WO2014053944A1

WO2014053944A1 - Extract from morigaceae and a method to prepare the extract

Info

Publication number: WO2014053944A1
Application number: PCT/IB2013/058765
Authority: WO
Inventors: Luke Chimuka; Phatsimo Gimamah MATSHEDISO
Original assignee: University Of The Witwatersrand, Johannesburg
Priority date: 2012-10-03
Filing date: 2013-09-23
Publication date: 2014-04-10
Also published as: AP2015008399A0; ZA201502701B

Abstract

This invention provides for a plant extract from the family Moringaceae which suitable for use as an ingredient in a food product, drink, dietary supplement, or a cosmetic product, and a pressurised hot water extraction method for preparing the extract. The extract comprises from about 1000 to about 2000 mg/kg Total Phenolic Content (TPC), as measured according to the method described with an incubation period of about 2 hours. The invention further provides a food product, drink, dietary supplement, or a cosmetic product comprising the extract.

Description

EXTRACT FROM MORINGACEAE AND

A METHOD TO PREPARE THE EXTRACT

INTRODUCTION

This invention relates to an extract of a Moringaceae plant, a method for the preparation of the extract, and to the use of the extract as an ingredient in food products, drinks, dietary supplements, or cosmetic products. In particular, this invention relates to a pressurised hot water extracted aqueous extract of a Moringaceae plant, and a method for the preparation of the extract

BACKGROUND

Many plants have been used for several centuries for its medicinal properties due to its relative accessibility and affordability, in particular in the countries of the developing world. These plants have phytochemicals which are produced in their systems to ensure their survival against harsh conditions such as UV radiation. Some of these substances include phenolic compounds which, when ingested, can act as antioxidants and boost the immune system of an individual. The challenge however is develop efficient extraction methods that deliver plant extracts that are high in target compound concentration, whilst being low in residual solvents and other harmful chemicals.

Conventional methods which use organic solvents (other than water) are often employed for the extraction of the essential compounds such as flavonoids from plant material. Distillation and soxhlet extraction for instance have widely been used for the extraction of these essential compounds. These methods use large volumes of organic solvents, which are not only expensive, but also environmentally unfriendly and potentially hazardous to human health.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a plant extract, suitable for use as an ingredient in a food product, drink, dietary supplement, or a cosmetic product, wherein the plant is selected from the family Moringaceae, wherein the extract is prepared by aqueous extraction, and wherein the extract comprises from about 1400 to about 2000 mg/kg Total Phenolic Content (TPC).

Preferably, the extract comprises from about 1000 to about 3500 mg/kg kaempferol, and from about 500 to about 1200 mg/kg quercetin.

More preferably, the extract comprises from about 8000 to about 10000 mg/kg calcium, from about 15000 to about 22000 mg/kg potassium, from about 1000 to about 6000 mg/kg Na, and from about 2000 to about 6000 mg/kg magnesium.

Most preferably, extract comprises from about 20 to about 100 mg/kg iron, from about 50 to about 100 mg/kg manganese, from about 10 to about 70 mg/kg silicon, and from about 5 to about 30 mg/kg zinc. The plant may be selected from the species Moringa olefeira, Moringa ovalifolia, or mixtures thereof, and the extract may be derived from the bark, seeds, flowers, fruit, leaves and/or combinations thereof.

In a preferred embodiment, the extract is derived from the leaves of the plant.

The extract may be an aqueous extract or a powder extract.

According to a second aspect of the present invention there is provided a method of preparing a plant extract, suitable for use as an ingredient in a food product, drink, dietary supplement, or a cosmetic product, the method comprising the steps of:

optionally rinsing and pre-drying the plant material, providing the plant material in a pressurised extraction vessel, providing a flow of water through the pressurised vessel, wherein the water is kept at a temperature of between about 50 deg C and about 200 deg C, to provide an aqueous extract, and optionally purifying the extract, or optionally evaporating the water from the aqueous extract,

wherein the plant is selected from the family Moringaceae, wherein the extract is prepared by aqueous extraction, and wherein the extract comprises from about 1400 to about 2000 mg/kg Total Phenolic Content (TPC).

Preferably, the extract of the method comprises from about 1000 to about 3500 mg/kg kaempferol, and from about 500 to about 200 mg/kg quercetin.

More preferably, the extract of the method comprises from about 8000 to about 10000 mg/kg calcium, from about 15000 to about 22000 mg/kg potassium, from about 1000 to about 6000 mg/kg Na, and from about 2000 to about 6000 mg/kg magnesium.

Most preferably, the extract of the method comprises from about 20 to about 100 mg/kg iron, from about 50 to about 100 mg/kg manganese, from about 10 to about 70 mg/kg silicon, and from about 5 to about 30 mg/kg zinc. The plant of the method may be selected from the species Moringa olefeira, Moringa ovalifolia, or mixtures thereof.

The extract of the method may be derived from the bark, seeds, flowers, fruit, leaves and/or combinations thereof.

In a preferred embodiment, the extract of the method is derived from the leaves of the plant.

Preferably the extraction of the method is completed within about 10 minutes, more preferably within about 5 minutes, and most preferably in less than about 2 minutes.

According to a third aspect of the present invention there is provided the use of an extract according to the invention in the preparation of a food product, drink, dietary supplement, or a cosmetic product.

According to a fourth aspect of the present invention there is provided an extract prepared according to the present invention.

According to a fifth aspect of the present invention there is a food product, drink, dietary supplement, or a cosmetic product comprising the extract according to the present invention, or an extract prepared according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Without thereby limiting the scope, the invention will now be described in more detail with reference to the following Figures in which:

Figure 1 shows a graphical representation of the effect of incubation time in the Total Phenolic Content (TPC) assay; Figure 2 shows chromatograms of a standard solution and a sample solution indicating the presence of myricetin, quercetin, and kaempferol;

Figure 3 shows graphical representations of the variations of quercetin and kaempferol concentrations for Moringa olifeira extract samples prepared at 25, 100, and 150 deg C;

Figure 4 shows a graphical representation of the reducing activity of

Moringa olifeira extract samples prepared at different temperatures;

Figure 5 shows a graphical representation of the DPPH radical scavenging activity of extract samples collected at different temperatures;

Figure 6 shows graphical representations of the macro element concentrations for nitric acid digestion samples, pressurised hot water extracted extracts, and boiling; and

Figure 7 shows graphical representations of the micro element concentrations for nitric acid digestion samples, pressurised hot water extracted extracts, and boiling.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described more fully hereinafter with reference to the accompanying figures, in which some, but not all of the embodiments of the invention are shown.

The invention as described hereinafter should not be construed to be limited to the specific embodiments disclosed, with slight modifications and other embodiments intended to be included within the scope of the invention. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

As used throughout this specification and in the claims which follow, the singular forms "a", "an" and "the" include the plural form, unless the context clearly indicates otherwise.

The terminology and phraseology used herein is for the purpose of description and should not be regarded as limiting. The use of the terms "comprising", "containing", "having", "including", and variations thereof used herein, are meant to encompass the items listed thereafter and equivalents thereof as well as additional items.

As used throughout this specification and in the claims which follow, unless the context indicates otherwise, the terms "Total Phenolic Content" or "TPC" should be understood to mean the total phenolic concentration of the extract as tested according to the Folin-Ciocalteu method as set out in this specification, the method in particular having an incubation time of 2 hours.

The word "aqueous", as used in this specification, should be understood to mean dissolved, suspended in, or contained in water.

As used in this specification the word "extract" is meant to include liquid, solid, or powdered concentrated preparations prepared from plant material.

"Polyphenol" as used in this specification should be understood to mean a compound containing more than one phenolic hydroxyl group, in particular a natural compound characterized by the presence of a number of phenol structural units.

As used in this specification the word "flavonol" means a class of polyphenol compounds comprising quercetin, gingerol, kaempferol, myricetin, rutin, and isorhamnetin. As used in this specification the word "antioxidant" means a compound that inhibits the oxidation of other compounds.

The term "macro elements", as used in this specification, should be understood to mean a group of chemical elements that represent the most abundant minerals found in the human body and that are required to support essential cellular functions. The macro elements include calcium, potassium, sodium, magnesium, and lithium.

The term "micro elements", as used in this specification, should be understood to mean a group of chemical elements that are found in the human body, at concentrations below that of "macro elements", and that are required to support essential cellular functions. The micro elements include aluminium, barium, cobalt, copper, iron, manganese, nickel, silicon, and zinc.

The term "food product", as used in this specification, should be understood to include breads and other baked goods, dairy based products, canned products such as vegetables, sauces, fat spreads, and seasonings.

The term "drink", as used in this specification, should be understood to include prepared water products, carbonated drinks, fruit juices, tea based drinks, and coffee based drinks.

The term "cosmetic product", as used in this specification, should be understood to include creams, lotions, liquids, sprays, powders, hair preparations such as shampoo, or any other product intended to be used for a cosmetic purpose.

The term "dietary supplement", as used in this specification, should be understood to include capsules, powders, tablets, caplets, liquids, powders for the preparation of meal replacement drinks, or any other product suitable for use, or purported to be suitable for use, as a dietary supplement. In its broadest form, the present invention relates to an extract of a Moringaceae plant. The extracts have been shown to have a high total phenolic content, comprise high concentrations of polyphenols, in particular flavonols, to have antioxidant activity, and to contain essential macro and micro elements.

Preparation of the Aqueous Extract of the Moringaceae Plant

A pressurised hot water extraction system ("PHWE system") was used to prepare the aqueous extracts from the leaves of the Moringa olefeira and Moringa ovalifolia plants.

The PHWE system used in the method of this invention comprised a solvent reservoir, a pump, a heating oven, a stainless steel pressurised extraction vessel, a back pressure regulator, a collection apparatus, and stainless steel connecting lines that comprised a preheating coil section. The continuous stainless steel connecting lines connected the pump with the stainless steel pressurised extraction vessel, which was placed in the heating oven, passing through the pressurised extraction vessel to the collection apparatus outside the oven.

The principle behind the PHWE system is to heat water at high pressure to allow it to remain in the liquid phase (as opposed to the vapour phase) as this allows for the manipulation of the physico-chemical properties of water.

Generally, water is a non-flammable, non-toxic solvent that is readily available and an acceptable solvent for the production of extracts to be used in applications where the final product will either be ingested by, or applied to, humans or animals. Water is also a highly polar solvent with a high dielectric constant at room temperature and atmospheric pressure due to the presence of hydrogen bonding, thereby limiting its potential to efficiently extract moderately polar to moderately non-polar compounds.

However, when heated, the properties of water change markedly as the hydrogen-bonded lattice is disrupted with thermal motion increases leading to a decrease in the dielectric constant. At high temperatures the physico- chemical properties of water, especially the relative permittivity, are favourable for the dissolution and extraction of less polar compounds. By adjusting the extraction temperature water can thus be turned into a suitable solvent for extraction of polar to medium polar solutes such as polyphenols.

Raising the temperature above the boiling point of the solvent increases the diffusion rate, solubility and mass transfer of the compounds and decreases the viscosity and surface tension of the solvent. The pressure in the pressurised extraction vessel is maintained high enough to ensure that water does not change from the liquid phase to the vapour phase, thereby to ensure the relatively lowered lower polarity of the water, thereby to enhance its capacity to dissolve more non-polar compounds.

Optimum conditions for pressurised water extraction depend on various factors including the properties of the water itself, the chemical properties of the solute, and the relevant extraction kinetics.

Without thereby wishing to be bound by the confines of any particular theory, it is proposed that the extraction mechanism in the PHWE system involves at least the following three steps which occur in the pressurised extraction vessel:

1. Upon the rapid introduction of the pressurised hot water, cells of the Moringaceae plant sample break open and the target compounds are desorbed from the active site of the matrix. Thus, the first kinetic step is dominated by the intermolecular adhesive and cohesive forces between the solute, the matrix and the solvent.

2. The second step is the diffusion of the water into the organic matrix. At higher temperature water becomes less viscous and its surface tension is lowered making it a much more diffusive solvent. This enhances extraction because water becomes more efficient in the extraction of the solutes from the organic matrix.

3. The third step of extraction is characterised by the dissolution of the target compounds into the water. By diffusion gradient the target compounds flow into the bulk solution where eventually they are collected. The driving force is the concentration gradient between that exists between the concentration of the target compounds in the solvent (water) and the concentration of the target compounds in the matrix.

0.5 grams of Moringa olefeira leaf powder and 0.5g of diatomaceous earth were weighed into the extraction vessel, which was then connected to the rest of the pressurised hot water extraction system. The heating oven was programmed to operate at 25 deg C for 20 minutes.

Deionised water was pumped through the pressurised system at a flow rate of 1.0 mL/min. The collected extract fractions were then stored for further analysis. This process was repeated with a fresh mixture of Moringa olefeira powder and diatomaceous earth at temperatures of 50 deg C, 100 deg C, 150 deg C and 200 deg C. The pressure in the system was kept at pressures ranging from 1000 - 3000 psi.

0.1g of Moringa ovalifolia was mixed with 0.9g of the diatomaceous earth and the extractions were repeated with the parameters as set out above. The ratio of Moringa ovalifolia to diatomaceous earth was different from the ratio for Moringa olefeira because Moringa ovalifolia is paste-like when wet, thereby reducing the flow through the system.

The Measurement of Total Phenolic Content

The Total Phenolic Content (TPC) of the extract fractions were determined by the Folin-Ciocalteu method. The extract samples were prepared using the method as described in Moraes de S R.A, Oldoni T.L.C, Regitano d'Arce M.A.B, Alencar S.M, Mammucari R, and Foster N.R, Antioxidant Activity and phenolic composition of herbal infusions consumed in Brazil, Cienc. Tecnol. Aliment, 6 pp. 41- 47, (2008).

0.5 mL of extract in distilled water (1 :10) was mixed with 2.5 ml_ of Folin- Ciocalteu reagent diluted in distilled water (1 :10 v/v). The mixture was hand shaken and after 5 minutes of rest, 2 mL of sodium carbonate 4% (v/v) was added. Samples were incubated for 2 hours in the dark and absorbance measured at 740 nm using UV Vis spectrometry (Varian, Cary 50 Cone, Germany). The calibration curve was prepared by four data points ranging from 10 to 100 g/L solutions of gallic acid in water.

During the process of oxidation of phenol, Folin-Ciocalteu reagent, a mixture of phosphotungstic (H3PW12O40) and phospbomolybdic (H₃PMo₁₂0₄o) acids are reduced to blue oxides of tungstene (W8O23) and molybdene ( o₈0₂3) respectively.

The extraction temperature and the incubation time directly influence the phenolic compounds released. In general, extractions at higher temperature gives increased mass transfer rates and higher extraction yields as a result of improved solute desorption from matrix active sites. This is because, at higher temperature, water becomes less polar and the solubility of the phenolic compounds are enhanced. The solubility of the phenolic compounds are governed by their chemical nature which may vary from simple to very highly polymerized structures. As seen in Figure 1 , with longer the incubation time more of the phenolic compounds are released. However, for the purposes of determining TPC values for the extracts of the present invention, and incubation period of 2 hours was used.

Table 1 shows that with increasing extraction temperature, the phenolic contents do increase. As already discussed above, at higher extraction temperature the water becomes less polar and hence dissolves more compounds which are less polar. More phenolics would therefore be extracted at moderately high temperatures. However, too high extraction temperatures IB2013/058765

12 degrade the phenols as seen by a drastic drop of the phenolic contents at 200 deg C.

Table 1 : Variation of total phenolic contents of the leave extracts with extraction temperature at incubation time of 2 hours

Temperature (deg C) TPC (mg/kg) ± % RSD

25 1432 ± 1.21

50 1507 ± 0.15

100 1757 ± 0.35

150 1984 ± 0.58

200 77 ± 33.36

Table 2 shows the results for TPC when extracts were prepared with boiling. Boiling the leave powder for fewer minutes resulted in higher concentrations of the phenolic contents. However boiling for longer times resulted in less phenolic contents recovered. The results also show the effectiveness of the PHWE system in extracting the phenolic compounds.

Table 2: Variation of total phenolic contents of 0.5 g leaf powder boiled in water for different times at incubation time of 2 hours

Boliing Time (minutes) TPC (mg/kg) ± % RSD

0 842 ± 1.03

5 942 ± 8.00

10 984 ± 6.61

15 939 ± 7.14

20 164 ± 2.79

Total Flavonol Content of the Prepared Extracts

A Bischoff high-pressure liquid chromatography (HPLC) system (Metrohm, Johannesburg, RSA) consisting of a Gemini Phenyl - C6 column (150 x 4.6 mm, 5 μητι i.d.) with a UV-Vis detector set at 254 nm was used for the quantification of the components.

A standard stock solution (100 mg/mL) containing a mixture of kaempferoi, myricetin, and quercetin was prepared by dissolving an appropriate amount of each compound in 00 mL of methanol. This stock solution was used for the preparation of intermediate standard solutions that were used for calibration curves during the analysis of the extracts for kaempferoi, myricetin, and quercetin concentration. When not in use the stock was stored at -18 deg C. Samples were isocratically eluted with methanol and 20 mM sodium dihydrogen phosphate buffer adjusted to pH 2.5 with citric acid (55:45 v/v and 0.1% formic acid). The flow rate was optimised to 1.0 mL/min, and the injection volume was 20 μΙ_ for both the extract samples and standard solutions. Samples were prepared in triplicate in each case.

The quantification of myricetin, quercetin and kaempferoi was done using a four-point calibration curve of standard solutions at concentrations ranging between 1.0 and 30 pg/mL.

The chromatogram shown in Figure 2 confirms the presence of the flavonols myricetin, quercetin and kaempferoi. The two peaks for quercetin and kaempferoi in the plant extract are clearly resolved with reasonable peak height. The samples were subjected to an acid hydrolysis reaction prior to quantification, which breaks the glycosidic bonds to release the flavonol aglycones which can then be detected and quantified.

Myricetin does not survive the acid hydrolysis reaction and the peak height is small and not resolved from the other polar substances that are eluted early.

Among flavonols, hydroxylation decreases retention owing to an increase in polarity (hydrogen bond formation ability), and the elution pattern is affected by the number of OH-groups. Accordingly, myricetin is retained for a shorter period of time on the column when compared to quercetin and kaempferoi, which is in agreement with the decrease in the number of OH- substituents. From Figures 3 (a), (b), and (c) it can be seen that there are relatively higher concentrations of the measured flavonols in the fractions collected within the first few minutes, which concentration then decreases in later fractions. This should be expected as the concentration (and therefore the concentration gradient) of the target compounds decline once the pressurised water is introduced into the pressurised extraction vessel.

The results also show that increasing the temperature results in increased concentrations of the flavonols. Figure 3 (a) shows a value of about 1700 mg/kg for kaempferol and about 700 mg/kg for quercetin when extraction was done at 25 deg C. As can be seen from Figure 3 (b), a value of about 3250 mg/kg for kaempferol and about 800 mg/kg for quercetin was obtained when the extraction was done at 100 deg C.

Without thereby wishing to be bound by the confines of theory, this would suggest that with increased temperature the mass transfers are enhanced and the cells break open more readily, thereby to release the target compounds. Further, it is suggested that the reduced viscosity and the improved diffusivity of water allows for better penetration through the matrix particles.

Furthermore, from Figure 3 (c) it can be seen that there is a significant loss of kaempferol at 150 deg C, while quercetin appears to be less affected. It is believed thai the compounds, in particular kaempferol, are relatively unstable at such a high temperature. An extraction temperature of about 100 deg C would therefore be preferred.

The distribution of phenolic compounds in plants at the tissue, cellular and subcellular levels is not uniform. The impact of geographical location on the extraction of total phenol content is also supported by the fact that variety of diverse factors such as worldwide changes in seasonal patterns, weather episodes and temperature changes, and biotic and abiotic stresses may affect the production of secondary metabolites in plants. Other contributing factors could be the time and period of collection, geographical origin, and climatic conditions at the time.

Reducing Activity of the Prepared Extracts

The reducing capacity of a compound may serve as a significant indicator of its potential antioxidant activity. In the reducing power assay, the presence of reductants (antioxidants) in the extract samples would result in reducing the Fe³⁺ ferricyanide complex to the Fe²⁺ ferrous form.

The reducing power of the Moringa olefeira aqueous extracts were determined by mixing 1 ml_ of the extract with 0.2 M phosphate buffer (5 ml_, pH 6.6), 1 % potassium ferricyanide (5 ml_), and then incubated at 50 deg C for 20 minutes. 10% trichloroacetic acid (5 mL) was then added to the mixture to stop the reaction. The mixture was then centrifuged at 3000 rpm for 10 minutes. The supernatant (5 mL) was mixed with distilled water (5ml_) and 0.1 % ferric chloride (1 mL). The absorbance was measured at 700 nm using a UV-Vis spectrophotometer (Varian, Cary 50 Cone, Germany), with the absorbance being directly proportional to the reducing power of the sample.

From Figure 4 it can be seen that with increasing extraction temperature, the extracts have the capability to reduce more of the ferricyanide to the ferrous form. In terms of the effect of extraction temperature, this result is consistent with the results of the flavonol assays and the TPC determinations.

DPPH Radical Scavenging Activity of the Prepared Extracts

DPPH is one of a few stable and commercially available organic nitrogen radicals and has a UV-Vis absorption maximum at 515 nm. The DPPH antioxidant assay is based on the ability of the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) radical, to decolourise upon the addition of antioxidants.

When DPPH accepts an electron donated by an antioxidant compound, the colour of the solution changes from blue to yellow, which can be quantitatively measured in terms of the changes in absorbance. Antioxidant efficiency is measured at ambient temperature which eliminates the risk of thermal degradation. This also allows for a reasonable prediction of the efficiency of the plant extracts in the presence of radicals in the human or animal body.

Figure 5 shows the radical scavenging performance of the different extract fractions collected at 25, 50, 100, 150, and 200 deg C. It also indicates the radical scavenging performance of a comparative 0.2 mg/mL Vitamin C solution tested according to the same parameters.

The most effective extract fraction was the fraction that was collected at 100 deg C as it reduces the radical by about 45%. The radical scavenging results for the fractions collected at 25 deg C and 50 deg C were comparable to that of the comparative Vitamin C solution. Furthermore, as can be seen from Figure 5, the extracts prepared at 150 deg C and 200 deg C were found to be relatively ineffective against the DPPH radical.

Macro and Micro Element Concentrations of the Prepared Extracts

Extract samples from the PHWE system were analysed for metal content using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) (Spectra Genesis, Spectro, Germany). In addition, concentrated nitric acid digested extract samples were analysed for metal content to evaluate the effectiveness of the PHWE system in the extraction of metals from the plant material.

For the digestion samples 8.0 ml_ of concentrated nitric acid was added to 0.1g of the leave powder into a self-regulating pressure control digestion vessel. 2.0 mL of hydrogen peroxide was added and the digestion was allowed to proceed for about 30 minutes. The samples were then filtered through a 0.45 pm filter into 25 mL volumetric flasks and filled up to the mark with deionised water.

In this study, the metal content of both Morina olefeira and Moringa ovalifolia PHWE extracts were investigated. The two plant species were found to contain the minerals which are generally classified as macro and micro elements. The results obtained from the pressurised hot water extraction system (Figure 6 (a) and (b)) were compared to the results obtained from digestion (Figure 6 (c) and boiling (Figure 6 (d) and (e)).

In terms of macro elements, the metals analysed show different extraction characteristics. As can be seen from Figure 6, the concentration of sodium (Na) increased with increased extraction temperature, while the concentrations for calcium (Ca), potassium (K), and magnesium (Mg) remained relatively constant with increased temperature.

In the analysis for sodium the lowest concentration was found at 25 deg C while the highest concentration of almost 6 000 mg/kg was detected at 200 deg C. It is possible that the Na ions are more tightly bound to the active sites, requiring the elevated temperatures for their release and dissolution.

Potassium was found to be the highest concentration of the metals analysed with concentration values ranging between 15 000 and 22 000 mg/kg. Potassium plays an important role in several plant functions, which would explain the relatively high values obtained.

Calcium was found to be the second most abundant metal species in the extracts of Mori^'nga olefeira. Calcium is also a major element needed in higher concentrations in the plants. Furthermore, magnesium is a major constituent of the chlorophyll molecule and hence it is actively involved in photosynthesis. Mg is a co-factor in several enzymatic reactions that activate the phosphorylation processes. The concentration of magnesium in the Moringa olefeira extracts were found to be about 4 000 mg/kg.

Figure 7 shows the efficiency of the pressurised hot water extraction system (Figure 7 (a)) compared to digestion (Figure 7 (b)) and boiling (Figure 7 (c) and (e)) in terms of the extraction of micro elements from the plant material.

Most of the metals (macro and micro elements) in the plant leaf powder were quantitatively extracted by the PHWE system. This is very important for the use of pressurised hot water extracted extracts of the plant as value additions in food products, drinks, dietary supplements, and cosmetic products.

Use of the Extract as an Additive to Foods, Drinks, Dietary Supplements and Cosmetics

It would be appreciated by those skilled in the art that, depending on the nature of the application involved, the pressurised hot water extracted extract could either be used in its aqueous form, or the extract could be evaporated by suitable methods to form a powder.

For instance, the aqueous extract may potentially have greater application in the preparation of drinks, such as prepared water, or in the preparation of cosmetics such as creams and lotions, while the powdered extract may potentially find greater application in dried food products, such as instant soups, or dietary supplements such as tablets or meal replacement shakes.

The extract can be used to produce oringa instant tea. The aqueous extract can be dried by conventional processes, such as freeze drying, to produce water soluble dried particles that can be reconstituted in water to produce a tea drink.

The extract can also be used to prepare an enriched fruit juice product, in particular an enriched apple juice product. In this case, the aqueous extract is blended with the fruit juice in a ratio of from 1 wt% to 50 wt%.

The extract can also be used to prepare an enriched prepared water product. This water product is prepared by mixing the aqueous extract with water in a ratio of from 1 wt% to 50 wt%, sugar, lemon juice, and suitable preservatives.

Claims

1. A plant extract, suitable for use as an ingredient in a food product, drink, dietary supplement, or a cosmetic product, wherein the plant is selected from the family Moringaceae, wherein the extract is prepared by aqueous extraction, and wherein the extract comprises from about 1400 to about 2000 mg/kg Total Phenolic Content (TPC).

2. An extract according to claim 1 , wherein the extract comprises from about 1000 to about 3500 mg/kg kaempferol, and from about 500 to about 1200 mg/kg quercetin.

3. An extract according to claim 1 or claim 2, wherein the extract comprises from about 8000 to about 10000 mg/kg calcium, from about 15000 to about 22000 mg/kg potassium, from about 1000 to about 6000 mg/kg Na, and from about 2000 to about 6000 mg/kg magnesium.

4. An extract according to any one of the preceding claims, wherein the extract comprises from about 20 to about 100 mg/kg iron, from about 50 to about 100 mg/kg manganese, from about 10 to about 70 mg/kg silicon, and from about 5 to about 30 mg/kg zinc.

5. An extract according to any one of the preceding claims, wherein the plant is selected from the species Moringa olefeira, Moringa ovalifolia, or mixtures thereof.

6. An extract according to any one of the preceding claims, wherein the extract is derived from the bark, seeds, flowers, fruit, leaves and/or combinations thereof.

7. An extract according to any one of the preceding claims, wherein the extract is derived from the leaves of the plant.

8. An extract according to any one of the preceding claims, wherein the extract is an aqueous extract.

9. An extract according to any one of claims 1 to 7, wherein the extract is a powder extract.

10. A method of preparing a plant extract, suitable for use as an ingredient in a food product, drink, dietary supplement, or a cosmetic product, the method comprising the steps of:

11. A method according to claim 10, wherein the extract comprises from about 1000 to about 3500 mg/kg kaempferol, and from about 500 to about 1200 mg/kg quercetin.

12. A method according to claim 10 or claim 11 , wherein the extract comprises from about 8000 to about 10000 mg/kg calcium, from about 15000 to about 22000 mg/kg potassium, from about 1000 to about 6000 mg/kg Na, and from about 2000 to about 6000 mg/kg magnesium.

13. A method according to any one of claims 10 to 12, wherein the extract comprises from about 20 to about 100 mg/kg iron, from about 50 to about 100 mg/kg manganese, from about 10 to about 70 mg/kg silicon, and from about 5 to about 30 mg/kg zinc.

14. A method according to any one of claims 10 to 13, wherein the plant is selected from the species Moringa olefeira, Moringa ovalifolia, or mixtures thereof.

15. A method according to any one of claims 10 to 14, wherein the extract is derived from the bark, seeds, flowers, fruit, leaves and/or combinations thereof.

16. A method according to any one of claims 10 to 15, wherein the extract is derived from the leaves of the plant.

17. A method according to any one of claims 10 to 16, wherein the extraction is completed within about 10 minutes.

18. A method according to any one of claims 10 to 16, wherein the extraction is completed within about 5 minutes.

19. A method according to any one of claims 10 to 16, wherein the extraction is completed in less than about 2 minutes.

20. Use of an extract according to any one of claims 1 to 9 in the preparation of a food product, drink, dietary supplement, or a cosmetic product.

21. An extract prepared by the method of any one of claims 10 to 19.

22. A food product, drink, dietary supplement, or a cosmetic product comprising the extract of any of claims 1 to 9, or an extract prepared according to the method of any one of claims 10 to 21.