Single-phase gels of nonpolar liquids with nonionic surfactants

Abstract

The present invention relates to a single-phase gel, which is formed from a non-polar liquid mixed with a non-ionic surfactant selected from an ester surfactant of the formula ROC(O)R 1 or RC(O)OR 2 or an ether surfactant of the formula ROR 2 wherein RO represents a residue of a sugar or a sugar alcohol, RC(O)O represents a sugar acid, C(O)R 1 represents a residue of a fatty acid, and R 2 represents a residue of a fatty alcohol. In the given non-ionic surfactant, the sugar is a C5 or C6 sugar, and the sugar acid and the sugar alcohol are a sugar acid derived therefrom or a sugar alcohol derived therefrom. The carbon chain length of the fatty acid or the fatty alcohol is at least 6, and the non-ionic surfactant has a ratio of hydroxyl groups to carbon atoms in the range of 1 :3 to 1 :8. The present invention also relates to a process for preparing the corresponding single-phase gel, and to the use of the corresponding gel for the texturization of foodstuffs or cosmetics or for the formulation of pharmaceuticals.

Description

[0001] Invention Field

[0002] This invention relates to a single-phase gel composed of a nonpolar liquid and a mixture selected from the formula ROC(O)R 1 Or RC(O)OR 2 Ester surfactants or ROR 2 It is formed by mixing nonionic surfactants with ether surfactants, where RO represents sugar or sugar alcohol residues, RC(O)O represents sugar acid, and C(O)R 1 R represents fatty acid residues. 2 Residues representing fatty alcohols. In the given nonionic surfactants, the sugar is a C5 or C6 sugar, and the sugar acid and sugar alcohol are derived from it. The fatty acid or fatty alcohol has a carbon chain length of at least 6, and the nonionic surfactant has a hydroxyl to carbon atom ratio in the range of 1:3 to 1:8. The invention also relates to methods for preparing the corresponding monophase gels, and the use of the corresponding gels for texturizing food or cosmetics, or for pharmaceutical formulations, and for dyes and varnishes. Background Technology

[0003] The growing awareness of human health issues has led to increased interest in reducing saturated fatty acids and eliminating trans fatty acids in liquid foods. Against this backdrop, organic gels formed from vegetable oils, which contain relatively low levels of trans and saturated fatty acids, represent a potential alternative to traditional solid fat-based foods.

[0004] To gelle vegetable oils, so-called gelling agents must be added. Gelation largely prevents the oil from separating from the system, and mechanical, physical, and sensory properties, such as consistency, texture, taste, and stability, are improved. In particular, low molecular weight gelling agents have received increasing attention in recent years as alternatives to crystalline triglycerides in edible oils.

[0005] Important oil gelling agents to mention in this regard include sterols, monoglycerides, fatty acids, natural waxes, and sugar alcohols. Most of these organic gelling agents share the characteristic of containing a nonpolar fatty acid residue and a hydrophilic alcohol group. Currently, the most commonly used gelling agents utilize fatty acids that cause hypercholesterolemia, such as stearic acid, as structuring agents.

[0006] Pang et al., in *Eur. J. Lipid Sci. Technol.* 2020, 12, pp. 1900-412, describe an erythritol-based sugar alcohol diester, specifically in the form of erythritol dioctanoate, wherein the two primary OH groups of erythritol are esterified with octanoic acid groups. Here, the two polar OH groups remain in the middle of the molecule. This compound has been used for the gelation of vegetable oils.

[0007] Zhu et al., in Chem. Mater. 2006, 18, pp. 5988-95, described diesters formed by trehalose with acetic acid, butyric acid, decanoic acid, and myristic acid, in which the acid groups are also bonded to the primary OH groups of the sugar, and these diesters can be used for gelation in organic solvents. The solvents used for gelation in Zhu's case include esters (such as ethyl acetate or butyl acetate), ketones, and similar polar solvents such as alcohols and acetonitrile.

[0008] US 10,081,748 B1 relates to gelling agents for oils, particularly mineral oils, wherein the gelling agent is capable of being added to a water / oil mixture and selectively producing an oil gel in the mixture. The gelling agent given in US 10,081,748 B1 is a monoester or diester of a C6-sugar alcohol and a medium-chain fatty acid such as caprylic acid, which is converted to the corresponding ester by means of the enzyme "Novozyme 435," and wherein the gel is formed by the aggregation of a hydrophilic component on one side and a nonpolar component on the other.

[0009] The compounds given in US 10,081,748 B1 allow for gel formation with petroleum and vegetable oils. However, these compounds are not optimal for gel formation with high-strength properties, as is desired for some applications in the food and cosmetic fields. Therefore, there is a need to develop reagents for preparing gel-based formulations using vegetable oils or nonpolar organic solvents that form high-strength gels even at low addition levels.

[0010] Murdan S. et al., J. Pharmaceutiac Science, Vol 88, No.6, 1999, pp. 608-614, describe organic gels based on sorbitan monostearate and sorbitan monopalmitate. For sorbitan tristearate, they noted that stable gels could not be obtained.

[0011] Shchipuov YA et al., J. Colloid and Interface Science 211, 1999, pp. 81-88, describe an organic gel with n-decane based on lecithin as the main gelling agent component. In addition to lecithin, up to 10% by weight (based on the total amount of gelling agent) of n-dodecyl-β-D-lactoamide and n-dodecyl-β-D-glucopyranoside were used to investigate the effect of the additives on the gel properties.

[0012] This invention aims to address this need. Summary of the Invention

[0013] In the research that forms the basis of this invention, it was surprisingly discovered that the chain length of the nonpolar portion of the gelling additive, and the size of the polar portion, are relevant to the gel properties achieved by the molecule. In particular, it was observed that smaller polar portions are advantageous for producing gels with higher strength (given the same dosage of additive), and particularly suitable gelling properties can be achieved by matching the sizes of the nonpolar and polar residues. Within the scope of this invention, the "size of the polar residue" is determined by the number of OH groups in the residue, while the size of the nonpolar residue is indirectly estimated by the number of carbon atoms in the compound. Furthermore, gels produced using nonionic surfactants were found to possess at least partial thixotropic properties.

[0014] Therefore, in a first aspect, the present invention relates to a single-phase gel comprising a nonpolar liquid and a mixture selected from the formula ROC(O)R 1 Or RC(O)OR 2 Ester surfactants or ROR 2 ether surfactants are nonionic surfactants, where RO represents sugar or sugar alcohol residues, RC(O)O represents sugar acid, and OC(O)R represents sugar acid. 1 R represents fatty acids. 2 The term refers to a fatty alcohol, wherein the sugar is a C5 or C6 sugar, the sugar acid and sugar alcohol are derived therefrom, and the carbon chain length of the fatty acid or fatty alcohol is at least 6, and the nonionic surfactant has a hydroxyl to carbon atom ratio in the range of 1:3 to 1:8.

[0015] In this invention, "nonpolar liquid" refers to a nonprotic compound that is liquid at room temperature. Preferably, the nonpolar liquid is polar (e.g., E0). T (30) Characterization, defined as the transition energy (in kcal / mol) of the longest wavelength Vis / NIR absorption band in a solution of a negatively solvated Reichardt dye (betaine 30) under standard conditions, and containing a substance with 145 kJ / mol or less, preferably in the range of 140 to 120 kJ / mol. Therefore, suitable nonpolar solvents are particularly straight-chain or branched alkanes such as n-hexane or n-heptane, as well as oils, especially vegetable oils or ketones.

[0016] In this invention, "single-phase gel" refers to a nonpolar liquid forming a single phase with a nonionic surfactant. This does not preclude the gel from containing other components, such as solids, colorants, or pigments, which exist as a separate phase within the gel, since solids are insoluble in gels. In the context of this invention, such mixtures should also be considered as single-phase gels.

[0017] However, the single-phase gel does not contain a separate liquid phase other than the phase formed by the nonpolar liquid.

[0018] The residue “OR” in the above formula represents a sugar or sugar alcohol residue, wherein the sugar is formed by adding a hydrogen atom to the residue to form “ROH”. The residue “R” forms the remainder of the sugar or sugar alcohol, wherein in C5 sugars there are 5 carbon atoms, 3 OH groups and an aldehyde or ketone functional group, and in C6 sugars there are 6 carbon atoms, 4 OH groups and an aldehyde or ketone functional group. In sugar alcohols, the aldehyde or ketone functional group is reduced to another OH group. It is also possible that one or more OH groups are deoxygenated to form CH2 groups, provided that the overall nonionic surfactant is formed from the sugar or sugar alcohol and has a hydroxyl to carbon ratio in the range of 1:3 to 1:8. According to the above definition, sugar anhydrides (i.e., substances derived from sugars by eliminating water, such as dehydrated sorbitol) are not considered sugars or sugar alcohols if they are present in the residue OR, such that ester and ether surfactants based on such substances are not covered by this invention.

[0019] Sugar acids, whose forming residue "RC(O)O", are sugar derivatives in which the primary OH group or aldehyde group of the sugar is oxidized to a carboxylic acid group.

[0020] In the context given by this invention, fatty acids generally refer to straight-chain alkane carboxylic acids, but according to the invention, the term should also include carboxylic acids having one or more OH groups (preferably one) and / or one or more (preferably up to two) short alkyl groups (C1-C3) on their alkane carboxylic acid chains, particularly in the form of methyl or ethyl groups. Furthermore, the term "fatty acid" includes unsaturated fatty acids having one or more double bonds in their chains.

[0021] Fatty alcohols are derivatives of fatty acids as described above, wherein the carboxylic acid functional group (-CO2H) is converted into an alcohol functional group (-CH2OH) through reduction.

[0022] In the context of the present invention, the polar molecular moiety (sugar / sugar alcohol / sugar acid) and the nonpolar molecular moiety (fatty acid or fatty alcohol) are covalently linked by an ester bond (-C(O)OC) or an ether bond (-COC-).

[0023] Sugars that can be used in the nonionic surfactants of the present invention, exemplarily, include C5 sugars such as arabinose, xylose, or ribose, and C6 sugars such as glucose, mannose, or galactose, as well as fructose and sorbitol. Exemplary sugar alcohols that may be mentioned include arabinitol, xylitol, ribitol, mannitol, sorbitol, eurythritol, or idotitol. Exemplary sugar acids that can be used in the nonionic surfactants include glucuronic acid, galacturonic acid, xylitol, and gluconic acid, galactonic acid, or xylic acid. However, these enumerations are not exhaustive, and other sugars, sugar alcohols, or sugar acids that can be used in the nonionic surfactants of the present invention are mentioned below.

[0024] The fatty acids contained in the nonionic surfactants of the present invention are preferably fatty acids in which the carboxylic acid functional group is substituted with an alkyl group, wherein the alkyl group is selected from the group consisting of: n-pentyl, n-hexyl, n-heptyl, n-octyl (an alkyl residue of octanoic acid), n-nonyl (an alkyl residue of nonanoic acid), n-decyl (an alkyl residue of decanoic acid), n-lauryl, isopentyl, isohexyl, isoheptyl, isooctyl, isononyl, isodecyl, isolauryl, 2,2-dimethylpropyl, 4-methyl-2-pentyl, 2,3-dimethylpentyl, 3-ethyl-2-pentyl, and 3-ethyl-5-methyloctyl. Other examples of saturated groups include n-undecyl, n-dodecyl, n-tridecyl (alkane residues of myristic acid), n-tetradecyl, n-pentadedecyl (alkane residues of palmitic acid), n-hexadecyl (alkane residues of heptadecanonical acid), n-heptadecyl (alkane residues of stearic acid), n-octadecyl, n-nonadedecyl (alkane residues of arachidic acid), n-eicosyl, 4-methyldodecyl, and 3-ethyl-5-methylpentadedecyl.

[0025] Unsaturated fatty acids that can be used in nonionic surfactants include fatty acids whose carboxylic acid functional groups are substituted with alkylene groups, said alkylene groups being selected from the group consisting of: n-pentenyl, n-hex-2-enyl, n-hept-3-enyl, n-oct-4-enyl, n-non-5-enyl, n-dec-6-enyl, n-dodec-3,6-dienyl, n-heptadec-9-enyl (alkenyl residue of oleic acid), isopentenyl, isohexenyl, isoheptenyl, isooctenyl, isononenyl, isodecanyl, isodecanyl, isodecanyl, 3,3,3-trimethylpropenyl, 4-methyl-2-pentenyl, 2,3-dimethylpentenyl, 3-ethyl-2-pentenyl, 2-isopropyl-2,2-dimethylpentynyl, and 3-ethyl-5-methyloct-2,4-dienyl. Other examples of unsaturated alkyl groups include n-heptadec-3,6-dienyl, 3-isopropyl-2,4-dimethylpentynyl, and 3,3,3-trimethylheptadecynyl.

[0026] Also suitable for use in nonionic surfactants are fatty acids whose carboxylic acid functional groups are substituted with hydroxy-alkyl groups, wherein the hydroxy-alkyl groups are preferably selected from the group consisting of: hydroxypentyl, hydroxyhexyl, hydroxyheptyl, hydroxyoctyl, hydroxynonyl, hydroxydecyl, hydroxydodecyl, hydroxyundecyl, hydroxydodecyl, hydroxytridecyl, hydroxytetradecyl, hydroxypentadecanyl, hydroxyhexadecyl, hydroxyheptadecyl, hydroxyheptadecyl, hydroxyoctadecyl, hydroxynonadecanyl, and hydroxyeicosyl. For hydroxycarboxylic acids, it is advantageous if the hydroxyl group is located on the α- or β-carbon atom of the carboxylic acid to ensure the formation of a sufficiently long "nonpolar" residue for interaction with nonpolar liquids.

[0027] The term "single-phase gel" in the context of this invention refers to a gel having only a single phase, typically formed by crosslinking with a nonionic surfactant, in which a nonpolar liquid is embedded. Specifically, the crosslinking with the nonionic surfactant is formed by the nonionic surfactant itself, and this invention does not cover crosslinking where the nonionic surfactant exists only as a supplement to other gelling agents (e.g., in the form of lecithin).

[0028] The term "thixotropic mixture" in this context refers to a mixture that, immediately after shearing, has a lower viscosity than before shearing, and wherein the viscosity rises to (or at least close to) the pre-shear viscosity after the shearing action has ended. This is also known as structural recovery in the resting phase (i.e., the flow properties of the mixture are time-dependent, where the viscosity decreases due to continuous external influences and only recovers to the initial viscosity after the external force has ended).

[0029] In a preferred embodiment, the single-phase gel comprises ROC(O)R as a nonionic surfactant. 1 Nonionic ester surfactants, of which R 1 This refers to saturated or unsaturated fatty acid residues with a straight or branched carbon chain length in the range of 8 to 20. Preferably, the straight or branched saturated or unsaturated fatty acids are selected from caprylic acid, nonanoic acid, capric acid, lauric acid, myristic acid, palmitic acid, heptadecanic acid, stearic acid, arachidic acid, decenoic acid, undecenoic acid, myristoleic acid, palmitoleic acid, and oleic acid.

[0030] In this case, "RO" can be a C5 or C6 sugar or a sugar alcohol derived from it, wherein the formula ROC(O)R 1 The surfactant can be formed by conventional two-part esterification. Since sugars have one less OH group in nonionic surfactants than the corresponding sugar alcohols, it is preferred in this respect that the carbon chain length of the fatty acid residues is in the lower part of a specified range, for example, in the range of 8 to 14, and preferably 8 to 12 or 6 to 12, while the carbon chain length of the fatty acid residues in the corresponding sugar alcohols is slightly larger, for example, in the range of 10 to 18 or 10 to 16.

[0031] In another preferred embodiment, the single-phase gel comprises ROC(O)R as a nonionic surfactant. 1 Nonionic ester surfactants, of which R 1 This refers to a branched fatty acid or β-hydroxy fatty acid residue having one or more methyl side chains.

[0032] In yet another preferred embodiment, the single-phase gel comprises ROR as a nonionic surfactant. 2 Nonionic ether surfactants, of which R 2Residues representing straight-chain or branched saturated or unsaturated fatty alcohols having a carbon chain length in the range of 10 to 20, preferably obtained by reduction of decanoic acid, lauric acid, myristic acid, palmitic acid, heptadecanonical acid, stearic acid, arachidic acid, decenoic acid, undecenoic acid, myristoleic acid, palmitoleic acid, oleic acid, or hydroxydecanoic acid. Regarding residue R... 2 The carbon chain length, as described above regarding the carbon chain length of fatty acid residues, is similarly preferred.

[0033] In this case, "RO" can be a C5 or C6 sugar or a sugar alcohol derived from it, wherein the formula ROR 2 The surfactant can be formed via a two-part conventional ether bond. To facilitate the formation of such a bond, the OH group in the fatty alcohol can first be modified with a leaving group, such as a p-toluenesulfonate group or a halogen such as Br or I, and the correspondingly modified fatty alcohol can then react with a sugar or sugar alcohol under alkaline conditions. If "RO" is a sugar, the nonionic ether surfactant can also be an "alkyl glycoside," in which the fatty alcohol is bonded to the sugar via a glycosidic bond. The bond thus formed is relative to COR. 2 The α position of the bond has another oxygen atom.

[0034] Furthermore, if "RO" is a sugar, the residue R 2 It can be a fatty alcohol that has an acid group in addition to an alcohol functional group. Such residues are preferably derived from α- or β-hydroxycarboxylic acids, with β-hydroxydecanoic acid being a particularly preferred hydroxycarboxylic acid in this regard. In the corresponding alkyl glycosides, the sugar is bonded to the alcohol residue of the hydroxycarboxylic acid via a glycosidic bond; in this case, the alkyl group of the hydroxycarboxylic acid, in contrast to the carboxylic acid functional group, forms a nonpolar molecular moiety, while the carboxylic acid functional group is classified as a polar molecular moiety.

[0035] In yet another preferred embodiment, the single-phase gel contains RC(O)OR 2 nonionic surfactants, wherein R 2 Residues of a straight-chain or branched saturated or unsaturated fatty alcohol having a carbon chain length in the range of 10 to 20, which are preferably obtained by reduction of decanoic acid, lauric acid, myristic acid, palmitic acid, heptadecanonical acid, stearic acid, arachidic acid, decenoic acid, undecenoic acid, myristoleic acid, palmitoleic acid, oleic acid or hydroxydecanoic acid.

[0036] The residue RC(O) in this context represents a residue of a glyconic acid linked by esterification to a straight-chain or branched saturated or unsaturated fatty alcohol. Glyconic acids that can be used in the context given in this invention include, for example, glucuronic acid, galacturonic acid, xylanonic acid, gluconic acid, galactobionic acid, mannolic acid, or xylanic acid, preferably in their respective D-forms, and most preferably D-gluconic acid, D-glucuronic acid, and D-mannolic acid.

[0037] Generally, for the aforementioned nonionic surfactant, it is preferred if the C5 or C6 sugar, sugar acid, and sugar alcohol contained therein are selected from the group consisting of xylose, arabinose, glucose, galactose, mannose, sorbitol, fructose, glucuronic acid, xylitol, mannitol, and sorbitol. The sugar, sugar alcohol, and sugar acid are characterized by high natural availability and corresponding low cost.

[0038] In a particularly preferred embodiment, the nonionic surfactant is of formula ROR. 2 ORRC(O)OR 2 The nonionic ester surfactant. In another particularly preferred embodiment, the nonionic surfactant is a nonionic surfactant of the formula ROC(O)R. 1 ORRC(O)OR 2 Nonionic ester surfactants or ROR 2 Nonionic ether surfactants, where RO represents residues of C5 sugar, C5 sugar alcohol, or C5 sugar acid.

[0039] As previously noted, the nonionic surfactant used in the gels of this invention should be formed such that the ratio of hydroxyl groups to carbon atoms is in the range of 1:3 to 1:8. "Number of OH groups" here refers to the number of free OH groups in the nonionic surfactant; that is, if, for example, the nonionic surfactant is generated from xylitol (5 OH groups) and lauric acid, one of the OH groups of xylitol is ester-bonded, resulting in a nonionic surfactant with only 4 OH groups. Correspondingly, xylose-based nonionic surfactants have 3 free OH groups because xylose, unlike xylitol, contains only 4 OH groups (and one aldehyde group) in its free form. CO2H, which may be present in the surfactant, is considered an OH group. The number of C atoms is determined by the number of C atoms in the sugar, sugar alcohol, or sugar acid and the number of R residues. 1 Or R 2 The total number of C atoms in the mixture. Particularly preferred ratios are 1:3.2 to 1:7, more preferably 1:3.5 to 1:6, and even more preferably in the range of 1:3.7 to 1:5.

[0040] The research that forms the basis of this invention has revealed that at least some of the gels of this invention possess thixotropic properties. Therefore, in a preferred embodiment, the gel of this invention is a thixotropic gel, preferably having a structural recovery after 10 seconds (the difference between the viscosity before shear loading and the viscosity under shear loading, which is x% higher than the viscosity under shear loading) of at least 10%, preferably at least 20%. In another embodiment, the thixotropic gel has a structural recovery after 60 seconds of at least 20%, preferably at least 30%, and more preferably at least 50%.

[0041] Another important parameter affecting the properties of nonionic surfactants in single-phase gels or thixotropic mixtures is the HLB value of the nonionic surfactant. Preferably, the nonionic surfactant used in the gels and thixotropic mixtures has an HLB value in the range of about 6 to 14, and more preferably about 7 to 12. The HLB value of the nonionic surfactant is calculated according to Griffin using the following formula:

[0042]

[0043] Where M is the molecular weight of the nonionic surfactant, M L This indicates the molecular weight of the lipophilic moiety. For ROC(O)R 1 The lipophilic molecular part is the fatty acid residue R starting from the C atom of the fatty acid that does not contain an OH group. 1 The alkyl chain (i.e., in non-hydroxylated fatty acids, it starts from the first carbon atom after the acid functional group; in hydroxylated fatty acids, it starts from the first carbon atom after the CHOH group). For RC(O)OR 2 and ROR 2 In fatty alcohols, the lipophilic molecular moiety is derived from the fatty alcohol residue "R". 2 The alkyl chain begins at C1, or if the fatty alcohol contains other OH groups, it begins from the first C atom after the CHOH group.

[0044] The present invention is not subject to any limitations regarding the amount of nonionic surfactant to be incorporated into the nonpolar liquid to form a gel, but generally, at least for economic reasons, the liquid is present in a significant excess relative to the nonionic surfactant. In most cases, the nonionic surfactant, based on the total amount of nonionic surfactant and nonpolar liquid, does not exceed 10% by weight in the single-phase gel. More preferably, if the proportion of the nonionic surfactant in the single-phase gel or thixotropic mixture is 0.05 to 7% by weight, preferably 0.1 to 6% by weight, more preferably 0.25 to 5% by weight, and more preferably 0.5 to 3% by weight.

[0045] The nonpolar liquid in the single-phase gel according to the invention is preferably present in the form of edible oil, vegetable oil, fish oil, insect fat, beef and mutton fat, kerosene, isopropyl palmitate, isopropyl myristate, pentane, hexane, heptane, octane, isooctane, decane, dibutyl ether, ethyl acetate, cyclohexane, cyclopentane, cyclooctane, isopropanol, terpenes, ethylene glycol ethers, ethyl laurate, ethyl myristate, or ethyl palmitate. In one embodiment, the nonpolar liquid may also be present in the form of dimethyl sulfoxide. In a particularly preferred embodiment, the nonpolar liquid in the single-phase gel is a renewable oil or fat, such as edible oil, vegetable oil, fish oil, or insect fat, as well as microbial oil.

[0046] Nonpolar liquids are in the form of alkanes, such as pentane, hexane, heptane, octane, isooctane, decane, or terpenes or glycol ethers, particularly in the context of dyes and varnishes, while oleic acid esters or oils of C2 to C6, especially C2 to C4 alcohols are also used in areas intended to come into contact with human body surfaces, such as in the cosmetics or food industries.

[0047] The nonpolar liquid constitutes the largest portion of the composition in the single-phase gel according to the invention, typically exceeding 80% by weight of the composition. In one embodiment, the nonpolar liquid accounts for 80 to 99.9% by weight, in a preferred embodiment 90 to 99.75% by weight, and more preferably 95 to 99.5% by weight.

[0048] In addition to nonpolar liquids and nonionic surfactants, monophasic gels may contain other components, which may be included depending on the desired use of the gel. These substances include, but are not limited to, preservatives, dermatologically active substances, antioxidants, pigments, or other colorants.

[0049] Other beneficial active substances, especially for cosmetic applications, are natural active substances and / or their derivatives, such as alpha-lipoic acid, phytoene, D-biotin, coenzyme Q10, alpha-glucosylrutin, carnitine, carnosine, natural and / or synthetic isoflavones, creatine, taurine and / or β-alanine.

[0050] The nonpolar gel of this invention may also incorporate other pharmaceutically or dermatologically active substances, such as soothing and skin-care substances. Examples of such substances include panthenol, allantoin, tannins, antihistamines, anti-inflammatory drugs, glucocorticoids (e.g., hydrocortisone), and plant-based active substances such as azulene and bisabolol, glycyrrhizic acid, witch hazel, and plant extracts such as chamomile, aloe vera, witch hazel, and licorice root.

[0051] In a nonpolar gel, the amount of the aforementioned active substances, antioxidants, etc. (one or more compounds) is preferably 0.001 to 10% by weight, particularly preferably 0.05 to 8% by weight, especially 1 to 5% by weight, based on the total weight of the single-phase gel.

[0052] According to the rheological properties of the single-phase gel of the present invention, it is preferred that the gel has a shear stress greater than 0.1 Pa, preferably in the range of 0.1 to 20 Pa, at its yield point after 24 hours. Alternatively or additionally, it is preferred that the gel has a storage modulus of at least 5 Pa (determined in the yield point and linear viscoelastic range), and preferably in the range of 8 Pa to 500 Pa. The relevant shear and storage moduli are determined in the context given in this invention by means of a rheometer (Anton Paar MCR 702e MultiDrive Rheometer), as shown in the Examples section.

[0053] The rheological properties of the thixotropic mixture according to the invention are preferably adjusted such that the structure determined as described in the Examples section is restored to at least 55%, preferably at least 60%, and more preferably at least 70%. The thixotropic properties are determined in the context of the invention by means of a rheometer (Anton Paar MCR 702e MultiDrive Rheometer), as shown in the Examples section.

[0054] In another aspect, the present invention relates to a method for preparing a single-phase gel, as described above, wherein the method includes the steps of

[0055] i) Provide a mixture of a nonpolar liquid and at least one nonionic ester or ether surfactant, as described above;

[0056] ii) Heat the mixture for a period of time, preferably at a temperature in the range of 30°C to 120°C, more preferably in the range of 40 to 100°C, until a homogeneous mixture is formed;

[0057] iii) Allow the mixture to stand to form a single-phase gel.

[0058] Within the scope of this method, the mixture is preferably heated in step ii) for a period of time, said period being from 5 minutes to 2 hours, and more preferably from 10 minutes to 60 minutes. For this purpose, it may be advantageous to support the formation of a homogeneous mixture in step ii) by mechanical treatment selected from the group consisting of: shaking, stirring, grinding (especially in a ball mill), ultrasonication, and vibration.

[0059] The term "allowing to stand" in the context of the method described herein means "allowing the mixture to stand without stirring or other movement."

[0060] In one embodiment, the mixture is left to stand under ambient conditions (20 to 25°C). In another embodiment, it is left to stand at a reduced temperature (e.g., 0 to 8°C, particularly 3 to 6°C). Such treatment has been shown to produce gels with even better mechanical properties than those left to stand under ambient conditions, or thixotropic mixtures with higher structural recovery.

[0061] In another aspect, the present invention relates to the use of single-phase gels, as described above, for food texturing, cosmetic texturing, pharmaceutical formulations, membranes, phase transfer materials, evaporation barriers, dyes and varnishes, 3D printing, or antifouling surface coatings. For evaporation barriers, for example, a thin layer of the gel according to the invention can be applied to the surface of an aqueous matrix or aqueous mixture to minimize water evaporation loss.

[0062] Thixotropic viscosity behavior is particularly desirable for dyes and varnishes. Varnishes based on nonpolar solvents, for example, have a dynamic viscosity of approximately 3000 mPas.

[0063] Cosmetics in which the gel according to the invention can be used include, for example, after-sun care gels, baby oil gels, body washes, facial care products, gel washes, creams, lip balms, lip glosses, bath gels, or tanning gels. Such cosmetics preferably have a yield point in the range of 0.5 to about 50 Pa, and more preferably in the range of 0.5 to 30 Pa.

[0064] In food texturing, a food product in one embodiment can be formed as a fat substitute, wherein it preferably has a linear viscoelastic range of 100 to 10,000 Pa.

[0065] The present invention will be described in more detail below with the aid of some embodiments; however, these embodiments should not be construed in any way as limiting the scope of protection of the claims or the applications on which they are based: Detailed Implementation

[0066] Preparation of nonionic surfactants:

[0067] 1) General operating instructions for preparing esters as nonionic surfactants

[0068] Esters (e.g., sorbitol monolaurate) are produced enzymatically. For this purpose, in a stirred tank reactor, equimolar amounts of sugar / sugar alcohol and fatty acids are reacted with a lipase (e.g., Candida albicans). Candida rugosa Lipase or Candida antarcticis ( Candida antarctica Lipase B was stirred in 2-methyl-2-butanol at 50°C for 24 hours.

[0069] The reaction mixture was then filtered, the solvent was evaporated, and the resulting product was purified by silica gel chromatography.

[0070] 2) General operating instructions for preparing ethers as nonionic surfactants

[0071] The ether compounds used in the following tests are conventionally obtained by reacting sugar alcohols with fatty alcohols modified with leaving groups (where, for example, toluenesulfonate esters or halides derived from alcohols are used as leaving groups). The post-treatment and purification of these compounds are similar to those described in the preparation of ester surfactants. The preparation of glycosyl glycosides from sugars and sugar alcohols is enzymatically carried out by reacting sugars with β-glucosidase and fatty alcohols in a eutectic solvent, as described in Delavault, A. https: / / onlinelibrary.wiley.com / doi / 10.1002 / cite.202100150. The post-treatment and purification are similar to those described in the preparation of ester surfactants.

[0072] The surfactants octyl xyloside, decyl xyloside, lauryl xyloside, myristyl xyloside, and carboxydecyl xyloside were purchased from Glycosurf (USA).

[0073] 3) Research on the gelling ability and properties of the prepared gel by nonionic surfactants.

[0074] Nonionic surfactants are weighed and mixed with a nonpolar liquid, wherein different concentrations of nonionic surfactants are set. The mixture thus prepared is heated to a temperature between 30 and 120°C to obtain a homogeneous phase. The mixture is then allowed to stand at 20-25°C for 1-24 hours, thereby forming a gel.

[0075] The samples thus obtained were subjected to rheological measurements. For this purpose, the shear modulus and storage modulus were determined using a rheometer (AntonPaar MCR 702e MultiDrive Rheometer), where measurements were taken at a constant angular frequency ω = 10 rad / s, with oscillating shear deformation distributed logarithmically between 0.05% and 15% shear deformation. For the measurements, a 25 mm diameter PP25 measuring plate was used, and the temperature was controlled at 20°C.

[0076] Thixotropic properties were also determined using a rheometer (Anton Paar MCR 702e MultiDrive Rheometer). For measurements, structural recovery was determined using a 3-interval thixotropic test (3-ITT). For this purpose, the viscosity in the first step was measured at a low shear rate of 0.1 s⁻¹. -1 The viscosity was measured at 10 points, with each measurement lasting 5 seconds (step 1 viscosity). In the second step, a shear test was performed for 100 seconds when measuring the viscosity. -1 Ten measurement points were used, each lasting 1 second (step 2 viscosity). After this interval, at 0 seconds... -1 The measurement was performed after shearing for 4 seconds to avoid interference signals in step 3. In step 3, a low shearing of 0.1 seconds was performed. -1 Viscosity was determined at 1000 measurement points, with each measurement lasting 0.5 s. A 25 mm diameter PP25 measuring plate was used for the measurements, and the temperature was controlled at 20°C.

[0077] The compositions of the mixtures of the studied nonionic surfactants with their respective nonpolar solvents (vegetable oil, isopropyl palmitate, or n-pentane) are given in the tables below. The shear stress and storage modulus parameters related to the yield point, as well as the linear viscoelastic range, are also reproduced in these tables.

[0078] Table 1: Gels formed by nonionic ester and ether surfactants and vegetable oils

[0079]

[0080] 1 = Glycoside (an alcohol bound to the C1 of a sugar)

[0081] Table 2: Gels formed by nonionic ester and ether surfactants with isopropyl palmitate or pentane

[0082]

[0083] 1 = Glycoside (an alcohol bound to the C1 of a sugar)

[0084] Table 3: Effects of cooling and carbon chain length of fatty acid alcohols

[0085]

[0086] 1 = Glycoside (an alcohol bound to the C1 of a sugar)

[0087] Table 4: Determination of gel thixotropic properties

[0088]

[0089] As shown in Table 1, surfactants with an OH / C atomic ratio of approximately 4 exhibit the best gel strength at the same amount of nonionic surfactant used in nonpolar liquids. It was also observed that gel strength depends on the amount of surfactant used, with higher amounts yielding higher strength (results not shown). In Table 1, all nonionic surfactants based on C5 sugars and C5 sugar alcohols showed superior storage modulus properties compared to similar systems based on C6 sugar alcohols and sorbitol. The samples also exhibited a high viscoelastic range, i.e., the range in which the sample structure remains intact before deformation (e.g., by flow) occurs (i.e., gels with high viscoelastic range values ​​remain stable under higher gel loads).

[0090] By improving the viscoelastic range, it can improve the chewiness / texture of food, the strength of dyes, the stability of pastes such as sunscreen (to improve dosage applicability), or the shape stability in 3D printing.

[0091] In Table 2, the results are confirmed for the gelation of isopropyl palmitate using ester- and ether-based nonionic surfactants.

[0092] As shown in Table 3, the cooling step improves the strength and elasticity of the gel. Therefore, the yield point and material elasticity can be influenced by using a cooling step. Furthermore, Table 3 shows that for xylose, a higher C / OH atomic ratio results in a higher viscoelastic range and higher shear stress and storage modulus values.

[0093] In Table 4, the gels for all studies exhibit viscoelastic behavior.

Claims

1. A single-phase gel comprising a nonpolar liquid and a mixture selected from formula ROC(O)R 1 Or RC(O)OR 2 Ester surfactants or ROR 2 ether surfactants are nonionic surfactants, where RO represents sugar or sugar alcohol residues, RC(O)O represents sugar acid, and OC(O)R represents sugar acid. 1 R represents fatty acid residues. 2 It represents a fatty alcohol residue, wherein the sugar is a C5 or C6 sugar, the sugar acid and sugar alcohol are derived from it, and the carbon chain length of the fatty acid or fatty alcohol is at least 6, and the nonionic surfactant has a hydroxyl to carbon atom ratio in the range of 1:3 to 1:

8.

2. The single-phase gel according to claim 1, characterized in that, The gel contains ROC(O)R 1 Nonionic ester surfactants, of which R 1 This refers to a straight-chain or branched saturated or unsaturated fatty acid residue having a carbon chain length in the range of 8 to 20, wherein the fatty acid is preferably selected from caprylic acid, nonanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, heptadecanoic acid, stearic acid, arachidic acid, decenoic acid, undecenoic acid, myristoleic acid, palmitoleic acid and oleic acid, or a branched fatty acid residue having one or more methyl side chains, or a β-hydroxy fatty acid residue.

3. The single-phase gel according to claim 1, characterized in that, The gel-encapsulated ROR 2 Nonionic ether surfactants, of which R 2 Residues of a straight-chain or branched saturated or unsaturated fatty alcohol having a carbon chain length in the range of 10 to 20, preferably selected from fatty alcohols derived from decanoic acid, lauric acid, myristic acid, palmitic acid, heptadecanic acid, stearic acid, arachidic acid, decenoic acid, undecenoic acid, myristoleic acid, palmitoleic acid, oleic acid, and hydroxydecanoic acid.

4. The single-phase gel according to claim 1, characterized in that, The gel contains RC(O)OR 2 Nonionic ester surfactants, of which R 2 Residues of a straight-chain or branched saturated or unsaturated fatty alcohol having a carbon chain length in the range of 10 to 20, which are preferably obtained by reduction of decanoic acid, lauric acid, myristic acid, palmitic acid, heptadecanonical acid, stearic acid, arachidic acid, decenoic acid, undecenoic acid, myristoleic acid, palmitoleic acid, oleic acid or hydroxydecanoic acid.

5. The single-phase gel according to at least one of the preceding claims, characterized in that, The gel has thixotropic properties.

6. The single-phase gel according to at least one of the preceding claims, characterized in that, Included in the formula ROC(O)R 1 ORRC(O)OR 2 Nonionic ester surfactants or ROR 2 The C5 or C6 sugars, sugar acids and sugar alcohols in nonionic ether surfactants are selected from the group consisting of: xylose, arabinose, rhamnose, glucose, galactose, mannose, sorbitol, fructose, xyuronic acid, glucuronic acid, galacturonic acid, xylitol, arabinitol, mannitol, sorbitol, gluconic acid, galactonic acid and xylic acid.

7. The single-phase gel according to at least one of the preceding claims, characterized in that, The nonionic ester or ether surfactant has an HLB value in the range of 6 to 14, preferably 7 to 12.

8. The single-phase gel according to at least one of the preceding claims, characterized in that, The nonionic ester or ether surfactant accounts for 0.05 to 7% by weight of the single-phase gel, preferably 0.25 to 5% by weight, and more preferably 0.5 to 3% by weight.

9. The single-phase gel according to at least one of the preceding claims, characterized in that, The nonpolar liquid is selected from the group consisting of: edible oils, vegetable oils, fish oils, insect fats, beef and mutton fats, kerosene, isopropyl palmitate, isopropyl myristate, pentane, hexane, heptane, isooctane, decane, dibutyl ether, ethyl acetate, cyclohexane, cyclopentane, cyclooctane, isopropanol, ethyl laurate, ethyl myristate, ethyl palmitate, terpenes, ethylene glycol ethers, and dimethyl sulfoxide.

10. The single-phase gel according to at least one of the preceding claims, characterized in that, The nonpolar liquid accounts for 80 to 99.9% by weight of the single-phase gel, preferably 90 to 99.75% by weight, and even more preferably 95 to 99.53% by weight.

11. The single-phase gel according to at least one of the preceding claims, characterized in that, The gel has a yield point after 24 hours, a shear stress greater than 0.1 Pa, preferably in the range of 0.1 to 20 Pa, and a storage modulus of at least 5 Pa, preferably in the range of 8 Pa to 500 Pa.

12. A method for preparing a single-phase gel according to any one of claims 1 to 11, comprising the steps of i) Providing a mixture of a nonpolar liquid and at least one nonionic ester or ether surfactant, as described in claim 1; ii) Heat the mixture for a period of time until a homogeneous mixture is formed, preferably at a temperature in the range of 30°C to 120°C, more preferably in the range of 40 to 100°C; iii) Allow the mixture to stand to form a single-phase gel.

13. The method of claim 12, wherein the mixture is heated in step ii) for a period of time to form a homogeneous mixture, said period of time being from 5 minutes to 2 hours, and preferably from 10 minutes to 60 minutes.

14. The method according to claim 12 or 13, wherein the formation of a homogeneous mixture in step ii) is supported by mechanical processing selected from the group consisting of: shaking, stirring, sonication and vibration.

15. Use of the single-phase gel according to any one of claims 1 to 11, for use in food texturing, cosmetic texturing, pharmaceutical preparations, membranes, phase transfer materials, or antifouling surface coatings, evaporation barriers, dyes and varnishes, and 3D printing.

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