Title: Aqueous composition comprising capsules based on gelled oil

containing an oxygen-sensitive active agent

Technical field

[0001 ] The present invention relates to an aqueous composition containing at least capsules comprising a core comprising at least one aqueous phase and at least one oxidation-sensitive hydrophilic active agent, notably ascorbic acid, and a shell surrounding the core, said shell comprising at least one unsaturated hydrocarbon- based plant oil and at least one suitably selected oil-structuring agent. A subject of the present invention is also the use of said composition in the cosmetic and dermatological fields, in particular for caring for, treating, cleansing and/or making up human skin of the body or the face, the hair and/or the lips.

[0002] It is known practice to introduce into cosmetic compositions various active agents that are intended to provide specific treatments to the skin and/or the hair. However, some of these active agents have the drawback of being unstable in aqueous medium and of degrading readily on contact with water, in particular on account of oxidation phenomena. They thus rapidly lose their activity over time, and this instability runs counter to the desired efficacy.

[0003] Thus, on account of its chemical structure (a-keto lactone), ascorbic acid is very sensitive to certain environmental parameters, for instance light, oxygen and water. Rapid degradation of formulated ascorbic acid thus arises when it is in contact notably with one of these parameters. Now, it has been sought for a long time to formulate ascorbic acid (or vitamin C) in the cosmetic and dermatological fields, in various presentation forms, due to its numerous beneficial properties. In particular, ascorbic acid stimulates the synthesis of connective tissue and notably of collagen, reinforces skin tissue defences against external attacking factors such as ultraviolet radiation and pollution, compensates for vitamin E deficiency in the skin, depigments the skin and has a free-radical-scavenging function. On account of its properties, ascorbic acid is efficient for cleansing the skin and also for combating the signs of ageing of the skin, for example for improving the radiance of the complexion and fading out wrinkles and/or fine lines in the skin.

[0004] Several solutions have already been envisaged in the prior art for reducing and/or retarding the degradation of ascorbic acid.

[0005] It has thus been proposed to use ascorbic acid in the form of a chemical derivative (magnesium ascorbyl phosphate, or fatty acid esters of ascorbic acid), but the bioavailability of these derivatives is very poor (J. Am. Acad. Dermatol., 1996, 34, 29-33).

[0006] The instability of ascorbic acid with respect to oxygen was able to be improved by using particular packagings such as double compartments under an inert atmosphere, as described in patent US-5 935 584, or by using two-phase emulsions, one phase of which consists of a dry powder containing ascorbic acid and the second of a liquid phase. The mixing of the two phases must be performed at the time of use (WO 98/43598). The solutions have drawbacks as regards the cost and complexity of manufacturing and also substantial constraints as regards the use.

[0007] It has also been recommended in US-A-5 140 043 to stabilize ascorbic acid by introducing it into aqueous-alcoholic solutions, formed from at least 50% water and having a pH of less than 3.5. On account of the high acidity of these solutions, their use in the cosmetic and/or dermatological field is sparingly envisageable. The reason for this is that repeated application of these solutions may disrupt the skin equilibrium and in particular irritate or even burn the skin. In addition, at acidic pH, although the colour change is stabilized, the generation of carbon dioxide (C02) is not.

[0008] Other methods for stabilizing ascorbic acid have been envisaged, for example dissolving ascorbic acid in non-aqueous polar solvents, as described in US A-4 372 874, or adding a large amount of glycol, as described in WO 96/24325, EP 0 755 674 and US 5 981 578. However, the use of polar solvents may cause irritations and the use of a large amount of polyol may have certain drawbacks such as lack of comfort during application to the skin.

[0009] Ascorbic acid may also be formulated in anhydrous media such as silicones (US-6 194 452) which are capable of creating an anhydrous barrier around ascorbic acid. A major drawback of such solutions results from the lack of freshness on application. [0010] WO-A-98/00103 describes the stabilization of vitamin C by using a silicone elastomer in oily dispersion. However, the composition obtained does not remain stable over time, notably when the composition is in the form of an emulsion, and release of the oil and of the water takes place on storage, which is the sign of a lack of stability of the emulsion and which is reflected by the appearance of oil and water at the bottom of the vessel containing the emulsion.

[001 1 ] Moreover, the microencapsulation of cosmetic or dermatological active agents for the purpose of better storage and/or sustained and controlled release is known.

[0012] Microencapsulation processes and the principles on which they are based are described in detail, for example, in Microencapsulation, Methods and Industrial Application, published under the direction of Benita, M. Dekker, 1996.

[0013] All these processes involve the use of polymers as constituent elements of the wall of the microparticle which will isolate the active agent from the external medium. These microparticles make it possible to encapsulating higher contents of water-soluble active agents than other vesicular systems such as liposomes, which are nanoparticles formed from phospholipid bilayers surrounding an aqueous core.

[0014] It has thus been sought to encapsulate various hydrophilic active agents, and, among these, oxidation-sensitive hydrophilic active agents such as ascorbic acid.

[0015] It is notably known practice from patent application WO 2018/077977 to encapsulate cosmetic active agents that are sensitive to the external medium by means of a multiple emulsion process using a gelled oil and ionic polymers.

[0016] The encapsulation approach may be advantageous on condition that cosmetic materials which have a barrier effect towards oxygen are provided. However, these materials may have the drawback of containing residual solvents or monomers, are not always easy to implement, either from the point of view of manufacturing the capsule or from the point of view of the release of the active agent during application to the skin, and they do not always have satisfactory sensory properties on application. In particular, resistance associated with the breaking of the shell and/or a residual deposit of said shell on the skin may be perceived at the time of application. [0017] There is thus still a need for a composition, which can be used notably in the cosmetic and/or dermatological fields, containing an oxidation-sensitive hydrophilic active agent and notably ascorbic acid, which does not have the drawbacks described above, which is stable and comfortable on application, which does not cause any skin irritation after this application, and which is compatible with the constraints of an industrial implementation of its manufacturing process.

[0018] The Applicant has discovered, unexpectedly, that the use of capsules based on plant oil gelled with at least one suitably selected oil-structuring agent makes it possible to limit the degradation of hydrophilic active agents that are sensitive to certain environmental parameters, for instance light, oxygen and water, and preferably oxidation-sensitive, notably ascorbic acid.

Subject of the invention

[0019] One subject of the present invention is thus an aqueous composition containing at least capsules comprising a core comprising an aqueous phase and at least one oxidation-sensitive hydrophilic active agent, notably ascorbic acid, and a shell surrounding the core, said shell comprising at least one unsaturated hydrocarbon- based plant oil and at least one oil-structuring agent chosen from:

- polyester compounds which may be obtained by reaction of a C4-C10 dicarboxylic acid, a polyol of formula (I): R1 -(OH)n, in which n is an integer between 3 and 8 and R1 is an aliphatic hydrocarbon-based chain containing from 3 to 10 carbon atoms, and a C16-C30, preferably C20-C24, monocarboxylic fatty acid;

- hydroxylated linear C ₁₈ -C ₂₄ fatty acids and triglycerides thereof; and

- mixtures thereof.

[0020] The present invention makes it possible to obtain compositions containing an oxidation-sensitive hydrophilic active agent and notably ascorbic acid, which are stable and comfortable on application, which do not cause any skin irritation after this application, which are easy to implement, notably as regards the manufacture of the capsule and the release of the active agent during application to the skin, and which have satisfactory sensory properties on application. In particular, no resistance associated with the breaking of the shell and/or no residual deposit of said shell on the skin is perceived at the time of application.

Definitions

[0021 ] The composition according to the invention is intended for topical application and thus contains a physiologically acceptable medium. The term “physiologically acceptable medium” means here a medium that is compatible with keratin materials.

[0022] In the context of the present invention, the term“keratin material” notably means the skin, the scalp, keratin fibres such as the eyelashes, the eyebrows, head hair, bodily hair, the nails, and mucous membranes such as the lips, and more particularly the skin (body, face, area around the eyes, eyelids).

[0023] In the text hereinbelow, the expression "at least one" is equivalent to "one or more" and, unless otherwise indicated, the limits of a range of values are included in that range.

Capsules

[0024] The capsules present in the composition in accordance with the invention comprise a core comprising an aqueous phase and at least one oxidation-sensitive hydrophilic active agent, notably ascorbic acid, and a shell surrounding the core, said shell comprising at least one unsaturated hydrocarbon-based plant oil and at least one suitably selected oil-structuring agent.

[0025] According to a particular embodiment of the invention, the capsules are spherical.

[0026] For the purposes of the present invention, the term "spherical" means that the capsules have a sphericity index, i.e. the ratio between its largest diameter and its smallest diameter, of less than 1 .2.

[0027] According to a particular embodiment, the capsules present in the composition in accordance with the invention are microcapsules or nanocapsules. [0028] For the purposes of the present invention, the term "microcapsules or nanocapsules" refers to capsules whose volume-mean diameter is between 500 nm and 3000 pm, preferably between 100 pm and 1000 pm.

[0029] The term“volume-mean diameter" means the parameter d(0.5) measured by laser scattering using a Mastersizer2000 particle size analyser from the company Malvern, the results being expressed in the form of volume particle size distributions giving access to the mean diameter.

[0030] In the case where the composition in accordance with the invention comprises microcapsules or nanocapsules, the oil-structuring agent and the concentration thereof in the oil will be chosen so as to obtain a material that is solid enough (hardness) to afford the microcapsules stability during the various manipulations to which they are subjected to prepare a cosmetic composition.

[0031 ] Adjusting the hardness will also be performed taking into account the application conditions, notably the ease with which the macrocapsules break on spreading so as to release the active agent without leaving a residual film on the skin.

[0032] The hardness of the oily gels constituting the shell of the capsule may be measured using a texturometer (such as a TA-XT machine from Swantech) according to a creep protocol. To do this, the oily gel is poured in the liquid state into a Teflon mould 600 pm thick heated beforehand to 65°C in an oven. After 24 hours, the maximum force required to make a cylindrical steel spindle 6 mm in diameter penetrate to a depth of 0.3 mm at a speed of 0.1 mm/s is measured, at room temperature.

[0033] According to a particular embodiment, the hardness of the oily gel allowing the formation of the shell of the capsules used in the context of the invention, measured under these conditions and expressed in g/mm ² , is between 10 and 250 g/mm ² and preferably between 20 and 150 g/mm ² .

[0034] The viscosity of the oily gels may also be characterized using a rheometer (MCR300 Anton Paar) in oscillation mode, in which the sample is subjected to a 0.1 % deformation in the linear domain, in rotation at a frequency of 1 Hz as a function of the temperature. A measuring spindle with sanded plate-plate geometry, 25 mm in diameter, and a 0.5 mm gap, is used. [0035] Under these dynamic-regime measuring conditions, the normalized complex modulus |G ^* | = (G' ² +G" ² ) ^1/2 , which is an indicator of the stiffness of the material, may be extracted. According to a particular embodiment of the invention, this parameter measured at 30°C is between 0.01 and 20 MPa (megapascals) and preferably between 0.1 and 10 MPa.

[0036] The hardness of the oily gels allowing the formation of the shell of the capsules is partly conditioned by their melting point and the fraction that is liquid at 45°C. These data are obtained by DSC (differential scanning calorimetry) using, for example, the DSC Q100 machine from the company TA Instruments. To perform the measurement, 3 mg of the oily gel are weighed out in a hermetic aluminium crucible and the sample is subjected to three successive temperature ramps from 25°C to 120°C, from 120°C to -20°C and then from -20°C to 120°C at a rate of 10°C/minute. An empty crucible is used as reference. During the final ramp, the transition from the solid state to the liquid state of the composition is characterized by the melting point (°C) and the heat of fusion (J/g).

[0037] The machine also makes it possible to calculate the liquid fraction of the composition at a certain temperature. Thus, it is possible to adapt the oily gel constituting the shell of the capsules of the invention in order to control this fraction that is liquid, for example at 45°C, which is a conventional temperature in the cosmetic field for studying the stability on storage of formulations.

[0038] In the context of the invention, oily gels with a melting point of between 40°C and 100°C, preferably between 55°C and 70°C, are chosen. The liquid fraction is chosen between 0% and 50%, preferably between 5% and 25%.

[0039] The capsules generally represent from 0.1 % to 60% by weight, preferably 0.3% to 40% by weight and better still from 0.5% to 20% by weight relative to the total weight of the composition forming the subject of the invention.

A) Core of a capsule

Oxygen-sensitive hydrophilic active agents

[0040] According to the invention, the term "hydrophilic active agent" refers to a compound which has a solubility in water of at least 0.25% at room temperature (25°C). [0041 ] In addition, according to the invention, the term "oxidation-sensitive hydrophilic active agent" refers to any active agent of natural or synthetic origin which is capable of undergoing degradation via an oxidation mechanism. This oxidation phenomenon may have several causes, in particular the presence of oxygen, of light, of metal ions, a high temperature, or certain pH conditions.

[0042] Examples of oxidation-sensitive hydrophilic active agents that may be mentioned, in a non-limiting manner, include ascorbic acid and derivatives thereof such as 5,6-di-O-dimethylsilyl ascorbate (sold by the company Exsymol under the reference PRO-AA), the potassium salt of dl-a-tocopheryl-2l-ascorbyl phosphate (sold by the company Senju Pharmaceutical under the reference Sepivital EPC), magnesium ascorbyl phosphate, sodium ascorbyl phosphate (sold by the company Roche under the reference Stay-C 50); phloroglucinol; enzymes; and mixtures thereof. Mention may also be made of resorcinol and derivatives thereof such as phenylethyl resorcinol, sold under the reference Symwhite 377 by the company Symrise, and also 4-butylresorcinol and tetrahydropyranylresorcinol.

[0043] Among the polyphenols, mention may be made of resveratrol and the 3-O-b- D-glucopyranoside derivative thereof, such as the product sold under the reference Polygonum cuspidatum root extract by the company Guilin Layn Natural Ingredients, and baicalin, such as the product sold under the reference Baicalin 95MM by the company MMP.

[0044] Mention may also be made of ferulic acid, such as the product sold under the reference Oryza Ferulix by the company Oryza Oil & Fat Chemical.

[0045] Among the oxidation-sensitive hydrophilic active agents, ascorbic acid will be more particularly preferred.

[0046] The ascorbic acid may be of any nature. Thus, it may be of natural origin in powder form or in the form of orange juice, preferably orange juice concentrate. It may also be of synthetic origin, preferably in powder form.

[0047] The amounts of oxidation-sensitive active agent in the composition of the invention are those conventionally used in the fields under consideration, for example from 0.1 % to 30% by weight and preferably from 0.5% to 10% by weight relative to the total weight of the composition forming the subject of the invention. Aqueous phase

[0048] The phase constituting the core of the capsules used in the composition in accordance with the invention and comprising the oxidation-sensitive hydrophilic active agent(s) comprises at least water.

[0049] According to a particular embodiment, the amount of water in the core of the capsules is at least 1 % by weight, preferably ranging from 2% to 50% by weight and better still from 5% to 15% by weight, relative to the total weight of the composition forming the subject of the invention.

[0050] The water used may be sterile demineralized water and/or a floral water such as rose water, cornflower water, chamomile water or lime blossom water, and/or a natural spring water or mineral water, for instance: Vittel water, Vichy basin water, Uriage water, Roche Posay water, Bourboule water, Enghien-les-Bains water, Saint Gervais-les-Bains water, Neris-les-Bains water, Allevar-les-Bains water, Digne water, Maizieres water, Neyrac-les-Bains water, Lons-le-Saunier water, Eaux Bonnes water, Rochefort water, Saint Christau water, Fumades water, Tercis-les-Bains water and Avene water. The aqueous phase may also comprise reconstituted spring water, i.e. a water containing trace elements such as zinc, copper, magnesium, etc., reconstituting the characteristics of a spring water.

[0051 ] This aqueous (or hydrophilic) phase may also contain any water-soluble or water-dispersible additive.

[0052] Water-soluble additives that may notably be mentioned are polyols comprising from 2 to 8 carbon atoms. The term “polyol” should be understood as meaning any organic molecule including at least two free hydroxyl groups. Examples of polyols that may be mentioned include glycerol, glycols, for instance butylene glycol, propylene glycol, isoprene glycol, dipropylene glycol, hexylene glycol, polyethylene glycols and polypropylene glycol. According to a particular embodiment of the invention, the polyol is chosen from glycerol and hexylene glycol. Preferably, the polyol is glycerol.

[0053] Water-soluble additives that may also be mentioned include primary alcohols, i.e. an alcohol including from 1 to 6 carbon atoms, such as ethanol and isopropanol. It is preferably ethanol. The addition of such an alcohol may notably be suitable when the composition according to the invention is used as a product for the body or the hair.

[0054] Mention may also be made of chelating agents (or sequestrants) such as ethylenediaminetetraacetic acid (EDTA) and salts thereof, pentasodium ethylenediaminetetramethylenephosphonate, glucono-5-lactone, sodium, potassium and/or calcium gluconate, citric acid, phosphoric acid, tartaric acid, potassium bitartrate, sodium acetate, sorbitol or phytic acid.

[0055] The amount of water-soluble or water-dispersible additives in the composition of the invention may range, for example, from 0 to 50% by weight, preferably from 0.5% to 30% by weight and even more preferentially from 2% to 20% by weight relative to the total weight of the composition forming the subject of the invention.

B) Envelope of a capsule

Unsaturated hydrocarbon-based plant oils

[0056] The term "oil" means any nonionic lipophilic compound that is insoluble in water and liquid at room temperature (25°C) and at atmospheric pressure (760 mmHg, i.e. 1 .013 x 10 ⁵ Pa). For the purposes of the present invention, the term "water- insoluble" refers to a compound whose solubility at spontaneous pH in water at 25°C and at atmospheric pressure is less than 1 % and preferably less than 0.5% by weight. Oils are soluble in organic solvents under the same temperature and pressure conditions, for instance chloroform, ethanol or benzene. Furthermore, oils are liquid at ordinary temperature (25°C) and at atmospheric pressure. Oils preferably have a melting point of less than 5°C and a viscosity of less than 500 cPs at 25°C at a shear rate of 1 s ^_1 .

[0057] In particular, the term "plant oil" means an oil as defined above, extracted from a species belonging to the plant kingdom.

[0058] For the purposes of the present invention, the term“hydrocarbon-based oil” means any oil predominantly including carbon and hydrogen atoms, and possibly ester, ether, fluoro, carboxylic acid and/or alcohol groups.

[0059] The plant oil(s) used in the context of the invention are unsaturated hydrocarbon-based plant oils, and in particular unsaturated fatty acid triglycerides such as soybean oil, castor oil, olive oil, ximenia oil, pracaxi oil, palm oil, linseed oil, sunflower oil, argan oil, rice bran oil, avocado oil, macadamia oil, peach kernel oil, apricot kernel oil, rapeseed oil, sweet almond oil, canola oil, coriander oil, cottonseed oil, sesame oil, corn germ oil, wheat germ oil, passionflower oil, grapeseed oil, safflower oil, evening-primrose oil, walnut oil, blackcurrant pip oil, musk rose oil, camellina oil, raspberry seed oil, cranberry oil, castor oil, meadowfoam oil, annatto oil, andiroba oil, Brazil nut oil, buriti oil, mongongo oil, marula oil, coffee oil, Inca inchi oil, aveline oil, jojoba oil or shea butter oil.

[0060] The plant oils according to the invention generally have not undergone any chemical transformation after extraction.

[0061 ] Among the plant oils mentioned above, soybean oil is preferably used.

[0062] According to a particular embodiment, the unsaturated hydrocarbon-based plant oil(s) are present in the composition in an amount ranging from 1 % to 30%, more preferentially in an amount ranging from 2% to 20%, and better still in an amount ranging from 3% to 10% by weight, relative to the total weight of the composition forming the subject of the invention.

[0063] The shell of the capsule may also comprise at least one additional oil other than the unsaturated hydrocarbon-based plant oils described above.

[0064] As additional oils that may be used in the composition of the invention, examples that may be mentioned include:

- hydrocarbon-based oils of animal origin, such as perhydrosqualene;

- saturated hydrocarbon-based oils of plant origin such as saturated liquid triglycerides of fatty acids including from 4 to 10 carbon atoms, for instance heptanoic or octanoic acid triglycerides, or alternatively, for example, caprylic/capric acid triglycerides such as those sold by the company Stearinerie Dubois or those sold under the names Miglyol 810 and Miglyol 812 by the company Cremer Oleo;

- synthetic esters and ethers, notably of fatty acids, for instance the oils of formulae R ^a COOR ^b and R ^a OR ^b in which R ^a represents a fatty acid residue including from 8 to 29 carbon atoms and R ^b represents a branched or unbranched hydrocarbon-based chain containing from 3 to 30 carbon atoms, for instance Purcellin oil, isononyl isononanoate, isopropyl myristate, 2-ethylhexyl palmitate, 2-octyldodecyl stearate, 2- octyldodecyl erucate or isostearyl isostearate; hydroxylated esters, for instance isostearyl lactate, octyl hydroxystearate, octyldodecyl hydroxystearate, diisostearyl malate or triisocetyl citrate; fatty alcohol heptanoates, octanoates or decanoates; polyol esters, for instance propylene glycol dioctanoate, neopentyl glycol diheptanoate and diethylene glycol diisononanoate; and pentaerythritol esters, for instance pentaerythrityl tetraisostearate; amino acid esters such as isopropyl lauroyl sarcosinate sold under the name Eldew SL-205 by the company Ajinomoto; ethers, for instance dicaprylyl ether sold under the name Cetiol OE by the company BASF;

- substantially linear or branched hydrocarbons of mineral or synthetic origin, such as volatile or non-volatile liquid paraffins, and derivatives thereof, petroleum jelly, polydecenes, isohexadecane, isododecane or hydrogenated polyisobutene, such as Parleam® oil;

- fatty alcohols containing from 8 to 26 carbon atoms, such as cetyl alcohol, stearyl alcohol and a mixture thereof (cetylstearyl alcohol), octyldodecanol, 2-butyloctanol, 2- hexyldecanol, 2-undecylpentadecanol, oleyl alcohol or linoleyl alcohol;

- alkoxylated and notably ethoxylated fatty alcohols, such as oleth-12, ceteareth-12 and ceteareth-20;

- partially hydrocarbon-based and/or silicone-based fluoro oils, such as those described in JP-A-2-295 912. Fluoro oils that may also be mentioned include perfluoromethylcyclopentane and perfluoro-1 ,3-dimethylcyclohexane, sold under the names Flutec PC1 ^® and Flutec PC3 ^® by the company BNFL Fluorochemicals; perfluoro-1 ,2-dimethylcyclobutane; perfluoroalkanes such as dodecafluoropentane and tetradecafluorohexane, sold under the names PF 5050 ^® and PF 5060 ^® by the company 3M, or bromoperfluorooctyl sold under the name Foralkyl ^® by the company Atochem; nonafluoromethoxybutane sold under the name MSX 4518 ^® by the company 3M and nonafluoroethoxyisobutane; perfluoromorpholine derivatives such as 4- trifluoromethylperfluoromorpholine sold under the name PF 5052 ^® by the company 3M;

- silicone oils, for instance volatile or non-volatile polymethylsiloxanes (PDMS) with a substantially linear or cyclic silicone chain, which are liquid or pasty at room temperature, notably cyclopolydimethylsiloxanes (cyclomethicones) such as cyclohexadimethylsiloxane and cyclopentadimethylsiloxane; polydimethylsiloxanes including alkyl, alkoxy or phenyl groups, which are pendent or at the end of a silicone chain, these groups containing from 2 to 24 carbon atoms; phenyl silicones, for instance phenyl trimethicones, phenyl dimethicones, phenyltrimethylsiloxydiphenylsiloxanes, diphenyl dimethicones, diphenylmethyldiphenyltrisiloxanes or 2-phenylethyl trimethylsiloxy silicates, and polymethylphenylsiloxanes;

- mixtures thereof.

Oil-structuring agents

[0065] The term "structuring" means the provision of effects ranging from increasing the viscosity (viscosity-enhancing or thickening) up to gelation of the oil (creation of a three-dimensional structure at the molecular level which "traps" the continuous oily phase) and includes the possibility of generating phases of liquid crystal type in the oil, all these factors being able to improve the stability of the phases dispersed in the oil.

[0066] The oil-structuring agent(s) that are useful in the context of the invention are chosen from:

- polyester compounds which may be obtained by reaction of a C4-C10 dicarboxylic acid, a polyol of formula (I): R1 -(OH)n, in which n is an integer between 3 and 8 and R1 is an aliphatic hydrocarbon-based chain containing from 3 to 10 carbon atoms, and a C16-C30, preferably C20-C24, monocarboxylic fatty acid;

- hydroxylated linear C ₁₈ -C ₂₄ fatty acids and triglycerides thereof;

and mixtures thereof.

1) Polyester compounds

[0067] The polyester compounds that may be suitable for use in the context of the invention are such as those described in patent EP 1 962 790 B1 .

[0068] When reference is made to these compounds as "polyesters" or "oligoesters", this refers to the multiple ester bonds in the compounds - derived from the reaction between the polyol and the monocarboxylic and dicarboxylic acids. This does not necessarily imply that the compounds bear polyester chains - of alternating carboxylic acid and polyol, although such chains may constitute a characteristic of these compounds.

[0069] The polyol used as starting material in the preparation of the polyesters used in the context of the invention typically contains at least 3 and up to 8 hydroxyl groups, and preferably contains an average ranging from 1 to 2 primary hydroxyl groups and at least one, in particular from 1 to 4, secondary hydroxyl groups. They may be considered as corresponding to formula (I): R ¹ -(OH) _n , in which n ranges from 3 to 8 and in particular from 3 to 6. The group R ¹ may be an aliphatic hydrocarbon-based group, which is usually saturated, containing from 3 to 10, in particular from 3 to 8 and notably from 3 to 6 carbon atoms and will usually be linear, although it may include branches. In the polyol (I), there will generally be one or two primary hydroxyl groups (on the terminal carbon atoms of the polyol) and at least one and usually n-2 secondary hydroxyl groups. Preferably, the polyol (I) corresponds to formula (la): HOH ₂ C- (CHOH) _P -CH ₂ 0H in which p ranges from 1 to 6, more usually from 1 to 4. Examples that may be mentioned include glycerol, C ₄ polyols such as threitol and erythritol, C ₅ polyols such as inositol, arabitol and xylitol, and Ce polyols such as sorbitol, and derived materials such as sorbitan. The C4 to Ce polyols are commonly the reduced or hydrogenated forms of corresponding sugars of tetrose, pentose and hexose type. Preferably, the polyol is chosen from glycerol, sorbitol and mixtures thereof.

[0070] It is possible to include relatively low proportions of residues derived from diols, for instance from ethylene, diethylene, triethylene or propylene glycols or from isosorbide (derived by sorbitol dianhydridization). The inclusion of such diol residues may make it possible to adjust properties of the polymers; however, the proportion of such residues will generally below, typically an average of not more than 20 mol%, more usually not more than 15 mol% and better still not more than 10 mol%, for example from 1 to 10 mol% and in particular from 1 to 5 mol% of polyol residues in the compounds.

[0071 ] Notably when the polyol contains four or more carbon atoms and four or more hydroxyl groups, usually two primary hydroxyl groups and two or more secondary hydroxyl groups, and in particular when the polyol corresponds to formula (la), p being equal to 3 or 4, it may be capable of reacting via an intramolecular etherification reaction (anhydridization) in order to form cyclic ethers. [0072] The dicarboxylic acid used as starting material in the preparation of the polyesters used in the context of the invention contains from 4 to 10 carbon atoms and will usually consist of aliphatic compounds. Typically, the dicarboxylic acid corresponds to formula (II): HOOC-R ² -COOH, in which R ² is a C ₂ to Cs hydrocarbon-based group which may be saturated or unsaturated, linear or branched, and which may be aromatic, for example a phenyl ring (thus leading to a phthalic, terephthalic or isophthalic dicarboxylic acid), or aliphatic, typically an alkylene or alkenylene group, and which may be cyclic or, preferably, open-chained. Usually, R ² is a group -(CH ₂ ) _m -, in which m ranges from 2 to 8. When mixtures of different dicarboxylic acids (or of reactive derivatives) are used, m may appear not to be an integer, since it will be an average. The suitable reactive derivatives of the dicarboxylic acids may be lower alkyl esters (usually diesters), for example of Ci to C ₄ , and in particular methyl, and anhydrides, in particular cyclic anhydrides such as succinic, maleic and phthalic anhydrides.

[0073] The monocarboxylic acid used as starting material in the preparation of the polyesters used in the context of the invention consists of C ₁₆ to C30, in particular C ₁₈ to C30 and preferably C ₂₀ to C ₂₄ fatty acids. Typically, they correspond to formula (III): R ³ C0 ₂ H, in which R ³ is a long-chain, preferably saturated and linear, aliphatic hydrocarbon-based group, specifically a C ₁₅ to C ₂₉ , usually C ₁₇ to C ₂₉ , in particular C ₁₉ to C ₂₃ hydrocarbon-based group, in particular an alkyl radical. The reactive monocarboxylic acid derivatives that may be used in the synthetic reaction may be lower alkyl esters, for example of Ci to C ₄ , and in particular methyl esters.

[0074] The chain lengths of the monocarboxylic fatty acids appears to be directly linked to the structuring efficiency of the compounds used in the context of the invention; the use of fatty acids with a chain shorter than C16 appears to lead to little structuring effect, for example thickening, the viscosity-enhancing or gelling, or even none at all (at least at room temperature), whereas longer chains, for example of C18 or in particular C20 or more, may lead to more efficient structuring agents. Consequently, the desired monocarboxylic acids are preferably stearic acid and behenic acid, and even more preferentially behenic acid. The presence of branches or unsaturations in the chains of the monocarboxylic acids is generally undesirable since it leads to much less efficient structuring agents. [0075] Mixtures of monocarboxylic acids may be used, if so desired, and this may be advantageous for allowing the properties of the polyester compounds to be adjusted. The use of combinations of long-chain monocarboxylic acids will generally give compounds whose properties are intermediate between the properties of the respective compounds prepared entirely with the respective fatty acids. The incorporation of small proportions of short-chain monocarboxylic acids (in particular less than 16 carbon atoms) or branched or unsaturated monocarboxylic acids (of any chain length) will have a tendency to make the compounds less susceptible to be structuring agents of gelling type. The proportions of short-chain or branched or unsaturated monocarboxylic acids will generally be small, typically an average of not more than 30 mol%, more usually not more than 25 mol% and desirably not more than 20 mol%, for example from 1 to 20 mol% and in particular from 5 to 15 mol% of the total monocarboxylic fatty acid residues in the compounds.

[0076] Significant thickening may be obtained with polyester molecules that are even relatively small and the compounds that may be used in the context of the invention typically have a number-average molecular weight ranging from 1000 to 10 000, more usually ranging from 1200 to 7000 and in particular ranging from 1300 to 6000 and a corresponding weight-average molecular weight ranging from 2500 to 20 000, more usually from 2500 to 12 000 and in particular from 2500 to 10 000 (on the basis of the molecular weights measured by gel permeation chromatography against polystyrene standards). Such molecular weight values correspond to nominal lengths of chains derived from the esterification-polymerization of the polyol and of the dicarboxylic acid ranging from about 1 to about 20, more usually ranging from about 1 to about 10 and in particular ranging from about 1 to about 7.5 repeating units (on the basis of an ester unit of dicarboxylic acid and of polyol bearing hydroxy/carboxy end groups). Naturally, the number of "repeating units" and the molecular weight are mean values which may thus not be whole numbers.

[0077] The extent of esterification of the total available hydroxyl groups in the reaction components used for preparing the compounds used in the context of the invention may have a significant effect on the efficiency of these compounds as structuring agents. Generally, a minimum of 40%, more usually at least 45% and preferably at least 50% of the total hydroxyl groups of polyol will be esterified. At lower degrees of esterification, the proportion of free hydroxyl groups is high enough to significantly reduce the solubility in the oil of the oligoesters and thus to have a detrimental effect on the thickening performance of the compounds. The maximum number of such ester residues will clearly depend on the number of hydroxyl groups in the original polyol. However, in practice, it is difficult to obtain a complete reaction, and as such the degree of esterification is usually not more than about 90%, for example up to about 80% of the hydroxyl groups in the original polyol (in the calculation of the number of hydroxyl groups in the original polyol, any one which reacts in order to form ethers under the reaction conditions, for example such as in the formation of sorbitol from sorbitan, is not included). Within these ranges, the proportion of free hydroxyl groups may be used in order to modulate or moderate the thickening effects of the compounds.

[0078] In order to generate a predominance of hydroxyl (relative to carboxyl) end groups in the oligoester product, the polyol will generally be used in molar excess relative to the dicarboxylic acid, more usually in a polyol/diacid mole ratio ranging from 1 .1 to 2, more usually from 1 .25 to 2. The amount of monocarboxylic acid used will depend on the number of hydroxyl groups in the polyol and on the proportion of hydroxyl groups that it is desired to esterify in the product. Generally the proportion used will range from 1 to 2.5, more usually from 1 to 2.2 and notably from 1 .2 to 2 mol of monocarboxylic acid per mole of polyol. Consequently, the ratios of the polyol, of the dicarboxylic acid and of the monocarboxylic acid used will generally be in the range extending from 1/0.5 to 0.95/1 to 2.5, more usually from 1/0.5 to 0.85/1 to 2.2 and preferably from 1/0.6 to 0.85/1 .2 to 2. The products of the invention typically have a hydroxyl number (OH number, in mg (KOH).g ¹ ) of at least 15 and usually up to 50, although higher values are possible, for example ranging up to about 250, more usually from 50, in particular from 60, to 220. Higher values may be obtained by means of the deliberate use of a highly hydroxylic polyol, such as sorbitol, as starting material, and by performing the synthesis so as to minimize the loss of free hydroxyl groups, for example by avoiding the synthetic cyclization-etherification side reactions by using non-acidic catalysts, notably alkaline catalysts, in relatively high contents (see below). One of the effects arising from the higher free OH content of such materials is that the products have higher melting points when compared with products that are otherwise similar having lower OH numbers. Consequently, the compounds of the invention are generally solid with melting points ranging from 50 to 70°C, although, for compounds with higher OH numbers, in particular greater than 100, the melting point may range up to 85°C.

[0079] As measured directly, the OH number includes the hydroxylic and also carboxylic OH groups, the contribution of the hydroxylic OH groups being able to be obtained by subtracting the acid number from the OH number, both measured in mg (KOH).g ¹ , in order to give a number which may be described as the "free OH number".

[0080] The compounds used in the context of the invention are oligoesters or polyesters of polyol, of dicarboxylic acid and of monocarboxylic acid, but their exact molecular structure is not clear. From the molecular weight measurements by gel permeation chromatography, it appears that the polyol and the dicarboxylic acid are linked so as to form an oligo- or polymer backbone and that the monocarboxylic acid is esterified with a portion or all of the remaining hydroxyl groups of polyol. It is probable that the compounds are mixtures of different molecules and probably include a few relatively straight linear chains, for instance those derived from a reaction between the dicarboxylic acid and a,w-primary hydroxyl groups such as in glycerol or sorbitol, a few

"twisted" chains such as those derived from a reaction between the dicarboxylic acid and non-terminal, in particular secondary, hydroxyl groups, and a few branched or even crosslinked chains or groups.

[0081 ] The compounds used in the context of the invention are mainly OH- terminated and the proportion of free carboxylate groups is small, as reflected by the measured acid numbers which typically correspond to an equivalent weight that is significantly higher for the content of carboxylic acid relative to the measured molecular weight. Typically, the acid numbers will usually be less than 10, for example less than 5 mg (KOH).g ¹ , although, when the polyol is sensitive to anhydridization, for example sorbitol, and when it is desired for the product to have low degrees of anhydridization, less drastic conditions may be used for the esterification, which may lead to somewhat higher acid numbers, for example up to 20 mg (KOH).g ¹ . By considering that the compounds used in the context of the invention and used therein are mainly OH- terminated (rather than carboxy-terminated), the OH number, and preferably the free OH number, will typically be significantly higher than the acid number (both measured in mg (KOH).g- ¹ ). [0082] The compounds used in the context of the invention may be prepared via a generally conventional esterification using a polyol, a dicarboxylic acid (or a reactive derivative) and a monocarboxylic acid (or a reactive derivative) as starting materials. The compounds that are useful in the context of the invention may notably be prepared via a direct one-step route in which the three components: the polyol, the dicarboxylic acid (or a reactive derivative) and the monocarboxylic acid (or a reactive derivative) are mixed and react together under (trans)esterification conditions, in particular at high temperatures and in the presence of a catalyst.

[0083] The reaction conditions will typically involve reaction temperatures ranging from 150 to 250°C and in particular from 170 to 240°C. When free acids are used as reagents in a direct esterification, the reaction may be performed at atmospheric pressure or under a moderate vacuum, for example at pressures ranging from 50 to 250 mbar, in particular about 100 mbar, in order to facilitate the removal of the reaction water, and the transesterification reactions using lower alkyl esters will usually be performed at ambient pressure.

[0084] The catalysts that are suitable for use will depend on the concrete starting materials and on the desired compound. For direct esterifications, typical catalysts include basic catalysts such as alkali metal hydroxides or carbonates, such as sodium or potassium hydroxide or carbonate, in particular potassium carbonate; or acid catalysts, such as sulfonic acids, for example p-toluenesulfonic acid or phosphorus oxy acids, such as phosphoric acid or, in particular if it is desirable to have colour-forming oxidation reactions, notably with starting polyols such as sorbitol, phosphorous acid, and catalysts combining phosphoric and/or phosphorous acid with an alkali, typically in a mole ratio ranging from 1/1 to 1/3; and, for transesterifications, typical catalysts include a relatively mild alkali metal base such as carbonates, in particular potassium carbonate, titanate esters, such as tetrabutyl titanate.

[0085] The amount of catalyst used will be chosen so as to obtain the desired rate of catalysis and will usually be within the range extending from 0.5% to 20% by weight on the basis of the weight of polyol used. Typically, the amount of catalyst will range from 0.75% to 10% by weight on the basis of the polyol. When it is desired to avoid side reactions such as a cyclization-etherification during the use of highly hydroxylic polyols such as sorbitol, notably when it is desired to prepare products with particularly high hydroxyl numbers, then a higher proportion of esterification catalyst, for example ranging up to 20%, in particular about 15%, by weight on the basis of the polyol, may be used in order to increase the preference for the desired reaction, and catalytic materials which promote cyclization such as acids will generally be avoided.

[0086] According to a particular embodiment of the invention, the polyester compound(s) are chosen from polyester compounds that may be obtained by reaction of sebacic acid, sorbitol and behenic acid.

[0087] An example that may notably be mentioned is the compound having the INCI name Sorbitol/sebacic acid copolymer behenate sold under the names Syncrowax ORM-PW-(MV) or Syncrowax OSW-PA-(MH) by the company Croda.

2) Hydroxylated linear Ci ₈ -C ₂ 4 fatty acids and triglycerides thereof

[0088] According to a particular embodiment of the invention, the hydroxylated linear C18-C24 fatty acid(s) are saturated. Preferably, the hydroxylated linear C18-C24 fatty acid is 12-hydroxystearic acid. This compound is notably sold under the reference 12- Hydroxystearic Acid Premium Grade 12H-P by the company Thai Kawaken.

[0089] An example of a triglyceride of a hydroxylated linear C18-C24 fatty acid that may be mentioned is trihydroxystearine (or glyceryl trihydroxystearate) sold under the names Thixcin R and Thixcin RPC by the company Elementis.

[0090] According to a particular embodiment of the invention, the oil-structuring agent(s) are chosen from polyester compounds that may be obtained by reaction of a C4-C10 dicarboxylic acid, a polyol of formula (I): R1 -(OH)n, in which n is an integer between 3 and 8 and R1 is an aliphatic hydrocarbon-based chain containing from 3 to 10 carbon atoms, and a C16-C30, preferably C20-C24, monocarboxylic fatty acid.

[0091 ] According to a preferred embodiment, the oil-structuring agent(s) are chosen from polyester compounds that may be obtained by reaction of sebacic acid, sorbitol and behenic acid.

[0092] According to a particular embodiment, the composition according to the invention comprises a total content of oil-structuring agents ranging from 5% to 50% by weight, better still from 10% to 40% by weight and preferably from 15% to 25% by weight, relative to the total weight of the composition forming the subject of the invention.

[0093] According to a particular embodiment of the invention, the mass ratio between the oil-structuring agent(s) chosen from the polyester compounds and the hydroxylated linear C18-C24 fatty acids and triglycerides thereof; and the unsaturated hydrocarbon-based plant oil(s) is between 0.05 and 1 .6 and preferably between 0.1 and 0.5.

C) Capsule preparation process

[0094] The capsules present in the composition in accordance with the invention may be obtained via a microfluidic process. With such a process, the capsules have a uniform size distribution.

[0095] To prepare the capsules present in the composition in accordance with the invention, use may be made, for example, of the device described in the publication “Controlled production of monodisperse double emulsions by two-step droplet breakup in microfluidic devices”, Okushima et al. , Langmuir, (2004), 20 9905-9908.

[0096] And more generally, the publication “Microfluidic Production of Multiple Emulsions”, Vladisavljevic, Micromachines, (2017), 8, 1 -34, may be consulted for the choice of the production device that is suited to the specifications for the application.

Aqueous composition comprising the capsules described above

[0097] The composition according to the invention is an aqueous composition in which the capsules described above are dispersed.

[0098] The composition preferably has a skin-friendly pH which generally ranges from 3 to 8 and preferably from 4.5 to 7.

[0099] Thus, the composition in accordance with the invention comprises at least water.

[00100] According to a particular embodiment of the invention, the amount of water is between 40% and 99.9% by weight and preferably between 80% and 98% by weight relative to the total weight of the composition. [00101 ] The composition in accordance with the invention may comprise at least one hydrophilic solvent, for instance substantially linear or branched lower monoalcohols containing from 1 to 8 carbon atoms, such as ethanol, propanol, butanol, isopropanol or isobutanol; polyols, such as propylene glycol, isoprene glycol, butylene glycol, glycerol, sorbitol, polyethylene glycols and derivatives thereof; and mixtures thereof.

[00102] The composition in accordance with the invention may also contain one or more adjuvants that are common in the cosmetic and dermatological fields, hydrophilic gelling agents and/or thickeners; moisturizers; emollients; hydrophilic active agents other than those described previously; free-radical scavengers; sequestrants; antioxidants; preserving agents; UV-screening agents; acidifying or basifying agents; fragrances; film-forming agents; dyestuffs (pigments such as iron oxides and titanium dioxide, nacres and soluble dyes); fillers; and mixtures thereof.

[00103] The amounts of these various adjuvants are those conventionally used in the fields under consideration. In particular, the amounts of active agents vary according to the desired aim and are those conventionally used in the fields under consideration, for example from 0.1 % to 20% and preferably from 0.5% to 10% by weight relative to the total weight of the composition.

[00104] Hydrophilic gelling agents that may be mentioned include, for example, carboxyvinyl polymers such as Carbopols such as Carbopol 980 (Carbomers) and Pemulens (acrylate/C10-C30 alkyl acrylate copolymer); polyacrylamides, for instance the crosslinked copolymers sold under the names Sepigel 305 (CTFA name: polyacrylamide/C13-14 isoparaffin/Laureth 7) or Simulgel 600 (CTFA name: acrylamide/sodium acryloyldimethyltaurate copolymer/isohexadecane/polysorbate 80) by the company SEPPIC; 2-acrylamido-2-methylpropanesulfonic acid polymers and copolymers, optionally crosslinked and/or neutralized, for instance poly(2-acrylamido- 2-methylpropanesulfonic acid) sold by the company Clariant under the trade name Hostacerin AMPS (CTFA name: ammonium polyacryloyldimethyl taurate or Simulgel 800 sold by the company SEPPIC (CTFA name: sodium polyacryolyldimethyltaurate/polysorbate 80/sorbitan oleate); copolymers of 2- acrylamido-2-methylpropanesulfonic acid and of hydroxyethyl acrylate, for instance Simulgel NS and Sepinov EMT 10 sold by the company SEPPIC; cellulose derivatives such as hydroxyethyl cellulose; polysaccharides and notably gums such as xanthan gum; and mixtures thereof.

[00105] The composition of the invention may comprise additional moisturizers such as protein hydrolysates and polyols, for instance glycerol, glycols, for instance polyethylene glycols; natural extracts; anti-inflammatory agents; oligomeric proanthocyanidins; vitamins such as vitamin A (retinol), vitamin E (tocopherol), vitamin B5 (panthenol), vitamin B3 (niacinamide), derivatives of these vitamins (notably esters) and mixtures thereof; caffeine; depigmenting agents such as kojic acid, hydroquinone and caffeic acid; salicylic acid and derivatives thereof; a-hydroxy acids, such as lactic acid and glycolic acid and derivatives thereof; retinoids, such as carotenoids and vitamin A derivatives; hydrocortisone; melatonin; extracts of algae, of fungi, of plants, of yeasts, of bacteria; steroids; antibacterial active agents, such as 2,4,4’-trichloro-2’- hydroxydiphenyl ether (or triclosan), 3,4,4’-trichlorocarbanilide (or triclocarban); tensioning agents; and mixtures thereof.

[00106] According to a particular embodiment, the composition according to the invention is free of ionic polymers such as anionic polymers and cationic polymers. For the purposes of the present invention, the expression "free of ionic polymers" refers to a composition comprising an amount of ionic polymers of between 0 and 1 % by weight and preferably between 0 and 0.5% by weight, relative to the total weight of the composition. Preferably, the composition according to the invention does not comprise any ionic polymers.

[00107] According to a particular embodiment, the composition in accordance with the invention is in the form of an aqueous gel in which are dispersed the capsules comprising the oxidation-sensitive hydrophilic active agent(s).

[00108] Needless to say, a person skilled in the art will take care to select the optional adjuvant(s) added to the composition according to the invention such that the advantageous properties intrinsically associated with the composition in accordance with the invention are not, or are not substantially, impaired by the envisaged addition.

[00109] Another subject of the invention is a cosmetic process for treating a keratin material, such as the skin, the scalp, the hair, the eyelashes, the eyebrows, the nails or mucous membranes, comprising the application to said keratin material of a composition according to the invention. [00110] The examples that follow serve to illustrate the invention without, however, being limiting in nature. The amounts indicated are weight percentages of starting material (SM), unless otherwise mentioned.

Examples

Example 1 of oily gel

[001 1 1 ] [Table 1 ]

[001 12] The oil and the polymer are brought to 80°C with stirring until the mixture is completely homogeneous, and the mixture is then returned to room temperature.

[001 13] The ascorbic acid degradation rate is determined as follows.

[001 14] 600 pi of the oily gel are deposited onto 1 .8 ml of an aqueous 1 % ascorbic acid solution, brought to pH 6 in a closed Wheaton flask. After 1 month at 45°C, the residual ascorbic acid concentration is measured, by HPLC chromatography, and the percentage of ascorbic acid degradation is then calculated: 100 ^c (initial concentration - final concentration)/(initial concentration).

[001 15] The above test is repeated, replacing the 20 g of the polymer Syncrowax ORM-PW-(MV) from Croda first with 20 g of 12-hydroxystearic acid (12 Hydroxystearic Acid Premium Grade 12H-P from Thai Kawaken) and then with 20 g of tristearine (Thixcin RPC from Elementis).

[001 16] The results obtained are collated in the table below. [001 17] [Table 2]

[001 18] It is found that when the soybean oil contains an oil-structuring agent as claimed, the percentage of ascorbic acid degradation is markedly less than that which is obtained when pure soybean oil is used.

Example 2 of ascorbic acid capsules

[001 19] To prepare the capsules present in the composition in accordance with the invention, use may be made, for example, of the device described in the publication “Controlled production of monodisperse double emulsions by two-step droplet breakup in microfluidic devices”, Okushima et al. , Langmuir, (2004), 20, 9905-9908.

[00120] To better understand the device used, reference may be made to figure 1 and to table 1 on page 9906 of the cited document. The device consists of microchannels made of a glass matrix and comprising two successive T junctions, connected together via a PEEK tube with an inside diameter of 0.75 mm and an outside diameter of 1 .58 mm ("two-chip module" configuration of table 1 ). The microchannels are made via the widely described standard techniques of chemical or mechanical etching. A person skilled in the art will know how to adapt the size of the channels as a function of the size range of the microcapsules that he wishes to obtain. The surface state of the first junction will be modified by silanization using a hydrophobic coupling agent in order to limit the coalescence of the water drops on the walls of the microchannel.

[00121 ] Circulation of the various phases constituting the microcapsule is achieved and controlled by means of plunger syringes equipped with temperature-maintenance devices such as heating strips. The three phases are first brought to a temperature of 75°C before being injected into the device, which is itself brought to this temperature by immersion in a water bath.

[00122] The first T junction makes it possible to produce a water-in-oil W/O inverse emulsion by injecting the internal phase consisting of a 20% ascorbic acid solution (neutralized to pH 6 with 50% KOH solution) into the organic phase consisting of the mixture of soybean oil and of structuring agent as described in Example 1.

[00123] The W/O emulsion is then introduced into the outer aqueous phase consisting of an aqueous 2% polyvinyl alcohol solution, at the second T junction, in order to produce the capsules of the invention.

[00124] The microcapsule dispersion is then very rapidly cooled in order to bring about solidification of the organic phase constituting the wall of the microcapsules. The microcapsules obtained are recovered by filtration and returned into an aqueous medium for storage and conservation.

[00125] The choice of the flow rates for each phase is established as a function of the ratio of the volumes of the internal phase and of the wall of the desired capsules, and of the size of the expected capsules. A starting point that may be taken is the proportion of flow rate following 1/3/200 between internal phase/organic phase/external phase, this proportion being adapted as a function of the dimensions of the device.

[00126] Homogeneous microcapsules about 200 pm in size, with good stability of the ascorbic acid, are obtained.

Example 3: emulsified gel containing the microcapsules of Example 2

[00127] [Table 3]

[00128] [Table 4]

[00129] [Table 5]

[00130] Phase B is introduced at 30°C into phase A with vigorous stirring (rotor-stator) and then brought to room temperature with stirring.

[00131 ] Phase C is added at room temperature with very gentle stirring until completely homogeneous.

[00132] A fresh, creamy gel, with good stability of the ascorbic acid, is obtained.