leave caffeine. This particular process avoids the use of potentially harmful or undesirable solvents, but it is time consuming and requires specialised equipment.

Caffeine obtained as a by-product of decaffeination is generally purified and is sold commercially as anhydrous crystalline caffeine. Caffeine in this form has poor solubility in aqueous media such as the water-in-oil or oil-in-water emulsions used for personal care product formulations such as lotions and creams. Furthermore, at concentrations above 1 %, caffeine can crystallise out of the formulation.

Caffeine extract known as "coffee oil" or "cold pressed coffee oil" can be obtained from green coffee beans by mechanical extraction using an oil seed press. Seed presses include hydraulic coffee bean presses or precision cold screw presses. Screw presses are available from, for example, oilpress.co (www.oilpress.co/oil-press-coffee.php). The cold press method of extraction has the drawback of low recovery of available caffeine from the coffee beans. The recovery of coffee oil varies between 7% and 9% based on the dry weight of coffee beans [see Lopez Fontal, EM., Revista Ingenieria e Investigation, vol. 27, No. 1 , Abril de 2007 (25-31 )]. The coffee beans do not contain a sufficient percentage of oil components to enable efficient caffeine extraction by this mechanical extraction route. OBJECT OF THE INVENTION

It is an object of the present invention to provide an alternative process for the preparation of a caffeine extract that overcomes one or more problems of the existing processes. SUMMARY OF THE INVENTION

The present invention provides a new process for the extraction of caffeine from coffee beans. In a preferred form, the present invention provides a process for preparing a caffeine extract. When applied to coffee beans the extraction process of the present invention provides a caffeine extract that has a high caffeine content and is in a form that is easy to formulate. In particular the caffeine extract is particularly suited for incorporation into personal care formulations such as skin care, hair care and cosmetic preparations.

Accordingly the present invention in one aspect broadly provides a process for the preparation of a caffeine extract including:

heating coffee beans with a solvent mixture including glycerol and water;

separating the resulting liquid phase from the solid phase; and

removing at least a portion of the solvent from the liquid phase to give a caffeine extract.

The present invention also provides a process for extracting caffeine from caffeine-containing plant material including:

heating coffee beans with a solvent mixture including glycerol and water;

separating the resulting liquid phase from the solid phase; and

removing solvent from the liquid phase to give a caffeine extract.

In a further aspect the present invention provides a caffeine extract obtained or obtainable by a process according to the present invention.

In a yet further aspect, the present invention provides a caffeine extract including caffeine, glycerol and water. Preferably the present invention provides a caffeine extract obtained or obtainable by a process of the present invention including caffeine, glycerol and water. More preferably, the caffeine extract includes a caffeine content of 5,000 ppm to 12,000 ppm and a water content of less than 25%.

The caffeine extract produced by a process of the present invention has been shown to contain six main constituents in addition to water and glycerol. The six main constituents, as identified by characteristic UV-visible spectroscopy and mass spectroscopy, comprise purine alkaloids (including caffeine) and phenolic acids (caffeoyl-quinic acid derivatives).

In a further embodiment the present invention provides a process for the preparation of a caffeine extract from ground coffee beans including:

heating the ground coffee beans with a solvent mixture of glycerol and water; separating the liquid phase from the solid phase; and

removing solvent from the liquid phase to give a caffeine extract.

In a preferred embodiment the present invention provides a process for the preparation of a caffeine extract from ground coffee beans including:

heating the ground coffee beans with a solvent mixture of glycerol and water at approximately 70°C;

separating the resulting liquid phase from the solid phase; and

removing solvent from the liquid phase under reduced pressure until the water content of the residual caffeine extract is less than approximately 25%.

In a more preferred embodiment the present invention provides a process for the preparation of a caffeine extract from ground coffee beans including:

heating the ground coffee beans with a solvent mixture of from 15% to 20% glycerol in water at approximately 70°C;

separating the resulting liquid phase from the solid phase; and

removing solvent from the liquid phase under reduced pressure at temperatures of less than 70°C until the water content of the residue is approximately 25%.

The caffeine extract produced in accordance with the present invention contains a high percentage of caffeine. The caffeine extract is in a physical form that is compatible with aqueous formulations. The caffeine extract can be formulated in personal care preparation, such as skin care formulations, hair care formulations and cosmetics to provide a product formulation with beneficial properties. Accordingly the present invention also provides for the use of a caffeine extract as defined herein as an ingredient for a personal care formulation, such as a skin care, hair care or cosmetic formulation.

In a further aspect there is provided a personal care formulation, such as a skin care, hair care or cosmetic formulation, including a caffeine extract as defined herein.

The general process of the present invention can be used to extract caffeine from other caffeine-containing plant material.

Accordingly, in yet another aspect the present invention provides a process for extracting caffeine from caffeine-containing plant material including:

treating the plant material with a solvent mixture including glycerol and water; separating the resulting liquid phase from the residual plant material; and removing at least a portion of the solvent from the liquid phase.

The caffeine extract produced in accordance with the present invention contains a high percentage of caffeine. If required, pure caffeine may be isolated from the caffeine extract using procedures well known to the skilled person. Suitable isolation and purification processes for caffeine are well known in the art and include chromatographic techniques, such as various forms of column chromatography; distillation; sublimation; liquid-liquid separation; crystallisation or combinations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is HPLC-MS profile of samples of the caffeine extract of the current invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Caffeine (1 ,3,7-trimethyl-1 H-purine-2,6(3H,7H)-dione) is a xanthine alkaloid found in a variety of plants. Caffeine can act as a stimulant and is widely consumed in the form of beverages such as tea, coffee and cola to reduce fatigue and restore alertness. Caffeine is also known to exhibit biological activity when applied to the skin. Accordingly, caffeine also finds utility in personal care products such as cosmetic, hair care and skin care preparations.

In a first preferred embodiment of the present invention, there is provided a process for obtaining a caffeine extract including: heating the caffeine source with a mixture of glycerol and water; separating the resulting liquid phase from the solid phase; and

The extraction process of the present invention can be used on any plant source of caffeine. Preferred sources of caffeine include ground coffee beans, including raw or lightly roasted ground coffee beans. Coffee grounds previously used for making a coffee beverage contain residual caffeine which can also be extracted using this method. Other caffeine-containing plant material, such as the tea plant {Camellia sinensis), may be used as a caffeine source.

Caffeine is present in raw coffee beans at levels of approximately 1.2% (Coffea Arabica) to 2.2% (Coffea Robusta). [see, for example, World Health Organisation, IARC Monograph, Vol 51 , Coffee, Tea, Mate, Methylxanthines and Methylglyoxal, 5.1 ; and http://www.caffeine-content.com].

Preferably the caffeine source is coffee beans. Preferably the coffee beans are coarsely ground prior to subjecting the material to the extraction process. The beans may be used in the green (raw) form. However, the beans may be lightly roasted prior to grinding. Light roasting makes the beans easier to grind and provides a slight "coffee" aroma in the caffeine extract.

Preferably a process for the preparation of a caffeine extract from ground coffee beans includes:

heating the ground coffee beans with a solvent mixture of glycerol and water; separating the resulting liquid phase from the solid phase; and

removing solvent from the liquid phase to give a caffeine extract.

Preferably the solvent mixture comprises glycerol and water. Preferably the solvent mixture comprises 10% to 25% glycerol in water. More preferably the solvent mixture comprises 15% to 20% glycerol in water. In a preferred embodiment the solvent mixture comprises approximately 15% glycerol in water.

Preferably the weight ratio of solvent mixture to coffee beans is from 8:1 to 2:1 , more preferably 5:1 to 3:1 . Most preferably the weight ratio of solvent mixture to coffee is approximately 4:1 .

Preferably the coffee beans are heated in the solvent mixture for between one and two hours. More preferably the coffee beans are heated in the solvent mixture for up to 90 minutes. Preferably the solvent and coffee mixture is heated at up to approximately 75°C, more preferably the mixture is heated at up to approximately 70°C. Most preferably the mixture is heated at 65°C to 70°C. Methods of heating the solvent and coffee bean mixture are well known, and include direct and indirect heating methods. Preferably indirect heating methods are used to minimise or avoid the possibility of thermal degradation.

Methods of separating solid and liquid components are well known in the art. After heating, preferably the liquid phase is separated from the solid (ground coffee beans) phase when the coffee and solvent mixture is still hot, preferably at 50°C to 70°C. The liquid phase can be separated from the ground coffee beans solid phase by filtration. Preferably the liquid phase is separated from the solid phase by a combination of decanting followed by filtration of the decanted liquid phase.

Preferably the liquid phase is evaporated under reduced pressure at temperatures of up to 70°C to remove water and glycerol. Lower temperatures will lead to longer evaporation times. Higher temperatures may cause chemical degradation. A preferred temperature range is 45°C to 55°C.

Preferably the liquid phase is evaporated until the measured water content of the remaining caffeine extract is less than 25%. More preferably the water content is between 20% and 25%. The amount of water in the extract can be reduced further by evaporation, however this increases energy costs and may lead to some thermal degradation of the components of the caffeine extract.

The process of the present invention utilises only non-toxic, economical, renewable and environmentally friendly solvents.

The extracted caffeine obtained by a process of the present invention is in the form of a brown liquid caffeine extract including caffeine, glycerol and water. Preferably the caffeine extract includes 5,000 ppm to 12,000 ppm caffeine. Preferably the water concentration of the caffeine extract is less than 25%. In one aspect the water concentration is approximately 25% w/w.

The process of the present invention can be carried out on any scale with suitably scaled equipment. Using this process caffeine extract has been obtained in amounts of up to 5 kg and up to 50 kg.

In a further aspect the present invention provides a caffeine extract obtained or obtainable by a process as hereinbefore defined. In a yet further aspect, the present invention provides a caffeine extract including caffeine, glycerol and water. More preferably the present invention provides a caffeine extract including a caffeine content of 5,000 ppm to 12,000 ppm and a water content of below 25%. Preferably the measured water activity (a_w) for the caffeine extract is less than 0.6. More preferably the measured water activity (a_w) value for the caffeine extract is between 0.5 and 0.6.

When used herein the term "caffeine extract" means an extract derived from plant matter including caffeine, glycerol and water. In a preferred form, "caffeine extract" means an extract derived from coffee beans including caffeine, glycerol and water and further comprising additional coffee bean-derived components including other purine alkaloids and caffeoyl-quinic acid derivatives such as chlorogenic acid. The skilled person will appreciate that other plant derived materials may be present in the caffeine extract obtained in accordance with the process of the present invention.

The precise composition of the caffeine extract will vary according to the nature of the raw material from which the extract is derived. With respect to caffeine extract obtained from coffee beans, the skilled person will appreciate that the nature and amount of components in the caffeine extract will depend on several factors. Relevant factors include the species of coffee plant from which the coffee beans have been harvested (e.g. Coffea canaephora (syn. robusta) or Coffea arabica) and the environmental and cultivation conditions such as soil type, altitude and temperature. In addition to caffeine, the caffeine extract may include other xanthine alkaloids, such as theophylline, and other plant derived compounds such as chorogenic acid.

The composition of the isolated caffeine extract can be analysed using analytical techniques well known to the skilled person, such as HPLC-MS.

The caffeine extract prepared in accordance with a preferred embodiment of the present invention does not promote microbiological growth. The water activity (a_w) of the caffeine extract is sufficiently low to discourage microbiological growth. Water activity is recognised as being extremely important to the shelf life and stability of many products (see, for example, http://www.csiro.au/Outcomes/Food-and- Agriculture/water-activity-in-food.aspx). A low water activity value indicates good stability and shelf life for a product. Water activity is an indicator of how tightly water is bound, structurally or chemically, in a product. Bound water is unavailable to support microbiological growth, accordingly products with a low water activity have good stability and storage properties. Water activity (a_w) is the ratio of the vapour pressure of water in a substance to the vapour pressure of pure water at the same temperature. Water activity of a product is measured in accordance with known techniques and protocols using, for example, a resistive electrolytic, capacitance or dew point hygrometer and protocols. The known in the art (see, for example, Man, C.M.D. et al. Shelf Life Evaluation of Foods, 2000, Springer ISBN 0-834-21782-1 ).

Water is present in the caffeine extract typically in amounts of approximately

25% or less. However, the measured water activity (a_w) for the caffeine extract is less than 0.6, typically approximately 0.57. Bacteria generally require an a_w value of at least 0.91 to support growth, and fungi requires an a_w value of at least 0.7 (see Rockland, L.B et al, Water Activity: Theory and Applications to Food (2nd ed.), 1987, Marcell Dekker, New York). The caffeine extract prepared in accordance with a preferred embodiment of the present invention does not promote microbiological growth and has good stability and shelf life.

However, if required, additional preservative agent or agents can be added to the caffeine extract. Suitable preservatives are well known in the art, and include phenoxyethanol added in an amount of up to approximately 1 % w/w, preferably 0.5% - 1 % w/w.

Microbiological analysis of the caffeine extract carried out in accordance with routine procedures known in the art confirms a total microbiological count of <20 cfu/g (total yeast and mould count of <20 cfu/g). Specifications for cosmetic use stipulate that the total yeast and mould count for an ingredient must be <100 cfu/g.

The process of the present invention surprisingly extracts a high percentage of the available caffeine from ground coffee beans. Using a preferred embodiment of the process of the present invention, the percentage of available caffeine extracted can be greater than 50%.

The caffeine extract produced in accordance with the present invention contains a high percentage of caffeine. Other major components are water (approximately 25%) and glycerol. Water and glycerol are commonly used as ingredients for the preparation of skin care, hair care and cosmetic formulations. The caffeine extract is in an aqueous-based liquid form that is compatible with aqueous formulations such as the oil-in-water or water-in-oil emulsions commonly used as a base for cosmetic, hair care and skin care products. As such, the caffeine extract of the present invention can be formulated in any suitable manner in accordance with methods known to the skilled person with one or more other ingredients to provide a formulation suitable for use as a cosmetic or skin care preparation.

Accordingly the present invention also provides for the use of a caffeine extract as defined herein as an ingredient for a personal care preparation, such as a cosmetic, hair care or skin care formulation.

In a further aspect there is provided a formulation including a caffeine extract as defined herein. Preferably the present invention provides a personal care preparation, such as a hair care, skin care or cosmetic formulation, including a caffeine extract as defined herein together with at least one carrier or excipient.

In a yet further aspect, the present invention provides a personal care preparation, such as a hair care, skin care or cosmetic formulation, including a caffeine extract of the present invention together with at least one further active ingredient.

Preferably the caffeine extract is incorporated in a hair care, cosmetic or skin care formulation in an amount of from 0.1 % to 20% w/w. More preferably the caffeine extract is incorporated in an amount between 0.5% and 5% w/w. More preferably the caffeine extract is incorporated in an amount of from 0.5% to 3%, most preferably 1 % to 3% w/w.

Preferably the personal care preparation is a skin care formulation. Examples of skin care formulations include those suitable for application to hands, body, face or facial skin around the eye area.

Methods of preparing skin care formulations are well known in the art.

Typical types of skin care formulations include water-in-oil or oil-in-water emulsions such as lotions, gels, ointments and creams. These emulsions generally have an aqueous component, an oil component and at least one emulsifier or emulsification agent. Methods of preparing suitable emulsions are well known in the art. Suitable ingredients are well known in the art, and are readily available from commercial sources.

Examples of suitable oils for preparation of skin care formulations include plant derived oils such as jojoba oil, olive oil, palm oil, coconut oil and almond oil. An emulsifier, such as cetearyl alcohol or cetearyl glucoside, is used to stabilise the water and oil phases to prevent separation. In addition to active ingredients, a wide variety of other ingredients such as colours, fragrances, preservatives, lubricants, thickening agents, humectants, blending agents and stabilizers can be incorporated into a formulation. Suitable additives are known in the art and can be formulated in accordance with known methods.

When a skin care formulation is prepared by a cold formulation process, the caffeine extract of the present invention is preferably incorporated into the aqueous phase. Where a hot formulation process is used, the caffeine extract is preferably incorporated after emulsification, and during the cooling process at temperatures of less than 40°C.

When used herein, unless otherwise stated, percentage ratios are quoted by weight; that is, % w/w. EXAMPLES

The following examples illustrate the invention, but are not intended as a limitation thereof.

Coffee beans are readily obtained from commercial sources. The caffeine extraction process described herein can be used to extract caffeine from whole beans or ground beans. Preferably the beans are those termed "industrial grade". Industrial grade coffee beans are blemished or lack acceptable flavour for use in making coffee beverages. Industrial coffee beans are readily available from commercial sources.

The process of the present invention can also be used to obtain a caffeine extract from spent coffee grounds normally discarded by coffee shops and cafes after being used for making a coffee beverage.

Preferably the coffee beans are ground prior to the extraction process. A variety of types of grinding or milling apparatus for grinding coffee beans are readily available from commercial sources. Examples of suitable commercially available coffee bean grinders include burr grinders and blade grinders.

Glycerol (propane-1 ,2,3-triol; also known as glycerine or glycerin) used for the extraction process is readily available from commercial resources. The glycerol used was commercially available standard commercial grade. Glycerol is considered non-toxic. It is typically obtained as a by-product of the biodiesel process. As such, it is an economical, renewable resource. It is extensively used in the food industry as well as in pharmaceutical, medical and personal care preparations. Glycerol acts as a humectant and a lubricant.

Water used for the extraction process was demineralised water.

The coffee beans were heated with the glycerol/water solvent mixture at temperatures of approximately 70°C. Suitable reaction vessels are known in the art, and include reaction pots fitted with a heater and stirring mechanism. Alternatively a soaking vat can be used in combination with soaking bags to accommodate the coffee beans.

Filtration methods are well known in the art. Filter papers, filter membranes and filter cloths may be used in the process of the present invention. Preferably oil filter paper is used. A particularly suitable filter system for the glycerol and water liquid phase is a cooking oil filter intended for use in filtration of cooking oil in commercial kitchens.

Solvent is preferably removed from the liquid phase under reduced pressure using apparatus known in the art. Suitable apparatus for reduced pressure evaporation are commercially available and include a rotary evaporator, such as a Rotavapor® manufactured by BLICHI Labortechnik AG, or a wiped film or falling film evaporator. Evaporators are used in conjunction with a vacuum pump. Suitable vacuum pumps, are known in the art and are readily available from commercial sources.

The water content of the caffeine extract was measured by standard methods known in the art using Karl Fisher analysis.

Water activity was measured in accordance with methods well known to the skilled person.

EXAMPLE 1

Preparation of Caffeine Extract

Coffea Arabica coffee beans (50 kg, dry weight, industrial grade, lightly roasted and ground). The ground coffee beans were combined with glycerol (30 kg) and demineralised water (170 kg) and heated at approximately 70°C for 1 .5 hours.

The mixture was allowed to settle briefly, the liquid phase was decanted off and filtered through a commercial cooking oil filter to remove residual coffee solids whilst the liquid phase was retained at approximately 70°C to maintain the solvent mixture at reduced viscosity.

The filtered liquid phase was evaporated under reduced pressure using a Rotovapor® at approximately 50°C at approximately 45 mbar. Evaporation was continued until the water content of the remaining caffeine extract residue dropped to 25%.

The resulting caffeine extract was obtained as a mobile brown liquid.

Yield of caffeine extract: 40kg, 25% moisture content as measured by Karl

Fischer analysis.

Water activity for the extract (a_w) =0.57.

Caffeine content of extract: 7,650 ppm (determined by HPLC-MS), equivalent to 7,650 mg/Kg.

Estimated total mass of

caffeine extracted: 0.306 Kg.

Caffeine yield: 51 % (percentage recovery based on estimated available caffeine, calculated on average caffeine content of Arabica coffee beans of 1 .2%).

Caffeine and other major components of the caffeine extract were profiled by HPLC-MS and identified by their characteristic UV-Visible spectra and Mass Spectra in accordance with known techniques and protocols.

Main components identified by HPLC-MS (in order of increasing retention time) were caffeoyl-quinic acid derivative, caffeoyl-quinic acid derivative (oxide), chlorogenic acid, caffeine, feruloyl-quinic acid and caffeoyl-tryptophan. The caffeine extract has a HPLC-MS profile that is similar to the profile shown in Figure 1 .

The caffeine extract is thermally stable at temperatures of up to 100°C.

Microbiological analysis of the caffeine extract of Example 1 showed a total microbiological count of <20 cfu/g (total yeast and mould count of <20 cfu/g). No S. aureus or Pseudomonas spp were detected.

EXAMPLE 2

Preparation of a 3% Caffeine Extract Skin Care Formulation

Hot Formulation Process. All percentages are % w/w.

Water (73.1 %) and phenoxyethanol/ethylhexyl glycerine (Euxyl PE9010, 1 .0%) were combined and heated with stirring to 55°C. Glycerol (4.0%) and xanthan gum (0.4%) were combined and added slowly. The aqueous mixture was heated to 75°C and held at this temperature.

Jojoba oil (4.0%), cetearyl alcohol/cetearyl glucoside (Montanov 68, 4.5%), caprylic/capric triglyceride (Myritol 318, 4.0%), coconut oil (4.0%) and stearic acid (1 .5%) were combined at 75°C and added to the aqueous mixture at 75°C and allowed to emulsify.

The mixture was allowed to cool under constant low shear stirring to 35°C. Tocopherol (vitamin E, 0.5%) was added under low shear stirring, followed by the caffeine extract of Example 1 (3%). The resulting mixture was stirred under low shear until homogeneous, and the pH was adjusted to 5.0 to 5.8 to give a cream formulation.

Tests to determine the changes in skin hydration were conducted using a corneometer which measures the change in the dielectric constant due to skin surface hydration changing the capacitance of a precision capacitor. Application of the cream formulation having 3% caffeine extract to a person's skin showed an improvement in skin hydration of 50.01 units after 1 hour after initial application and 59.14 units after 3 hours after initial application.

TEST METHODS AND DATA

The 3% Caffeine Extract skin care formulation of Example 2 was tested was found to meet the A criteria for acceptance as specified in the British Pharmacopeia Appendix XVI-C for the Efficiency of Antimicrobial Preservative Test of Topical Preparations. Reference cultures used were P. seruginosa (ATCC 9027), S. aureus (ATCC6538), C. albicans (ATCC 10231 ) and A. niger (ATCC 16404).

Real time shelf stability testing of the 3% Caffeine Extract skin care formulation of Example 2 after 18 months and 24 months showed no difference in form and colour, no change in specific gravity, little variation in pH and little variation in viscosity and met all the acceptable criteria for real time shelf stability testing.

On evaluation, the 3% Caffeine Extract skin care formulation of Example 2 was found to have a better activity than a placebo in the improvement of the appearance of skin hydration. The formulation improves skin hydration and skin condition.

ADVANTAGES An advantage of the preferred embodiment of the present invention is that it is simple, fast, economical and straightforward. The extraction process uses non-toxic cheap solvents and avoids the need for chlorinated solvents, toxic solvents or flammable solvents.

The process is a simple, efficient extraction process using glycerol as a solvent. Glycerol is a cheap, non-toxic, biodegradable and recyclable liquid manufactured from renewable plant resources. Glycerol is commonly produced as a by-product in biodiesel production. Surprisingly the extraction process of the preferred embodiment is high yielding, and extracts a large amount of the caffeine present in the coffee beans. Recovery of in excess of 50% of the estimated caffeine present in the coffee beans has been obtained.

The process of the invention forms an efficient use of resources and is cost effective. It uses "industrial grade" beans which are rejected during the selection process for food grade coffee beans. The process is high yielding and uses cheap non-toxic solvents and renewable resources in addition to being time energy efficient.

The caffeine is isolated as a viscous liquid caffeine extract including caffeine, water and glycerol. The water content is low (typically 20% to 25%) and the water activity (a_w) is typically less than 0.6. Microbial growth is therefore discouraged, so the caffeine extract has good stability and storage properties.

Once it has adopted a crystalline form, caffeine can be difficult to formulate in a typical skin care preparation. Solid caffeine has not been observed to precipitate or crystallise out from the caffeine extract, even at high concentrations such as 12,000 ppm at 25°C.

The residual glycerol and water in the caffeine extract are compatible with typical formulations for cosmetic and skin care preparations. The caffeine extract produced by the preferred embodiment is in an ideal form for incorporation into the emulsion formulations such as creams, gels and lotions typically used in cosmetic and personal care formulations. The residual glycerol in the caffeine extract can provide humectant, preservative and lubricant properties. The caffeine extract has perceived enhanced "natural" characteristics due to the use of a plant derived solvent. In addition to caffeine, the glycerol also extracts a variety of other plant derived chemicals from the coffee beans, such as purine alkaloids (xanthines) and phenolic acids (caffeoyl-quinic acid derivatives) which may offer beneficial properties.

VARIATIONS

It will of course be realised that while the foregoing has been given by way of illustrative example of this invention, all such and other modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of this invention as is herein set forth.

Throughout the description and claims this specification the word "comprise" and variations of that word such as "comprises" and "comprising", are not intended to exclude other additives, components, integers or steps.

Claims

1 . A process for preparing a caffeine extract from coffee beans including:

mixing the coffee beans with a solvent mixture including glycerol and water to form a bean mixture and heating the bean mixture;

separating a resulting liquid phase from a solid phase from the treated bean mixture; and

removing at least a portion of the solvent mixture from the liquid phase to produce the caffeine extract.

2. A process according to claim 1 wherein the coffee beans are ground prior to heating with the solvent mixture.

3. A process according to claim 1 or claim 2 wherein the solvent mixture is from 10% to 25% glycerol in water.

4. A process according to any one of claims 1 to 3 wherein the solvent mixture is from 15% to 20% glycerol in water.

5. A process according to any one of claims 1 to 4 wherein the coffee beans and solvent mixture are heated together at up to 75°C.

6. A process according to any one of claims 1 to 5 wherein the weight ratio of solvent mixture to coffee beans is from 8:1 to 2:1.

7. A process according to any one of claims 1 to 6 wherein the weight ratio of solvent mixture to coffee beans is approximately 4:1.

8. A process according to any one of claims 1 to 7 wherein the liquid phase is separated from the solid phase by filtration.

9. A process according to any one of claims 1 to 8 wherein solvent mixture is removed from the liquid phase by evaporation under reduced pressure at temperatures of up to 70°C.

10. A process according to any one of claims 1 to 9 wherein the liquid phase is evaporated until the measured water content of the residue is less than 25%.

1 1. A process according to claim 1 including:

heating ground coffee beans with a solvent mixture of from 15% to 20% glycerol in water at approximately 70°C for at least one hour;

separating the resulting liquid phase from the solid phase; and removing the solvent mixture from the liquid phase under reduced pressure until the water content of the residue is less than approximately

25%.

12. A caffeine extract derived from coffee beans when produced by a process according to any one of claims 1 to 1 1.

13. A caffeine extract derived from coffee beans when produced by a process according to any one of claims 1 to 1 1 , said caffeine extract including caffeine, water and glycerol, wherein the water is present in an amount of less than 25%.

14. A caffeine extract according to claim 12 or claim 13 wherein the measured water activity (a_w) value is less than 0.6.

15. A caffeine extract according to any one of claims 12 to 14 wherein caffeine is present in an amount of from 5,000 ppm to 12,000 ppm.

16. A caffeine extract produced by the process claimed in any one of claims 1 to 1 1 wherein the caffeine extract includes caffeoyl-quinic acid derivatives, caffeoyl- quinic acid derivative (oxide), caffeoyl-quinic acid derivatives (chlorogenic acid), caffeine, feruloyl-quinic acid, caffeoyl-tryptophan, glycerol and water.

17. A caffeine extract produced by the process claimed in any one of claims 1 to 1 1 wherein the caffeine extract has a HPLC-MS profile substantially similar to the profile shown in Figure 1 .

18. Use of a caffeine extract according to any one of claims 12 to 17 as an ingredient for a skin care formulation.

19. A skin care or cosmetic formulation including a caffeine extract according to any one of claims 12 to 17.

20. A skin care or cosmetic formulation according to claim 19 wherein the caffeine extract is present in an amount of from 0.1 % to 20% w/w.

21. A skin care or cosmetic formulation according to claim 19 wherein the caffeine extract is present in an amount of from 0.5% to 5% w/w.

22. A skin care or cosmetic formulation according to claim 19 wherein the caffeine extract is present in an amount of from 1 % to 3% w/w.