Melanoidin-coated mineral UV filter particles and methods for their preparation

Abstract

The present disclosure pertains to a process for the preparation of melanoidin-coated inorganic UV filter particles, using melanoidin and titanium- and / or zinc oxide particles as starting material and wherein either: A. a mixture of the titanium- and / or zinc oxide particles and melanoidin in water is ultrasonic treated, followed by spray drying the mixture to form melanoidin-coated titanium- and / or zinc oxide particles; B. the titanium- and / or zinc oxide particles are activated by acid treatment, followed by slow introduction of the melanoidin to the activated titanium-and / or zinc particles to form a melanoidin / titanium- and / or zinc oxide complex, and separation and drying of the resulting melanoidin-coated particles, or C. the titanium- and / or zinc oxide particles are subjected to high mechanical shear and heating, followed by introduction of the melanoidin through a nozzle and separation and drying of the resulting melanoidin-coated titanium- and / or zinc oxide particles. The disclosure is also directed to the resulting melanoidin-coated particles, sunscreen protection agents comprising said particles and compositions comprising said sunscreen protection agents.

Description

[0001] MELANOIDIN-COATED MINERAL UV FILTER PARTICLES AND METHODS FOR THEIR PREPARATION

[0002] Field

[0003] The present disclosure is in the field of melanoidin-coated mineral UV-such filter particles such as titanium- and / or zinc oxide particles and methods for preparing said melanoidin-coated mineral UV filter particles , their use as sunscreen protective agent and compositions comprising said sunscreen protective agent .

[0004] Background

[0005] UV exposure is known to cause skin damage such as aging, sunburn and skin cancer . The danger of UVB region ( 280-320 nm) absorption has been well recogni zed for it can cause skin damage . Whereas UVA radiation ( 320-400 nm) is less recogni zed, it can also cause dermatological problems . Therefore , protecting human skin from UVA radiation as well as UVB radiation has been an important issue and various materials are in demand for the ef fective skin protection from harmful UV radiation .

[0006] Sunscreen is an over-the-counter formula that easily protects human skin from UV radiation by application on the skin directly . Sunscreen can be classi fied into two main categories : organic sunscreens and inorganic sunscreens . Organic sunscreens like oxybenzone and avobenzone protect skin by absorbing UV, however, organic sunscreens can cause health problems when it is applied on skin directly with high concentration . Inorganic sunscreens have been widely used due to their ability of reflecting and scattering UV radiation . Examples thereof are titanium oxide and zinc oxide . Titanium oxide has been used as UV blockers due to its excellent UV protection ability, photostability and relatively low dermatologic toxicity often in combination with Zinc Oxide which is also a known inorganic UV filter .

[0007] For instance , KR 100968715 relates to a cosmetic composition for sunscreen, and more particularly to a cosmetic composition for sunscreen containing an inorganic sunscreen as an active ingredient . The composition of the publication does not contain an organic sunscreen but contains only an inorganic sunscreen . The cosmetic composition comprises titanium dioxide as an inorganic ultraviolet screening agent , and the inorganic ultraviolet ray shielding agent is a mixture of neopentylglycol dihexanoate , cyclomethicone , polyglyceryl-- and a blocking agent base .

[0008] Crystalline TiCy which has photocatalytic activity can induce damage on human skin and this problem poses challenges to application of TiCy in cosmetic fields . Also , white cast phenomena of TiCy is one of the drawbacks that make wide application in cosmetics di f ficult since they tend to leave a white layer on human skin .

[0009] In MIARALIPOUR SHAYAN ET AL : " Ti02 / porous adsorbents : Recent advances and navel applications" , JOURNAL OF HAZARDOUS MATERIALS , ELSEVIER, AMSTERDAM, NL, Part 341 , 5 Aug 2017 ( 2017- 08- 05 ) , pp 404-423 , an overview is given of Ti02-supported aborbant materials for heterogeneous photocatalysis . In this publication the use of TiCy / clinoptilolite photocatalyst, activated with H2O2, is described to decolorize molasses wastewater.

[0010] In DAVID C: "Adsorption of melanoidin using microporous ZnO nano particle : Experimental and ANN approach" , "Adsorption of melanoidin using microporous ZnO nano particle: Experimental and ANN approach" , RES . J. of PHARMAC . , BIOLOG. AND CHEM. SC. IND, part 8, Suppl. 3, 1 MAy 2017 (2017-05- 01) , pp . 213-223, ZnO nanopartciles are described as absorbents for decolorization of synthetic melanoidin.

[0011] The type of photocatalytic crystalline nanoparticles as described by the two publications above are by their nature undesirable for cosmetic applications.

[0012] In order to overcome aforementioned disadvantages, various strategies have been developed such as application of TiO2 in the purely rutile structure or surface coating of the TiO2.

[0013] For instance, US 2008 / 0020054 relates to cosmetic and dermatological preparations for protecting human skin and hair against UV radiation, comprising surface-coated titanium dioxide particles which are transparent in the visible region and have a crystallite size of from 10 to 20 nm and a specific surface area of from 90 to 110 m 2 / g, wherein the surface coating of the titanium dioxide particles comprises a multicoating of a) aluminum oxide and b) methicone or a copolymer of methicone and dimethicone or a multicoating of a) aluminum oxide, b) methicone or a copolymer of methicone and dimethicone and c) silicon dioxide . EP 3029095 is directed to the use of subpigmentary titanium dioxide , which is obtained in a Synrutil process and due to impurities has a beige-brown-gray or slightly yellowish color, as an absorber for UV radiation in coatings , especially in wood preservatives , in plastics and cosmetics .

[0014] Also JP H08143438 describes the preparation of rutile titanium oxide particles so as to avoid leaving a white layer on the skin .

[0015] Journal of Industrial and Engineering Chemistry ( 2020 ) published 2-3-2020 , describes melanoidin-coated titaniumoxide particles . The coated particles are prepared by treating titanium isopropoxide with dihydroxy acetone ( DHA) to prepare TiCy microspheres . Said microspheres are subsequently carboxylated with chloroacetic acid . The carboxylated particles are then esteri fied with DHA. The terminal acid groups of the DHA are subsequently treated with arginine to prepare a melanoidin coating . Here the melanoidin-coated titanium oxide is prepared by forming the melanoidin in si tu on the titanium oxide particle . The melanoidin is thus synthetically obtained and does not have the same advantageous properties as naturally occurring melanoidin such as for instance from cof fee grain .

[0016] Furthermore , it does not have the environmental advantages of using melanoidins from food waste materials .

[0017] Also KR 102 258 010 describes titanium oxide particles wherein synthetic melanoidin is formed in si tu on the titanium oxide .

[0018] Despite the various publications describing titanium oxide particles for use as sunscreen protective agents , the prior art products and their preparation processes leave much to be desired . There is a need for sunscreen protection agents that provide protection to both UVB and UVA radiation, do not pose a threat with respect to its photocatalytic activity and does not leave a white layer on the skin . Further, sunscreen protection agents with these properties are desired that can be prepared in an environmentally sustainable , economically viable and practical and reproducible way .

[0019] Summary

[0020] The present disclosure provides a process for the preparation of melanoidin-coated inorganic UV filter particles that is inexpensive and elegant in its simplicity, ef ficiency and costs . It provides stable melanoidin-coated titanium- and / or zinc particles of homogeneous particle si ze with suitable UV-absorbing properties .

[0021] The present disclosure pertains to a method for the preparation of melanoidin-coated inorganic UV filter particles , using melanoidin and titanium- and / or zinc oxide particles as starting material and wherein either :

[0022] A. a mixture of the titanium- and / or zinc oxide particles and melanoidin in water is ultrasonic treated, followed by spray drying the mixture to form melanoidin-coated titanium- and / or zinc oxide particles ;

[0023] B . the titanium- and / or zinc oxide particles are activated by acid treatment , followed by slow introduction of the melanoidin to the activated titanium- and / or zinc oxide particles to form a melanoidin / titanium- and / or zinc oxide complex, and separation and drying of the resulting melanoidin-coated particles , or C . the titanium- and / or zinc oxide particles are subj ected to high mechanical shear and heating, followed by introduction of the melanoidin through a noz zle and separation and drying of the resulting melanoidin-coated titanium- and / or zinc oxide particles .

[0024] Preferably, the inorganic UV filter particles comprise titanium oxide as their main oxide .

[0025] Preferably the acid used for the acid treatment of method B is carboxylic acid having 1-4 carbon atoms , more preferably the carboxylic acid is acetic acid .

[0026] In one embodiment the mechanical high shear of method C is conducted by exerting an ultrasonic treatment at a temperature of between 15- 100 ° C .

[0027] Preferably the melanoidin used to coat the titanium- and / or zinc oxide has been extracted from food waste material such as spent cof fee and cocoa- and beer- production side products .

[0028] Preferably a fractioni zed melanoidin is used having a molecular weight (Mw) of between above 50 KDa . More preferably a molecular weight between 50 to 200 KDa, most preferable a range between 80 and 150 kDA, is used .

[0029] The present description also pertains to melanoidin-coated titanium- and / or zinc oxide particles obtainable by the processes according to the invention .

[0030] The description is also directed to a sunscreen protection agent comprising the melanoidin-coated titanium- and / or zinc oxide particles according to the description and compositions comprising said the sunscreen protection agent .

[0031] Figure 1 gives the absorption spectrum of the melanoidin- coated particles according to the present disclosure .

[0032] Detailed Description

[0033] The present disclosure provides a process for the preparation of melanoidin-coated inorganic UV filter particles that is inexpensive and elegant in its simplicity, ef ficiency and costs . It provides stabile melanoidin-coated titanium- and / or zinc particles of homogeneous particle si ze with suitable UV-absorbing properties .

[0034] The present disclosure pertains to a method for the preparation of melanoidin-coated inorganic UV filter particles , using melanoidin and titanium- and / or zinc oxide particles as starting material and wherein either :

[0035] A. a mixture of the titanium oxide particles and melanoidin in water is ultrasonic treated, followed by spray drying the mixture to form melanoidin-coated titanium- and / or zinc oxide particles ;

[0036] B . the titanium- and / or zinc oxide particles are activated by acid treatment , followed by slow introduction of the melanoidin to the activated titanium particles to form a melanoidin / titanium- and / or zinc oxide complex, and separation and drying of the resulting melanoidin-coated particles , or

[0037] C . the titanium- and / or zinc oxide particles are subj ected to high mechanical shear and heating, followed by introduction of the melanoidin through a noz zle and separation and drying of the resulting melanoidin-coated titanium oxide particles .

[0038] In the present method melanoidin and titanium- and / or zinc oxide particles are used as starting material in contrast to melanoidin and / or titanium oxide being created in si tu .

[0039] This provides the advantage of better controlling the melanoidin coating and freedom-of choice of using melanoidins of any source , including melanoidins extracted from food waste products . All methods A, B, and C were found to provide stably coated particles .

[0040] Preferably, the inorganic UV filter particles comprise titanium oxide as their main oxide since it is considered to provide the best UV protection . With the term "main" is meant here that at least 50 wt . % of the inorganic UV filter particles are titanium oxide particles .

[0041] Any titanium oxide particle that are commercially available may be suitably be used for the present process as long as they have proper homogeneous particle si zes . Examples of suppliers are DuPont , The Chemours Company, Venator Materials Pic . , and Grupa Azoty S .A.

[0042] Also zinc oxide particles are commercially available and any particle may be suitably be used for the present process as long as they have proper homogeneous particle si zes .

[0043] When using a combination of titanium oxide and zinc oxide particles , it is generally desired that the starting particles have the same particle si ze .

[0044] The particle si ze of the starting material may vary from 5 to 25 micrometers , preferably between 5 and 10 micrometers .

[0045] Melanoidins are a class of brown, hydrophilic nitrogencontaining polymers which are formed during the thermal processing of foods - such as cof fee , cocoa, bread, malt , barley, Brewers Spent Grain (BSG) , soy, meat , and honey . During thermal processing of such foods , amino acids and reducing sugars , such as aldose and d-xylose , react to form what are termed initial Maillard reaction products . Under continued heating, melanoidins are formed by cycli zations , dehydrations , retro-aldoli zations , rearrangements , isomeri zations and condensations of those initial Maillard reaction products . The complexity of the Maillard reaction pathways results in a range of final reaction products , with inter alia the time of heating, type of heating, temperature , initial chemical composition of the system, moisture content , water activity and pH value being determinative of the final composition .

[0046] The melanoidins suitable for use in the present description preferably are the ones that have been extracted from food waste material such as spent cof fee and cocoa- and beerproduction side products . Since spent cof fee has the highest amounts of melanoidin this is the preferred melanoidin source .

[0047] In order to control the coating thickness , the process and as a result the resulting particle si ze , generally a fractioni zed melanoidin is used . Preferably melandoidin having a molecular weight (Mw) above 50 KDa is used . More preferably melanoidin having a molecular weight (Mw) of between 50 to 200 KDa, and most preferably between 80 and 150 kDA is used . The melanoidin may be used in powder form, suspension, wetted or in solubili zed form .

[0048] Method A

[0049] In method A, a mixture of the titanium and / or zinc oxide particles and melanoidin in water is ultrasonic treated . Said ultrasonic treatment may be performed at increased temperatures of between 20- 100 ° C . This ultrasonic treatment serves to intimately mix and homogeni ze the starting materials .

[0050] Upon complete homogeni zation the mixture is spray dried to form melanoidin-coated titanium- and / or zinc oxide particles . The resulting melanoidin-coated titanium- and / or zinc oxide particles were found to be stably coated and of homogeneous si ze .

[0051] Method B

[0052] In method B, the titanium- and / or zinc oxide particles are activated by acid treatment . For the activation of the oxide particles ' surface any carboxylic acid having 1-4 carbon atoms may be used . However, preferably acetic acid is used for its low cost price and lower risk of side reactions . When wishing to reduce the risk of degrading the titanium- and / or zinc oxide particles higher carboxylic acids or lower concentrations may be used . The amount of the carboxylic acid used may be varied from 5 to 50 wt% of the total weight of the titanium- and / or zinc oxide present . In order to speed up the activation process the temperature of the mixture may be increased . Generally a temperature of from 20 to 100 ° C is used .

[0053] After activation the melanoidin is slowly introduced to the activated titanium particles to form a melanoidin / titanium oxide complex . The formation of a melanoidin / titanium oxide complex is indicated by the increase of the pH . Generally speaking the starting pH of the activated titanium- and / or zinc oxide slurry is about 2 . After completion of the complex formation the pH has increased to above 7 .

[0054] After completion of the complexation the resulting melanoidin-coated particles may be separated and dried . This may be done by conventional means such as filtering and drying via oven drying, freeze drying, spray drying or any other conventional ways . The resulting melanoidin- coated titanium- and / or zinc oxide were found to be stably coated and of homogeneous si ze .

[0055] Method C

[0056] In method C the titanium oxide particles are subj ected to mechanical high shear and heating . This is may be done by exerting high shear to the mixture , preferably by exerting an ultrasonic treatment . Also other homogeni zation methods known in the art such as (ball ) milling, extrusion, and kneading can be used . Optionally the high shear treatment is conducted at a temperature of between 15- 100 ° C .

[0057] After the mechanical high shear, the melanoidin is introduced through a noz zle . The use of a noz zle ensures proper contact between the titanium oxide particles and the melanoidin . ( Spraying) Noz zles are known in the art and need no further elucidation here . For handling purposes the melanoidin may be pre-wetted prior to introduction via the noz zle . The resulting melanoidin-coated titanium oxide particles were found to be stably coated and of homogeneous si ze .

[0058] The present description also pertains to melanoidin-coated titanium- and / or zinc oxide particles obtainable by the processes according to the invention because the resulting melanoidin-coated titanium- and / or zinc oxide particles provided with the above-described methods have superior properties over the titanium oxide particles of the prior art . They have homogenous thickness of the coatings , which can be easily controlled and set . It provides UV protection over both the UVA and the UVB range , and by carefully setting the coating' s thickness and choosing the proper titanium oxide and / or zinc oxide particle si ze particles can be obtained that pose no threat with respect to photocatalytic activity .

[0059] The description is further directed to a sunscreen protection agent comprising the melanoidin-coated titanium oxide particles according to the description and compositions comprising said sunscreen protection agent .

[0060] The compositions comprising said sunscreen protection agent does not leave a white layer on the skin . The compositions may be cosmetic compositions with UV protection or sunscreen compositions . These compositions may be in the form of a liquid, a gel , an emulsion, a paste , solid or compact powder . In addition to the sunscreen protection agent according to the present disclosure other conventional ingredients may be present in the compositions depending on its purpose , such as fillers , colorants and / or pigments , perfumes , oils and fats , solvents , surfactants , wetting agents , penetrants , and antimicrobial agents .

[0061] The following examples are illustrative , but not limiting, of the methods / compositions of the present disclosure

[0062] EXAMPLE 1

[0063] Melanoidin-coated titanium oxide particles were prepared using method A. Scanning electron microscopy showed the resulting particles to have homogeneous si ze with certain agglomerated particles also present . The D50 particle si ze was measured to be 6- 10 micrometers .

[0064] Figure 1 depicts the absorption spectrum of the melanoidin- coated particles obtained in example 1 . This spectrum shows the melanoidin-coated titanium oxide particles provide protection throughout the whole UV range from 215 nm to 400nm .

Claims

CLAIMS1 . Method for the preparation of melanoidin-coated inorganic UV filter particles , using melanoidin and titanium- and / or zinc oxide particles as starting material and wherein either :A. a mixture of the titanium- and / or zinc oxide particles and melanoidin in water is ultrasonic treated, followed by spray drying the mixture to form melanoidin-coated titanium oxide particles ;B . the titanium- and / or zinc oxide particles are activated by acid treatment , followed by slow introduction of the melanoidin to the activated titanium particles to form a melanoidin / titanium oxide complex, and separation and drying of the resulting melanoidin-coated particles , orC . the titanium- and / or zinc oxide particles are subj ected to high mechanical shear and heating, followed by introduction of the melanoidin through a noz zle and separation and drying of the resulting melanoidin-coated titanium- and / or zinc oxide particles .2 . Method according to claim 1 , wherein the inorganic UV filter particles comprise titanium oxide as their main oxide .3 . Method according to claim 1 or 2 wherein the acid used for the acid treatment in method B is carboxylic acid having 1-4 carbon atoms , preferably acetic acid .4 . Method according to any one of claims 1-3 wherein the mechanical high shear of method C is performed byexerting an ultrasonic treatment at a temperature of between 15- 100 ° C .5 . Method according to any of the preceding claims wherein the melanoidin used is extracted from waste food products , preferably from spent cof fee and cocoa- and beer- production side products .6 . Method according to claim 5 wherein a fractioni zed melanoidin is used having a molecular weight (Mw) of at least 50 KDa .7 . Melanoidin-coated titanium oxide particles obtainable by the processes according claims 1- 6 .8 . Melanoidin-coated titanium-and / or zinc oxide particles comprising melanoidin that has been extracted from waste food products .9 . Sunscreen protection agent comprising the melanoidin- coated titanium-and / or zinc oxide particles according to claim 7 or 8 .10 . Composition providing sunscreen protection comprising the sunscreen protection agent according to claim 9 .

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