MAKING THESE

The present invention relates to a sheet-like particulate comprising a lipophilic cellulose- 5 based polymer. The invention also relates to a method for production of these sheet-like particulates. Moreover the invention relates to the use of these sheets for structuring of non-aqueous liquids or as foam stabiliser.

BACKGROUND OF THE INVENTION

10 The structure and morphology of a consumer product is essential for the properties and the appreciation of the product. For example a food product like a margarine should not be too soft and not be too hard, and should be spreadable under all normal household conditions and should melt at in body temperature when consumed. This can be achieved by using a correct ratio of saturated and unsaturated fats and oils in the formulation of the

15 product. Similarly a deodorant stick should keep its consistency during storage,

nevertheless should deliver its constituents when applied to the skin. These required conditions may lead to contradictory requirements in product development.

It is well known that thickeners and fibres can be used to create useful structures, both in 20 foods as well as in cosmetic or personal care products. Numerous fibrous materials have been described, and several methods have been disclosed to produce fibrous materials.

Aeration may be another method to create useful structures for consumer products like food products and personal care products. Many food products are aerated, such as 25 mousses, ice cream, and whipped cream. These food products contain small gas bubbles, and the gases may include air, nitrogen, and/or carbondioxide. Aerated food products are being developed with two aspects which are of importance: first the foamability (how easy is it to aerate the food product), and second the stability of the aeration during storage (how well remain the air bubbles intact upon storage of the aerated food product).

30

WO 2006/007393 A1 and US 2010/0247908 A1 disclose a method to produce fibres using liquid-liquid dispersion in a shear field.

WO 2007/068344 A1 discloses a surface-active fibrous material used to stabilise gas 35 bubbles in a food product. WO 2010/121490 A1 , WO 2010/121491 A1 , and WO 2010/121492 A1 disclose foams stabilised by ethylcellulose nanoparticles.

US 2012/0045495 A1 discloses films that can be used in oral care compositions, and may contain useful ingredients like zinc compounds. The films may be prepared from cellulose materials like preferably hydroxypropyl methyl cellulose. Similarly WO 2005/058265 A1 discloses films that may be prepared from cellulose ethers.

Wege et al. (Langmuir 2008, 24, 9245-9253) disclose stabilisation of foams and emulsions with microparticles from hydrophobic cellulose. They produce microparticles in various structures made from hypromellose phthalate (which is hydroxypropyl methylcellulose phthalate), in a stirred vessel using a high shear mixer. This polymer is soluble in water, dependent on the pH: at low pH it is not soluble, while upon increase of pH to above 5.5 the polymer becomes soluble.

SUMMARY OF THE INVENTION

In spite of these disclosures, there still is a need to produce new materials, which can be used to structure non-aqueous liquid phases and/or to stabilise aerated aqueous products. The non-aqueous liquid phases may be oils or other lipophilic compounds. These non-aqueous liquid phases may be incorporated as ingredients of products such as oil-in-water emulsions or water-in-oil emulsions. And especially there is a need for materials that can stabilise foams and that are able to reform a foam after destruction of such foam. We have now determined that this objective can be met by sheet-like particulates comprising a lipophilic cellulose-based polymer. These sheet-like particulates are very efficient structurants of non-aqueous liquids, such as vegetable oil in a food product, or lipid compounds in personal care products such as skin creams. Moreover they can be used as stabiliser of aerated aqueous products.

Using these sheet-like particulates has the advantage that in case of structuring food products, less saturated fats are required to structure the food product. Nevertheless similar sensory and in-use physical properties can be achieved, like rheology,

spreadability, storage stability, and chemical stability. Reducing the amounts of saturated fat in a product, makes a food product healthier. When applied in personal care products, new structures can be made which are liked by consumers. Examples of this are a superior sensory feeling such as silky feel (like in skin care cream), or delivery of actives on the skin (like in skin cleansing product). Also improved temperature stability can be achieved. The advantage of the sheet-like particulate as foam stabiliser, is that very stable aqueous foams can be obtained. Another advantage is that the foams can be regenerated after the foam has been destroyed with minimal loss of foam volume. These regenerated foams are very stable as well and can be kept for relatively long time without loss of foam volume.

Hence in a first aspect the present invention provides a sheet-like particulate comprising a lipophilic cellulose-based polymer,

wherein the sheet-like particulate has a thickness z ranging from 0.1 to 2 micrometer, and a length y ranging from 20 micrometer to 2,000 micrometer, measured along the longest coplanar axis,

and a width x ranging from 10 micrometer to 500 micrometer, measured perpendicular to the direction of the length y coplanar with the sheet-like particulate plane.

In a second aspect the present invention provides A method for preparation of a sheet-like particulate according to the first aspect of the invention; wherein the method comprises the following steps:

a) dissolving the lipophilic cellulose-based polymer in an organic solvent, preferably ethanol or acetone, preferably at a concentration between 5 and 17.5% by weight; b) providing a dispersion medium comprising a second solvent, preferably water, wherein the organic solvent and the second solvent are miscible or partially soluble in each other, and wherein the lipophilic cellulose-based polymer is insoluble in the second solvent;

c) adding the solution from step a) to the dispersion medium from step b); while

subjecting this mixture to shear by transporting the dispersion through a gap between two confronting surfaces,

wherein the surfaces are spaced at a distance ranging from 100 to 500 micrometer, wherein the shear rate in the gap ranges from 5x10 ³ s ^"1 to 1x10 ⁵ s ^"1 ; and

d) optionally isolating and/or drying of the sheet-like particulate obtained from step c). In a third aspect the present invention provides Use of a composition in the form of a sheet-like particulate according to the first aspect of the invention or obtained from the method according to the second aspect of the invention, as structurant of a non-aqueous liquid phase.

In a fourth aspect the present invention provides Use of a composition in the form of a sheet-like particulate according to the first aspect of the invention or obtained from the method according to the second aspect of the invention, as stabiliser for gas bubbles in an aqueous foam composition.

DETAILED DESCRIPTION

Definitions

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. All percentages, unless otherwise stated, refer to the percentage by weight. The abbreviation 'wt%' refers to percentage by weight. In case a range is given, the given range includes the mentioned endpoints. Ambient temperature is considered to be a temperature between about 20°C and about 25°C, preferably between 20°C and 25°C, preferably between 20°C and 23°C.

In the context of the present invention, an average particle diameter is generally expressed as the d4,3 value, which is the volume weighted mean diameter. The volume based particle size equals the diameter of the sphere that has the same volume as a given particle.

The term 'aerated' means that gas has been intentionally incorporated into a composition, for example by mechanical means. The gas can be any gas, but is preferably, in the context of food products, a food-grade gas such as air, nitrogen, nitrous oxide, or carbon dioxide. Hence the term 'aeration' is not limited to aeration using air, and encompasses the 'gasification' with other gases as well. The extent of aeration is measured in terms of 'overrun' (with unit '%'), which is defined as: volume of aerated product - volume of initial mix _{A nnn} , _ΙΛ , overrun = x 100% (1 )

Volume of initial mix where the volumes refer to the volumes of aerated product and unaerated initial mix (from which the aerated product is made). Overrun is measured at atmospheric pressure. The overrun of an aerated product and the volume fraction of gas in the aerated product generally relate in the following way: volume fraction gas (in %) = 100 x overrun / (1 + overrun) (2)

After formation, a foam will be vulnerable to coarsening by mechanisms such as creaming, Ostwald ripening and coalescence. By creaming, gas bubbles migrate under the influence of gravity to accumulate at the top of a product. Ostwald ripening or disproportionation refers to the growth of larger bubbles at the expense of smaller ones. Coalescence refers to merging of air bubbles by rupture of the film in between them.

A stable foam or aerated product in the context of the present invention is defined as being stable for at least 30 minutes, more preferred at least an hour, more preferred at least a day, even more preferred at least a week, and most preferred at least a month, and most preferred several months. A stable foam can be defined to be stable with regard to total foam volume, and/or gas bubble size, and looses maximally 20% of its volume during 1 month storage. On the other hand systems may exist which loose more than 20% of their volume during 1 month storage, which nevertheless are considered to have a good stability, as the stability of such foams is much better than comparative foams that do not contain sheet-like particulate. Foams of which the average bubble size strongly increases over time are regarded to be less stable than foams of which the average bubble size remains small over time.

By the term 'sheet-like particulate', we mean an anisotropic water-insoluble structure of which one dimension is small, relative to the other two dimensions. This can be translated into that the sheet-like particulate is a thin sheet of solid material of a continuous material. The sheet-like particulate may be a regularly or irregularly shaped flat sheet (compare to a paper sheet or a plastic bag), or may be in the form of any regularly or irregularly shaped morphology (compare to a crumbled paper sheet or plastic bag). A sheet-like particulate which would be in a similar shape as a flat paper sheet or as a crumbled paper sheet, is considered to be a sheet-like particulate in the context of the present invention.

In the context of the present invention the dimensions of the sheet-like particulate are defined as having a width x, a length y, and a thickness z. The length y of the sheet-like particulate is typically measured along the longest coplanar axis, from one end to other end of the sheet-like particulate. The width x of the sheet-like particulate typically would be perpendicular to the direction of the length coplanar with sheet-like particulate plane. The thickness of the sheet-like particulates is defined as the distance between the two flat surfaces of the formed sheets-like particulates. The meaning of thickness z, length y and width x are illustrated in Figure 1. Typically the surface area to volume ratio is defined as ratio of the surface area of the sheet (two sides combined) to the volume of the particle.

A 'non-aqueous liquid phase' as used in this context relates to a liquid at ambient conditions (temperature about 20°C, atmospheric pressure), and where said liquid has a tendency to flow, as determined by having a loss modulus G" larger than the storage modulus G' at shear rates γ (gamma) ranging from 1 per second to 500 per second. The non-aqueous character is defined as the material not being able to dissolve more than 10% by weight in water under ambient conditions, preferably less than 5% by weight, preferably less than 1 % by weight, preferably less than 0.5% by weight, preferably less than 0.2% by weight.

In the present context, the contact angle is measured as the angle in the oil droplet, as schematically depicted in Figure 2.

Composition of the invention: sheet-like particulate

In a first aspect the present invention provides a sheet-like particulate comprising a lipophilic cellulose-based polymer,

wherein the sheet-like particulate has a thickness z ranging from 0.1 to 2 micrometer, and a length y ranging from 20 micrometer to 2,000 micrometer, measured along the longest coplanar axis,

and a width x ranging from 10 micrometer to 500 micrometer, measured perpendicular to the direction of the length y coplanar with the sheet-like particulate plane.

In order to achieve good structuring capacity, the sheet-like particulate should have a good compatibility to a continuous non-aqueous liquid phase. A poor compatibility causes agglomeration of the sheet-like particulates and weak interaction with the continuous phase, which may induce a reduction of mechanical properties. The preferential route is to use sheet-like particulates that are compatible with the continuous phase, which are either made from appropriate starting materials or modified chemically of physically during the process of their production. The compatibility between sheet-like particulate and non-aqueous liquid can be estimated by measuring the wetting of the sheet-like particulate by the non-aqueous liquid. Measure for this is the three phase contact angle of non-aqueous liquid or water droplet in air placed on the substrate made from the same material the sheet-like particulates are made from. Alternatively the contact angle of non-aqueous liquid droplet in water (or other way around) on the substrate can be measured as well. Here the implicit assumption is that both sheet-like particulate and substrate have the comparable surface roughness and that line tension effects can be neglected. A better non-aqueous liquid wetting (or poorer water wetting) are indicative of better compatibility between the sheet-like particulate and the non-aqueous liquid phase. Therefore one can convert the problem of compatability between the sheet-like particulate and non-aqueous liquid phase to a problem of preparing sheet-like particulates with optimal lipophilicity measured via the contact angle.

Here we define the lipophilic cellulose-based polymer as a compound that is derived from cellulose, which preferably has a three-phase contact angle between sunflower oil, and a film of the lipophilic cellulose-based polymer, and air of less than 70° at 20°C. Preferably the angle is less than 50°, most preferred less than 40°.

The contact angle can be measured using standard equipment like the Drop shape analysis DSA100 (Kruss GmbH, Neunkirchen am Brand, Germany). This technique is common in the art.

The lipophilic cellulose-based polymer can be considered to be a cellulose derivative. A cellulose derivative is defined to be a compound that is based on cellulose, and wherein the cellulose has been modified by a chemical reaction. Preferably the lipophilic cellulose- based polymer comprises an alkylated cellulose ether. Examples of such alkylated cellulose ethers are methyl-ethylcellulose, ethylcellulose, propylcellulose or butylcellulose. Another preferred lipophilic cellulose-based polymer is cellulose diacetate. Also combinations of these compounds are within the scope of the present invention.

Preferably the lipophilic cellulose-based polymer comprises an alkylated cellulose ether, preferably ethylcellulose. The general structural formula of ethylcellulose is:

The degree of substitution of the ethylcellulose preferably used in the present invention is preferably from 2 to 3, preferably from 2.4 to 2.6, more preferably about 2.5. The average number of hydroxyl groups substituted per anhydroglucose unit (the 'monomer') is known as the 'degree of substitution' (DS). If all three hydroxyls are replaced, the maximum theoretical DS of 3 results.

Suitable sources and types of the ethylcellulose preferably used in the present invention are supplied by for example Ashland (formerly Hercules), Aldrich, and Dow Chemicals. Suitable ethylcellulose preferably has a viscosity ranging from 5 to 300 mPa.s at a concentration of 5% in toluene/ethanol 80:20, more preferably from 100 to 300 mPa.s at these conditions. Preferably, the dimensions of the sheet-like particulate is such that the thickness of the sheet-like particulates ranges from 0.1 to 1.8 micrometer, preferably from 0.1 to 1 .6 micrometer. Preferably the length y ranges from 20 to 1 ,500 micrometer, more preferred from 50 to 1 ,000 micrometer. Preferably the width x ranges from 20 to 300 micrometer, more preferred from 20 to 280 micrometer.

Most preferred, the thickness z of the sheet-like particulates ranges from 0.2 to

1 .5 micrometer, and/or the length y ranges from 100 micrometer to 600 micrometer, and/or the width x ranges from 50 micrometer to 250 micrometer. Some of the properties of the sheet-like particulates may be influenced by the zeta- potential of the sheet-like particulates. The zeta-potential is a measure for the surface charge of a colloidal particle, and determines whether particle attract or repulse each other. At a relatively high absolute value of the zeta-potential the ethylcellulose particles are well dispersed, due to repulsion of the particles. Preferably the absolute zeta-potential of the sheet-like particulates is more than 25 millivolt. In that case good foam stability can be achieved, when the sheet-like particulates are used as aqueous foam stabiliser. Composition of the invention comprising non-aqueous liquid phase structured by sheet-like particulate

In a further aspect of the first part of the invention, the present invention provides a composition comprising a non-aqueous liquid phase, wherein the non-aqueous liquid phase is structured by a sheet-like particulate according to the first aspect of the invention.

The concentration of the sheet-like particulate is such that preferably the concentration of the sheet-like particulates ranges from 0.1 to 15% by weight of the non-aqueous liquid phase, preferably ranges from 0.2 to 10% by weight of the non-aqueous liquid phase preferably ranges from 0.2 to 5% by weight of the non-aqueous liquid phase.

By using sheet-like particulates of the invention for structuring, applying shear to the structured non-aqueous liquid leads to shear alignment. This means that under shear forces the sheet-like particulates can align, and therewith give the impression to the consumer that a solid-liquid transition is obtained. This can be perceived to be analogous to a melting curve of a solid fat which melts upon chewing in the mouth or applying to the skin, and gives a positive impression to the consumer. Preferably the non-aqueous liquid phase is chosen from the group consisting of edible oils or fats, vegetable oil or fat, dairy oil or fat, fish oil or fat, mineral oil or mineral oil derivative, petrolatum or petrolatum derivative, silicon oil or silicon oil derivative.

In case of edible fats and oils, the terms 'fat' and 'oil' are used interchangeably. Where applicable the prefix 'liquid' or 'solid' is added to indicate if the fat or oil is liquid or solid at ambient temperature as understood by the person skilled in the art. The term 'structuring fat refers to a fat that is solid at ambient temperature. A structuring fat may serve to structure a composition at room temperature. The term 'liquid oil' refers to an oil that is liquid at ambient temperature. In common language, liquid fats are often referred to as oils but herein the term fats is also used as a generic term for such liquid fats.

Edible oils contain a large number of different triacylglycerols (TAGs) with varying physical properties. The TAGs are esters of glycerol and three fatty acids. The TAGs in edible oils contain fatty acids with an even number of carbon atoms in the chains, generally varying between 4 and 24 in number. Common fatty acids from vegetable origin are C10, C12, C14, C16, C18, C20 and C22, and most common TAGs are composed of these fatty acids. The fatty acids may be saturated, or monounsaturated or polyunsaturated. Each fatty acid can contain up to three double bonds at certain positions in the chain.

Additionally especially fish oil contains a high number of unsaturated fatty acids with more than one unsaturated bond in the chain, up to even 4 or 5 double bonds. The terms 'triacylglycerols', 'TAGs', and 'triglycerides' may be used interchangeably in here. In the context of the present invention, triglycerides are understood to be edible oils and fats.

Both a structuring fat as well as the liquid oil may originate from various edible natural oils. Fats include: plant oils (for example: allanblackia oil, apricot kernel oil, arachis oil, arnica oil, argan oil, avocado oil, babassu oil, baobab oil, black seed oil, blackberry seed oil, blackcurrant seed oil, blueberry seed oil, borage oil, calendula oil, camelina oil, camellia seed oil, castor oil, cherry kernel oil, cocoa butter, coconut oil, corn oil, cottonseed oil, evening primrose oil, grapefruit oil, grape seed oil, hazelnut oil, hempseed oil, illipe butter, lemon seed oil, lime seed oil, linseed oil, kukui nut oil, macadamia oil, maize oil, mango butter, meadowfoam oil, melon seed oil, moringa oil, mowrah butter, mustard seed oil, olive oil, orange seed oil, palm oil, palm kernel oil, papaya seed oil, passion seed oil, peach kernel oil, plum oil, pomegranate seed oil, poppy seed oil, pumpkins seed oil, rapeseed (or canola) oil, red raspberry seed oil, rice bran oil, rosehip oil, safflower oil, seabuckthorn oil, sesame oil, shea butter, soy bean oil, strawberry seed oil, sunflower oil, sweet almond oil, walnut oil, wheat germ oil); fish oils (for example: sardine oil, mackerel oil, herring oil, cod-liver oil, oyster oil); animal oils (for example: butter or conjugated linoleic acid, lard or tallow); or any mixture or fraction thereof. Dairy fat is of animal origin, and most commonly is sourced from the milk of mammals like cows, sheep, and goats. The oils and fats may also have been modified by hardening, fractionation, chemical or enzymatic interesterification or by a combination of these steps.

Generally natural oils contain at least 80% of triglycerides. Natural oils also may contain other compounds than triglycerides, such as diglycerides, monoglycerides and free fatty acids. Also compounds like lecithin, other emulsifiers, phytosterols, phytostanols, waxes, colourants like carotenoids, vitamins like vitamin A, D, E, and K, and antioxidants like the tocopherols (vitamin E) may be present in a natural oil.

Preferably the non-aqueous liquid comprises a vegetable oil, for example sunflower oil, palm oil, olive oil, rapeseed oil, or any other suitable vegetable oil or combination of oils. In case the non-aqueous liquid is an edible oil, the edible oil containing the composition of the invention may be used as a food product, or as an ingredient of a food product. In case the non-aqueous liquid comprises materials like mineral oil, petrolatum, and/or silicon oil, and derivatives of these compounds, the structured non-aqueous liquid may be used as an ingredient of personal care products. Such personal care products may be a skin cream, a body lotion, bodywash, handwash, facial foam, shampoo, or hair conditioner. When applied in personal care products, new structures can be made which are liked by consumers. Examples of this are a superior sensory feeling such as silky feel (like in skin care cream), or deliver actives on the skin (like in skin cleansing product). Preferably, the composition is a water-in-oil emulsion, containing between 1 % by weight and 99% by weight of non-aqueous liquid phase. The non-aqueous liquid phase in that case is a continuous phase, containing droplets of an aqueous phase.

Preferably and alternatively, the composition is an oil-in-water emulsion, containing between 1 % by weight and 95% by weight of non-aqueous liquid phase. The nonaqueous liquid phase in that case is dispersed as droplets or particles in a continuous aqueous phase.

The first aspect of the invention additionally provides a food product or a personal care product or a home care product comprising a non-aqueous liquid phase that is structured by a sheet-like particulate according to the invention. It may be used as such, or mixed with other ingredients.

A food product or an edible product in the context of the present invention encompasses, but is not limited to, food products including beverages, dietetic foods, dietary

supplements, pharmaceutic compositions, and others. The products may contain ingredients common in the art and may be made by methods common in the art.

In the context of the present invention, a home care product is a product which is normally used for cleaning items such as hard surfaces in the home, or cleaning items such as the dishes and other kitchen hardware, or may be laundry detergents in liquid or solid form (powders, tablets), or may be laundry conditioners. Examples of such products are liquid or gel cleaners for the kitchen, bathroom, or toilet, and dishwashing liquid. In the context of the present invention a personal care product is a product which is used by a consumer for cleaning, hygiene, and/or beauty. Cosmetic products in the context of the present invention encompasses, but is not limited to, skin creams, body lotions, shampoos, hair conditioners, toothpastes, deodorants, hair styling products, personal soap bars, and liquid personal soaps. Possible products that may contain the non-aqueous liquid phase that is structured by the sheet-like particulate according to the invention are food products such as water-in-oil emulsions or oil-in-water emulsions, or personal care products, such as skin creams. These personal care products may be oil-in-water emulsions. Also double emulsions and multiple emulsions (like oil-in-water-in-oil and water-in-oil-in-water emulsions) are emulsions of which the non-aqueous liquid phase can be structured by the sheet-like particulates of the invention.

In the case of food products, the non-aqueous liquid phase can be a lipid phase, for example droplets of a dairy fat or a vegetable oil dispersed in an aqueous phase to form an oil-in-water emulsion. Examples of oil-in-water emulsions are dressings and

mayonnaise-type products, and dairy spreads. In case of water-in-oil emulsion such as margarines, butter, and other spreads, the lipid phase can be considered to be the continuous vegetable oil phase or butter fat phase, as applicable. Preferably, the food product of the invention is a marinade, sauce, seasoning, butter, spray product, spread, liquid shallow frying product, seasoning, dressing, mayonnaise, low-fat mayonnais, or ice cream.

The amount of non-aqueous liquid phase in such products may range from 1 % by weight to 99% by weight of the product, depending on the product. For example a shortening may contain 99% by weight of edible oil or fat. A margarine contains about 80% edible oils and fats. A water-in-oil spread may contain from 20 to 70% by weight of edible oils and fats. A dressing or mayonnaise may contain from about 5% by weight up to 80% by weight of non-aqueous lipid phase. A dairy spread may contain about 20 to 30% by weight of edible oils and fats. A skin cream may contain about 5 to 20% by weight of lipid compounds.

Many food emulsions are stabilised by structuring fat, often solid fat particles, especially margarine-type of emulsions and spreads. These are water-in-oil emulsions. The solid fat usually is mainly a saturated fat, which is considered to be unhealthy when consumed in large amounts. Therefore replacing saturated fats by the sheet-like particulates has the advantage that the amount of saturated fat can be reduced, and has a beneficial health effect for the health of the consumer. Nevertheless similar sensory and in-use physical property can be achieved as conventional emulsions containing solid fat, like rheology, spreadability, storage stability, and chemical stability. The sheet-like particulates lead to structuring of the non-aqueous liquid phase. By rheology measurements it can be shown that the physical behaviour of the structured lipids is such that it resembles lipid phases that are structured by solid triglycerides (for example like in butter and margarine), for example in meltdown behaviour upon increase of temperature. Also extended temperature stability can be obtained. Also the viscosity (in Pa.s) of a structured non-aqueous liquid can be determined as function of the shear rate (in 1/s) in order to compare for example a margarine (structured by solid (saturated) fat crystals) and structured non-aqueous liquid.

In case of personal care products (e.g. skin cream, a body lotion, bodywash, handwash, facial foam, shampoo, or hair conditioner), the non-aqueous liquid phase may be chosen from materials like mineral oils, petrolatum, and silicon oils, and derivatives of these compounds, and combinations of these.

Composition of the invention: aerated aqueous composition stabilised by sheet-like particulate

In a further aspect of the first part of the invention, the present invention provides An aerated aqueous composition, comprising a sheet-like particulate according to the first aspect of the invention, wherein at least part of the sheet-like particulates is located at the water - gas bubble interface, and wherein the composition has an overrun of at least 5%.

The concentration of the sheet-like particulate is such that preferably the concentration of the sheet-like particulates ranges from 0.0005% to 1 % by weight of the aerated composition, preferably from 0.001 % to 0.5% by weight of the aerated composition. The advantage of the sheet-like particulate as foam stabiliser, is that very stable aqueous foams can be obtained. Another advantage is that the foams can be regenerated after the foam has been destroyed with minimal loss of foam volume. These regenerated foams are very stable as well and can be kept for relatively long time without loss of foam volume. The aqueous foams that are stabilised using the sheet-like particulates of the invention, preferably having an overrun of at least 10%, preferably at least 30%, preferably at least 100%. More preferred the overrun may range from at least 50% to at least 100% or even to 400%, or to 600%, or to 700%, or even more. Preferably though, the overrun of the foams is maximally 400%.

Some of the properties of the sheet-like particulates may be influenced by the zeta- potential of the sheet-like particulates. The zeta-potential is a measure for the surface charge of a colloidal particle, and determines whether particle attract or repulse each other. At a relatively high absolute value of the zeta-potential the ethylcellulose particles are well dispersed, due to repulsion of the particles. In that case good foam stability can be achieved, when the sheet-like particulates are used as aqueous foam stabiliser.

Preferably the absolute value of the zeta-potential of the sheet-like particulate is more than 25 millivolt.. Preferably the absolute value of the zeta-potential remains constant, or at least more than 25 millivolt during the shelf life of the aqueous foam

Another advantage of the sheet-like particulates of the invention, is that the aerated aqueous composition that is stabilised using the particulates can have a broad range of properties. Preferably the sheet-like particulates are used in the stabilisation of an acidic aerated aqueous composition. Preferably the pH of such aqueous composition is lower than 5, preferably the pH is lower than 4, preferably the pH is lower than 3. Alternatively, the sheet-like particulates are used in the stabilisation of an alkaline aerated aqueous composition. Preferably the pH of such aqueous composition is higher than 9, preferably the pH is higher than 10, preferably the pH is higher than 1 1 . Preferably the sheet-like particulates are used in the stabilisation of an aerated aqueous composition having an ionic strength of at least 0.05 mol/L, preferably an ionic strength of at least 0.1 mol/L, preferably an ionic strength of at least 0.15 mol/L.

Preferably, the gas bubble size in the aerated composition is such that at least 50% of the gas bubbles has a volume based equivalent diameter of maximally 1 ,000 micrometer. Preferably at least 50% of the volume of the gas in the composition is made up of gas bubbles having a volume based equivalent diameter of maximally 60 micrometer, preferably maximally 50 micrometer. More preferred at least 50% of the volume of the gas in the composition is made up of gas bubbles having a volume based equivalent diameter of maximally 40 micrometer. Preferably at least 80% of the volume of the gas in the composition is made up of gas bubbles having a volume based equivalent diameter of maximally 70 micrometer, preferably maximally 60 micrometer, preferably maximally 50 micrometer.

Preferably, the aerated composition of the invention further comprises a non-aqueous liquid phase. Preferably the non-aqueous liquid phase is chosen from the group consisting of edible oils or fats, vegetable oil or fat, dairy oil or fat, fish oil or fat, mineral oil or mineral oil derivative, petrolatum or petrolatum derivative, silicon oil or silicon oil derivative.

Preferably the composition is an oil-in-water emulsion, containing between 1 % by weight and 95% by weight of non-aqueous liquid phase.

The terms edible fats and oils, and non-aqueous liquid phase are similar as defined herein before. Preferably the non-aqueous liquid comprises a vegetable oil, for example sunflower oil, palm oil, olive oil, rapeseed oil, or any other suitable vegetable oil or combination of oils. In case the non-aqueous liquid is an edible oil, the aerated

composition of the invention may be used as a food product, or as an ingredient of a food product.

In case the non-aqueous liquid comprises materials like mineral oil, petrolatum, and/or silicon oil, and derivatives of these compounds, the aerated composition may be used as an ingredient of personal care products.

The first aspect of the invention additionally provides a food product or a personal care product or a home care product comprising an aerated composition according to the invention. It may be used as such, or mixed with other ingredients.

Method for preparation of sheet-like particulate

In a second aspect the present invention provides A method for preparation of a sheet-like particulate according to the first aspect of the invention; wherein the method comprises the following steps:

a) dissolving the lipophilic cellulose-based polymer in an organic solvent, preferably

ethanol or acetone, preferably at a concentration between 5 and 17.5% by weight; b) providing a dispersion medium comprising a second solvent, preferably water, wherein the organic solvent and the second solvent are miscible or partially soluble in each other, and wherein the lipophilic cellulose-based polymer is insoluble in the second solvent; c) adding the solution from step a) to the dispersion medium from step b); while subjecting this mixture to shear by transporting the dispersion through a gap between two confronting surfaces,

wherein the surfaces are spaced at a distance ranging from 100 to 500 micrometer, wherein the shear rate in the gap ranges from 5x10 ³ s ^"1 to 1x10 ⁵ s ^"1 ; and

d) optionally isolating and/or drying of the sheet-like particulate obtained from step c).

In step a) the organic solvent in the method according to the invention is a solvent in which the lipophilic cellulose-based polymer can be dissolved. Examples of these solvents are alcohols, preferably ethanol, ethyl acetate, acetic acid, acetone, N,N- dimethylformamide (DMF), or any suitable combination of these solvents. Preferred organic solvents are the common solvents acetone or ethanol. The concentration of the lipophilic cellulose-based polymer in the solvent preferably ranges from 5% to 17.5% by weight, preferably from 5% to 15% by weight, more preferred from 5% to 12.5% by weight, most preferred from 7.5% to 12.5% by weight. Preferably the temperature in this step ranges from 10 to 60°C, more preferred from 15 to 40°C. Most preferred the temperature ranges from 20 to 25°C. Preferably the lipophilic cellulose-based polymer is homogeneously dissolved in the solvent in this step a). In step b) the second solvent preferably is water. The preferred lipophilic cellulose-based polymer is ethylcellulose, and this ethylcellulose is not soluble in the preferred second solvent water. Preferably the volume of the dispersion medium in step b) ranges from 10 to 200 times the volume of the solvent with dissolved lipophilic cellulose-based polymer from step a), more preferred the volume of the dispersion medium ranges from 50 to 150 times the volume of the solvent with dissolved lipophilic cellulose-based polymer from step a). Preferably the temperature in this step ranges from 10 to 60°C, more preferred from 15 to 40°C. Most preferred the temperature ranges from 20 to 25°C.

In step c) by adding the solution from step b) to the solution from step a), a dispersed phase of the lipophilic cellulose-based polymer within the dispersion medium is formed. In step c) the dispersion is subjected to shear by transporting the liquid mixture through a gap between two confronting surfaces. The gap between these confronting surfaces ranges from 100 to 500 micrometer. The shear rate ranges from 5x10 ³ to 1x10 ⁵ s ^"1 , more preferred from 7x10 ³ to 8x10 ⁴ s ^' Preferably the temperature in this step ranges from 10 to 60°C, more preferred from 15 to 40°C. Most preferred the temperature ranges from 20 to 25°C. The temperature of the mixture may rise due to the extensive mixing process and the energy input into the mixing operation.

Preferably the gap in step c) is formed by an annular space between two concentric cylinders, wherein at least one of the cylinders rotates relative to the other cylinder, preferably at a rotation speed ranging from 10,000 to 30,000 rpm. Preferably the rotation speed ranges from 15,000 to 25,000 rpm. Typically the internal cylinder is able to rotate, and this inner cylinder is usually called the rotor (and the outside cylinder the stator). Preferably the cylinders are conically shaped, while the gap between the two surfaces preferably remains constant. The flow of liquid from step c) in that case is from the wide bottom of the cone to the narrow top of the cone, meaning that the cross-sectional area of the flow path decreases in the direction of the flow.

A device that may be used to perform the method of the invention is a colloidal mill - high shear mixer IKA mill with rotor-stator design (supplier IKA®-Werke GmbH & Co. KG, Staufen, Germany). Rotor-stator mills typically operate at high rotational speeds of the rotor. The differential speed between the rotor and the stator imparts high shear and turbulent flow in the gap between the rotor and the stator. The shear rate in the gap between the rotor and the stator may be varied from 5x10 ³ s ^"1 to 1x10 ⁵ s ^"1 , more preferred from 7x10 ³ to 8x10 ⁴ s ^' The Reynolds number (Re) that gives a measure of the ratio of the inertial forces to the viscous forces in that case may range from 3x10 ⁴ to 3x10 ⁵ , more preferred from 3.2x10 ⁴ to 2.5x10 ⁵ .

One of the advantages of the method of the invention for preparation of sheet-like particulates is its simplicity and easy scalability. As a whole, it can be used for

synthesizing large amounts of sheet-like particulates in an inexpensive way using basic laboratory equipment such as colloidal mill and eco-friendly medium such as water. The anisotropic sheet-like particulates are synthesized in solution in a dispersed state and can be used directly.

If necessary, sheet-like particulates can be easily separated and dried or transferred to another medium using wide spread procedures as centrifugation and filtration. Hence in step d) the sheet-like particulate material obtained in step c) optionally is isolated and/or dried. Drying may be done like (over) air drying, (vacuum) drum drying, microwave (vacuum) drying, and freeze drying. This material then can be used for various purposes, like structuring of non-aqueous liquid and/or stabilising of aqueous foams. Drying of the sheet-like particulate may influence the structuring properties of the dried sheet-like particulate. Preferably, a freeze drying step is applied in step d), because in that case the viscosity of a non-aqueous liquid phase may be higher than when using a method like drying of the sheet-like particulate in an oven.

Composition obtainable by the method of the invention

The present invention also provides A composition in the form of a sheet-like particulate obtainable by the method according to the second aspect of the invention.

Any preferred aspects disclosed in the context of the first or second aspect of the invention, are also applicable to the composition in the form of a sheet-like particulate obtainable by the method according to the invention, mutatis mutandis. The present invention also provides a composition comprising a non-aqueous liquid phase, wherein the non-aqueous liquid phase is structured by a sheet-like particulate obtainable by the method according to the second aspect of the invention.

Preferably the sheet-like particulate as prepared is dried before being used for structuring a non-aqueous liquid phase. Hence step d) in the method described above preferably is applied as well for structuring of a non-aqueous liquid phase.

The present invention also provides an aerated aqueous composition, comprising a sheetlike particulate obtainable by the method according to the second aspect of the invention, and wherein at least part of the sheet-like particulates is located at the water - gas bubble interface, and wherein the composition has an overrun of at least 5%.

Method for preparation of compositions of the invention

In a further aspect of the second aspect the present invention, the present invention provides a method for preparation of a composition comprising a non-aqueous liquid phase that is structured by a sheet-like particulate according to the invention, comprising a step wherein a non-aqueous liquid phase is brought into contact with a sheet-like particulate according to the first aspect of the invention, or obtained according to the method of the second aspect of the invention. The contacting of the sheet-like particulate with the non-aqueous liquid can be done by any method commonly known to the skilled person. The temperature at which the contacting is performed preferably ranges from 10 to 90°C, preferably from 10 to 70°C. In a further aspect of the second aspect of the present invention, the present invention provides a method for preparation of an aerated aqueous composition according to the invention, wherein the method comprises the following steps:

a) providing a dispersion in water of a sheet-like particulate according to the first aspect of the invention, or obtained according to the method of the second aspect of the invention; and

b) aerating the mixture from step a) to an overrun of at least 5%.

Such an aerated composition can be produced by any commonly available method for aeration, for example using an aerolatte, Kenwood mixer, or a BA Mixer.

Any preferred aspect disclosed in the context of the first aspect of the invention, is also applicable to the second aspect of the invention, mutatis mutandis.

Use of the sheet-like particulate for structuring of non-aqueous liquid

In a third aspect the present invention provides Use of a composition in the form of a sheet-like particulate according to the first aspect of the invention or obtained from the method according to the second aspect of the invention, as structurant of a non-aqueous liquid phase. Possible products that may be structured by the composition in the form of sheet-like particulate according to the invention are food products such as water-in-oil emulsions or oil-in-water emulsions, or personal care products, such as skin creams. These personal care products may be oil-in-water emulsions. Also double emulsions and multiple emulsions (like oil-in-water-in-oil and water-in-oil-in-water emulsions) are emulsions of which the non-aqueous liquid phase can be structured by the sheet-like particulates of the invention.

Use of the sheet-like particulate for stabilising aqueous foam

In a fourth aspect the present invention provides Use of a composition in the form of a sheet-like particulate according to the first aspect of the invention or obtained from the method according to the second aspect of the invention, as stabiliser for gas bubbles in an aqueous foam composition. The advantage of the sheet-like particulate as foam stabiliser, is that very stable aqueous foams can be obtained. Another advantage is that the foams can be regenerated after the foam has been destroyed with minimal loss of foam volume. These regenerated foams are very stable as well and can be kept for relatively long time without loss of foam volume. DESCRIPTION OF FIGURES

Figure 1: Schematic representation of the thickness z, length y, and width x used to define the dimensions of the sheet-like particulate of the invention (for illustration purposes). The upper picture is a cross-section of the sheet-like particulate, across the length y or the width x, and indicates that x and y are measured following the plane of the sheet-like particulate. The numeral T refers to the sheet-like particulate. The lower picture indicates that x and y are measured using the longest dimension, and perpendicular to each other. Figure 2: Schematic representation of the contact angle as defined herein. Droplet is dark, on the surface of a film. The contact angle as indicated is the angle in the droplet between the surface and the tangential line hitting the droplet.

Figure 3: Schematic representation of the equipment used for preparation of sheet-like particulates in example 2.

Figure 4: Images of sheet-like particulates prepared in example 2.

Top images: Micrographs made using optical light microscope of ethylcellulose sheet-like particulates from 7.5% ethylcellulose solution in acetone in a water suspension (at 20,000 rpm). The scale bars are equal to 50 micrometer (left) and 200 micrometer (right). Bottom images: Micrographs of ethyl cellulose sheets from 7.5 wt % in ethanol prepared in water suspension (at 5, 000 rpm). The scale bars are equal to 500 micrometer (left) and 50 micrometer (right).

Figure 5. Images of structures prepared with varying ethylcellulose concentrations, from example 2: a 2.5%, b 5%, c 12.5%, d 17.5%.

Figure 6: Images of ethylcellulose N100 sheet-like particulates, prepared at different shear rates in example 2: a) 3,000 rpm, scale bar 500 micrometer; b) 5,000 rpm, scale bar 100 micrometer; c) 10,000 rpm, scale bar 200 micrometer; d) 20,000 rpm, scale bar 50 micrometer.

Figure 7: Scanning electron microscopy images of dried sheet-like particulates, prepared at two gap sizes in example 2: top 180° gap, bottom 270° gap; bar size of both images 30 micrometer.

Figure 8: Viscosity of 3.56 wt% ethylcellulose rods (1 ) added to soybean oil, compared to pure soybean oil (2), as function of shear stress. Figure 9: Viscosity of 2.55 wt % ethylcellulose sheet-like particulates (1 ) and 2.89 wt% ethylcellulose fibres (2) added to soybean oil, and pure pure soybean oil (3), as function of shear stress.

Figure 10: Viscosity of sunflower oil structured with ethylcellulose sheet-like particulates, at 1 wt% (curve 1 ), 2 wt% (curve 2), 3 wt% (curve 3), and pure sunflower oil (curve 4), as function of shear rate.

Figure 11: Viscosity (in Pa.s) as function of shear rate (in 1/s) of sunflower oil structured with 2.5 wt% ethylcellulose sheet-like particulates that is dried by freeze drying (curve 1 ), or oven dried (curve 2).

Figure 12. Pictures of foams stabilised by ethylcellulose sheet-like particulate during a period of 24 days (from left to right: 10 minutes, 5 days, 15 days, 24 days).

EXAMPLES

The following non-limiting examples illustrate the present invention.

Raw materials used:

• Ethylcellulose: Aqualon ^® Ethylcellulose (type N200) was purchased from Ashland Inc.

(Covington, Kentucky, USA). Mw about 200 kg/mol, ethoxyl content was 48.0-49.5%, and degree of substitution was 2.46-2.57. Viscosity was 150-250 mPa.s (at 5% and 25°C in 80/20 toluene/ethanol).

Also type N100 was used, with ethoxyl content 48.0-49.5%, degree of substitution was 2.46-2.57, and viscosity was 80-105 mPa.s (at 5% and 25°C in 80/20 toluene/ethanol).

• Hypromellose phthalate HP-55 (hydroxypropyl methylcellulose phthalate), supplier Shin-Etsu Chemical Co., Ltd., (Tokyo, Japan).

· Acetone: supplied by Sigma-Aldrich Corp. (St. Louis, MO, USA).

• Ethanol (95%) supplied by Sigma-Aldrich Corp. (St. Louis, MO, USA).

• Sunflower oil (100%) bought at a local grocery.

• Soybean oil (100%): bought at a local grocery.

• Dimethicone: Polydimethylsiloxane, trademark & product name: PMX-200 Fluid,

50 cPs, molecular weight: 3,200; refractive index: 1.402, specific gravity: 0.960, manufacturer: Dow Corning (Midland Ml, USA).

• Demineralised water was obtained from a Millipore filter system. Example 1 - Measurement of Contact Angle

The contact angle of ethylcellulose was determined using a Drop shape analysis DSA100 (Krijss GmbH, Neunkirchen am Brand, Germany). In the present context, the contact angle is measured as the angle in the droplet of oil, as schematically depicted in Figure 2. The method applied was the following:

dissolve ethylcellulose in a solvent to make homogenous solution;

case a few drops of a solution onto a whole glass slide, under slowly spinning the glass slide to evenly spread the drops on the glass slide;

dry, smooth and even film formed after solvent has evaporated;

- 5 microliter drop of demineralised sunflower oil or dimethicone is brought onto the surface, at ambient pressure, humidity and temperature;

Measured contact angles:

Sunflower oil - ethylcellulose film: 37°.

Dimethicone - ethylcellulose film 24°.

Example 2 - Preparation of sheet-like particulates of ethylcellulose

Sheet-like particulates have been prepared in a colloid mill which is schematically depicted in Figure 3. The equipment contains a liquid reservoir 2, and a rotating conical shape 3. The conical shape 3 forms a gap 4 with the confronting wall. Liquid is pumped from the reservoir 2 through the gap 4 to the recirculation pipe 5, via pump 6, and recirculation pipe 5 to the reservoir 2. The instrument used was an IKA® magic LAB® (supplier IKA®-Werke GmbH & Co. KG, Staufen, Germany), which contains two conical rotors, which can be rotated in opposite directions, causing friction and high shear rates. The gap between these two cones can be changed, as well as the rotation speed (in rpm). With a relatively small gap size and high rotation speed (for example 20,000 rpm), a high shear rate can be achieved.

Variation of solvent and rotation speed

Experimental parameters: 350 mL anti-solvent (water), 3-5 mL ethylcellulose solution in solvent, gap between two conical rotors 180° (translating to 159 micrometer), all processes at room temperature.

A solution of ethylcellulose N200 in acetone was prepared at a concentration of 7.5 wt%. The solution was injected into sheared media of demineralised water in reservoir 2 once the preset revolution rate of 20,000 rpm had been reached. The mill was run for approximately 5 minutes after all ethylcellulose had been injected, to recirculate the dispersion. The resulting sheets were in the form of a foamy surface layer on the water, which was collected and either dried or stored in vials. See Figure 4 top for pictures of obtained sheet-like particulates.

Similarly a solution of ethylcellulose N200 in ethanol was prepared at a concentration of 7.5 wt%, and prepared in the same way at a rotation speed of 5,000 rpm. See Figure 4 bottom for pictures of obtained sheet-like particulates. Variation of ethylcellulose concentration

Experimental parameters: 350 mL anti-solvent (water), 3-5 mL ethylcellulose solution in solvent, gap between two conical rotors 180° (translating to 159 micrometer), all processes at room temperature. Solutions of ethylcellulose N 100 in ethanol were prepared at concentrations of 2.5, 7.5, 12.5, and 17.5 wt%. The solution was injected into sheared media of demineralised water in reservoir 2 once the preset revolution rate of 20,000 rpm had been reached. The mill was run for approximately 5 minutes after all ethylcellulose had been injected, to recirculate the dispersion. The resulting structures were dependent on the concentration of ethylcellulose, as shown in

Variation of rotation speed of colloid mill

Experimental parameters: 350 mL anti-solvent (water), 3-5 mL ethylcellulose solution in solvent, gap between two conical rotors 180° (translating to 159 micrometer), all processes at room temperature.

A solution of ethylcellulose N100 in ethanol was prepared at a concentrations of 7.5 wt%. This solution was split in four parts, and these parts were processed in the colloid mill at four different rotation speeds: 3,000, 5,000, 10,000, and 20,000 rpm. In these four cases sheet-like structures were obtained, as shown in Figure 6.

Variation of angle of gap of colloid mill

The angle of the gap between the two conical rotors was adjusted to 180° (translating to 159 micrometer), or to 270° (translating to 239 micrometer). Images of the materials obtained are shown in Figure 7. The materials are rather similar, hence the difference between the two gap sizes does not have a major influence on the final sheet-like particulate. Dimensions were determined using SEM microscopic images, and were determined to be as indicated in the following table:

Table 1 Dimensions of sheet-like particulate as function of gap size.

The width refers to the longest horizontal stretch of a sheet-like particulate. The number of measurements for the two gap widths were 30 and 15 sheet-like particulate, respectively, and averages were determined from these measurements. Example 3 - Structuring of vegetable oil using sheet-like particulates of

ethylcellulose

The sheet-like particulates from example 2 (as described under Variation of solvent and rotation speed', produced at 20,000 rpm) have been used to structure sunflower oil or soybean oil. After the sheet-like particulates were dried, they were added to vegetable oil in low weight percent solutions. The polymer and oil were vigorously stirred for a 24 hour period at room temperature. Upon complete mixing (dispersion) of the sheet-like structures in the oil, the solutions became highly viscous, and exact viscosities were measured via rheology. When comparing sheet-like particulates to ethylcellulose rods, ethylcellulose fibers and ethylcellulose particles, it was found that sheet-like particulates required the lowest weight percent to increase oil viscosity than rods, fibers or particles. Rods were defined as having an aspect ratio length over diameter (L/d) equal to or smaller than 20. Fibres were defined as having an aspect ratio length over diameter (L/d) of larger than 20. Ethylcellulose particles are nanoparticles that were obtained by precipitation of ethylcellulose N200 polymer solution in acetone by adding equal volume of antisolvent water and using a magnetic stirrer instead (similarly as described in

WO 2010/121490 A1 ). The average particle diameter of these particles ranged from about 170 to about 200 nanometer.

Rheological analysis was performed in a controlled stress rheometer (AR-2000

Rheometer, TA Instruments, New Castle, Delaware, USA; with parallel plate 40mm, the gap used was 1000 micrometer, at room temperature 25°C). The results of the rheology tests are shown in Figure 8, Figure 9, and Figure 10. Figure 8 shows the viscosity of rods in soybean oil as function of the shear stress, compared to pure soybean oil. The rods were mixed with the soybean oil at a concentration of 3.56% by weight. This shows that the viscosity decreases when the shear stress increases. Figure 9 shows the viscosity of sunflower oil and sunflower oil to which ethylcellulose fibres (2.89% by weight) or ethylcellulose sheet-like particulates (2.55% by weight) are added. A clear trend was established, with sheet-like particulates thickening oil more than fibres, fibres more than rods, and all three structures thickening oil much more than individual ethylcellulose particles at comparable volume structures. The sheet-like particulates are the best oil thickeners, creating highly viscous oils with low weight percent concentration of ethylcellulose. In all cases the measured viscosity of the structured oils decreased with increasing shear stress or shear rate.

Figure 10 shows the effect of the concentration of sheet-like particulates (1 %, 2%, and 3% by weight, respectively) on the viscosity of sunflower oil. This graph shows that with each 1 % of sheet-like particulates, the viscosity increases by roughly an order of magnitude.

Figure 1 1 shows the viscosity (in Pa.s) as function of shear rate (in 1/s) of sunflower oil structured with 2.5 wt% ethylcellulose sheet-like particulates. The sheet-like particulates are made from ethylcellulose N 100 as described in example 2. Part of the obtained sheet- like particulates was freeze dried at pressure of 0.01 mbar at -85°C, during one day. The other part was dried in an over at 45°C during two days. The dried sheet-like particulates were mixed with sunflower oil, by using an Ultra Turrax mixer (IKA®-Werke GmbH & Co. KG, Staufen, Germany) at rotation speed of 6,500 rpm at room temperature. Due to the mixing process the temperature of the oil increased up to 30°C. Mixing time required to obtain a homogeneous mixture for the freeze-dried sheet-like particulates was 2 to 5 minutes. For the oven-dried sheet-like particulates, the required mixing time was 5 to 15 minutes.

Rheology was determined using a rheometer (Anton Paar, Physica MCR501 , Austria) with a parallel-plate (PP 25), at room temperature). Figure 1 1 curve 1 shows sunflower oil structured by freeze dried sheet-like particulates, and curve 2 sunflower oil structured by oven dried sheet-like particulates. This shows that the viscosity of sunflower oil structured by freeze dried sheet-like particulates is higher than the oven-dried sheet-like particulates. Example 4 - Aerated aqueous compositions with sheet-like particulates of ethylcellulose

Sheet-like particulates as prepared in example 2 were used to stabilise aqueous foams. The IKA® magic LAB colloidal mill was used: gap between two conical rotors 180° (translating to 159 micrometer), 20,000 rpm.

A solution of ethylcellulose N200 at a concentration of 7.5% in acetone was prepared. The solution (3-5 mL) was injected into sheared demineralised water (350 mL) once the revolution rate of 20,000 rpm had been reached. The mill was run for approximately 30-60 seconds after all polymer had been injected. The resulting foam was collected and stored in vials (see Figure 12). It was shown that the foams stabilised by the ethylcellulose sheetlike particulate maintained the same volume for a period of at least 24 days.

As a comparison, sheet-like particulates were prepared from hydroxypropyl

methylcellulose phthalate HP-55 (similarly as used by Wege et al., ibid.). A 10% HP55 solution in acetone was prepared. 70 mL of solution was injected into 350 mL of acidic water (pH = 2.75) once the revolution rate 20,000 rpm had been reached. The mill was run for approximately 30-60 seconds after all polymer had been injected. The resulting foam was collected and stored in vials. The water was acidic, as the HP-55 polymer is not soluble under acidic conditions.

The foam stabilised by the ethylcellulose sheet-like particulate maintained approximately the same volume for a period of 30 days at least. After 30 days the foam was destroyed by centrifugation, and then shaken again to reform the foam. The following normalised foam volume was determined:

Table 2 Normalised foam volume of foam stabilised by the ethylcellulose sheet-like particulate

time normalised foam

[day] volume

0 1 .0

20 1 .0

23 1 .0

30 0.96

31 1 .03

36 1 .03 The foam that was reformed after destroying the initial foam maintained the same volume for 10 to 20 days, and then it lost some volume to stay at about 70-80% of the original foam volume. Foams made from HP55 lost volume within the first 30 days after preparation, before being destroyed by centrifugation, and after being reformed quickly lost more volume, at around 40-60% original volume after ten days.

In order to further determine the stability of the foams stabilised by the ethylcellulose sheet-like particulate, the volume change was observed when the foams were diluted with salty water to obtain a concentration of 0.1 M NaCI, as well diluting with plain, after which the pH was adjusted with acid or base to pH 2.2, or pH 12.1 , respectively. Finally one sample was diluted with plain water without further additions. Even with the wide range of solution characteristics, the foam exhibited very stable characteristics, as shown in the following table.

Table 3 Normalised foam volume of foam stabilised by the ethylcellulose sheet-like particulate added to water under various conditions

The acidic foam demonstrated the best stability of the three systems, followed by the salt solution, with the basic solution having the lowest stability. Even with basic solution, however, the foam maintained about 70% of the original volume over thirty days (Figure 15). The zeta-potential of the ethylcellulose sheet-like particulates was determined over the shelf-life of the aqueous foams. The zeta-potential was determined by electrophoresis, using the Metasizer Nano ZS instrument (Malvern Instruments, Malvern, UK). Table 4 Zeta-potential of ethylcellulose sheet-like particulate in aqueous foam.

These data show that the ethylcellulose sheet-like particulates remained stable as exemplified by the rather constant value of the zeta-potential. Only after destruction of the foam after 30 days and reformation of the foam again, the zeta-potential increased. A few days later it had decreased again to a similar value as before destroying the foam.