Lignin fraction-based emulsifier and its use

Abstract

This application relates to an emulsifier containing a lignin fraction and its use for preparing emulsions. This application also relates to cosmetics containing such emulsifiers and methods for preparing them.

Description

[Technical Field]

[0001] This invention relates to emulsifiers and their use in cosmetics or food products. [Background technology]

[0002] Stable colloidal dispersions or emulsions are included in a variety of products and goods, particularly in cosmetics and pharmaceuticals, as well as in household goods, food, and other industrial sectors.

[0003] Oil-in-water emulsions are thermodynamically unstable systems consisting of oil droplets dispersed in an aqueous medium. They tend to break down through complex physicochemical mechanisms including aggregation, coalescence, Ostwald maturation, creaming, and sedimentation (1). To produce stable emulsions with long shelf lives and resistance to environmental stress, it is necessary to incorporate stabilizers such as emulsifiers, thickeners, or gelling agents (2).

[0004] Today, the most commonly used emulsifiers in skincare products are petroleum-based surfactants. These include cationic surfactants such as polyquaternium-10, anionic surfactants such as sodium dodecyl sulfate (SDS) and linear alkylbenzene sulfonates (LAS), and nonionic surfactants such as fatty alcohol ethers and polymers of acrylic acid grafted with hydrophobic alkyl acrylates.

[0005] The use of such surfactants causes environmental problems. When used in skincare products, they are discharged into aquatic ecosystems and / or accumulate in agricultural soils (3), leading to environmental pollution. In fact, synthetic surfactants are difficult to remove in wastewater treatment (4). Furthermore, surfactants can reduce the effectiveness of microorganisms used to remove pollutants that cause environmental pollution, and their toxicity to organisms, from mammals to bacteria, is well known (5,6).

[0006] On the other hand, there is a growing demand for organic and / or natural cosmetics. Today, the types of surfactants that can be used in organic or naturally derived cosmetics, such as those found at COSMOS, are limited.

[0007] Therefore, there is a need for environmentally friendly and sustainable alternatives to conventional petroleum-based surfactants.

[0008] Consequently, various natural emulsifiers have emerged as alternatives to synthetic emulsifiers. These natural emulsifiers come from a variety of natural sources, such as plants, animals, or microorganisms, and can be divided into two main categories (namely, proteins and polysaccharides) (7).

[0009] Proteins act as emulsifying stabilizers by adsorbing to the oil-water interface through electrostatic interactions. Most polysaccharides act as emulsifying stabilizers mainly by forming a dense network in the continuous phase to form a gel, in which case they slow down the movement of droplets by forming a polymer barrier between dispersed droplets and prevent creaming (8,9). However, certain polysaccharide derivatives, such as gum arabic, guar gum, and chemically modified starch or cellulose derivatives, can also adsorb to the oil-water interface. These exhibit surface / surfactant activity by adsorbing to the surface of oil droplets and preventing aggregation and coalescence through steric or electrostatic repulsion. In the case of gum arabic and guar gum, this is due to the presence of protein subunits in their structure (10). In the case of cellulose derivatives, the surfactant activity is due to various hydrophobic and hydrophilic groups along the cellulose backbone. They form a strong mechanical barrier against coalescence and contribute to high stabilization (11).

[0010] Notable emulsifiers also include synthetic compounds prepared from natural starting materials such as sugars and plant lipids, including palm, coconut, soybean, rapeseed, or sunflower. Examples include alkyl polyglycerides and sucrose esters of fatty acids. Unfortunately, the supply of these compounds to the cosmetics sector is limited due to competition with the food industry.

[0011] Plant-derived emulsifiers are attracting increasing attention due to their biocompatibility, biodegradability, low toxicity, and especially the low production costs of by-products and those derived from by-products.

[0012] However, sustainable and environmentally friendly surfactants represent only a small part of the surfactant market. In the cosmetics sector in particular, there is still a need for new surfactants to replace synthetic ones. [Overview of the project]

[0013] In a first embodiment, the present invention relates to an emulsifier in the form of a lignin fraction: -6.0 to 8.5% by weight, preferably 7.0 to 8.2% by weight, more preferably 7.2 to 8.0% by weight of lignin monomer, -Lignin dimers in an amount of -14.0% to 20.0% by weight, preferably 15.0% to 20.0% by weight, more preferably 15.5% to 18.0% by weight, and -Lignin oligomers in an amount of -70% to 80% by weight, preferably 71.8% to 78.0% by weight, more preferably 74.0% to 77.3% by weight, It consists of, The emulsifier is characterized in that the weight percentage is relative to the total weight of lignin monomers, dimers, and oligomers in the emulsifier. Preferably, the percentage is measured by size exclusion chromatography.

[0014] Furthermore, the lignin fraction has the following characteristics: - Weight-average molar mass (Mw) of 1200-1600 g / mol, e.g., 1200-1500 g / mol; and / or - The number-average molar mass (Mn) is 500 to 800 g / mol, for example 600 to 700 g / mol; and / or - The polydispersity index is 1.85 to 2.40, preferably from 1.95 to 2.20; It may be an emulsifier characterized by having at least one of the above.

[0015] In some embodiments, the emulsifier may comprise or consist of a lignin fraction as described above solubilized in a C2-C6 alkanediol, preferably propanediol.

[0016] In another embodiment, the lignin fraction in the emulsifier is obtained from technical alkali lignin. Preferably, the lignin fraction is obtained from technical alkali lignin by a single step of extraction with a solvent selected from the group consisting of C2-C6 alcohols and C3-C8 ketones.

[0017] In certain embodiments, the lignin fraction of the emulsifier is at least partially esterified with an alkanate group, for example a hexanoate group, where its aliphatic primary hydroxyl group is C2-C 18 In another embodiment, the present invention relates to the use of a lignin fraction as defined above as an emulsifier for stabilizing oil-in-water emulsions, preferably in cosmetic compositions or pharmaceutical compositions, or food compositions. Usually, the lignin fraction occupies 0.1 to 5% by weight, preferably 0.5 to 4.0% by weight, for example 2.0 to 3.0% by weight or about 2.5% by weight, based on the total weight of the oil-in-water emulsion.

[0018] In certain embodiments, the lignin fraction is also used as a pigment.

[0019]

[0020] ​A further object of the present invention is a cosmetic, pharmaceutical or food composition, preferably a cosmetic composition containing the emulsifier defined above. For example, the cosmetic composition can be selected from the group consisting of creams such as daily cream or body cream, body milk, makeup remover, hair conditioner, concealer stick or concealer cream, liquid soap, shampoo, and nutritional mask.

[0021] In a further embodiment, the present invention relates to a makeup product containing the emulsifier defined above, and the makeup product is preferably selected from foundation, blush, eyeshadow, colored body or face cream such as BB cream, mascara, eyeliner, and concealer.

[0022] The present invention also relates to a method for preparing the emulsifier defined above from technical lignin, and the method includes a step (i) of subjecting technical lignin to extraction using a solvent selected from the group consisting of C2-C6 alcohols, C3-C8 ketones and combinations thereof, preferably a solvent selected from methyl ethyl ketone (MEK), acetone, isopropanol and ethanol, more preferably ethanol or MEK.

[0023] In some embodiments, step (i) comprises - contacting the technical lignin with the solvent under conditions that allow extraction of the target lignin molecules; - separating the liquid fraction and the solid fraction and recovering the liquid phase; and - removing the solvent from the liquid fraction and recovering the emulsifier in the form of a lignin fraction; and includes.

[0024] The starting technical lignin is preferably selected from organosolv lignin or alkali lignin, preferably alkali lignin.

[0025] In some embodiments, the method omits the acid and / or base treatment of technical alkaline lignin that is performed prior to extraction, and / or the method includes a single extraction step with a polar solvent.

[0026] This method further: - Step (ii) involves subjecting the lignin fraction obtained in step (i) to enzymatic transesterification with a fatty acid methyl or ethyl ester, preferably with hexanonate ethyl, in the presence of Candida Antarctica lipase-B (CAL-B); and / or - A step of solubilizing an optionally esterified lignin fraction in a solvent selected from alkanediols, levulinate ketals such as methyl levulinate or ethyl levulinate, glycerol levulinate ketal, lower alcohols (e.g., C2-C6 alcohols), preferably ethanol and isopropanol, and lower alcohol / H2O mixtures, preferably C2-C6 alkanediols such as propanediol; Includes.

[0027] The present invention also relates to a method for preparing an oil-in-water emulsion, the method being: (a) To provide an emulsifier in the form of the previously defined lignin fraction, at least partially solubilized in a polar solvent, preferably a C2-C6 alkanediol; (b) Adding lignin solution to the aqueous phase under stirring to readjust the pH of the aqueous phase to 5.5 to 7.0, preferably about 6.0; and (c) Add an oil phase to the solution obtained in step (b) under high shear to obtain an oil-in-water emulsion; Includes.

[0028] The present invention further relates to a method for preparing cosmetics, such as makeup products: (a) To provide the emulsifier or oil-in-water emulsion described herein, and (b) Combining the emulsifier or the oil-in-water emulsion with one or more cosmetic excipients; Includes. [Brief explanation of the drawing]

[0029] [Figure 1A] Figure 1A shows the most common monolignols, also known as lignol precursors, corresponding to the three different aromatic structural units of lignin: coniferyl alcohol (also called the G unit), synapyl alcohol (also called the S unit), and para-coumaryl alcohol (also called the H unit). [Figure 1B] Figure 1B shows examples of lignin monomers that can be produced during the pulping process and present in alkaline lignin. R1 and R2 are independently H, OH, or OCH3, respectively. [Figure 1C] Figure 1C shows an example of a lignin dimer that can be produced during the pulping process and present in alkaline lignin. R1 and R2 are independently H, OH, or OCH3, respectively. (From C. Crestini et al., Biomacromolecules, vol.12, no.11, pp.3928-3935, Nov.2011, doi:10.1021 / bm200948r) [Figure 1D] Figure 1D shows an example of lignin oligomers produced during the pulping process. Prothmann, J., et al., Anal Bioanal Chem 410, 7803-7814 (2018), https: / / doi.org / 10.1007 / s00216-018-1400-4 [Figure 2A]Figure 2A shows size exclusion chromatography of the fractionated lignin LFI-1 and the starting technical lignin. Dotted line: chromatogram corresponding to the starting technical lignin; solid line: chromatogram corresponding to the lignin fractionated by MEK (LFI-1 - the present invention); the peak at 20.2 min represents toluene as the peak reference in THF, Mixed E Column, 2 × 300 mm × 7.5 mm, THF 1 mL / min, detection UV 280 nm. MEK fractionation allows for the removal of high molecular weight polymers while increasing the proportion of lignin dimers and monomers in the recovered fraction. [Figure 2B] Figure 2B shows size exclusion chromatography of lignin LFI-1 fractionated with MEK and lignin LFI-2 fractionated with ethanol. Solid line: chromatogram corresponding to alkaline lignin fractionated with ethanol (LFI-2 - present invention), dotted line: chromatogram corresponding to alkaline lignin fractionated with MEK (LFI-1). The peak at 20.2 min indicates toluene as the peak reference in THF, Mixed E Column, 2 × 300 mm × 7.5 mm, THF 1 mL / min, detection UV 280 nm. Similar lignin fractions were obtained by fractionation with EtOH or MEK. [Figure 2C] Figure 2C shows size exclusion chromatography of lignin fractionated with MEK and ethyl acetate CLF (comparative), and the starting technical lignin. CLF refers to the lignin fraction obtained by two-step sequential extraction with ethyl acetate (AcOEt) and then methyl ethyl ketone (MEK). Solid line: chromatogram corresponding to alkaline lignin, dotted line: chromatogram corresponding to CLF. CLF (comparative) consists of a lignin oligomer fraction with almost no lignin monomers and dimers. The peak at 20.2 min indicates toluene as the peak reference in THF, Mixed E Column, 2 × 300 mm × 7.5 mm, THF 1 mL / min, detection UV 280 nm. [Figure 3] Figure 3 shows the optimized process for preparing the emulsion according to the present invention. [Figure 4] Figure 4 shows the sensory stability and optical microscopy analysis of emulsions prepared from technical lignin, lignin fraction CLF (comparative), and lignin fractions of the present invention (LFI-1 and gLFI-1) before and after storage at 25°C or 40°C, according to Example 1. Figure 4 also shows the results after 1 day using comparative lignin fraction PF570 prepared as described in Example 8 (*: not tested). [Figure 5] Figure 5 shows the evaluation of various emulsions prepared using LFI-1 according to the optimized or alternative process of the present invention, before and after storage at 25°C or 40°C. Functional stability, precipitation, and microstructure were evaluated. [Figure 6] Figure 6 shows the evaluation of two emulsions of the present invention, prepared using LFI-1 according to the optimized or alternative process of the present invention, before and after storage at 25°C or 40°C. Functional stability, precipitation, and microstructure were evaluated. [Figure 7] Figure 7 shows the functional profiles obtained in Example 7 for two oil-in-water emulsions prepared using the lignin fraction of the present invention, compared to those of a commercially available product (benchmark product). [Figure 8] Figure 8 shows size exclusion chromatography of the lignin fraction of the present invention (LFI-1), starting technical lignin, and comparative lignin fractions (PF568, PF569, and PF570) prepared according to US2015 / 0141628 (see Example 8 below). The peak at 20.2 min indicates toluene as the peak reference in THF, Mixed E Column, 2 × 300 mm × 7.5 mm, THF 1 mL / min, detection UV 280 nm. [Figure 9]Figure 9 shows size exclusion chromatography of the lignin fraction of the present invention (LFI-1), starting technical lignin, and comparative lignin fraction (PF575D) prepared according to base-acid treatment by EtOH extraction (see Example 8). The peak at 20.2 min indicates toluene as the peak reference in THF, Mixed E Column, 2 × 300 mm × 7.5 mm, THF 1 mL / min, detection UV 280 nm. [Modes for carrying out the invention]

[0030] Lignin is the second most abundant biopolymer in nature, after cellulose, and accounts for 30% of the organic matter in the biosphere. Large quantities of lignin are produced annually as a by-product or by-product of the papermaking and biorefinery industries. Therefore, there is growing interest in the efficient utilization of lignin due to concerns about reducing resource waste.

[0031] Lignin is a complex polyphenol polymer composed of three phenylpropane monomers (also known as monolignols), namely coniferyl alcohol, synapyl alcohol, and para-coumaryl alcohol, which are crosslinked in various ways by ether links or carbon-carbon bonds. The relative amounts of precursor "monomers" (monolignols) vary depending on the plant source. The structure of lignin is the result of a complex biosynthetic pathway, as described by Crestini et al. (Biomacromolecules, 2011, 12, 3928-3935). The biosynthetic pathway involves oxidative radicalization of the monolignol and subsequent radical coupling of two monomer radicals to form a dehydrodimer. The coupling occurs at the β-position of the monolignol, resulting in the formation of arylglycerol-β-aryl ether (β-O-4'), pinoresinol (β-β'), phenylcoumaran (β-5'), spirodienone (SD), or diphenylethane (β-1') dimers. In subsequent processes, the dimer is newly dehydrogenated to a phenoxy radical, which can then bond to another monomer radical in an end-wise coupling mode. When two lignin oligomers bond at positions 4 and / or 5, diaryl ether (4-O-5') and diphenyl (5-5') lignin subunits are formed. Meanwhile, the 5-5' subunit undergoes α-β-O-4-4' coupling to form a dibenzodioxosine unit (DBDO). Both DBDO and the 4-O-5' coupling mode constitute branching points in lignin. Refer to Crestini's (13) Scheme 1, which shows the coupling modes of monolignol and oligomeric lignin chains, and Crestini's Chart 1, which shows examples of interunit bonding in lignin.

[0032] Due to its phenolic properties, lignin exhibits interesting characteristics such as antioxidant, anti-UV, and stabilizing effects. The use of lignin as an emulsion stabilizer has been proposed in prior art, for example, in Rojas et al., 2007 (Materials, Chemicals and Energy from Forest Biomass, Argyropoulos, ACS symposium Series, Chapter 12, 182-198), or through coupling to nanoparticles as in international application WO2017 / 093185, or through coupling to PEG moieties as in Perkins et al., 2017 (Colloids and Surfaces A: Physicochemical and Engineering Aspects, 530, 200-208).

[0033] However, despite its intriguing properties, the valuation of lignin remains limited to low-value uses such as energy production through combustion.

[0034] These facts stem from the complex structure of lignin. Lignin originates from the polymerization of three different monomers (so-called ligol precursors) and exhibits a heterogeneous structure because it can be crosslinked in various ways, such as radical-radical coupling. Furthermore, lignin obtained from industrial production (so-called technical lignin) has a wide molecular weight distribution. In fact, during the pulping or organosolving process, the original lignin present in lignocellulosic biomass is altered not only through the breakdown of chemical bonds but also through the formation of new bonds, resulting in multiple molecules including long-chain lignin, medium-molecular-weight oligomers, lignin dimers, and low-molecular-weight molecules such as monomers.

[0035] Molecular weight can significantly affect the physical and chemical properties of lignin, particularly in applications requiring surface interactions. Furthermore, its high polydispersity, polarity, and network structure limit the solubility of technical lignin in conventional solvents, hindering its value enhancement. In particular, lignin can precipitate in aqueous media, restricting its use in the cosmetic field. To address this issue, fractionation processes for technical lignin have been developed to obtain lignin fractions with low polydispersity and uniform molecular weight. Such processes rely on multiple steps of precipitation and solvent extraction.

[0036] Under these circumstances, the inventors attempted to devise an emulsifier from lignin. Surprisingly, they demonstrated that lignin with low polydispersity did not exhibit the best emulsifying properties. In contrast, the inventors revealed that certain lignin fractions containing lignin monomers, dimers, and oligomers in distinct proportions, and with a polydispersity of approximately 1.9–2.2, exhibited better emulsifying properties than starting alkaline lignin or highly fractionated lignin obtained by multi-step fractionation processes. Without being bound by any theory, the inventors believe that the presence of both lignin monomers and dimers in distinct amounts in combination with lignin oligomers is important for obtaining an efficient emulsifier. In fact, the inventors showed that the present fraction, combining oligomeric chains and short lignin chains (LFI-1 and LFI-2), is more effective in stabilizing the oil / water interface for extended periods than starting from technical alkaline lignin and oligomeric lignin fractions (CLF). In fact, the lignin fraction of the present invention in the prepared oil-in-water emulsion showed less oil droplet sedimentation and no aggregation compared to other test lignins (Examples 3 and 5). The lignin fraction of the present invention can also provide an oil-in-water emulsion with satisfactory functional properties: the emulsion spread well and had a soft, powdery, and non-greasy effect on the skin, as demonstrated in Example 7.

[0037] The inventors have further demonstrated that enzymatic transesterification with ethylhexanoate can further enhance the stabilization and emulsification efficiency of the lignin fraction of the present invention.

[0038] In addition, the lignin fraction of the present invention was obtained by a very simple extraction method based on a single and rapid extraction step of technical lignin using a polar solvent, preferably a solvent acceptable for cosmetic use. The polar solvent is preferably selected from short-chain ketones and alcohols. The polar solvent may be a green solvent, such as an agro-based solvent. Therefore, the lignin fraction of the present invention can be obtained by a cost-saving and environmentally friendly process. It should be noted that fractionation methods described in the prior art (e.g., double extraction steps or liquid-liquid extraction as described in US Patent No. 2015 / 0141268) result in lignin fractions with different monomer, dimer, and oligomer distributions and impair emulsifying properties. Furthermore, acid and / or basic treatment of technical lignin before extraction with a polar solvent (as described in CN Patent No. 11226159) can also impair the composition of the final lignin fraction by causing a decrease in monomer and dimer content (see Example 8).

[0039] Finally, the inventors demonstrated that the pH of the aqueous phase affects the resulting emulsion. Therefore, the inventors devised a method to optimize the formation of an oil-in-water emulsion by pre-solubilizing the lignin fraction with an alkanediol and diluting it with water whose pH has been readjusted to around 6.0 before adding the oil phase under stirring.

[0040] Therefore, the present invention relates to a novel lignin fraction comprising both lignin oligomers and lignin monomers / dimers, and its use as an emulsifier.

[0041] The present invention also relates to a method for preparing such an emulsifier, and a method for preparing an oil-in-water emulsion based on the use of the emulsifier.

[0042] In a further summary, the present invention also relates to cosmetics, more preferably tinted cosmetics such as skin foundations, that contain the lignin fraction of the present invention. In such cosmetics, the lignin fraction of the present invention can have two functions: acting as an emulsifier and as a pigment.

[0043] In a further summary, the present invention also relates to a method for preparing cosmetics comprising the lignin fraction of the present invention as an emulsifier and / or pigment.

[0044] Method for preparing an emulsifier from technical lignin The present invention relates to a method for preparing emulsifiers described herein from technical lignin. The emulsifiers described herein can be obtained by any suitable method that can reproduce the monomer, dimer, and oligomer distribution as described above. For example, the emulsifier can be obtained by solid-liquid extraction of technical lignin with a suitable solvent such as MEK. Other methods are also possible, such as solubilizing the technical lignin with a suitable solvent (aqueous solvent or aqueous alcohol solvent) followed by ultrafiltration and / or diafiltration.

[0045] In a specific gist, the emulsifiers described herein are obtained by subjecting technical lignin to a solid-liquid extraction step using a suitable solvent preferably selected from C2-C6 alcohols, C3-C8 ketones and mixtures thereof, such as methyl ethyl ketone (MEK) and ethanol.

[0046] In particular, the present invention relates to a method for preparing an emulsifier from technical lignin, the method comprising the step (i) of subjecting the technical lignin to direct extraction with a polar solvent.

[0047] In some embodiments, the polar solvent is selected from short-chain ketones and alcohols. The polar solvent may be a green solvent (e.g., an agro solvent).

[0048] In a preferred embodiment, the solvent is selected from C2-C6 alcohols, C3-C8 ketones, and combinations thereof, for example, C2-C4 alcohols, C3-C6 ketones, and combinations thereof.

[0049] As used herein, C2-C6 alcohols encompass C2, C3, C4, C5, and C6 alcohols. C2-C6 alcohols include ethanol, propanol, butanol, pentanol, hexanol, and isomers such as isopropanol, tert-butanol, isobutanol, and isopentanol.

[0050] As used herein, C2-C6 ketones encompass C2, C3, C4, C5, C6, C7, and C8 ketones. C3-C8 ketones encompass acetone, methyl ethyl ketone (also known as butanone), pentanone, hexanone, heptanone, octanone, and their isomers.

[0051] In preferred embodiments, the solvent is selected from methyl ethyl ketone (MEK), acetone, isopropanol, and ethanol, and combinations thereof, preferably ethanol and / or MEK. MEK is the preferred solvent.

[0052] Ethanol is typically used as anhydrous ethanol or ethanol with a water content of at most 5%, preferably at most 2%, by volume (i.e., ethanol 98°).

[0053] As used herein, “emulsifying agent” or “emulsifier” means a compound or substance that acts as a stabilizer of an emulsion, i.e., a compound or substance that prevents or limits aggregation phenomena such as coalescence or aggregation (where the coalescence of droplets causes an increase in droplet size over time) and / or gravity separation (e.g., sedimentation), particularly in oil-in-water emulsions.

[0054] As used herein, “technical lignin” refers to a “lignin” derivative obtained as a result of the deligninization process of lignocellulosic biomass. In some lignocellulosic biomass, the technical lignin structure can be altered by the processes and chemical reactions used in the treatment of the biomass / starting material. Various types of processes can be used to recover lignin. A well-known chemical pulping process is the kraft process, which separates lignin from cellulose and hemicellulose at 170°C using sodium hydroxide and sodium sulfide. Another process is the bisulfite process, in which lignin is produced as lignosulfonate. The lignin obtained from these two processes contains sulfur. Sulfur-free pulping processes include the soda pulping process and the organosolve process, which produce alkaline lignin (also known as soda lignin) and organosolve lignin, respectively. Alkali lignin is generally obtained by the soda pulping method (also called the alkaline pulping method). This very well-known process relies on treating wood pulp with an alkaline solution (such as sodium hydroxide or Na2CO3) as a pulping agent. Alkali lignin is generally recovered from the black liquor produced during alkaline pulping by acid precipitation. Organosolve lignin is obtained by the organosolve process, a pulping technique (generally in the presence of acid) in which lignocellulose raw materials are suspended in an aqueous organic solvent at temperatures above 140°C.

[0055] In all these cases, the natural lignin is broken down by the cleavage of numerous aryl ether bonds, the dissolution of lignin fragments, and the formation of condensed structures with stable CC bonds.

[0056] In certain embodiments, the technical lignin is either organosolve lignin or alkaline lignin. In more specific embodiments, the technical lignin is alkaline lignin.

[0057] The starting lignocellulosic biomass for preparing technical lignin may be of any type.

[0058] In some embodiments, technical lignin is prepared from plant biomass selected from the group consisting of coniferous trees (e.g., pine), broad-leaved trees, herbaceous plants such as plants belonging to Graminae, and their derivatives. Derivatives include by-products or by-products of industrial products or agricultural food products, such as bagasse, stems and leaves, or straw.

[0059] In some embodiments, technical lignin is prepared from lignocellulosic biomass obtained from maize, rice, wheat, rye, oats, sorghum, sarkanda, and combinations thereof.

[0060] For example, technical lignin can be prepared from wheat straw, Saccharum munja, and combinations thereof.

[0061] For example, technical lignin can be prepared from beech wood by the organosolve process. Alternatively, technical lignin can be prepared from wheat straw and Saccharum munja by alkali pulping.

[0062] In certain embodiments, the technical lignin is alkaline lignin having a pH lower than 5, preferably between 2.5 and 4.5, for example, 3.0 to 4.0.

[0063] In certain embodiments, the technical lignin has an average weight-average molar mass (Mw) of 1800 to 4500 g / mol, such as 1800 to 4000 g / mol or 2500 to 4000 g / mol, and / or a number-average molar mass (Mn) of 600 to 1100 g / mol, such as 650 to 1000 g / mol or 750 to 1000 g / mol.

[0064] In certain embodiments, the particle size of the technical lignin is less than 300 μm, preferably less than 250 μm. In some additional embodiments, the technical lignin has a particle size distribution characterized by a d90 being lower than 250 μm, preferably about 200 μm, and a d50 being 50 to 80 μm, preferably about 65 μm.

[0065] In this specification, "about X" means a range determined by "10% of X ± X", preferably "5% of X ± X".

[0066] In a preferred embodiment, the technical lignin used as a starting material in the process of the present invention has the following characteristics: - The pH of alkaline lignin should be 3.0-4.0; and / or - The Mw of alkali lignin is 1800-4000 g / mol; and / or - The Mn content of alkali lignin is 600-1000 g / mol; and / or - Alkali lignin has a particle size distribution characterized by d90 being less than 250 μm, preferably 180-220 μm, and d50 being 50-80 μm, preferably 60-75 μm; Alkali lignin (i.e., obtained by an alkaline pulping process) is characterized by having one or more (preferably all) of the following.

[0067] In some embodiments, the technical lignin has a polydispersity index (PI) of about 2.80 to 3.10, such as about 2.95. In some embodiments, the technical lignin has a maximum molar mass (Mmax) of at least 14,000 g / mol, such as 14,000 to 18,000 g / mol.

[0068] The Mw, Mn, PI, and Mmax of the starting technical lignin can be determined by any suitable method known to those skilled in the art, such as size exclusion chromatography (SEC), which will be described later.

[0069] In the process of the present invention, the technical lignin is subjected directly to extraction with the solvent of the choice, meaning that the technical lignin is not subjected to any fractionation or extraction prior to step (i). In particular, the technical lignin is not subjected to extraction using a solvent other than the solvent used in step (i), such as ethyl acetate. Furthermore, the technical lignin is not subjected to any additional acid or base treatment prior to step (i), for example, with an acidic or basic aqueous solution. More generally, in the process of the present invention, the technical lignin is not treated with an aqueous solution, whether the aqueous solution is acidic or basic. In particular, the process of the present invention does not include a step of resuspending or dissolving the technical lignin or lignin fraction in an aqueous solution containing an acidic or basic aqueous solution.

[0070] In certain embodiments, the method of the present invention does not include a step of extracting or fractionating the technical lignin with ethyl acetate, or more generally, any ester solvent, before or after step (i). In preferred embodiments, step (i) is the only step of solvent extraction or solvent fractionation carried out in the method of the present invention.

[0071] In some embodiments, the technical lignin is not subjected to any pretreatment step prior to step (i).

[0072] The extraction step (i) is typically carried out by resuspending the technical lignin in the solvent of the choice in a suitable container. No aqueous solution containing water is added in this step. The mixture can be stirred for at least 5 minutes, for example, at least 10 minutes, 30 minutes, or 60 minutes, for example, 60 minutes to 2 hours, or 2 hours to 4 hours, for example, by orbital stirring or by mechanical or magnetic agitator. The extraction time depends on the amount of technical lignin to be extracted.

[0073] Typically, at least 1 L of solvent per 1 kg of technical lignin may be used, for example, 5 L to 60 L of solvent per 1 kg of technical lignin, particularly 5 L to 50 L of solvent, for example, 5 L to 10 L, 10 L to 20 L, 20 L to 30 L, or 30 L to 40 L of solvent.

[0074] Extraction is usually carried out at 15°C to 40°C, for example, at room temperature. Preferably, the mixture of lignin and solvent is not heated.

[0075] At the end of the extraction, the liquid phase containing the soluble lignin fraction is separated from the solid phase, which mainly consists of insoluble long-chain lignin polymers, and recovered. This separation step can be carried out by methods known to those skilled in the art, such as decantation, filtration (e.g., on a glass filter), or centrifugation. Preferably, the liquid phase is recovered by filtration.

[0076] Subsequently, the solvent in the liquid phase is removed by evaporation under reduced pressure to obtain the fractionated lignin (also called the lignin fraction) of the present invention. Alternatively, for example, the lignin fraction can be recovered from the liquid phase by concentrating the liquid phase and then precipitating it with a hydrophobic solvent such as hexane. Alternatively, the lignin fraction obtained after concentration can be freeze-dried.

[0077] The lignin fraction is usually obtained in a solid form, such as a powder.

[0078] As fully explained above and below, the obtained lignin fraction is characterized by having a specific composition in distinct proportions of lignin monomers, dimers, and oligomers. While we do not wish to be bound by any theory, we believe that this specific composition contributes to the improvement of the emulsifying properties of the lignin fraction.

[0079] In some embodiments, the resulting lignin fraction can be used directly (for example) as an emulsifier to stabilize the oil-in-water emulsion.

[0080] The inventors have determined that the emulsifying properties of the lignin fraction obtained in step (i) are due to short-chain fatty carboxylic acids (e.g., C2-C2-C2). 18 It was shown that this can be improved by esterification with fatty acids. In fact, lignin monomers, dimers, and oligomers contain both aliphatic and phenolic hydroxyls, which can be esterified.

[0081] In some embodiments, the method of the present invention further comprises the step (ii) of esterifying the lignin fraction obtained in step (i).

[0082] Typically, step (ii) converts the free aliphatic primary hydroxyl groups present in the lignin molecule into alkyl esters, preferably C2-C 18 Alkyl esters may be formed. C2-C 18 The alkyl ester chain may be linear or branched, but is preferably linear.

[0083] Step (ii) can be carried out by any esterification technique known to those skilled in the art.

[0084] In a preferred embodiment, step (ii) is carried out by enzymatic transesterification. In other words, the transesterification is catalyzed by a suitable enzyme. Preferably, the enzyme is a lipase belonging to enzyme classification (EC) 3.1.1.3, and the reaction is catalyzed by an ester, preferably a methyl or ethyl fatty acid ester (typically linear or branched, preferably linear C2-C). 18 Carboxylic acid, preferably C4-C 10 This is carried out in the presence of a methyl / ethyl ester of a carboxylic acid.

[0085] In fact, this type of enzymatic transesterification allows for the selective esterification of aliphatic primary hydroxyl groups without causing side reactions with phenolic hydroxyl groups. Since phenolic groups contribute to the antioxidant properties of lignin, it is advantageous to keep these groups in a free state.

[0086] Several types of lipases are commercially available for industrial use. By immobilizing the enzyme on a solid support (for example, polymer beads such as acrylic resin beads), it is possible to recycle the enzyme.

[0087] The enzymes studied include, but are not limited to, Candida Antarctica lipase B (CAL-B), Rhizopus oryzae lipase, Candida rugosa lipase, Pseudomnas fluorescens lipase, porcine pancreatic lipase, and their variants. Lipases can be isolated from natural products or synthesized recombinantly.

[0088] The preferred lipase is Candida Antarctica lipase B (CAL-B). For example, CAL-B immobilized on acrylic resin (5,000 U / g or higher, recombinant expressed in Aspergillus niger), such as that sold by Sigma Aldrich, can be used.

[0089] The ester may be, for example, methyl or ethylhexanoate.

[0090] Preferably, the esterification of the lignin fraction is carried out by enzymatic transesterification (transesterification) using CAL-B as the lipase and ethylhexanoate as the ester.

[0091] Enzymatic transesterification is carried out under standard conditions. For example, especially when the lipase is CAL-B, the lignin fraction obtained in step (i) is solubilized in a suitable solvent such as MEK (e.g., 10-50 g of lignin fraction per liter of solvent). After solubilization, the enzyme (i.e., CAL-B) and the ester (e.g., ethylhexanoate) are added, and the mixture is reacted with stirring, preferably until a sufficient conversion rate is obtained. The mixture can also be heated and / or subjected to reflux (e.g., in a Dean-Stark apparatus). Transesterification may take several hours. In the case of CAL-B, the reaction may need to be continued for about 48 hours to obtain a suitable graft yield. The mass ratio of alkyl reagent to lignin can be 0.5-2.0, for example, about 1. The enzyme can be added at a rate of 50-3000 U per gram of lignin, for example, 250-2500 U per gram of lignin, or approximately 1000 U per gram of lignin. Advantageously, the enzyme can be immobilized on a support so that it can be easily recovered at the end of the reaction.

[0092] At the end of the reaction (and after cooling), the esterified lignin fraction can be recovered by any standard method. For example, the mixture can be filtered and concentrated under reduced pressure as needed. The esterified lignin fraction can be recovered by precipitation (e.g., in hexane), filtered with washing, and dried under vacuum.

[0093] Typically, enzymatic transesterification can esterify 5–25% of the aliphatic hydroxyl groups present in the lignin fraction (for example, 20% mol / mol esterification relative to the aliphatic hydroxyl groups present in the lignin fraction).

[0094] The resulting esterified lignin fraction can be sold and / or used as an emulsifier, or may undergo additional steps such as dispersion or solubilization in a suitable carrier and packaging.

[0095] In relation to this problem, the inventors have shown that pre-solubilizing the lignin fraction obtained in step (i) or its esterified product obtained in step (ii) in a suitable solvent makes it easier to obtain an oil-in-water emulsion.

[0096] Therefore, in one embodiment, the method of the present invention includes a further step of solubilizing the optionally esterified lignin fraction in a solvent.

[0097] The solvent is typically selected to solubilize the lignin fraction while remaining acceptable for cosmetic use.

[0098] The solvents covered include alkanediols, alkyl levulinates such as methyl levulinate esters or ethyl levulinate esters, ketal levulinates such as glycerol ketal levulinate, propylene glycol ketal methyl levulinate (methyl-LPK), ethyl-LPK, n-butyl-LPK, lower alcohols (e.g., C2-C6 alcohols, preferably ethanol and isopropanol), and lower alcohol / H2O mixtures (e.g., EtOH / H2OH of 99 / 1 to 50 / 50 v / v).

[0099] As used herein, "alkanediol" refers to an alkyl group having two hydroxyl groups, which may be branched or linear. The general formula for an alkanediol is C n H (2n+2) In O2, n is an integer. Preferably, n is an integer between 2 and 8, more preferably between 2 and 6.

[0100] In particular, the alkanediols of interest include C2-C6 alkanediols, such as ethanediol, propanediol, butanediol, pentanediol, and methylpropanediol, as well as their isomers. Preferred alkanediols are ethanediols such as ethane-1,2-diol (also called ethylene glycol) and propanediols such as propane-1,3-diol. A preferred alkanediol is propane-1,3-diol.

[0101] In this case, the lignin fraction, which may be solubilized in the alkanediol, acts as an emulsifier.

[0102] Typically, the weight ratio of the lignin fraction to the alkanediol is 0.01–0.8, for example 0.1–0.5, for example approximately 0.25.

[0103] The solubilization process can be carried out using a standard procedure. For example, the lignin fraction is added to the solvent while stirring. If necessary, the mixture can be gently heated (below 50°C) to promote solubilization.

[0104] The method of the present invention may include additional steps such as packaging the emulsifier in a suitable vial under a protected atmosphere, decolorizing the emulsifier, and sterilizing the emulsifier (e.g., by UV- or gamma irradiation, steam, pulsed light, or a combination thereof).

[0105] The lignin fraction obtained in step (i) or optionally in step (ii) may be colored, which can be unfavorable for use in optical compositions. Therefore, in some embodiments, the method of the present invention may include a decolorization step aimed at obtaining a lignin fraction having a lighter color.

[0106] In this step, it can be carried out by any method known to those skilled in the art, such as treatment with ozone, hydrogen peroxide, and / or UV, filtration with activated carbon, bentonite treatment, and combinations thereof. This step can be carried out after step (i) and before the steps as options for solubilization and packaging.

[0107] In some specific embodiments, especially when the lignin fraction is used in colored cosmetics, a decolorization step is not necessary. In fact, the lignin fraction of the present invention is naturally brown or beige, and can be used in cosmetics such as makeup products (e.g., colored creams such as foundations, blushes, eyeshadows, BB creams, mascaras, eyeliners, concealers) not only as an emulsifier but also as a pigment.

[0108] In one embodiment, the present invention relates to a method for preparing an emulsifier from technical lignin selected from organosolv lignin or alkali lignin, preferably alkali lignin. This method comprises: step (i) of directly subjecting the technical lignin to extraction using a polar solvent selected from ethanol, MEK, isopropanol, and acetone, preferably ethanol or MEK, solubilizing the technical lignin with the solvent under conditions that enable extraction of the target lignin molecules, separating the liquid phase and the solid phase, recovering the liquid phase, and removing the solvent from the liquid phase to obtain an emulsifier in the form of a lignin fraction.

[0109] In a particular embodiment, the method of the present invention -C2-C 18 enzymatically transesterifying the lignin fraction obtained in step (i) with a lipase belonging to enzyme classification 3.1.1.3 such as CAL-B in the presence of a methyl or ethyl ester of a C4-C8 carboxylic acid, preferably ethylhexanoate, and / or solubilizing the lignin fraction esterified with a C2-C6 alkanediol, preferably propanediol, as required, further comprises one or all of the above.

[0110] Furthermore, the method of the present invention may further include the steps of decolorizing the lignin fraction and / or packaging the lignin fraction.

[0111] The present invention also relates to emulsifiers obtained or that can be obtained by the process of the present invention.

[0112] Lignin fraction according to the present invention The method for preparing the emulsifier of the present invention makes it possible to obtain a lignin fraction exhibiting specific polydispersity, i.e., a specific quantitative distribution of lignin monomers, lignin dimers, and lignin oligomers.

[0113] In fact, the process of the present invention makes it possible to remove the long polymer chains of lignin while leaving the oligomers and short-chain lignin derivatives intact.

[0114] While we do not wish to be bound by any theory, the inventors believe that the unique composition of the lignin fraction of the present invention contributes to improved emulsifying properties compared to technical lignin and highly fractionated lignin.

[0115] Accordingly, the present invention also relates to an emulsifier in the form of a lignin fraction, wherein the lignin fraction is -6.0 to 8.5% by weight, preferably 7.0 to 8.2% by weight, more preferably 7.2 to 8.0% by weight of lignin monomer, -Lignin dimers in an amount of -14.0% to 20.0% by weight, preferably 15.0% to 20.0% by weight, more preferably 15.5% to 18.0% by weight, and -Lignin oligomers in an amount of -70% to 80% by weight, preferably 71.8% to 78.0% by weight, more preferably 74.0% to 77.3% by weight, It consists of, Here, the weight percentage is characterized by being a relative value to the total weight of the lignin monomer, dimer, and oligomer in the emulsifier.

[0116] In certain embodiments, the lignin fraction essentially consists of lignin monomers, dimers, and oligomers in the amounts defined above, meaning that the sum of the weight percentages of lignin monomers, dimers, and oligomers accounts for at least 95%, preferably at least 96%, 97%, 98%, or 99%, of the total weight of the lignin fraction.

[0117] In some embodiments, the lignin fraction consists of the amounts of lignin monomers, dimers, and oligomers defined above, and the sum of the weight percentages of lignin monomers, dimers, and oligomers is 100%.

[0118] In a preferred embodiment, the lignin fraction is -7.4% to 7.9% by weight of lignin monomer; -15.6% to 17.8% by weight of lignin dimers; and -74.3% to 77.0% by weight of lignin oligomers, Consists of or essentially consists of these, The weight percentage is a relative value to the total weight of lignin monomers, dimers, and oligomers in the emulsifier.

[0119] For example, the lignin fraction consists of approximately 7.6% lignin monomers, approximately 17.3% lignin dimers, and approximately 75.1% lignin oligomers.

[0120] As another example, the lignin fraction consists of approximately 7.7% lignin monomers, approximately 16.1% lignin dimers, and approximately 76.2% lignin oligomers.

[0121] As used herein, "lignin monomer" refers to monophenol derivatives produced in the pulping process of lignocellulosic biomass and that may be contained in technical lignins such as alkaline lignin. The lignin monomers present in the lignin fraction of the present invention have a molecular weight of at most 350 g / mol, preferably 100 to 350 g / mol. An example of the target lignin monomer is shown in Figure 1B. GC-MS analysis of the starting alkaline lignin showed that the main lignin monomers included acetosyringone, syringaldehyde, vanillin, ferulic acid, coumaric acid, acetosyringone, syringic acid, benzoic acid, vanillic acid, and benzaldehyde.

[0122] As used herein, "lignin dimer" refers to a molecule composed of at least two building blocks (or constituent units) (which may be the same or different) selected from lignin monomers and / or monolignols. Lignin dimers are also produced from natural lignin by the decomposition of lignin during the pulping process of lignocellulosic biomass and / or from the covalent bonds of the two building blocks. Lignin dimers are generally characterized by five different types of bonds between phenolic units, including 5,5'-ring-ring direct bonds, β-O-4, β,1-diketones, α,1-monoketones, α,5-monoketones, and α,2-methyl side-chain-ring bonds. An example of a lignin dimer is shown in Figure 1C. Lignin dimers present in the lignin fraction of the present invention generally have a molecular weight of at most 700 g / mol, preferably 350-700 g / mol.

[0123] As used herein, "monolignols" (also called lignin precursors) correspond to naturally occurring molecules involved in lignin biosynthesis. The three main precursors of natural lignin are coniferyl alcohol (also called G units), synapyl alcohol (also called S units), and paracoumaryl alcohol (also called H units) (Figure 1A).

[0124] As used herein, lignin oligomers refer to oligomers composed of at least three building blocks (or constituent units) (which may be the same or different) selected from lignin monomers and / or monolignols. Lignin oligomers are also produced from intrinsic lignin during the pulping process of lignocellulosic biomass.

[0125] For examples of oligomers that can be generated during industrial pulping processes, see, for example, Prothmann, J. et al., Anal Bioanal Chem 410, 7803-7814 (2018) https: / / doi.org / 10.1007 / s00216-018-1400-4.

[0126] The lignin oligomers present in the lignin fraction of the present invention typically have a molecular weight of at most 10,000 g / mol, preferably 700 to 9,900 g / mol. The average molecular weight of the lignin oligomers is preferably 900 to 2,300 g / mol, for example, about 1,200 g / mol.

[0127] Typically, lignin oligomers have 3 to 20 monomers and / or monolignols, preferably 3 to 10, for example, 3 to 6 lignin monomers and / or monolignols, for example, 3, 4, 5, or 6 monomers and / or monolignols.

[0128] In a particular embodiment, the oligomer present in the lignin fraction of the present invention has one or more of the following characteristics (preferably all of them): - The weight-average molar mass (Mw) is 1400-1700 g / mol, for example, 1400-1650 g / mol or 1500-1600 g / mol; and / or - The number-average molar mass (Mn) is 900-1300 g / mol, for example, 1000-1200 g / mol or 1050-1150 g / mol; and / or - The polyvariance index is approximately 1.4.

[0129] The Mw, Mn, and PI of the oligomer can be determined, for example, by HP-SEC analysis, as described later.

[0130] Generally, the lignin fraction of the present invention contains lignin molecules having a molecular weight of 100 to 10,000 g / mol.

[0131] In some embodiments, the lignin fraction of the present invention comprises lignin molecules having a weight-average molar mass (Mw) of 1200 to 1600 g / mol, such as 1200 to 1500 g / mol, and / or a number-average molar mass (Mn) of 500 to 800 g / mol, such as 600 to 700 g / mol.

[0132] In certain embodiments, the polydispersity index of the lignin fraction of the present invention is 1.85 to 2.40, preferably 1.95 to 2.20.

[0133] In some embodiments, the lignin fraction of the present invention has a maximum molar mass (Mmax) lower than 10,000 g / mol, for example, 7,000 to 9,000 g / mol or 7,500 to 8,500 g / mol, for example, about 8,000 g / mol.

[0134] The molecular weight range, Mw, Mn, Mmax, and polydispersity index (PI) of the lignin fraction of the present invention can be determined by HP-SEC, for example, based on the relative area of ​​the elution peaks of each target compound.

[0135] For example, the quantitative composition of the lignin fraction can be determined by high-performance size exclusion chromatography (HP-SEC) analysis under the following conditions: - Stationary phase: Polystyrene-divinylbenzene - Eluent: Tetrahydrofuran -Detection: UV absorption at 280nm

[0136] Typically, HP-SEC analysis is performed as follows: The lignin fraction to be analyzed is solubilized at a concentration of 1 mg / mL in a suitable solvent (e.g., THF containing 1% toluene (internal standard)) and filtered as necessary. Next, the lignin fraction is injected into a column, usually polystyrene-divinylbenzene (e.g., Mixed E column 3 μm 600 x 7.5 mm (Polymer Laboratories)), and eluted at a constant flow rate using a suitable solvent (e.g., 1 mL / min of BHT-stabilized THF). The eluted lignin species are detected with a UV absorption detector (e.g., 280 nm or 320 nm).

[0137] A chromatogram corresponding to UV absorption is obtained.

[0138] In a stationary phase with porous beads, molecules are separated based on their hydrodynamic volume, and in the case of polymers, the hydrodynamic volume is usually extrapolated to the molar mass. Therefore, molecules with a hydrodynamic volume smaller than the pores migrate to the beads, thereby extending the elution pathway and increasing the retention time in the column. Molecules larger than the pores cannot diffuse into the beads. Therefore, they move with the mobile phase without entering the pores of the beads and reach the end of the column faster than smaller species.

[0139] In most cases, retention time is linearly correlated with the logarithm of the molecular mass of the substance, and therefore the molar mass (g / mol) of the eluted chemical species can be obtained based on a calibration curve. On the other hand, the proportion of each eluted species in the lignin fraction can be determined by integrating the corresponding peaks from the area under the curve of the UV absorption peaks obtained by SEC analysis.

[0140] In some embodiments, the lignin fraction is characterized by the chromatogram shown in Figure 2B and obtained by the SEC analysis described in Example 1. In this SEC analysis, the proportions of monomers, dimers, and oligomers are determined by peak area integrals from 17 to 19.5 minutes for monomers, from 16 to 17 minutes for dimers, and less than 16 minutes (11 to 16 minutes) for oligomers.

[0141] The inventors also demonstrated that the lignin fraction of the present invention may have a specific hydroxyl group content. The lignin molecule contains three types of hydroxyl groups, namely aliphatic hydroxyl, phenolic hydroxyl, and acidic alcohol (i.e., OH contained in the -COOH group). Each hydroxyl group is derivatized using 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphosphorane, 31 It can be identified and quantified by 1P NMR.

[0142] Therefore, in certain embodiments, the lignin fraction of the present invention (before any possible esterification) contains 1.25% to 1.65 mmol / g, for example, 1.40 ± 0.05 mmol / g of aliphatic OH groups, after derivatization with 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphosphoran. 31 This was proven by 1P NMR.

[0143] As described above, the lignin fraction can preferably be esterified by enzymatic transesterification. Therefore, in one embodiment, the emulsifier in the form of the lignin fraction of the present invention is C2-C 18 The lignin fraction is esterified with an alkanoate group, such as a hexanoate group. In some embodiments, the lignin fraction is characterized by having 5-25% mol / mol, for example about 20% mol / mol, of its aliphatic hydroxyl groups esterified, where this ratio represents the number of moles of esterified aliphatic hydroxyl groups relative to the initial number of moles of aliphatic hydroxyl groups present in the lignin fraction.

[0144] The emulsifier of the present invention may be in a dry form, for example, in the form of a powder. Alternatively, the emulsifier of the present invention may be in liquid form, for example, the lignin fraction may be dispersed, preferably solubilized, in a suitable carrier or solvent such as a C2-C6 alkanediol, for example, propanediol. As described above, ketal levulinates such as alkyl levulinates, glycerol ketal levulinates, methyl levulinate propylene glycol ketal (methyl-LPK), ethyl-LPK, n-butyl-LPK, lower alcohols (e.g., C2-C6 alcohols), preferably ethanol and isopropanol, and other solvents such as lower alcohol / H2O mixtures (e.g., 99 / 1 to 50 / 50 v / v EtOH / H2OH).

[0145] Typically, the weight ratio of lignin fraction to solvent is 0.01 to 0.8, for example, 0.1 to 0.5, for example, about 0.25.

[0146] In some embodiments, the emulsifier may further contain excipients such as cosmetic excipients. For example, the emulsifier may further contain stabilizers such as antioxidants, preservatives, and / or suspending agents. Such excipients may account for 0.01% to 5% of the total weight of the emulsifier.

[0147] -Method of using the emulsifier of the present invention As shown in the Examples section, the lignin fraction of the present invention is effective in stabilizing oil-in-water emulsions with an oil content of up to 80% by weight, and even higher, in both non-esterified and esterified forms. This stabilizing effect lasts for several months during storage.

[0148] Accordingly, the present invention also relates to the use of the lignin fraction of the present invention in both non-esterified and esterified forms, and more generally to the use of the emulsifier of the present invention for stabilizing emulsions, particularly oil-in-water emulsions. More generally, the present invention relates to the use of the lignin fraction, as provided herein, as an emulsifier in the preparation of oil-in-water emulsions.

[0149] The lignin fraction of the present invention can be used in a wide range of fields, including pharmaceuticals, cosmetics, household care, detergents, and the food industry.

[0150] Therefore, the lignin fraction of the present invention, more generally an emulsifier or oil-in-water emulsion, can be found in a wide variety of products, including pharmaceuticals, cosmetics, household care products, detergents, and food products. Cosmetics, in particular, include skin cosmetics and hair care products.

[0151] It is preferably applied in the pharmaceutical and cosmetic fields.

[0152] In a preferred embodiment, an oil-in-water emulsion stabilized with the emulsifier of the present invention, for example, the lignin fraction of the present invention, is used in a cosmetic composition.

[0153] The cosmetic compositions covered are not limited to, but include creams such as face creams or body creams, body milks, makeup removers, hair conditioners, makeup products (especially tinted creams such as foundations, blushes, eyeshadows, and BB creams, mascaras, eyeliners, and concealers), liquid soaps, shampoos, and nourishing masks.

[0154] In fact, the inventors have shown that the lignin fraction of the present invention provides emulsions with satisfactory high organic functional properties. Indeed, emulsions prepared using the lignin fraction of the present invention spread well on the skin, have a soft, powdery feel on the skin, and are non-greasy.

[0155] In certain embodiments, the lignin fraction of the present invention, and more generally the emulsifier of the present invention, are also used to improve the functional properties of a composition, preferably a cosmetic composition.

[0156] It goes without saying that the present invention also relates to compositions comprising the emulsifier of the present invention. More precisely, the present invention relates to compositions comprising emulsions, in particular oil-in-water emulsions stabilized by the emulsifier of the present invention.

[0157] As described above, the composition may be of any type. In addition to the lignin fraction provided herein, the composition may optionally contain one or more other excipients (e.g., pharmaceutically or cosmetically acceptable excipients) in combination with one or more active ingredients, e.g., one or more cosmetic active ingredients, or one or more pharmaceutically active ingredients.

[0158] In the present invention, the lignin fraction (present in the emulsifier) ​​is typically present in an oil-in-water emulsion at an amount of 0.1% to 5%, preferably 0.5% to 4.0%, for example 2.0% to 3.0%, or for example about 2.5%, relative to the total weight of the emulsion.

[0159] For illustrative purposes, if the emulsifier is in the form of a lignin fraction solubilized in propanediol at a weight ratio of 0.25, the emulsifier may account for 12.5% ​​by weight of the total weight of the emulsion (this corresponds to 2.5% by weight of the lignin fraction).

[0160] Preferably, the composition, which is a cosmetic composition, may contain 0% to 10% of an active ingredient and 70% to 99.9% of other excipients, the proportion of which is expressed by weight relative to the total weight of the emulsion.

[0161] This application also provides a method for preparing an oil-in-water emulsion based on the use of an emulsifier according to the present invention.

[0162] This delicious - A step of providing an aqueous phase containing the emulsifier of the present invention; - A step of mixing the aqueous phase with the oil phase to form an oil-in-water emulsion; It consists of including.

[0163] The inventors have shown that, following preliminary solubilization in an alkanediol, solubilization in an aqueous phase at pH 5.5-7.5 (usually around 6.0), followed by the addition of an oil phase, emulsion formation is promoted and lignin precipitation can be prevented.

[0164] More precisely, the inventors have shown that when pre-solubilized lignin (e.g., lignin fraction + propanediol) is added to an aqueous phase (e.g., neutral pH), the pH decreases and becomes more acidic (e.g., around 3.0). By readjusting the pH of the aqueous phase to 5.5-7.5, the solubilization of the lignin fraction is facilitated, and precipitation when the oil phase is added can be avoided. Once proper solubilization of the lignin fraction is achieved by pH adjustment, the oil phase can be added. Such a process also makes it possible to obtain an emulsion with improved temporal stability, i.e., an emulsion that does not undergo significant precipitation or aggregation over time.

[0165] In a particular gist, the present invention also relates to a method for preparing an oil-in-water emulsion: This delicious, (a) To provide the lignin fraction of the present invention that is at least partially solubilized in a solvent; (b) Adding lignin solution to the aqueous phase under stirring to readjust the pH of the aqueous phase to 5.5 to 7.0, preferably about 6.0; and (c) Add an oil phase to the solution obtained in step (b) to obtain an oil-in-water emulsion; Includes.

[0166] In step (a), solvents such as alkyl levulinic acid esters, glycerol ketal levulinic acid esters, methyl levulinic acid propylene glycol ketal (methyl-LPK), ethyl-LPK, n-butyl-LPK, n-butyl-LPK, lower alcohols (e.g., C2-C6 alcohols), preferably ethanol and isopropanol, and lower alcohol / H2O mixtures (e.g., 99 / 1 to 50 / 50 v / v EtOH / H2OH) may be used. Preferably, the solvent is a C2-C6 alkanediol, more preferably a propanediol. The weight ratio of the lignin fraction to the alkanediol is 0.01 to 0.8, for example 0.1 to 0.5, for example about 0.25.

[0167] The pH of the aqueous phase in step (b) can be adjusted using organic or inorganic bases and acids, respectively, that are suitable for the intended use of the final emulsion (e.g., acceptable as a cosmetic or pharmaceutical). Concentrated aqueous solutions of bases and acids, such as concentrated aqueous solutions of sodium hydroxide or citric acid, can be used.

[0168] Preferably, step (b) is carried out by mechanical or magnetic means under stirring at a rotational speed of, for example, about 100 to 1000 rpm, or for example, about 500 to 600 rpm.

[0169] In step (c), the emulsion is preferably obtained after adding the oily phase under high-speed, high-shear stirring, for example, using a rotor-stator device or homogenizer. For example, a rotational speed of 10,000 rpm can be applied. Alternatively, ultrasound can be used to promote emulsification.

[0170] The oil phase can make up to 80% by weight, or even more, of the final emulsion. For example, the oil-in-water emulsion obtained in step (c) is: -20% to 99%, preferably 40% to 90% aqueous phase (including the lignin fraction in the solvent); and -1% to 80%, preferably 10% to 60% oil phase; It may contain, and the proportion is expressed as weight relative to the total weight of the emulsion.

[0171] The aqueous phase is typically water, such as distilled water or ultrapure water. The aqueous phase may contain one or more additional excipients, such as suspending agents, antioxidants, preservatives, pigments, colorants, humectants, gelling agents, solubilizers, coemulsifiers, and combinations thereof.

[0172] The oil phase may be of any type, such as mineral oil, synthetic oil, vegetable oil, or animal oil. Preferably, the oil is selected to be suitable for pharmaceutical or cosmetic use.

[0173] In some embodiments, the oil phase is selected from fatty esters, sweet almond oil, sunflower oil, calendula oil, olive oil, jojoba oil, coconut oil, argan oil, avocado oil, borage oil, palm oil, and other vegetable oils.

[0174] The oil phase contains one or more components incorporated into the oil-in-water emulsion and can be incorporated into sophisticated compositions such as cosmetics.

[0175] These components may, for example, be lipophilic active ingredients with cosmetic effects. Examples of active ingredients with cosmetic effects include, but are not limited to, lipophilic plant extracts such as caffeine, absolutes, or essential oils.

[0176] The oil phase may also contain one or more excipients, such as pigments, functional polymers, clays, fatty alcohols, fatty acids, coemulsifiers, and combinations thereof.

[0177] The method for preparing an oil-in-water emulsion according to the present invention may include one or more additional steps.

[0178] In some cases, a creaming effect (two phases: bulk and creaming phase) may be observed during emulsion formation due to the rise of oil droplets. This phenomenon does not mean that the stability of the emulsion is affected. The formation of a creamy phase can be prevented by adding a suspending agent. Therefore, in some embodiments, the process of the present invention may preferably include a step of adding an excipient, such as a suspending agent, before step (b) to avoid the formation of a creaming phase.

[0179] In this specification, suspending agents refer to substances added to promote the suspension and / or dispersion of particles and to reduce sedimentation. Suspending agents include, but are not limited to, carrageenan, xanthan gum, sclerotium gum, carbe gum, guar gum, tara gum, konjac gum, and cellulose ethers and their derivatives (such as methylcellulose (MC), sodium carboxymethylcellulose (CMC), and hydroxypropyl methylcellulose (HPMC)) as well as acrylate derivative polymers.

[0180] Typically, the suspension agent may be added to the aqueous phase in step (b).

[0181] In a further summary, the present invention relates to a method for preparing cosmetics, such as makeup products: this method is (a) To provide the emulsifier or oil-in-water emulsion described herein; and (b) Combining an emulsifier or oil-in-water emulsion with one or more excipients and / or one or more active ingredients having cosmetic effects; Includes.

[0182] In another summary, the present invention also relates to a method for preparing cosmetics comprising the following steps: This method is (i) the step of preparing an oil-in-water emulsion based on the method provided herein; and (ii) The step of mixing the oil-in-water emulsion with one or more excipients and / or one or more cosmetic active ingredients; Includes.

[0183] In a further embodiment, the present invention also relates to cosmetics, for example, colored cosmetics comprising a lignin fraction or emulsifier provided herein.

[0184] In such cosmetics, the lignin fraction can have two functions: as an emulsifier and as a pigment in the product. In fact, as mentioned above, the lignin fraction of the present invention is naturally beige or brown and can therefore be used as a pigment.

[0185] The cosmetics of the present invention include, but are not limited to, foundations, blushes, eyeshadows, tinted body or face creams such as BB creams, and makeup products such as mascaras, eyeliners, and concealers.

[0186] A further object of the present invention is to use the lignin fraction provided herein as an emulsifier and / or a pigment in cosmetics.

[0187] The following examples are provided for illustrative purposes only and are not limiting.

[0188] Examples Chemical substances and starting materials Methyl ethyl ketone and ethyl acetate were purchased from Carlo Erba Reagents (France) and used as is. Forage (a mixture of wheat straw and Sarkanda) soda technical lignin was purchased from Green Value (Switzerland). Ethyl hexanoate was purchased from Sigma Aldrich (France), propanediol (Zemea) from DuPont (USA), and refined sweet almond oil from Jan Dekker (France). Other reagents and Candida Antarctica-derived lipase acrylic resin (≧5,000 U / g, recombinant, Aspergillus niger expression) (referred to as CAL-B) were purchased from Sigma Aldrich.

[0189] The characteristics of technical alkaline lignin are as follows: - pH: 3~4 - Particle size <250μm, d50: approx. 65μm, d90: approx. 200μm

[0190] Example 1: Preparation and characterization of lignin fraction Method of invention Alkali lignin was magnetically stirred in MEK (40 L / kg) at room temperature for 2 hours.

[0191] The mixture was filtered through a glass filter, and the filtrate was then evaporated under reduced pressure to remove MEK. The first lignin fraction (LFI-1) of the present invention was then recovered as a brown solid (58% by weight).

[0192] A similar protocol was followed using ethanol as the extraction solvent. The second lignin fraction (LFI-2) of the present invention is obtained as a brown solid (68% by weight).

[0193] Fractionation process (comparison) Fractionation was carried out according to Jin et al. (12). This process involved a two-step sequential extraction with ethyl acetate (AcOEt) and then methyl ethyl ketone (MEK).

[0194] Alkali lignin was magnetically stirred in ethyl acetate (AcOEt) (17 L / kg per 1 kg of lignin) at room temperature for 2 hours. The mixture was filtered through a glass filter, and the insoluble residue was collected for further extraction. The insoluble residue was magnetically stirred in MEK (17 L / kg) at room temperature for 2 hours. The mixture was filtered through a glass filter, and the filtrate was evaporated under reduced pressure to remove the MEK, yielding the second comparative lignin fraction (CLF) as a brown solid (22% by weight).

[0195] Characterization of the lignin fraction - Size exclusion flask The lignin fraction to be analyzed was dissolved in a vial at a concentration of 1 mg / mL in THF (containing 1% toluene) and filtered as necessary. Next, the lignin fraction was injected into a polystyrene-divinylbenzene column, a Mixed E column (3 μm x 7.5 mm x 600 mm) manufactured by Polymer Laboratories, and eluted at a constant flow rate of 1 mL / min using BHT-stabilized THF. The eluted lignin species were detected using a UV absorption detector.

[0196] - 31 P NMR 31 ¹P NMR samples (~25 mg) were prepared using 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphosphorane (~50 μL) as the phosphorylation reagent and a mixed solvent of CDCl3 / pyridine (1 / 1.6, ~0.5 mL) as the solvent. A delay time of 6 seconds was used between two consecutive pulses, and a total of 128 scans were performed. The following regions were integrated: aliphatic hydroxyls (149.1–144.2 ppm), phenolic hydroxyls (143.8–137.0 ppm), and acidic regions (136.6–133.6 ppm), with triphenylphosphine (-5.0 ppm) as the internal standard (~20 mg).

[0197] result The chromatograms obtained by SEC chromatography are shown in Figures 2A-2C. Figure 2A shows the chromatogram of LFI-1 compared to the chromatogram of the starting technical lignin. Figure 2B shows the chromatograms of LFI-1 and LFI-2. Figure 3B shows the chromatograms of CLF and the starting technical lignin.

[0198] The proportions of monomers, dimers, and oligomers were calculated according to the area of ​​each peak, with monomers integrated from 17–19.5 min, dimers from 16–17 min, and oligomers from less than 16 min (11–16 min).

[0199] The SEC results showed that LFI-1 and LFI-2 consisted of nearly identical proportions of monomers, dimers, and oligomers. After fractionation with MEK or ethanol, the two lignin fractions, LFI-1 and LFI-2, showed a decrease in the proportion of monomers and oligomers compared to the starting technical lignin. In contrast, LFI-1 and LFI-2 showed an increase in the proportion of dimers compared to the starting technical lignin. Therefore, single-step fractionation with EtOH or MEK resulted in an increase in dimers and a decrease in monomers and oligomers.

[0200] In contrast, CLF showed a significant decrease in monomer and dimer ratios compared to the starting technical lignin. On the other hand, CLF showed a high increase in oligomer ratio compared to the starting technical lignin. Two-step fractionation yields a lignin fraction that is more monodisperse and has a higher oligomer ratio compared to the starting technical lignin or the lignin fraction of the present invention.

[0201] Table 1: Mass percentage of monomers, dimers, and oligomers in the lignin fraction based on SEC characterization. TIFF2026514119000001.tif36150

[0202] CLF exhibits the highest Mw and Mn values ​​compared to the other fractions. The Mw and Mn values ​​of LFI-1 and LFI-2 are very similar and lower than those of the starting lignin. These results indicate that CLF is composed almost entirely of high molecular weight lignin, while LFI-1 and LFI-2 are rich in low molecular weight lignin.

[0203] After single-step fractionation, the polydispersity index of the lignin fraction decreased (LFI-1 and LFI-2 vs. starting technical lignin), but the polyacidity index of CLF remained higher.

[0204] Of note is the departure lignin M Max While the concentration of is 16000 g / mol, the concentration of LFI-1 is M Max That is only 8000 g / mol.

[0205] Table 2: Mw, Mn, and polyvariance index TIFF2026514119000002.tif36145 Table 2a: Mw, Mn, and polydispersity index of oligomers present in each lignin fraction (elution time 11-16 minutes) TIFF2026514119000003.tif36141

[0206] For both LFI-1 and CLF-1, a decrease in aliphatic OH groups was observed compared to the aliphatic OH groups of the starting technical lignin. While CLF showed a slightly higher amount of aliphatic OH groups than LFI-1, this is likely due to a higher amount of oligomers characteristic of CLF. No differences were observed in the phenolic or acidic OH groups of LFI-1 and CLF compared to the starting technical lignin.

[0207] Table 3: NMR 31 Types of OH contained in the lignin fraction by P TIFF2026514119000004.tif24126

[0208] Example 2: Esterification protocol Lignin was placed in a round-bottom flask and dissolved in MEK (25 g / L). Ethyl hexanoate (mass ratio 1:1 to the lignin-containing resin) and CAL-B (20% by mass of the lignin-containing resin) were introduced into the reaction flask. Enzymatic esterification was carried out under reflux using a Dean-Stark apparatus and magnetically stirred for 48 hours. After cooling to room temperature, the mixture was filtered to recover the supported lipase. The solution was concentrated under reduced pressure and precipitated in hexane under magnetic stirring. The precipitated lignin was recovered by filtering through a glass filter. The washed precipitated lignin gLFI-1 was dried overnight under vacuum.

[0209] result The graft yield of gLFI-1 was 1.2 w / w, which corresponds to 12% mol / mol esterification of aliphatic hydroxyl groups present in the lignin fraction.

[0210] Example 3: Comparative study on stability The purpose of these studies was to compare the stability of emulsions obtained using starting technical lignin or various lignin fractions, namely gLFI-1, LFI-1 (invention), and CLF (comparative).

[0211] Emulsion preparation The oil-in-water emulsion was prepared as shown in Figure 3, or more precisely, as follows: Pre-solubilization of the lignin fraction into propanediol was performed using a Turbotest® (VMI, France) mixer with a deflocculator turbine at 700 rpm for 5 minutes under stirring. The resulting solution was added to ultrapure water with stirring (550 rpm, 10 minutes). The pH of the aqueous phase was readjusted to a target pH of 6.0 with stirring (550 rpm, 5 minutes). Emulsification of the aqueous phase with sweet almond oil (10%) was performed using a T25 digital Ultra-Turrax® (IKA, Germany) equipped with a rotor-stator turbine S25N-25F at 10,000 rpm for 10 minutes. Table 4: Composition of the tested emulsions TIFF2026514119000005.tif41142

[0212] - Stability evaluation The emulsion was considered stable if no accretion (a phenomenon in which droplet size increases over time due to the accretion of droplets) occurred and lignin precipitation (settlement) occurred at all or very little. The creaming effect (two phases: bulk and creaming phase) could occur due to the movement of oil droplets, but it did not affect the stability of the emulsion. As described herein, the creaming effect can be prevented by adding a suspending agent to the aqueous phase.

[0213] - For stability evaluation, 15 mL of lignin emulsion was placed in an Eppendorf container and kept at 25°C and 40°C. The stability of the emulsion was assessed by sensory analysis and light microscopy as follows: The functional stability of emulsions stored at -25°C and 40°C was examined after 1 day, 7 days, 14 days, 1 month, and 3 months. - Optical microscopy analysis was performed on emulsions stored at 25°C after 1 day, 7 days, 14 days, 1 month, and 3 months (see below). -Of the 10 mL emulsion, the creaming phase was measured in mL units. - The amount of sediment that settled was measured in milliliters from 10 mL of emulsion.

[0214] Optical Microscope Observation: A single drop of the dispersion or emulsion sample was placed on a microscope glass slide covered with a coverslip. The sample was then observed under bright-field conditions at room temperature using a Nikon (Ni-U NIKON) optical microscope equipped with a DS-Fi3 digital camera (5.9 MP CMOS 2880x2048, 15 frames / second), at varying magnifications. NIS-Elements Viewer 5.21 was used for analyzing the micrographs.

[0215] -result The results of sensory evaluation and optical microscopy are shown in Figure 4. All emulsions exhibited creaming due to a lack of suspending agent. After stabilization at 40°C for 3 months, the creaming phase of the emulsions with added starting technical lignin and CLF became more concentrated. No change in the creaming phase was observed in the emulsions with added LFI-1 and gLFI after stabilization at 40°C for 3 months. Noticeable precipitation was observed in the emulsion prepared from starting technical lignin, but the precipitation within the lignin fraction was not particularly noticeable.

[0216] A significant reduction in precipitation was observed in the fractions LFI-1 and gLFI-1, particularly in gLFI-1. In conclusion, the time-dependent stability data at 25°C and 40°C showed that emulsions prepared from grafted or ungrafted LFI-1 fractions were the most stable, exhibiting the least precipitation, smallest droplet size, and best size uniformity.

[0217] Example 4: Process effect on the stability of oil-in-water emulsion To evaluate the impact of the preparation process on stability, several oil-in-water emulsions were prepared using LFI-1 as follows. Various oil-in-water emulsions were prepared using the general protocol shown in Figure 3.

[0218] -Test 1: Pre-dissolve in propanediol and set the target pH to 6: Pre-solubilization (2.5%) of the lignin fraction (LFI-1) of the present invention to propanediol was performed using a Turbotest® mixer (VMI, France) with a deflocculator turbine at 700 rpm for 5 minutes under stirring. The resulting solution was added to ultrapure water with stirring (550 rpm, 10 minutes). The pH of the aqueous phase was readjusted with stirring (550 rpm, 5 minutes) to a target pH of 6.0. Emulsification of the aqueous phase with sweet almond oil (10%) was performed using a T25 digital Ultra-Turrax® (IKA, Germany) equipped with a rotor-stator turbine S25N-25F at 10,000 rpm for 10 minutes. Table 5: Composition of Test 1 TIFF2026514119000006.tif31124

[0219] Test 2: Pre-solubilize with propanediol, but do not readjust the pH: Pre-solubilization (2.5%) of the lignin fraction (LFI-1) of the present invention to propanediol was performed using a Turbotest® mixer (VMI, France) with a deflocculator turbine at 700 rpm for 5 minutes under stirring. The resulting solution was added to ultrapure water with stirring (550 rpm, 10 minutes) to adjust the pH to 3. Emulsification of the aqueous phase with sweet almond oil (10%) was performed using a T25 digital Ultra-Turrax® (IKA, Germany) equipped with a rotor-stator turbine S25N-25F at 10,000 rpm for 10 minutes. Table 6: Composition of Test 2 TIFF2026514119000007.tif36145

[0220] Test 3: No pre-solubilization with propanediol, pH target set to 6: The lignin fraction (LFI-1) (2.5%) of the present invention was added to ultrapure water under stirring (500 rpm, 10 minutes). The pH of the aqueous phase was readjusted under stirring (550 rpm, 5 minutes) to a target pH of 6.0. Emulsification of the aqueous phase with sweet almond oil (10%) was performed using a T25 digital Ultra-Turrax® (IKA, Germany) equipped with a rotor-stator turbine S25N-25F at 10,000 rpm for 10 minutes.

[0221] Table 7: Structure of Test 3 TIFF2026514119000008.tif31140 The stability of the three emulsions was evaluated as described in Example 3.

[0222] -result The results of sensory evaluation and optical microscopy are shown in Figure 5. A stable emulsion can be obtained by pre-solubilizing the lignin fraction, adjusting the pH of the aqueous phase, and then adding the oil phase. When the lignin fraction (LFI-1) was added to the aqueous phase without pre-solubilization, the resulting emulsion exhibited a heterogeneous microstructure with fragile droplets and sedimentation. By not readjusting the pH to approximately 6.0, an unstable emulsion with large phase transitions, fragile droplets, and a heterogeneous microstructure was obtained. Therefore, by pre-solubilizing the lignin in alkanediol before adding the oil phase, and readjusting the pH of the aqueous phase to 6, the most stable lignin emulsion with the least sedimentation, the smallest droplet size, and the best size uniformity was obtained.

[0223] Example 5: Additional stability testing Using the non-grafted lignin fraction LFI-1 of the present invention, the following emulsions were prepared according to the optimization process described in Figure 3 and Example 3: Table 8: Composition of Emulsion 1 TIFF2026514119000009.tif36148

[0224] Table 9: Composition of Emulsion 2 TIFF2026514119000010.tif36148

[0225] The time-dependent stability of the two emulsions was evaluated as follows: - The lignin emulsion was placed in 15 mL Eppendorf containers and kept at 25°C and 40°C. The stability of the emulsion was assessed by sensory analysis and optical microscopy as follows: The functional stability of emulsions stored at -25°C and 40°C was examined after 1 day, 7 days, 14 days, 1 month, and 3 months. - Optical microscopy analysis was performed on emulsions stored at 25°C, measured at 1 day, 7 days, 14 days, 1 month, and 3 months. -Of the 10 mL emulsion, the creaming phase was measured in mL units. - The amount of sediment that settled was measured in milliliters from 10 mL of emulsion.

[0226] result: The results of sensory evaluation and optical microscopy are shown in Figure 6. The two emulsions were shown to have a homogeneous microstructure. No precipitation was observed after storage at 25°C for 3 months. In conclusion, the lignin fraction of the present invention is an effective emulsifier that meets the requirements of the cosmetics field.

[0227] Example 6: Cosmetic Formulation The following cosmetics were prepared: Table 10: Skin care or body care prescriptions TIFF2026514119000011.tif36127

[0228] The final pH of the formulation was 6.5. The formulation was homogeneous and demonstrated stability for at least 3 months at 25°C or 40°C.

[0229] Table 11: Composition of foundation TIFF2026514119000012.tif57149

[0230] The final pH of the foundation was 6.5, and the viscosity was 9000 Pa·s. The foundation showed a homogeneous appearance with appropriate viscosity. Even without the addition of a gelling agent or a suspending agent, the foundation was stable over time. The foundation also showed good pigment homogeneity and color development when applied. The foundation was non-greasy and soft when applied to the skin.

[0231] Example 7: Sensory analysis of a cosmetic product containing the lignin fraction of the present invention and a commercial product Two water-in-oil emulsions of the present invention were subjected to sensory tests and compared with commercial products. The commercial product was a sunscreen product (water-in-oil emulsion) containing pigments with less than 60% oil phase. The emulsions according to the present invention were prepared according to the process provided in Example 3 and Figure 3, and the emulsions had the following compositions: Table 12: Emulsion 1 (prepared with LFI-1) TIFF2026514119000013.tif36141

[0232] Table 13: Emulsion 2 (prepared with gLFI-1) TIFF2026514119000014.tif31120

[0233] The protocol used for the sensory analysis was as follows: - Panel: 21 people - Room temperature: 20 °C - Humidity: 34.9 ± 3.9% - Individual booths compliant with AFNOR NF EN ISO8589:2007 - Microbiological analysis and irritation test of the lignin emulsion - Statistical analysis: Analysis of variance (Anova), Tukey's test - Selection of evaluation items:

[0234] Table 14: Selection of evaluation items TIFF2026514119000015.tif67161

[0235] Result: Figure 7 shows the sensory profile. The sensory profile indicates that the two emulsions of the present invention have several evaluation items similar to those of commercial products (for example, glossy appearance, smoothness, refreshing feeling, ease of stretching). The observed differences in the evaluation items of the covering power can be explained by the fact that no pigment was added to the two lignin emulsions compared to the commercial products added with pigments.

[0236] Furthermore, the sensory profiles of the two lignin emulsions were very similar, but the emulsion containing the grafted lignin fraction gLFI was slightly higher in ease of stretching, indicating the added value of grafting.

[0237] It should be noted that compared with commercial products containing more than 50 components, the tested lignin emulsions of the present invention were composed of only 4 components, so such good sensory results are very surprising. The lignin emulsions of the present invention had shape retention, ease of slipping, and high gloss on the skin, showing interesting sensory characteristics compared to commercial products.

[0238] Example 8: Comparative Analysis In order to explain the influence of the preparation method of the lignin fraction on the distribution of oligomers, dimers, and monomers and the emulsification characteristics, a comparative experiment was conducted.

[0239] - Comparative Analysis Part 1 Several lignin fractions were prepared from the same alkaline technical lignin used for the preparation of LFI-1 and LFI-2, following a method called “Limited-Solubility Solvent Purification” as described in US2015 / 0141628 (see paragraphs 0278-0280). This method is based on liquid-liquid extraction. In this method, an acidic lignin solution is mixed with a solvent with limited solubility (e.g., MEK) to obtain a two-phase system. The solvent phase is recovered and can be subjected to a purification step with a strong acid cation exchanger to remove cations.

[0240] The following protocols were used: In a beaker, 1 g of technical lignin (the same as in Example 1) was suspended in 100 mL of water to obtain an aqueous lignin solution with a pH of approximately 3.

[0241] The aqueous lignin solution was transferred to a separatory funnel, and 100 mL of MEK, a solubility-limiting solvent, was added. The system was stirred and decanted once. The (orange / light brown) aqueous phase was discarded, and the solvent phase (very concentrated) was collected. The solvent phase was stirred for 1 hour and 30 minutes in the presence of a strong acid cation exchange resin (28 g of Amberlist IR120), and the resin was removed by filtration.

[0242] The solvent phase was divided into two parts: -The first portion was concentrated under reduced pressure and freeze-dried to obtain sample PF568. The yield was 81% wt.

[0243] The second portion was added dropwise to hot water (85°C), stirred, and cooled overnight. After filtration, the precipitated lignin was recovered. The precipitated lignin was washed with water, filtered, and freeze-dried to obtain sample PF569; the yield was 52% wt.

[0244] In US2015 / 0141628, treatment with a strong acid cation exchange resin was optional, so an alternative protocol was also implemented.

[0245] Technical lignin (2.5 g of the same material as in Example 1) was resuspended in water (250 mL) in a beaker to obtain an aqueous lignin solution with a pH of approximately 3.

[0246] The aqueous lignin solution was transferred to a separatory funnel, and 100 mL of MEK, a solubility-limiting solvent, was added. The system was stirred and decanted once. The (orange / light brown) aqueous phase was discarded, and the solvent phase (very concentrated) was collected. The solvent phase was concentrated under reduced pressure and freeze-dried to obtain the lignin fraction (sample PF570).

[0247] -HP-SEC analysis The comparative lignin fraction was analyzed by HP-SEC as described in Example 1 and compared with technical lignin and LFI-1.

[0248] Figure 8 shows the SEC chromatograms of the comparative fractions (PF569, PF570, and PF568) and the SEC chromatograms of technical lignin and LFI-1. The comparative chromatograms do not overlap with the chromatogram of LFI-1. All comparative fractions show an increase in the proportion of high molecular weight oligomers. Notably, PF569 is rich in oligomers, while monomers and dimers are reduced. The following table shows the composition of each lignin fraction:

[0249] Table 15: Percentage of monomers, dimers, and oligomers in the lignin fraction by SEC analysis TIFF2026514119000016.tif73166

[0250] Therefore, it is clear that the method of preparing the lignin fraction directly affects its composition.

[0251] The PF570 fraction appears to be similar in composition to LFI-1. Therefore, this fraction was used for emulsion analysis.

[0252] - Emulsion analysis Using the comparative lignin fraction PF570, an oil-in-water emulsion was prepared according to the protocol described in Example 3. The stability of the obtained emulsion was also evaluated as described in Example 3. After one day, the emulsion shows significant signs of precipitation along with a shiny oily surface. The precipitation indicates that some of the extracted lignin is not located at the oil-water interface. The oily surface is the main state where emulsification is unstable. Microscopic observation shows that the droplet size distribution is larger compared to the "LFI-1" and "g-LFI-1" emulsions (Figure 4).

[0253] Therefore, the method for preparing the lignin fraction also has a great influence on the emulsification characteristics.

[0254] - Comparative Analysis Part 2 This analysis was carried out to evaluate the effects of acidic and basic treatments before extracting technical lignin with a solvent such as ethanol. Such pretreatment is described, for example, in CN No. 11226159 publication.

[0255] Technical lignin (2.5 g of the same as in Example 1) was mixed with a NaOH solution (1250 mL - 10 wt% in water, 2.5 M), and magnetically stirred at room temperature for 20 hours. Then, the mixture was filtered through a glass filter. The filtrate was collected and acidified to pH 2 - 3 using 6 M hydrochloric acid. The precipitated residue was filtered and washed with deionized water until the pH reached about 6. Then, the powder was freeze-dried. 1 g of the powder was mixed with 50 mL of 96° EtOH. The mixture was vigorously revolved and shaken at room temperature for 30 minutes, and then centrifuged (15 minutes, 4800 rpm, 5°C). The supernatant was collected, pooled, and evaporated using a rotary evaporator to recover sample PF575D (extraction yield 79.1 wt%), and analyzed by HP-SEC as described in Example 1.

[0256] The HP SEC analysis of PF575D is shown in Figure 8. The comparative fraction PF575D has significantly reduced monomers and dimers compared to the fraction of the present invention.

[0257] The acidification following the basic treatment had a clear effect on the composition of the final lignin fraction.

[0258] Table 16: Percentage of monomers, dimers, and oligomers in the lignin fraction by SEC analysis TIFF2026514119000017.tif52157

[0259] References cited in the background technology section (1) Principles of Colloid and Surface Chemistry, Revised and Expanded, 0th Edition; Hiemenz, PC, Rajagopalan, R, (eds.); CRC Press, 2016; https: / / doi.org / 10.1201 / 9781315274287 (2) McClements, DJ; Gumus, CE. Natural emulsifiers—biosurfactants, phospholipids, biopolymers, and colloidal particles: Molecular and physicochemical basis of functional performance; Advances in Colloid Interface Sci. 2016, 234, 3-26; https: / / doi.org / 10.1016 / j.cis. 2016.03.002; (3) Corada-Fernandez, C.; Gonzalez-Mazo, E.; Lara-Martin, PA; Evaluation of anaerobic biodegradation of linear alkylbenzene sulfonates (LAS) using a water / seed system (OECD 308); J. Hazard. Mater.; 2018, 360, 24-31; https: / / doi.org / 10.1016 / j.jhazmat; 2018.07.087. (4) Johnson, P.; Trybala, A.; Starov, V.; Pinfield, VJ. Environmental impacts of synthetic surfactants and the possibility of replacement with biosurfactants; Advances in Colloid Interface Sci. 2021, 288, 102340; https: / / doi.org / 10.1016 / j.cis. 2020.102340. (5) Ivankovic, T.; Hrenovic, J.; Surfactants in the Environment; Arch. Ind. Hyg. Toxicol. 2; 2010, 61(1), 95-110; https: / / doi.org / 10.2478 / 10004-1254-61-2010-1943 (6) Holt, MS; Waters, J.; Comber, MHI; Armitage, R.; Morris, G.; Newbery, C.; AIS / CESIO Environmental Surfactant Monitoring Program; SDIA Wastewater Treatment Pilot Study on Linear Alkylbenzenesulfonic Acid (LAS); Water Res. 1995, 29(9), 2063-2070; https: / / doi.org / 10.1016 / 0043-1354(95)00020-L (7) Bouyer, E.; Mekhloufi, G.; Rosilio, V.; Grossiord, J.-L; Agnely, F; Proteins, polysaccharides, and their complexes used as stabilizers in emulsions; Alternatives to synthetic surfactants in the pharmaceutical field; Int. J. Pharm.; 2012, 436(1-2), 359-378; https: / / doi.org / 10.1016 / j.ijpharm; 2012.06.052. (8) Benna-Zayani, M.; Kbir-Ariguib, N.; Travelsi-Ayadi, M.; Grossiord, J.-L; Stabilization of W / O / W double emulsions by polysaccharides as low-elasticity gels; Colloids Surf. Physicochem. Eng. Asp.; 2008, 316(1-3), 46-54. https: / / doi.org / 10.1016 / j.colsurfa. 2007.08.019. (9) Dickinson, E.; Galazka, VB; Emulsification stabilization by ionic and covalent complexes of β-lactoglobulin and polysaccharides; Food Hydrocoll.; 1991, 5(3), 281-296; https: / / doi.org / 10.1016 / S0268-005X(09)80114-8 (10) Dickinson, E.; Effects of hydrocolloids and dispersions on properties at interfaces; Food Hydrocoll.; 2003, 15 (11) Costa, C; Rosa, P; Filipe, A; Medronho, B; Romano, A; Liberman, L; Talmon, Y; Norgren, M.; Cellulose-stabilized oil-in-water emulsions: Structural characteristics, microrheology, stability;Carbohydr.Polym.;2021,252,117092;https: / / doi.org / 10.1016 / j.carbpol;2020.117092. (12) Jin, H.; Shi, H.; Jia, W.; Sun, Y.; Sheng, X.; Guo, Y.; Li, H.; Sun, H.; A room-temperature fractionation process for industrial alkaline lignin with controllable molecular weight using Green's solvent. Int. J. Biol. Macromol.; 2022, 207, 531-540; https: / / doi.org / 10.1016 / j.ijbiomac; 2022.03.049. (13) Crestini et al. Biomacromolecules, 2011, 12, 3928-3935.

Claims

1. An emulsifier in the form of a lignin fraction, - 6.0 to 8.5% by weight, preferably 7.0 to 8.2% by weight, more preferably 7.2 to 8.0% by weight of lignin monomer, -Lignin dimers in an amount of -14.0% to 20.0% by weight, preferably 15.0% to 20.0% by weight, more preferably 15.5% to 18.0% by weight, and - 70% to 80% by weight, preferably 71.8% to 78.0% by weight, more preferably 74.0% to 77.3% by weight of lignin oligomers, It consists of, An emulsifier characterized in that the weight percentage is a relative value to the total weight of lignin monomers, dimers, and oligomers in the emulsifier.

2. Furthermore, the lignin fraction has the following characteristics: - Weight-average molar mass (Mw) of 1200–1600 g / mol, e.g., 1200–1500 g / mol; and / or - Number-average molar mass (Mn) of 500–800 g / mol, e.g., 600–700 g / mol; and / or - The polyvariance index is 1.85 to 2.40, preferably 1.95 to 2.20; The emulsifier according to claim 1, characterized by having at least one of the following.

3. The lignin fraction is C ２ -C ６ The emulsifier according to claim 1 or 2, which is solubilized in an alkanediol, preferably a propanediol.

4. The lignin fraction contains methyl ethyl ketone (MEK) and ethanol, among other C23 compounds. ２ -C ６ Alcohol, C ３ -C ８ An emulsifier according to any one of claims 1 to 3, obtained from technical alkaline lignin by solid-liquid extraction using a solvent selected from ketones and combinations thereof.

5. The hexanoate group is aliphatic, like a primary hydroxyl group C ２ -C １８ An emulsifier according to any one of claims 1 to 4, wherein the emulsifier is at least partially esterified with an alkanoate group.

6. The use of the lignin fraction according to any one of claims 1 to 5, Use of oil-in-water emulsions as emulsifiers to stabilize them, preferably in cosmetic compositions, pharmaceutical compositions, or food compositions.

7. The use according to claim 6, wherein the lignin fraction accounts for 0.1 to 5.0% by weight, preferably 0.5 to 4.0% by weight, for example 2.0 to 3.0% by weight or about 2.5% by weight, based on the total weight of the oil-in-water emulsion.

8. The use according to claim 6 or 7, wherein the lignin fraction is also used as a pigment.

9. A cosmetic, pharmaceutical, or food composition, preferably a cosmetic composition, comprising the emulsifier described in any one of claims 1 to 5.

10. The cosmetic composition according to claim 9, selected from the group consisting of a cream such as a daily cream or body cream, body milk, makeup remover, hair conditioner, concealer stick or cream, liquid soap, shampoo, and nourishing mask.

11. A makeup product comprising an emulsifier according to any one of claims 1 to 5, Makeup products are preferably selected from foundation, blush, eyeshadow, tinted body or face cream such as BB cream, mascara, eyeliner, and concealer.

12. A method for preparing an emulsifier according to any one of claims 1 to 5 from technical lignin, C ２ -C ６ An alcohol, C ３ -C ８ A method comprising step (i) of subjecting technical lignin to extraction using a solvent selected from the group consisting of ketones and combinations thereof, preferably methyl ethyl ketone (MEK), acetone, isopropanol and ethanol, more preferably a solvent selected from ethanol or MEK.

13. Step (i) is, - Contacting the technical lignin with a solvent under conditions that allow for the extraction of the target lignin molecule; - Separating the liquid and solid fractions, and recovering the liquid phase; and - Removing the solvent from the liquid fraction and recovering the emulsifier in the form of a lignin fraction; The method according to claim 12, including the method described in claim 12.

14. The method according to claim 12 or 13, wherein the technical lignin is alkaline lignin.

15. The method according to any one of claims 12 to 14, wherein the technical alkaline lignin is not treated with acid and / or base before extraction, and / or the method comprises a single extraction step using a polar solvent.

16. Furthermore, - Step (ii) of subjecting the lignin fraction obtained in step (i) to enzymatic transesterification with a fatty acid methyl or ethyl ester, preferably with ethylhexanoate, preferably in the presence of Candida Antarctica lipase-B (CAL-B); and / or -Optionally esterified lignin fractions are converted into alkanediols, levulinic acid ketals such as methyl levulinate or ethyl levulinate, glycerol levulinic acid ketals, lower alcohols (e.g., C13). ２ -C ６ Alcohols, preferably ethanol and isopropanol, and lower alcohols / H ２ O mixture, preferably C such as propanediol ２ -C ６ A step of solubilizing the alkanediol in a solvent of a choice; The method according to any one of claims 12 to 15, including the method described in any one of claims 12 to 15.

17. A method for preparing an oil-in-water emulsion, (a) Polar solvent, preferably C ２ -C ６ To provide an emulsifier in the form of a lignin fraction according to any one of claims 1 to 5, at least partially solubilized in an alkanediol; (b) Adding lignin solution to the aqueous phase under stirring to readjust the pH of the aqueous phase to 5.5 to 7.0, preferably about 6.0; and (c) Add an oil phase to the solution obtained in step (b) under high shear to obtain an oil-in-water emulsion; Methods that include...

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