Cosmetic composition containing starch particles with controlled morphology and methods for obtaining said particles

Abstract

Cosmetic composition comprising microparticles of starch with a modified morphology obtained from native starch, characterized in that said particles have dimensions ranging 1-100 μm and a shape chosen from the group consisting in: porous irregular polyhedrons, microscopic platelets or lamellae, deflated or crumpled spheres, irregular toroids; and in that said particles are obtained using physical methods of treatment, chosen from the group consisting in: - enzymatic hydrolysis; - microprecipitation in the presence of a non-solvent of starch; - dripping in the presence of a non-solvent of starch; - lyophilisation; - spray-drying; - grinding. The cosmetic compositions according to the present invention, in addition to having texturizing properties, can advantageously replace the microplastics contained in finished cosmetic products.

Description

“Cosmetic composition containing starch particles with controlled morphology and methods for obtaining said particles”.* * * *

[0001] The present invention relates to a cosmetic composition containing starch microparticles having a controlled morphology, suitable for replacing microplastics, which are a common ingredient in many cosmetic products.

[0002] Moreover, the invention relates to methods for obtaining said microparticles from native starch, without chemical alterations thereof.

[0003] Microplastics are defined as fragments less than 5 mm in length and constitute a growing environmental concern, in that they have a significant impact on the environment, in particular on oceans and seas. Cosmetic products, like creams, lotions, detergents and personal care products, are important sources releasing microplastics in the environment. Such products can contain microplastics purposefully added to the ingredients thereof. Indicatively, the microplastics used in the cosmetic field comprise microparticles having dimensions of about of 5-25 pm.

[0004] The microplastics used in the cosmetic field come from different sources and are widely used in order to modulate the properties of cosmetic products. The cosmetic microparticles can be plastic microspheres, used as abrasive and peeling products, e.g. microbeads provided in scrubs and toothpaste, and polymers in the form of powder, used to improve the tactile pleasantness and the optic properties of cosmetic products.

[0005] When cosmetic products containing microplastics are rinsed or inadequately disposed of, the microparticles can reach aquatic ecosystems, starting from surface water streams, ultimately causing marine pollution. The release of such materials into oceans generally damages the marine ecosystem. Moreover, microplastics can seep into soil through leaching by rainwater runoff and accumulate in soil. The microplastics accumulated in soil or dispersed in seas can then enter into the food chain, with potential effectson human health when they are ingested through the consumption of fish and other contaminated organisms. Therefore, the problem of microplastics in consumer products (among which cosmetic products) is an urgent issue in order to protect the environment and human health. In this regard, many countries issued regulations banning the purposeful insertion of microplastics into products: among them there is the recent European Commission Regulation (EU) 2023 / 2055 banning the so-called “Synthetic Polymer Microparticles” (SPM). In this context, the need to find alternatives to traditional microplastics is apparent: the use of natural and eco-sustainable compositions from the point of view both of industrial processing and environment, characterized by physical-chemical features similar to those of microplastics, offers the possibility of finding valid alternatives to microplastics.

[0006] Starches are polysaccharides (soluble in hot water but insoluble in cold water) widely used in cosmetic industry for their versatile, beneficial properties for skin and hair. The use of starches in cosmetic products entails many advantages, among which naturality in that they are natural and eco-compatible ingredients, feature that attracts consumers oriented toward natural products; the capability of adsorbing humidity adapting cosmetic products for use in humid climates or in order to control shiny skin; their tolerability by sensitive skins, that allows to prepare cosmetic products suitable for a wide range of skin types; their impalpable texture, which favours their use as an excipient.

[0007] Starches can absorb humidity, improve the texture of products and provide a soft feeling: due to these properties, starches are precious ingredients in a wide range of skin and hair care products. For their versatility and the ability to form gels, starches are useful in a wide range of industrial and food applications, for use as rheological modifiers when solubilized in aqueous phase. At the same time, when starches are used in particle form, their morphology plays a crucial role in determining their physical andfunctional properties.

[0008] The shape and dimensions of microparticles are of paramount importance in order to obtain cosmetic formulae fit for purpose. In particular, lamellar particles are characterized by a gliding feeling to tact and are connoted by marked adhesion to skin, thanks to the interaction between skin surface and the face of each lamella.

[0009] In contrast to lamellar particles, spherical particles have a lower adhesion, but they have a unique tact feeling, thanks to the ball-bearing effect, which allows to get a sophisticated sensoriality. Moreover, such particles have optical properties suitable for obtaining a soft-focus effect. The monodispersity of granulometric distribution is highly desirable for this kind of powders; spherical particles homogeneous in term of dimension enhance the so-called ball-bearing effect and the homogeneity of the soft-focus effect.

[0010] The morphology of native starches is strictly related to their botanical origin, and can be modified through suitable physical treatments (e.g. solubilization, precipitation, drying, sieving, etc.), it is known that commercial starches can be found in different forms, among which starch granules, retrograded starch, pre-gelatinized starch, and modified starch.

[0011] Starch granules fundamentally consists of two kinds of polysaccharides: amylopectin, which has a branched structure, and amylose, that has a more linear structure. The properties of starches are affected by their dimension, shape, and arrangement of starch granules, and also by the presence of amylose (linear molecules, a(l-4) bonds) and amylopectin (branched molecules, a(l-4) and a(l-6) bonds). E.g., gelatinization is the process wherein starch absorbs water and forms a gelatinous structure. Retrogradation is the successive recrystallization of the gelatinized starch.

[0012] In literature, different techniques of structural modification of particles of sundry nature have been described, allowing to obtain particles of different shape.Known techniques for structural modification

[0013] The following techniques: enzymatic hydrolysis, lyophilization, micro precipitation, spray drying are known techniques for the modification of the dimensions and the morphology of substances of sundry nature, and can be exploited for manipulating starches.Enzymatic hydrolysis

[0014] For starch, it is known that enzymatic hydrolysis can be performed by using an enzyme (belonging to amylases category), hydrolysing glycosidic bonds (alpha-amylase) inside the structure of starch, converting the starch into simpler sugars like maltose and dextrose. Such hydrolysis can occur in different condition of temperature and pH, so affecting the morphology of the resulting starch. The use of alpha-amylase in food industry is widespread, in order to improve the solubility, the viscosity and other functional properties of maize starch in various products.

[0015] The action of alpha-amylase on maize starch can lead to different outcomes according to the process conditions. E.g., a prolonged action of alpha-amylase at temperatures lower than the gelatinization temperature leads to the formation of superficial pores on starch microparticles, whose depth and number can be modulated according to the process parameters. In contrast, the exposition to the enzyme over the gelatinization temperature will lead to a progressive diminution of the average molecular weight of starch, with the concomitant production of oligomers and reduction of the viscosity of the solution.Lyophilization

[0016] Lyophilization is a drying technique providing the removal from water from a frozen sample, through under vacuum sublimation. This technique is commonly used in food industry for producing isolates and extracts under strict thermal control. During the lyophilization technique, the foodstuff is frozen, then water is removed in form of vapour without passing from the liquid state (sublimated). This process allows to preserve very effectively the integrity and the organoleptic properties of the material (e.g.thermolabile materials). Typically, freezing temperatures during lyophilization range -30-50°C https: / / en.wikipedia.org / wiki / Freeze drying.Spray drying

[0017] Spray drying is another drying technique widely used in food and pharmaceutical industry. In this process, a solution (or suspension) of starch is atomized into small drops, which are rapidly dried in a hot chamber. The drying speed, temperature and concentration of material can be controlled in order to obtain a wide range of morphologies. In the case of starches, it is known that more moderate drying conditions can lead to the formation of retrograded starch, while more rapid drying conditions can lead to gelatinized starch. The choice of drying conditions is crucial in order to obtain the desired morphology.

[0018] The different morphologies of starches obtained through the use of freeze-dryers and spray dryers find application in different sectors. E.g., lyophilized starches are used in pharmaceutical formulations in order to improve the solubility and the stability of medications, while spray drying allows to obtain pre-gelatinized starches widely used in food industry in order to improve product stability. Nonetheless, in the above-mentioned cases, the properties of starch particles are not exploited to improve the flowability and / or the optical properties of the preparations.Microprecipitation

[0019] Microprecipitation is an advanced technique used to produce microparticles with dimensions in the order of micrometres or nanometres.

[0020] In order to obtain desired dimensions and morphologies, selecting the reagents, material of the final product and anti-solvent, is crucial. Moreover, parameters like temperature, stirring and the addition of the solution containing the starting material to a non-solvent bath affect the formation of nuclei and the controlled growth of microparticles.

[0021] US 20220265525 Al describes starch-containing particles having an average particle diameter of 0.5 to 20 pm and a maximum particlediameter of less than 30 m, starch containing 90% by weight or more of amylopectin. Such particles may contain an inorganic oxide, wherein the content of starch is 30-90% by weight and the content of the inorganic oxide is 10-70% by weight. The production method of such particles includes an emulsification step of mixing a dispersion liquid of starch, a surfactant, and a nonaqueous solvent to prepare an emulsified liquid containing emulsified droplets; a dehydration step of dehydrating the emulsified droplets; and a step of separating the nonaqueous solvent dispersion body obtained in the dehydration step into solid and liquid to obtain spherical starch particles as solid matter. Also, the emulsified liquid obtained in the emulsification step may be cooled to a range of -50 to 0° C, thereby to use a frozen emulsified liquid in which water in the emulsified droplets is frozen. Also, it is preferable that the sphericity of the particles be 0.85 or more, that is, the particles be spherical. When the particles are spherical particles, the rolling properties of cosmetics improve. The sphericity is particularly preferably 0.90 or more. Here, the sphericity was calculated from a photograph of a scanning electron microscope by an image analysis method.

[0022] WO 2021175775 Al of the same applicant describes the use of native or surface-treated native starches, wherein the use of starches of unusual vegetal origin, like ginger, mung bean, amaranth, white turmeric, Chinese taro, cowherb allows to obtain starch particles having morphologies that have advantageous properties when used in cosmetic compositions. The examples of surface treatment are coatings with silicones, oils, waxes, silica (physical) or reactive silanes (chemical).

[0023] The paper by Wu Wenqi et al: "Effects of Extrusion Technology Combined with Enzymatic Hydrolysis on the Structural and Physicochemical Properties of Porous Corn Starch", Food and Bioprocess Technology; 2020; vol. 13, no. 3: 442-451 describes the preparation of porous starch particles, starting from com starch that underwent extrusion, bioextrusion (starch mixed with alpha-amylase) compared to starch thatunderwent enzymatic hydrolysis. Extrusion was performed using a twin screw extruder. This modification resulted in the formation of more pores on the surface of native starches, as revealed by scanning electron microscopy (SEM). Porous starch is used in the areas of food, agriculture, pharmaceuticals, and cosmetics as protection for oxidization-labile substances and haemostatic agents, as an adsorbent for heavy metal ions, and as a novel delivery system for poorly water-soluble drugs.

[0024] WO 2021144245 Al describes the use of native and / or porous starch as white pigment in dental health products and in particular in toothpastes. The native starch is not gelatinized but is under granular form. Porous starch is a granular starch that has been hydrolysed by one or multiple amylolytic enzymes until multiple pores are visible on the surface of the starch granule by microscopic technique. Porous starch may be produced through an enzymatic hydrolysis of native starch granules with one or multiple amylolytic enzymes, such as alpha-amylase and amyloglucosidase, at a temperature inferior to the gelatinization temperature of the starch; the drying of the porous starch is performed through a flash dryer.

[0025] CN 101240082 A describes microporous starch granule, which is a starch granule having micropores on the surface, and a pore diameter of the micropores on the surface of the starch granule is 5 to 10 pm; and a method for producing the same. The method of production is enzymatic hydrolysis through amylase, followed by spray drying.

[0026] The paper by Kozlowska Justyna et al: "Microparticles based on natural and synthetic polymers for cosmetic applications", International Journal of Biological Macromolecules, 2019; vol. 129: 952-956 describes spherical microparticles of sodium alginate and mixture of sodium alginate and starch obtained using encapsulator BUCHI B-395 Pro. Such particles are used for peeling products. The drying of the microparticles occurs at room temperature.

[0027] Aim of the present invention is obtaining cosmeticcomposition based on starch microparticles with modified morphology through physical techniques, capable of acting as an alternative to the microplastics commonly used in cosmetic products.

[0028] Such aim is obtained with cosmetic compositions having the features defined in claim 1.

[0029] The object of the present invention also concerns a method combining different physical manipulation techniques in order to obtain particles having controlled shape and dimension, different in form and dimensions from the particles of “native” starch, i.e. as provided in nature, obtained through physical isolation processes from vegetal tissues of the starting botanical species.

[0030] The starting starch is obtained from different crops like e.g. potato, maize, rice, wheat, tapioca, oat, ginger, mung bean, amaranth, white turmeric, Chinese taro, cowherb (Gypsophila vaccaria). Such list is representative and not exhaustive. Each of such starches is provided with different chemical-physical properties, and a characteristic swelling temperature, indicatively ranging 55-85°C.

[0031] It is worth noting that the modified starches obtainable according to the methods of the present invention are not intended to replace 1 : 1 the microplastics customarily used in cosmetic industry with an exact reproduction of the dimensions and shapes of said microparticles, but instead are intended to provide new white or coloured powders having texturizing properties and / or provided with other technically desirable properties in the final cosmetic products, as an alternative to microplastics.

[0032] The dimensions of the modified starch microparticles obtainable according to the methods of the present invention range 0,1-100 pm, preferably 0,1-30 pm, even more preferably 0,1-20 pm.

[0033] Surprisingly, it was observed that the freezing temperature of -80°C used during lyophilization in all the physical methods performed in the preparation of microparticles allows to obtain improved results, in that thefreezing speed of water molecules of the gel determines in its turn the depth of the walls of the aerogel cellular structure.

[0034] It is worth underlining that with the methods according to the present invention, starch undergoes physical modifications only, i.e. it remains chemically unaltered, with all the advantages from the point of view of biocompatibility and non-toxicity, but with particles having desired shape and dimensions, provided with different degrees of porosity.

[0035] Further advantages and properties of the present invention are disclosed in the following description, in which exemplary, non-limiting embodiments of the present invention are explained in detail based on the drawings: figures 1A-1D show four microphotographs taken with SEM electronic microscope with different magnification (figure 1A 500x, figure IB 1500x, figure 1C 3000x, figure ID lO.OOOx) of starch microparticles obtained through a first method of enzymatic hydrolysis; figures 2A-2D show four microphotographs taken with SEM electronic microscope with different magnification (figure 2A 500x, figure 2B 1500x, figure 2C 3000x, figure 2D lO.OOOx) of starch microparticles obtained through a second method of enzymatic hydrolysis; figures 3A-3C show three microphotographs taken with SEM electronic microscope with different magnification (figure 3A 3000x, figure 3B 1500x, figure 3C 3000x) of starch microparticles obtained through a spray-drying method; figures 4A-4D show four microphotographs taken with SEM electronic microscope with different magnification (figure 4 A 100 x, figure 4B lOOx, figure 4C 500 x, figure 4D 100x,) of starch microscopic platelets or lamellae obtained in the presence of trehalose and subsequent lyophilization; figures 5A-5F show six microphotographs taken with SEM electronic microscope with different magnification (figure 5 A 1500x, figure 5B3000x, figure 5C 1500x, figure 5D 3000x, figure 5E 500x, figure 5F 1500x) of starch microscopic platelets or lamellae obtained in the presence of trehalose, different natural colorants and subsequent lyophilization; figures 6A-6B show two microphotographs taken with SEM electronic microscope, both at a magnification of 500x, of two examples of “deflated” or “crumpled” spheres; figures 7A-7D show four microphotographs taken with SEM electronic microscope with different magnification (figure 7A 500x, figure 7B and 7C 1500x, figure 7D 3000x) of toroid microparticles.

[0036] The embodiments here illustrated concern cosmetic compositions consisting of native starch microparticles, whose morphology is modified using the following physical methods.Enzymatic hydrolysis

[0037] The use of enzymes like alpha-amylase in specific process conditions leads to the modification of native forms of the chosen starch.

[0038] For example, by treating maize starch at 37 °C for 24 hours in the presence of alpha-amylase, a superficial modification occurs, modulating its morphology and its flowability.

[0039] Previous filtration and water washing, the drying treatment occurs through lyophilization in order to remove water traces present in the wet powder.

[0040] The enzymatic hydrolysis of native starch according to the present invention comprises the following steps:A. dispersing native starch in an acid buffer in a proportion ranging 1% - 40% in weight under stirring, at a temperature ranging 25 - 60°C;B. adding alpha-amylase from preferably non-genetically modified microorganisms and allow it to work for 3-30 hours;C. deactivating the alpha-amylase by adding a substance chosen from a group consisting of an acid, a base or a salt identified according to the specific alpha-amylase employed; alternatively, the deactivation ofalpha-amylase can occur through thermal denaturation of the enzyme, too;D. filtering the solution and washing the by-product at least twice;E. freezing the wet powder at a temperature of at least -80° and lyophilizing.EXAMPLE 1

[0041] A first method for starch particle modification through enzymatic hydrolysis comprises the following steps:A. To 1 L of phosphate buffer (PBS), adding 100 g of starch, so as to obtain a final concentration of 100 g / L. Under stirring, bring the temperature to 37°C;B. Adding 600 mg of alpha-amylase to the starch solution at 37°C and letting it work for 24 hours;C. Inserting 2.5 g of tannic acid for 30 min;D. Filtering the solution and washing the by-products repeatedly (at least twice);E. Freezing the wet powder at -80°C and lyophilizing.

[0042] Figures 1A-1D show porous maize starch particles obtained through the method of EXAMPLE 1. Such particles can be suitably used in cosmetic compositions, e.g. in pressed powders for eyelid decoration (eyeshadow). The obtained particles have enhanced flowability properties with respect to native starch. Moreover, their adhesion and homogeneity are also enhanced. The average dimension of the so-obtained particles ranges 10 - 20 pm.EXAMPLE 2

[0043] A second method for starch particle modification through enzymatic hydrolysis comprises the following steps:A. To 1 L of citrate buffer, adding 200 g of starch, so as to obtain a finalconcentration of 200 g / L. Under stirring, bringing the temperature to 50°C;B. Add 1,2 g of alpha-amylase to the starch solution at 50°C and letting it work for 4 hours;C. Inserting 2.5 g of sodium hydroxide (NaOHaq) up to basic pH (> 9) for 30 min;D. Filtering the solution and repeatedly washing the by-products (at least twice);E. Freezing the wet powder at -80°C and lyophilizing.

[0044] Figures 2A-2D show porous maize starch particles obtained through the method of EXAMPLE 2. Such particles can be suitably used in cosmetic compositions, e.g. in pressed powders for face decoration (face powder). The obtained particles have enhanced flowability properties with respect to native starch. Moreover, their adhesion and homogeneity are also enhanced. The average dimension of the so-obtained particles ranges 10 - 20 pm.Microscopic platelets or lamellae

[0045] In cosmetic industry, powders consisting of particles with lamellar morphology are crucial for countless applications: important examples thereof are talc, mica and kaolin, widely used. On account of their morphology, such materials are characterized by flowability (the particles can disperse uniformly by gliding one over the other) and adhesion (the particles are provided with flat faces capable of optimizing the contact surface with skin). Their accurate design can improve quality and consumer satisfaction, and obtaining such morphologies through renewable materials is a good opportunity.

[0046] When, exceeding the starch solubilization temperature in water, and having formed a gel, said gel is frozen and water is subsequently sublimated through lyophilization, a material having a cell structure of anaerogel is obtained. Such material, after suitable grinding, produces fragments having lamellar shape. The insertion of hydrosoluble molecules (e.g., trehalose) in water during starch dissolution allows to intersperse such molecules in the lamellae structure, modulating properties thereof, like fragility or aspect.

[0047] The optional presence of trehalose, or of other suitable mono- or di-saccharides, ensures a fine lamellar morphology by modulating the fragility of the aerogel.

[0048] Obtaining microscopic platelets or lamellae according to the present invention comprises the following steps:A. dissolving native starch in distilled water in a proportion ranging 5% - 30% in weight and heating the solution to a temperature of 80-100°C under stirring; optionally adding trehalose or a mono- or di-saccharide in a proportion of 0,5 - 55% in weight with respect to the initial quantity of starch, directly to the starting solution, or adding it at a later stage;B. maintaining the contact with trehalose or sugar or carbohydrate for at least one hour;C. freezing at -80° and lyophilizing;D. grinding and micronizing the white block obtained in step C.Optionally, to the solution a colorant can be added, allowing to obtain coloured starch microparticles in lieu of white microparticles, which can be used to prepare eyeshadows, face powders, blush or rouge, etc.EXAMPLE 4

[0049] The method for obtaining starch platelets or lamellae comprises the following steps:A. To 1 L of distilled H2O, adding 100 g of starch, so as to have a final concentration of 100 g / L. Under stirring, bringing temperature to 90°C and maintaining such temperature for at least one hour;B. Adding 1 L of trehalose 0,15 M to the starch solution, and letting it to work at room temperature for at least one hour;C. Freezing at -80°C and lyophilizing;D. Mechanically grinding and micronizing the white, friable block obtained in step C through an air mill (jet-mill PilotMill-2, Fiorenzuola d’Arda (PC)) (injection pressure = 2.5 bar; ring pressure 2.5 bar).

[0050] Figures 4A-4D show the microscopic platelets or lamellae obtained through the above-detailed method.EXAMPLE 5

[0051] In an embodiment alternative to EXAMPLE 4, the method according to the invention comprises the following steps:A. To 1 L of distilled FEO, adding 100 g of starch and 51 g of trehalose, so as to have a final starch concentration of 100 g / L. Under stirring, bringing temperature to 90°C and maintaining such temperature for at least one hour;B. Freezing at -80°C and lyophilizing; a white, friable block is obtained;C. Mechanically grinding and micronizing the white, friable block obtained in step C through an air mill (jet-mill PilotMill-2, Fiorenzuola d’Arda (PC)) (injection pressure = 2.5 bar; ring pressure 2.5 bar).

[0052] In both cases, the lyophilization temperature of about -80°C is of paramount importance. With a lyophilization temperature of -20 °C the same results cannot be obtained, in that the freezing speed of the gel water molecules determines in its turn the thickness of the walls of the cellular structure.

[0053] In an embodiment alternative to the preceding one, to the modified starches in the shape of platelets or lamellae according to the previous method, different colorants can be added, so as to obtain final coloured powders. In particular, hydrosoluble natural colorants like walnut mordant dye, safflower yellow, elderberry and beetroot extracts and bluespirulina were used, in the presence or in the absence of trehalose.EXAMPLE 6

[0054] In this case, the steps A, C, and D are performed as abovedescribed. During step B, natural colorants or active ingredients are added to the solution, optionally containing trehalose, and such solution is added to the starch solution under stirring at room temperature for one hour.

[0055] Figures 5A-5F show six microphotographs taken with a microscope of coloured platelets or lamellae obtained through the abovedescribed method. As the microphotographs are black and white photographs, it is worth specifying that figure 5 A shows platelets or lamellae coloured with a blue colorant (blue spirulina), figure 5B shows platelets or lamellae coloured with a yellow colorant (safflower yellow), while figures 5C-5F show different nuances of red-rose (elderberry and beetroot extract), brown (walnut mordant dye).

[0056] Such particles can be suitably used in cosmetic compositions, e.g. powder foundation in lieu of the more classical white excipient (talc, mica). The platelets or lamellae so obtained can stick to skin in a stronger way in comparison to native starch particles. The average dimension of particles so obtained (EXAMPLE 5 and EXAMPLE 6) ranges 10 - 30 pm according to the intensity of grinding.Deflated or crumpled spheres

[0057] Microscopic spheres are an important component in a wide range of cosmetic products, among which creams, lotions, foundations, skincare products and others. Such spheres play crucial roles in the cosmetic field, among which the enhancement of sensorial aspects like spreadability, soft-focus effect and blendability. Obtaining spherical starch microparticles is an intriguing solution to the problem posed by microplastics pollution.

[0058] The attainment of this particular morphology is due to twospecific steps: microprecipitation and drying through lyophilization. In the first step the starch, over its swelling temperature, is dripped into an alcoholic solution under stirring: the contact of the starch solution with a non-solvent leads to precipitation and microparticle generation. The non-solvent is chosen among monofunctional alcohols, preferably C1-C4 alcohols or diols, both miscible with water. After separating the solid part (wet powder made of microparticles) from the liquid part through simple filtration, the frozen powder is dried through lyophilization.

[0059] The attainment of deflated or crumpled spheres according to the present invention comprises the following step:A. dissolving native starch into distilled water in a proportion ranging l%-30% in weight and heating the solution to a temperature of 80- 100°C under stirring for at least one hour;B. dripping the starch solution in a hydrosoluble non-solvent, preferably monofunctional alcohols or diols, in a volume equal to the volume of water used in the solution of step A, under stirring at room temperature for less than one hour;C. filtering the solution, freezing at -80°C and lyophilizing: a white powder is obtained;D. grinding and / or sieving the white powder of step C.

[0060] Examples of deflated or crumpled spheres according to the present invention are shown in figures 6A, 6B. As can be observed in the figures, starch particles are not perfectly spherical. The treatment of native starch according to the above method modifies the shape of the native granules, giving them a more irregular shape, that in the present description was named “deflated or crumpled”, like a balloon that has been punctured and therefore is slightly deflated without exploding.EXAMPLE 7

[0061] The method for the production of deflated or crumpled spherescomprises the following steps:A. To 1 L of distilled H2O, adding 75 g of starch, so to have a final concentration of 75 g / L. Under stirring, bringing the temperature to 90°C and maintaining it for at least one hour;B. Dripping the starch solution into 1 L of denatured ethanol under stirring at room temperature for not more than one hour;C. Filtering the solution, freezing at -80°C and lyophilizing; a white powder is obtained;D. Grinding and / or sieving the white powder of step C.

[0062] Figures 6A-6B show two examples of deflated spheres obtained through the above-described method.

[0063] Such particles can be suitably used in cosmetic compositions, like e.g. powder lipsticks in lieu of the more classical polymeric texturizing agents. The average dimension of the so-obtained particles (EXAMPLE 7) ranges 10 - 30 pm according to the intensity of grinding.Toroid or donut microparticles

[0064] A further morphology obtainable through the present invention is toroidal. To the best of present knowledge there are not provided, in cosmetic use, powders with such non-conventional morphology. In addition to being provided with the intrinsic properties of starch (e.g. purity and a high white point, the toroid starch microparticles (or “donut” particles) are solid particles characterized by a structure approximating a discoid shape with a tapering in the central portion (biconvex discoid). Such particles conveniently combine the advantages of the lamellar morphology to those of the spheroidal morphology:- the presence of a more developed surface allows to obtain an enhanced adhesion with respect to purely spherical morphologies;- the superficial regularity and the lack of asperities allow to improve the sensoriality and creaminess of the powder, in comparison to thepurely lamellar morphologies;- both the above-described features are enhancements with respect to the native starch shape (e.g. of maize starch).

[0065] Toroid microparticles are an evolving field of research in materials science, with innovative potentials in different sectors, thanks to their versatility and unique properties.

[0066] In the present invention, such morphology is obtained through a physical manipulation (partial solubilization / re-precipitation) of starch. By dripping a non-solvent in an aqueous solution containing swelled starch, the non-solvent structures the starch particles, which undergo a remodelling so forming a toroid. The non-solvents are monofunctional alcohols preferably C1-C4 or diols, both miscible with water. After filtration and freezing, the powder is treated in the freeze-dryer for drying.

[0067] The attainment of toroid microparticles according to the present invention comprises the following steps:A. dissolving native starch in distilled water in a proportion ranging 1% - 30% in weight and heating the solution at the swelling temperature characteristic for the specific native starch, maintaining it under stirring for at least one hour;B. dripping a volume of non-solvent chosen among hydrosoluble monofunctional alcohols or diols equal to the volume of distilled water, with a first flow ranging 5 - 10 mL / min and a second quantity of non-solvent at a flow ranging 11 - 15 mL / min;C. filtering the solution, freezing the wet powder at about -80°C and freeze-drying so obtaining a white powder;D. grinding and / or sieving the white powder obtained in step C.EXAMPLE 8

[0068] The method for the production of toroid microparticles comprises the following steps:A. To 1 L of MilliQ H2O (obtained through ion-exchange resins), adding 55 g of starch so as to obtain a final concentration of 55 g / L. Under stirring, bringing the temperature to the swelling temperature of the specific starch (e.g. 66°C for maize starch) maintaining it for at least one hour;B. Dripping ethanol with a flow of 8 mL / min (I L) and repeating a second time with a flow of 12 mL / min (1 L);C. Filtering the solution, freezing the wet powder at -80°C and freeze- drying. A white product is obtained;D. Grinding and micronizing the white product obtained in the step C (injection pressure = 2.5 bar; ring pressure 2.5 bar)

[0069] Figures 7A-7D show the toroid particles obtained with the above-described method. A toroid s a surface of revolution with a hole. The axis of revolution passes through the hole and so does not intersects the surface. https: / / en.wikipedia.org / wiki / Toroid. As can be easily observed in the figures, the toroid particles are not perfect toroids, but exhibit various irregularities, see especially figure 7B and 7D. Such irregularity encompasses also the collapse of the hole radius to a point leading to biconcave-like particles (https: / / en.wikipedia.org / wiki / Biconcave_disc).Spray-drying

[0070] The technology of spray-drying allows to obtain various morphologies by modulating the parameters of temperature (inlet and outlet), pressure, aspiration rate and flow rate. By choosing the correct initial concentration and the relative viscosity of the input solution and process temperatures, starch particles of spheroidal morphology can be obtained. Such particles are characterized by the rough aspect of their surface.

[0071] In the input solution other components can be used, like trehalose or other mono- or di-saccharides, so as to add functionalities to starch.

[0072] The spray-drying treatment of native starch according to the present invention comprises the following steps:A. dissolving the native starch in distilled water in a proportion ranging 1% - 30% in weight and heating the solution at a temperature ranging 70-100°C under stirring; optionally, adding trehalose or another mono- or di-saccharide to the solution;B. drying the particles in a spray-drier using a spraying pressure of 5 bar so as to obtain particles with a diameter not larger than 30 pm;C. recovering the particles from the collection vessel.EXAMPLE 3

[0073] In this example a Mini-Spray Dryer B-290 of BUCHI Italia s.r.l., (Comaredo, Italy) was used. The method for modifying starch particles through spray-drying comprises the following steps:A. To 1 L of distilled water EEO adding 100 g of tapioca starch, so to have a final concentration of 100 g / L. Under stirring, the temperature is modulated according to the kind of starch and maintained for at least one hour (>70°C for tapioca starch). During this step, trehalose or another mono- or di-saccharide can be added, to be incorporated into the starch particle;B. Setting the parameters of the spray-dryer so as to collect the sample and dry it:- Dosing pump 15% (about 5 ml / min)- Process gas temperature 120°C;- Atomizing air pressure 6 bar;- Air flow of the atomizer 500 1 / h- Aspirator 80% (ca. 30 m3 / h)- Nozzle diameter 0.7 mmC. Collecting the particles so obtained from the collection vessel.

[0074] Figures 3A-3C show some examples of morphologiesobtainable by using the spray-drying process of the EXAMPLE 3 applied to starches. The particles exhibit a peculiar rough morphology (deflated or crumpled spheres), different from any other native or modified starch on the market. Such particles can be conveniently used in cosmetic compositions, like e.g. foundations in oil-in-water emulsions. Such particles have the capability of modifying the touch of the formulation by enhancing the viscosity thereof, with respect to native starch. The average dimension of the particles so obtained ranges 10 - 30 pm.

[0075] In the following, there are provided some illustrative examples of the use of starches provided with a special morphology according to EXAMPLES 1 - 8.

[0076] EXAMPLE 9 - Pressed powderThe product is obtained by inserting in a powder mixer the ingredients of the above table and mixing up to homogeneity (4 min at a speed of 2000 RPM). The mixture is then dosed in a metallic caseback and pressed in order to obtain said face pressed powder.

[0077] EXAMPLE 10 - Powder eyeshadowThe product is obtained by inserting in a powder mixer the ingredients of the above table and mixing up to homogeneity (4 min at a speed of 2000 RPM).The mixture is then dosed in a metallic pan and pressed in order to obtain said eyeshadow.

[0078] EXAMPLE 11 - Powder rouge or blushThe product is obtained by inserting in a powder mixer the ingredients of the above table and mixing up to homogeneity (4 min at a speed of 2000 RPM). The mixture is then dosed in a metallic caseback and pressed in order to obtain said blush.

[0079] EXAMPLE 12 - Oil-in-water emulsionThe product is obtained by inserting in a rotor-stator homogenizer the ingredients of the phase A up to homogeneity. The ingredients of the phase B are added slowly under stirring. The mixture is then homogenized at 10000 RPM to refine the emulsion and then brought to room temperature.

[0080] EXAMPLE 13 - LipstickThe product is obtained by inserting in a mixer the ingredients of the above table and mixing up to the fusion temperature of the waxes and complete homogeneity of the mass, that is then casted in moulds, allowed to cool and extracted in the form of a lipstick “bullet”.

[0081] The cosmetic composition comprising starch particles with modified morphology according to the present invention can be used in the finished cosmetic products listed in EXAMPLES 9-13, but also in cosmetic products for skincare and haircare.

Claims

CLAIMS1. Cosmetic composition comprising microparticles of starch with a modified morphology obtained from native starch, characterized in that said particles have dimensions ranging 1-100 pm and a shape chosen from the group consisting in: porous irregular polyhedrons, microscopic platelets or lamellae, deflated or crumpled spheres, irregular toroids; and in that said particles are obtained using physical methods of treatment, chosen from the group consisting in:- enzymatic hydrolysis;- microprecipitation in the presence of a non-solvent of starch;- dripping in the presence of a non-solvent of starch;- lyophilisation;- spray-drying;- grinding.

2. Cosmetic composition comprising starch microparticles according to claim 1, wherein the dimensions of said microparticles are 1-30 pm, even more preferably 1-20 pm.

3. Cosmetic composition comprising starch microparticles according to claim 1, wherein when the method of treatment of said microparticles comprises lyophilisation, the freezing temperature is about -80°C.

4. Cosmetic composition comprising starch microparticles according to claim 1 or 2, obtained through enzymatic hydrolysis, wherein said enzymatic hydrolysis comprises the following steps:A. dispersing the native starch in an acid buffer in a proportion ranging 1% - 40% in weight under stirring, at a temperature ranging 25 - 60°C;B. adding alpha amylase obtained preferably from non-genetically modified microorganisms and leaving it to work for 3-30 hours;C. deactivating said alpha amylase by adding a substance chosen from an acid, a base or a salt according to the specific alpha amylase; alternatively, the deactivation of alpha amylase can occur even through thermal denaturation of the enzyme;D. filtering the solution and washing the by-products at least twice, so obtaining a wet powder;E. freezing the wet powder at about -80°C and drying.

5. Cosmetic composition comprising starch microparticles according to claim 1 or 2, wherein said microscopic platelets or lamellae are obtained through a method comprising the following steps:A. dissolving the native starch in distilled water in a proportion ranging 5% - 30% in weight and heat the solution to a temperature ranging 80-100°C under stirring; optionally adding trehalose or a mono- or di-saccharide in a proportion of 0,5 - 55% in weight with respect to the initial quantity of starch; said trehalose or mono- or di-saccharide can be added directly to the starting solution or successively;B. maintaining the contact with trehalose or said mono- or disaccharide for at least one hour;C. freezing at about -80°C and drying;D. grinding and micronizing the white block obtained in step C.

6. Cosmetic composition comprising starch microparticles according to claim 5, wherein during step B natural colouring or actives are added to the solution, preferably food colouring.

7. Cosmetic composition comprising starch microparticles according to claim 1 or 2, wherein said deflated or crumpled spheres are obtained through a method comprising the following steps:A. dissolving the native starch in distilled water in a proportion ranging l%-30% in weight and heating the solution at a temperature of 80-100°C under stirring for at least one hour;B. dripping the starch solution into a hydrosoluble non-solvent, preferably monofiinctional C1-C4 alcohols or diols, in a volume equal to the volume of the water used in solution A, under stirring at room temperature for a time shorter than one hour;C. filtering the solution, freezing at about -80°C and drying; a white powder is obtained;D. grinding and / or sieving the white powder of step C.

8. Cosmetic composition comprising starch microparticles according to claim 1 or 2, wherein the toroid microparticles are obtained through a method comprising the following steps:A. dissolving the native starch in distilled water in a proportion ranging 1% - 30% in weight and heating the solution at the swelling temperature characteristic of the specific native starch, maintaining it under stirring for at least one our;B. dripping a volume of hydrosoluble non-solvent, preferably monofunctional C1-C4 alcohols or diols with a first flow ranging 5 -10 mL / min and a second quantity of non-solvent at a flow ranging 11 - 15 mL / min;C. filtering the solution, freezing the wet powder at about -80°C and drying so obtaining a white powder;D. grinding and / or sieving the white powder obtained in step C.

9. Cosmetic composition comprising starch microparticles according to claim 1 or 2, wherein the spray-drying method comprises the following steps:A. dissolving the native starch in distilled water in a proportion ranging 1% - 30% in weight, and heating the solution at a temperature of 70-100°C under stirring; optionally, adding trehalose or another mono- or di-saccharide to the solution;B. drying said particles in a spray-dryer using an atomization pressure of 5 bar so as to obtain particles having a diameter nothigher than 30 pm;C. recovering the microparticles from the collection vessel.

10. Cosmetic composition according to one or more of claims 1 to 9, wherein the starting native starch is obtained from crops of potato, maize, rice, wheat, tapioca, oatmeal, ginger, mung bean, amaranth, white turmeric,Chinese taro, cowhwerb.

11. Use of the cosmetic compositions according to claims 1-10 in cosmetic products for replacing microplastics.

12. Finished cosmetic products comprising cosmetic compositions according to one or more of the preceding claims, wherein said finished cosmetic product are loose or compact powders, powder eyeshadow, powder blush, oil-in water emulsions, foundations, lipsticks, skin care products and hair care products.

13. Cosmetic compositions according to claim 10, wherein the starting native starch is maize starch.

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