Process for obtaining an antioxidant composition from lignin, lignin liquor or black liquor - Patent application

Abstract

The present invention relates to a process for producing an antioxidant composition from lignin, lignin liquor or black liquor, comprising contacting the lignin, lignin liquor or black liquor with an oxidizing agent, said contacting being carried out at a temperature above 160°C under alkaline conditions, and when the oxidizing agent is oxygen, a gas mixture comprising oxygen or an oxygen generating compound or composition, said agent is added such that the oxygen partial pressure is less than 0.3 MPa. The present invention also relates to the antioxidant composition obtainable by the process of the present invention and to its uses.

Description

[Technical field]

[0001] The present invention relates to a method for obtaining an antioxidant composition. [Background technology]

[0002] Organic matter has a strong tendency to oxidize by reacting with oxygen. This applies to most common organic materials, such as plastics, pesticides, cosmetics, elastomers, fibers, fuels, lubricants, silage, feed and food. There are several processes by which organic materials can oxidize, including autoxidation, biogenic oxidation, combustion and photooxidation, which can severely affect the properties of products and / or shorten their life span.

[0003] Antioxidants, inhibitors (of oxidation) or scavengers are organic or inorganic compounds that are added to organic or biological materials that may be oxidized with the aim of retarding such oxidation and generally extending the life of the substrate. Naturally occurring antioxidants, mainly polyphenols, have attracted increasing attention due to their environmental compatibility and safety for consumers. Polyphenols isolated from fruits, berries, vegetables, medicinal plants and grubs have been favorably studied for their antioxidant activity. In this context, there has also been interest in by-products of the food industry and agriculture for economic and ecological reasons. The antioxidants that have been best characterized to date are flavonoids, lignans, stilbenes and phenolic acids.

[0004] Lignin is an important component of the structural framework of plants and constitutes some of the major components of the cell wall. Lignin is obtained from many sources, such as pulp, wood and paper, sugarcane and cereal straw, using various pulping methods. Physical, chemical and biochemical processes are used to extract lignin from other cellulosic materials.

[0005] Lignin is also known to act as a stabilizer in reactions induced by oxygen and its reactive species, and to have properties that retard the aging of biological systems and complexes. The antioxidant properties of lignin have many potential applications in industry, health care, and agriculture. Lignin's high thermal and biological activity allows it to be used as a substitute for molecules with lower molecular weights, or when the antioxidant activity of a single molecule is insufficient. However, this antioxidant activity is highly dependent on the lignocellulosic material from which it is obtained, the method used for its extraction, and the treatments applied during its isolation and purification. For lignin to exhibit antioxidant activity, it is essential that it has free phenolic hydroxyl groups and methoxy substituents at the ortho positions of the aromatic rings. However, some compounds, such as side chain carbonyl groups, have a negative effect on the antioxidant activity of lignin. The radical scavenging activity of lignin is reduced by various factors such as high molecular weight, polydispersity, and heterogeneity, which are important for the functionalization of lignin.

[0006] Furthermore, although lignin derivatives are known to have antioxidant properties (Pan X. et al. J. Agric.Food Chem., Vol. 54, No. 16, 2006, pp. 5806-5813), the high variability of such properties has made it difficult to industrially apply lignin derivatives as antioxidants. Depolymerization of lignin is a viable route to prepare lower molecular weight products with higher functionality / hydroxyl value and higher reactivity, i.e., depolymerized lignin. Classical depolymerization processes are carried out under high temperature and pressure (as high as 8-12 mPa) reaction conditions, and the high temperature and pressure processes are associated with high capital / operation costs, making large-scale industrial applications more challenging. Summary of the Invention

[0007] Therefore, there is a need in the art for alternative methods to obtain antioxidant compositions from lignin derivatives.

[0008] In a first aspect, the present invention relates to a method for producing an antioxidant composition from lignin or black liquor, comprising contacting lignin, lignin liquor or black liquor with an oxidizing agent, said contacting being carried out at a temperature above 160° C. under alkaline conditions, and where the oxidizing agent is oxygen, a gas mixture comprising oxygen or an oxygen generating compound or composition, the agent is added such that the oxygen partial pressure is less than 0.3 MPa.

[0009] In another aspect, the present invention relates to an antioxidant composition obtainable by the process of the present invention.

[0010] In another aspect, the present invention relates to the use of an antioxidant composition according to the present invention as an ingredient in cosmetic, pharmaceutical, plastic, rubber, latex, fuel, lubricant or food formulations.

[0011] Another aspect of the invention relates to a cosmetic, pharmaceutical, plastic, rubber, latex, fuel, lubricant, food formulation or feed formulation comprising the antioxidant composition of the invention. [Brief description of the drawings]

[0012] [Figure 1] Antioxidant activity (DPPH measurement, black) and phenolic content (TPC, grey) of products obtained from hardwood (H, left) and softwood (S, right) processing wastes. A comparison of starting materials such as kraft lignin (KL) and black liquor (BL) is shown for each wood origin. The results are expressed as antioxidant activity relative to an equal mass of the commercial antioxidant BHT. [Diagram 2] The antioxidant activity (DPPH measurement) of products obtained from hardwood (H) and softwood (S) based on an equal mass of BHT was compared with other commercially available antioxidants of natural (rosemary extract and α-tocopherol) or synthetic (Irganox 1010 and TBHQ) origin. [Diagram 3] The effect of reaction temperature on radical scavenging activity and product yield. RSA: Radical scavenging activity. [Figure 4] The effect of reaction time (min) at a reaction temperature of 240°C on re-lignification. Relig: re-lignification, PD: polydispersity. Description of the Invention

[0013] The present inventors have developed a process for obtaining compositions with high antioxidant activity from lignin, lignin liquor or black liquor. The method of the present invention employs mild depolymerization conditions, which result in activation by functionalization of certain parts of lignin, thereby avoiding the problems and drawbacks of classical depolymerization processes carried out under high temperature and pressure conditions, such as high capital / operational costs and more challenging for large-scale industrial applications. The method of the present invention allows for controlled fragmentation of lignin, lignin liquor or black liquor and at the same time functionalization with sufficient OH groups per molecule, resulting in products with high antioxidant activity.

[0014] Method of the invention The present invention provides a process for producing an antioxidant composition from lignin or black liquor, comprising contacting the lignin, lignin liquor or black liquor with an oxidizing agent, said contacting being carried out at a temperature above 160°C under alkaline conditions, and where the oxidizing agent is oxygen, a gas mixture comprising oxygen or an oxygen generating compound or composition, the agent is added such that the oxygen partial pressure is less than 0.3 MPa.

[0015] As used herein, the term "antioxidant composition" refers to a composition that reduces the amount of oxidation over a given period of time compared to the oxidation that would occur in the absence of the composition, or means a material that extends the time it takes for a given amount of oxidation to occur compared to the oxidation that would occur in the absence of the composition.

[0016] Antioxidant activity can be determined using any known test method, such as the DPPH (2,2-diphenyl-1-picrylhydrazyl) or ABTS test. Antioxidant capacity can also be determined by measuring the ability of an antioxidant compound to react with a given free radical, or by determining that such a compound will have the ability to reduce the complex formed between Fe(III) ions and the TPTZ (2,4,6-tripyridyl-s-triazine) reagent. Among these tests that utilize the measurement of the ability of an antioxidant to react with free radicals, the ORAC test (Oxygen Radical Absorbance Capacity), the TEAC test (Trolox Equivalent Antioxidant Capacity or Trolox equivalent antioxidant capacity) are mentioned. In addition, the Radical Scavenging Index (RSI), which is an index of radical scavenging capacity, can also be used to determine antioxidant capacity. In a preferred embodiment, antioxidant capacity is determined by the DPPH method (RSA, radical scavenging activity).

[0017] The first step of the method of the present invention comprises contacting lignin, lignin liquor or black liquor with an oxidizing agent.

[0018] As used herein, "lignin" refers to a naturally occurring branched phenolic biopolymer composed primarily of the three phenylpropanoid building blocks p-hydroxyphenylpropane, guaiacylpropane and syringylpropane.

[0019] "Lignin liquor," as used herein, refers to a waste stream resulting from a process of pretreating lignocellulosic biomass to break down the structure of the biomass for the purpose of removing the polymeric sugar fraction (mainly cellulose and / or hemicellulose) and other extractives from the starting material. In addition to lignin, this waste liquor may contain soluble reactive and non-reactive soluble chemicals as well as degraded and dissolved lignocellulosic fragments.

[0020] "Industrial lignin" as used herein refers to lignin recovered from a lignin liquor by chemistry, acid precipitation, solvent extraction and / or physical separation techniques such as filtration based on molecular weight fractionation to isolate the lignin from other soluble materials present in the lignin liquor.

[0021] "Black liquor" as used herein refers to the waste liquor obtained from the Kraft process, which is obtained during the cooking of pulpwood to remove lignin, hemicellulose and other extractable materials from the wood and liberate the cellulose fibers into paper pulp. It contains the inorganic elements from the cooking process from which it originated, as well as most of the woody matter that has been broken down and dissolved. The latter include acetic acid, formic acid, saccharinic acid, many other carboxylic acids (all as sodium salts), dissolved hemicelluloses (especially xylans), methanol, and hundreds of other components.

[0022] In a preferred embodiment, the starting material is a sulfur-containing lignin. Examples of sulfur-containing lignins are kraft lignin and lignosulfonates.

[0023] In a more preferred embodiment, the starting material is kraft lignin.

[0024] As used herein, "Kraft lignin" refers to the major by-product of the Kraft pulping process, a traditional method of breaking the bonds of chemical building blocks of wood using sodium hydroxide and sodium sulfide under strong alkaline conditions to obtain cellulose pulp from biomass. This process produces a large amount of Kraft lignin. During Kraft cooking of wood, lignin is depolymerized by cleavage of aryl ether bonds into various fragments of different molecular weights, which become soluble in alkaline solutions. After cooking, the lignin dissolved in alkali is acidified and concentrated for recovery. The recovered Kraft lignin has several unique characteristics that distinguish it from natural and other industrial lignins. One of the main characteristics is the presence of a large amount of condensed chemical structures and a large amount of phenolic hydroxyl groups as a result of the large amount of β-aryl bonds broken during the cooking process. Kraft lignin has sulfur in its chemical structure due to sulfurization.

[0025] In another preferred embodiment, the starting material is lignosulfate lignin.

[0026] As used herein, "lignosulfonates" refers to salts of wood that have been treated with sulfur dioxide (SO 2 It refers to another type of sulfur-containing lignin obtained from the sulphite chemical pulping process, which is based on cooking with aqueous solutions of sulphur dioxide and base (calcium, sodium, magnesium or ammonium). Lignosulfonates are highly cross-linked polymers with a sulfur content of about 5% and composed of two types of ionizable groups: sulfonate groups (pKa ≦ 2) and hydroxyl groups (pKa ≈ 10). Lignosulfonates are highly soluble in water and alkaline or basic solutions as well as in highly polar organic solvents.

[0027] In a preferred embodiment, the starting material is sulfur-free lignin. Examples of sulfur-free lignins are organosolv lignin, soda lignin and Klason lignin.

[0028] In another preferred embodiment, the starting material is organosolv lignin.

[0029] "Organosolv lignin" is the common name for lignin obtained as a by-product by fragmenting hardwood, softwood and herbaceous crops using solvents such as alcohols, organic acids or mixtures thereof. It exhibits interesting properties such as low molecular weight, narrow molecular weight distribution, low solubility in water and high phenolic and aliphatic hydroxyl content.

[0030] In another preferred embodiment, the starting material is soda lignin.

[0031] As used herein, "soda lignin" refers to the product obtained by treating lignocellulosic materials such as bagasse, sisal, wheat straw, hemp, and kenaf with highly alkaline solutions (typically sodium hydroxide) under conditions similar to kraft pulping, except that hydrogen sulfide anions are not included. In the soda pulping process, lignin is extracted by hydrolytic scission of the native lignin network. The process allows the recovery of lignin through several steps, including acid precipitation, heating, and filtration.

[0032] In another preferred embodiment, the starting material is Klason lignin.

[0033] As used herein, "Klason lignin" refers to the residue obtained after total acid hydrolysis or autohydrolysis of the carbohydrate portion of wood.

[0034] In another preferred embodiment, the starting material is exploded lignin.

[0035] "Exploded lignin" as used herein refers to lignin contained in or extracted from the waste liquor obtained by pretreating biomass with heat and saturated steam. The final step involves rapid depressurization to break down the structure of the biomass. This process separates the lignin and cellulose in solid form from the hemicellulose, which remains soluble. The cellulose is converted to simple sugars by enzymatic hydrolysis for valorisation, while the exploded lignin is recovered as a solid.

[0036] In another preferred embodiment, the starting material is black liquor.

[0037] "Black liquor" as used herein refers to the waste liquor obtained from the Kraft process during the cooking of pulpwood to remove lignin, hemicellulose and other extractable materials from the wood and liberate the cellulose fibers into paper pulp. It is a complex colloidal system consisting of water, organic and inorganic sulfur compounds, inorganic sodium salts primarily in the form of carbonates and sulfides, residual caustic soda, hemicellulose and lignin.

[0038] In a preferred embodiment, the starting material is obtained from softwood. Preferred, non-limiting examples of softwood are pine or spruce. In a preferred embodiment, the starting material is obtained from pine, more specifically, the starting material is black liquor derived from pine.

[0039] In another preferred embodiment, the starting material is obtained from hardwoods. Preferred, non-limiting examples of hardwoods are birch, poplar, eucalyptus, beech, oak, maple, cherry, ash, aspen, elm or acacia. In a more preferred embodiment, the starting material is obtained from eucalyptus.

[0040] In another preferred embodiment, the starting material is obtained from herbaceous biomass such as American millet, miscanthus, corn stover cereal crops, pasture grasses, oilseed crops, tuber crops and legumes, flowers, gardens, parks, prunings, vineyards, orchards or mixtures of all of these.

[0041] As used herein, "oxidizing agent" refers to a chemical species that undergoes a chemical reaction that removes one or more electrons and has the ability to oxidize other substances. In a preferred embodiment, the oxidizing agent is selected from the group consisting of oxygen, a gas mixture comprising oxygen and an oxygen generator compound or composition.

[0042] As used herein, "oxygen generator compound or composition" refers to a compound or composition that releases oxygen through a chemical reaction.

[0043] Preferred, non-limiting examples of oxygen generator compounds are ozone, hydrogen peroxide, deionized water, O 2 plasma and alcohol. In a preferred embodiment, the gas mixture comprising oxygen is air.

[0044] In another preferred embodiment, air is supplied continuously to the reaction zone.

[0045] Contacting the lignin or black liquor with the oxidizing agent in the process of the invention is carried out under alkaline conditions at a temperature above 160°C, and when the oxidizing agent is oxygen, a gas mixture comprising oxygen, or an oxygen generator compound or composition, the agent is added such that the oxygen partial pressure is less than 0.3 MPa.

[0046] The alkaline conditions and / or temperatures above 160°C are maintained throughout the residence time for at least 95% of the residence time, at least 90% of the residence time, at least 85%, at least 80%, at least 75%, at least 70%, at least 65%, at least 60%, at least 55% or at least 50%.

[0047] As used herein, "alkaline conditions" refers to a pH greater than 10.

[0048] In a preferred embodiment, the alkaline conditions are achieved with an Arrhenius base.

[0049] As used herein, an "Arrhenius base" is a base that, in aqueous solution, reacts with OH - Refers to a compound that increases ion concentration.

[0050] In a preferred embodiment, the Arrhenius base is selected from the group consisting of sodium hydroxide, sodium carbonate, potassium hydroxide, magnesium hydroxide and calcium hydroxide, hi a more preferred embodiment, the Arrhenius base is sodium hydroxide.

[0051] In a preferred embodiment, when the process of the present invention comprises using oxygen under alkaline conditions using an alkali metal agent at a temperature above about 200° C., a pressure above about 6.895 MPa, for a time of about 10 minutes or less, the starting material is not black liquor.

[0052] As used herein, "alkali metal agent" refers to alkali metal hydroxides, e.g., NaOH, KOH, LiOH.

[0053] Sodium hydroxide of different concentrations can be added to the medium in which the lignin, lignin liquor or black liquor is contacted with the oxidizing agent. In a preferred embodiment, the concentration of sodium hydroxide is 1 to 120 g / l. In another preferred embodiment, this concentration is 2 to 100 g / l, more preferably 5 to 95 g / l, more preferably 10 to 95 g / l, more preferably 10 to 85 g / l, more preferably 15 to 80 g / l, more preferably 20 to 75 g / l, more preferably 25 to 70 g / l, more preferably 30 to 65 g / l, more preferably 35 to 60 g / l, more preferably 40 to 55 g / l.

[0054] In another preferred embodiment, the concentration of sodium hydroxide is 2 to 80 g / l.

[0055] In one embodiment, when the starting material is black liquor, no additional alkaline agent or Arrhenius base is added to obtain alkaline conditions in the process of the present invention. In a particular embodiment, when the starting material is black liquor, the starting material contains sodium hydroxide at a concentration of about 2-4 g / l.

[0056] In a preferred embodiment, the residence time of the method of the present invention is less than 30 minutes, preferably 10 to 30 minutes, more preferably 10 to 25 minutes, more preferably 10 to 20 minutes, more preferably 10 to 15 minutes. In another preferred embodiment, the residence time is less than 15 minutes, preferably less than 14 minutes, more preferably less than 13 minutes, more preferably less than 13 minutes, more preferably less than 12 minutes, more preferably less than 11 minutes, more preferably less than 10 minutes.

[0057] As used herein, "residence time" refers to the average length of time that lignin, lignin liquor, or black liquor is in contact with an oxidizing agent under alkaline conditions.

[0058] According to the invention, contacting the lignin or black liquor with the oxidizing agent under alkaline conditions can be carried out under conditions of different oxygen partial pressure, total pressure or pH.

[0059] In a preferred embodiment, the contact of the lignin, lignin liquor or black liquor with the oxidizing agent is carried out at an oxygen partial pressure of 0.05 to 0.5 MPa. In another preferred embodiment, the oxygen partial pressure is 0.06 to 0.14 MPa, more preferably 0.07 to 0.13 MPa, more preferably 0.08 to 0.12 MPa, more preferably 0.09 to 0.2 MPa, more preferably 0.1 to 0.25 MPa, more preferably 0.15 to 0.3 MPa, more preferably 0.2 to 0.35 MPa, more preferably 0.25 to 0.4 MPa, more preferably 0.3 to 0.45 MPa, more preferably 0.35 to 0.5 MPa.

[0060] In a preferred embodiment, the contact of the lignin, lignin liquor or black liquor with the oxidizing agent is carried out at an oxygen partial pressure of less than 0.3 MPa. In another preferred embodiment, the oxygen partial pressure is 0.01 to 0.3 MPa. In another preferred embodiment, the oxygen partial pressure is 0.05 to 0.3 MPa. In another preferred embodiment, the oxygen partial pressure is 0.06 to 0.14 MPa, more preferably 0.07 to 0.13 MPa, more preferably 0.08 to 0.12 MPa, more preferably 0.09 to 0.2 MPa, more preferably 0.1 to 0.25 MPa, more preferably 0.15 to 0.3 MPa, more preferably 0.2 to 0.25 MPa, more preferably 0.25 to 0.3 MPa, more preferably 0.25 to 0.275 MPa.

[0061] Additionally, in a preferred embodiment, the contact of the lignin, lignin liquor or black liquor with the oxidizing agent is carried out at a total pressure of 2 to 5.5 MPa. In another preferred embodiment, the total pressure is 2.5 to 5 MPa, more preferably 3 to 4.5 MPa, more preferably 3.5 to 4 MPa.

[0062] In other preferred embodiments, contacting the lignin, lignin liquor or black liquor with the oxidant is carried out at a pH greater than 10 and less than 14. In preferred embodiments, the pH is greater than 11.9, more preferably greater than 12, more preferably greater than 12.1, more preferably 12.2, more preferably 12.3, more preferably 12.4, more preferably 12.5, more preferably 12.6, more preferably 12.7, more preferably 12.8, more preferably 12.9, more preferably 13, more preferably 13.1, more preferably 13.2, more preferably 13.3, more preferably 13.4, more preferably 13.5, more preferably 13.6, more preferably 13.7, more preferably 13.8, more preferably 13.9.

[0063] The method of the invention requires that the contact of the starting material with the oxidizing agent is carried out at a temperature above 160°C. In a preferred embodiment, this temperature is about 160-260°C, preferably about 205-255°C, preferably 210-250°C, preferably 215-245°C, preferably 220-240°C, preferably 225-235°C. In another preferred embodiment, this temperature is 170°C, more preferably 175°C, more preferably 180°C, more preferably 185°C, more preferably 190°C, more preferably 195°C, more preferably 200°C, more preferably 205°C, more preferably 210°C, more preferably 215°C, more preferably 220°C, more preferably 225°C, more preferably 230°C, more preferably 235°C. In another preferred embodiment, this temperature is about 240°C. In another preferred embodiment, this temperature is less than 250°C, more preferably less than 245°C, more preferably less than 240°C. In another preferred embodiment, the starting material is lignin and the temperature is not 175°C. In another preferred embodiment, the starting material is lignin and the temperature is not 200° C. In another preferred embodiment, the starting material is lignin and the temperature is not 225° C.

[0064] Furthermore, in the method of the present invention, the starting material can be used in different concentrations. In a preferred embodiment, the kraft lignin as the starting material is added in a concentration of 7 to 100 g / l. In a more preferred embodiment, the kraft lignin is added in a concentration of 7 to 95 g / l, more preferably 10 to 95 g / l, more preferably 25 to 95 g / l, more preferably 30 to 90 g / l, more preferably 35 to 85 g / l, more preferably 40 to 80 g / l, more preferably 45 to 75 g / l, more preferably 50 to 70 g / l, more preferably 55 to 65 g / l.

[0065] The process of the invention may comprise further steps such as separation, recovery from one of the separated phases and / or purification, aimed at recovering and purifying the antioxidant composition.

[0066] In a preferred embodiment, the method of the present invention further comprises a step of fractionating the composition based on the molecular weight of the compound that constitutes part of the composition. In a preferred embodiment, the molecular weight cutoff of the fraction is at least 1000 Da. In another preferred embodiment, the molecular weight cutoff of the fraction is at least 1500 Da, at least 1600 Da, at least 1700 Da, at least 1800 Da, at least 1900 Da, at least 2000 Da, at least 2500 Da, at least 3000, at least 3500 Da, at least 4000 Da, at least 4500 Da or at least 5000 Da.

[0067] Several known methods, including analytical and preparative methods, can be used to fractionate compositions based on their molecular weight. Examples of suitable methods include size exclusion chromatography (SEC), dialysis, filtration, matrix-assisted laser desorption / ionization (MALDI) or field-flow fractionation (FFF), preparative SEC or continuous spin fractionation.

[0068] As a preferred, non-limiting example, tangential ultrafiltration can be performed which separates two fractions (retentate and permeate).

[0069] As used herein, "permeate" refers to the fraction of the feed that passes through the membrane and contains the lower molecular weight fraction (antioxidant composition).

[0070] According to the method of the present invention, the product low molecular weight (LMW) antioxidant composition can be recovered from the permeate by any method known in the art. As preferred, non-limiting examples, recovery of the antioxidant product can be achieved by adjusting the pH, concentrating the permeate by evaporation, and extraction with an organic solvent followed by evaporation of the organic phase.

[0071] In a preferred embodiment, the pH is adjusted to about 1 to 4, more preferably about 2 to 3. Any acidifying agent can be used for the above adjustment.

[0072] "Acidifier" as used herein refers to any compound that can be used to reduce the pH of a composition.Acidifier can be selected from the group consisting of lignite, gibberellic acid, citric acid, sodium pyrosulfite, malic acid, oxalic acid, succinate, acetic acid, butyric acid, valeric acid, lactic acid, pyruvic acid, malonic acid, formic acid, hydrochloric acid, nitric acid, phosphoric acid, erythronic acid, tetronic acid, sulfuric acid and fumaric acid.In a more preferred embodiment, the acidifier is sulfuric acid.

[0073] After pH adjustment, the permeate can be concentrated by any method known in the art, such as evaporation. In a preferred embodiment, the volume is reduced to up to about 1 / 12-1 / 15 of its initial volume by removing water. The antioxidant composition can then be extracted with an organic solvent.

[0074] As used herein, "organic solvent" refers to a carbon-based substance capable of dissolving or dispersing one or more other substances. Organic solvents can be hydrocarbons, alcohols, ethers, and chlorine-based solvents. Preferred non-limiting examples of organic solvents include acetone, benzene, chlorobenzene, acetic acid, chloroform, 2-butanone, 1-butanol, 2-butanol, 3-pentanol, p-xylene, m-xylene, o-xylene, ethanol, ethyl acetate, ethylene glycol, formamide (DMF), pyridine, toluene, pentane, 1-propanol, nitromethane, methanol, hexane, methylene chloride, ether (MTBE), triethylamine, N-methyl-2-pyrrolidinone (NMP), tetrahydrofuran, ... The organic solvent is selected from the group consisting of tetrahydrofuran (THF), carbon tetrachloride, cyclohexane, diethyl ether, diethylene glycol, glycerin, heptane, dimethyl sulfoxide (DMSO), acetonitrile, t-butyl alcohol dimethyl ether, diglyme (diethylene glycol dimethyl ether), 1,2-dimethoxyethane (glyme, DME), 2-propanol 1,2-dichloroethane, dioxane, hexamethylphosphorastriamide (HMPT), hexamethylphosphoramide (HMPA). In a preferred embodiment, the organic solvent is selected from the group consisting of ethyl acetate, butanol, 3-pentanol, octanol, toluene and hexane. In a more preferred embodiment, the organic solvent is ethyl acetate. The volume ratio of the pre-evaporated permeate to the organic solvent can be 1:1, 1:2, 1:3 or 1:4.

[0075] The extraction step involving evaporation of the organic solvent will be carried out at a temperature depending on the organic solvent, and will be carried out at the evaporation temperature. The evaporation temperature varies depending on the pressure, and therefore the temperature and pressure can be adjusted to evaporate the organic solvent sufficiently. Specifically, when using ethyl acetate, the evaporation can be carried out at 75-80°C and normal pressure. The concentration step can be carried out in a rotary evaporator.

[0076] As used herein, "depolymerization" refers to the process of converting complex lignin compounds into smaller molecules by cleaving the bonds between the units that modify the propanyl side chains and aromatic rings of lignin, and providing oxygenate sites to the resulting fragments.

[0077] As a result of the depolymerization that occurs during the practice of the method of the present invention, the molecular weight of the lignin is reduced by about 10%, about 15%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90% or less compared to the molecular weight of the lignin prior to application of the method of the present invention. As used herein, the term "molecular weight" is understood to mean the weight average molecular weight (Mw) that represents the average value closest to the midpoint of the bell curve.

[0078] In some embodiments, when using starting materials derived from softwood, the depolymerization that occurs during the practice of the methods of the invention results in a decrease in the polydispersity index of the starting material of at least about 10%, at least about 15%, at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95% or more.

[0079] In some embodiments, when using starting materials derived from hardwood, the depolymerization that occurs during the practice of the methods of the invention results in a decrease in the polydispersity index of the starting material by at least about 5%, at least about 10%, at least about 15%, at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, or at least about 50%.

[0080] The term "polydispersity index" is defined below in relation to the antioxidant compositions of the present invention, but applies equally to the methods of the present invention.

[0081] Antioxidant Compositions and Uses Thereof In another aspect, the present invention relates to an antioxidant composition obtainable by the process of the present invention.

[0082] In a preferred embodiment, the antioxidant composition of the present invention exhibits a higher antioxidant capacity, specifically about 1.5 times higher, compared to commercially available butylated hydroxytoluene BHT. In a more preferred embodiment, the antioxidant capacity is measured by the DPPH method (RSA, radical scavenging activity). In another preferred embodiment, the antioxidant composition of the present invention exhibits a 2 times higher antioxidant capacity compared to kraft lignin. In a more preferred embodiment, the antioxidant capacity is evaluated by the DPPH method (RSA, radical scavenging activity).

[0083] In another preferred embodiment, the total phenol content of the antioxidant composition of the present invention is about 1-4 times higher, preferably about 1.5-3.5 times higher, more preferably about 2-3 times higher, more preferably about 2-2.5 times higher, preferably about 2.25 times higher, compared to kraft lignin. In a more preferred embodiment, the phenol content is evaluated by the Folin-Ciocalteau method. In another preferred embodiment, the phenol content is evaluated by the DPPH method.

[0084] In another preferred embodiment, the antioxidant composition of the present invention is characterized by an average molecular weight (Mw) of about 650-850 Da. In another preferred embodiment, the antioxidant composition of the present invention is characterized by a polydispersity index of less than 2.2. In a more preferred embodiment, the PDI is determined by HPLC-RID using 0.1 M NaOH as the mobile phase.

[0085] As used herein, "average molecular weight" refers to the ordinary arithmetic mean or average of the molecular masses of individual polymers, which is determined by measuring the molecular masses of n polymer molecules and dividing the sum of the masses by n.

[0086] As used herein, "polydispersity index" or PDI, sometimes referred to as molecular weight distribution, refers to the ratio of weight average molecular weight (Mw) to number average (Mn). PDI is used to estimate the average homogeneity of a particle solution, with larger values ​​of PDI corresponding to a larger particle size distribution of the particle sample. PDI can be obtained using a variety of means: GPC, rheological solution viscosity, membrane penetration (Van't Hoff equation), light scattering (Zimm plot).

[0087] The antioxidant compositions of the present invention have substantially reduced nitrogen and sulfur content relative to the starting materials.

[0088] In some embodiments, the nitrogen content of the antioxidant composition of the present invention is at least 2 times lower, at least 4 times lower, at least 6 times lower, at least 8 times lower, at least 10 times lower, at least 20 times lower, at least 30 times lower, at least 40 times lower, at least 50 times lower, at least 100 times lower than the nitrogen content of kraft lignin. In some embodiments, the nitrogen content of the antioxidant composition of the present invention is less than about 0.1%, less than about 0.09%, less than about 0.08%, less than about 0.07%, less than about 0.06%, less than about 0.05%, less than about 0.04%, less than about 0.03%, less than about 0.02%, less than about 0.01%, less than about 0.005%, less than about 0.001% or less (measured on a dry basis). Nitrogen content can be performed by elemental analysis, which provides not only the nitrogen content but also the carbon and hydrogen content.

[0089] In some embodiments, the amount of sulfur in the antioxidant compositions of the present invention is at least 2 times lower, at least 4 times lower, at least 6 times lower, at least 8 times lower, at least 10 times lower, at least 20 times lower, at least 30 times lower, at least 40 times lower, at least 50 times lower, or at least 100 times lower than the amount of sulfur in kraft lignin. In some embodiments, the sulfur content of the antioxidant composition of the present invention is less than about 3%, less than about 2%, less than about 1%, less than about 0.9%, less than about 0.8%, less than about 0.7%, less than about 0.6%, less than about 0.5%, less than about 0.4%, less than about 0.3%, less than about 0.2%, less than about 0.1%, less than about 0.09%, less than about 0.08%, less than about 0.07%, less than about 0.06%, less than about 0.05%, less than about 0.04%, less than about 0.03%, less than about 0.02%, less than about 0.01% or less (measurements are on a dry basis). Sulfur measurements can be performed according to UNE-EN 15104 and DIN / EN 15289. Thus, the process of the present invention can produce antioxidants that are substantially free of nitrogen and sulfur.

[0090] The antioxidant composition of the present invention is substantially free of vanillin (4-hydroxy-3-methoxybenzaldehyde) when the starting material is black liquor obtained from pine wood. In another preferred embodiment, when the starting material is black liquor obtained from pine wood, the amount of vanillin is less than 2%, more preferably less than 1.8%. In a more preferred embodiment, the vanillin content is determined by HPLC-MS.

[0091] In another preferred embodiment, the antioxidant composition of the present invention comprises 3.4% or less vanillin / isovanillin, preferably when the composition is derived from softwood. In another preferred embodiment, the antioxidant composition of the present invention comprises 5.5% or less vanillin / isovanillin, preferably when the composition is derived from hardwood.

[0092] As used herein, "vanillin / isovanillin" refers to vanillin and any of its isomers, and therefore values ​​given in concentration for the amount of vanillin / isovanillin present should be understood as the sum of the concentrations of vanillin and of all the different vanillin isomers, such as isovanillin and any other vanillin isomers.

[0093] In another preferred embodiment, the antioxidant composition of the present invention comprises less than 5.2% methyl vanillate, more preferably less than about 4.3% methyl vanillate.In another preferred embodiment, the antioxidant composition of the present invention comprises less than 1% methyl vanillate.

[0094] In another preferred embodiment, the antioxidant composition of the present invention has a phenolic OH content expressed as milliequivalents of gallic acid per gram of sample of 600-800 mGAE / g, preferably 650-800 mGAE / g. In a more preferred embodiment, when the starting material is proceeded from hardwood, the antioxidant composition has a phenolic OH content expressed as milliequivalents of gallic acid per gram of sample of about 685 mGAE / g. In another preferred embodiment, when the starting material is proceeded from softwood, the antioxidant composition has a phenolic OH content expressed as milliequivalents of gallic acid per gram of sample of 770 mGAE / g.

[0095] In other preferred embodiments, the antioxidant composition of the present invention, when derived from hardwood, comprises one or more compounds selected from the group consisting of dihydroxybenzoyl)oxy-hydroxybenzoic acid, methyl vanillate, vanillic acid, decarboxyellagic acid, protocatechuic aldehyde, 2-carboxysyringaldehyde / syringylglycoxalic acid, syringaldehyde, vanillyl lactic acid, taxifolin, pyrocatechol, vanillin / isovanillin, 1-syringoyl-1,2-dihydroxyethane, homosyringic acid, syringyl alcohol diacetate isomer 3, acetosyringone isomer 1, 5-syringovanillic acid, vanillin / isovanillin, dimethyl m-hemipate / dimethyl isohemipicate, 5-hydroxyguaiacyl-guaiacylbenzodioxane dimer, and coumaryl alcohol / acetoxybenzaldehyde.

[0096] In a more preferred embodiment, the antioxidant composition comprises dihydroxybenzoyl)oxy-hydroxybenzoic acid dimer, methyl vanillate monomer, vanillic acid monomer, decarboxyellagic acid dimer, protocatechuic aldehyde monomer, 2-carboxysyringaldehyde / syringyl glycoxalic acid monomer, syringaldehyde monomer, vanillyl lactic acid monomer, taxifolin dimer, pyrocatechol monomer, vanillin / isovanillin monomer, 1-syringoyl-1,2-dihydroxyethane monomer, homosyringic acid monomer, syringyl alcohol diacetate isomer 3 monomer, acetosyringone isomer 1 monomer, 5-syringovanillic acid (syringovanillic acid dimer), 5-syringovanillic acid (5- ... acid dimer, vanillin / isovanillin monomer, dimethyl m-hemipate / dimethyl isohemipic acid monomer, 5-hydroxyguaiacyl-guaiacylbenzodioxane dimer, and coumaryl alcohol / acetoxybenzaldehyde monomer.

[0097] Characterization of the antioxidant composition can be performed by any method known in the art, for example high performance liquid chromatography coupled with time-of-flight mass spectrometry (HPLC-ESI-QTOF-MS / MS), as more particularly described in the experimental section of this specification.

[0098] In another preferred embodiment, the antioxidant composition of the present invention, when derived from hardwood, comprises about 7-10%, more preferably about 8.3%, of dihydroxybenzoyl)oxy-hydroxybenzoic acid, more preferably as a dimer.

[0099] In another preferred embodiment, the antioxidant composition of the present invention comprises about 6-7%, more preferably 5.2%, of methyl vanillate, more preferably as a monomer, when derived from hardwood.

[0100] As used herein, the terms "monomer," "dimer," and "trimer" are used to define compounds having one, two, or three aromatic rings, respectively.

[0101] [Table 1]

[0102] In other preferred embodiments, the antioxidant composition of the present invention, when derived from softwood, comprises one or more compounds selected from the group consisting of one or more compounds set forth in Table 1. In some embodiments, the antioxidant composition of the present invention, when derived from softwood, comprises one or more compounds selected from the group consisting of vanillyl lactate, protocatechualdehyde, methyl tri-O-methyl gallate, pyrocatechol, methyl tri-O-methyl gallate, vanillin / isovanillin, 1,2,3-propanetriol, 1-[4-[[2-(4-hydroxy-3-methoxyphenyl)ethenyl]oxy]-3-methoxyphenyl] / ethanone, 1-[4-hydroxy-2-[(4-hydroxy-3,5-dimethoxyphenyl)methyl]-3,5-dimethoxyphenyl], 4-hydroxycinnamyl alcohol 4-β-D-glucoside, vanillyl mandelic acid, 4-hydroxycinnamyl alcohol 4-β 1,2-Dimethyl 3,4,5-trimethoxy-1,2-benzenedicarboxylate, Methyl vanillate, Hydroxybenzaldehyde, 1-Methoxy-1-(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)-3-propanol / 1-Methoxy-1-(3,4,5-trimethoxyphenyl)-2-(2-methoxyphenoxy)-ethane, Coumaryl alcohol / acetoxybenzaldehyde ethyl vanillin and 4-Hydroxycinnamyl alcohol 4-β-D-glucoside.

[0103] In another preferred embodiment, the antioxidant composition of the present invention, when derived from softwood, is selected from the group consisting of vanillyl lactic acid monomer, protocatechuic aldehyde monomer, methyl tri-O-methyl gallate, pyrocatechol monomer, vanillin / isovanillin monomer, 1,2,3-propanetriol dimer, 1-[4-[[2-(4-hydroxy-3-methoxyphenyl)ethenyl]oxy]-3-methoxyphenyl] / ethanone, 1-[4-hydroxy-2-[(4-hydroxy-3,5-dimethoxyphenyl)methyl]-3,5-dimethoxyphenyl] dimer, 4-hydroxycinnamyl alcohol 4-β-D-glucoside dimer, vanillyl mandelic acid monomer, 4-hydroxycinnamyl alcohol 4-β-D-glucoside dimer, , coumaryl alcohol / acetoxybenzaldehyde monomer, 1,2-dimethyl 3,4,5-trimethoxy-1,2-benzenedicarboxylate monomer, methyl vanillate, hydroxybenzaldehyder, 1-methoxy-1-(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)-3-propanol / 1-methoxy-1-(3,4,5-trimethoxyphenyl)-2-(2-methoxyphenoxy)-ethane dimer, coumaryl alcohol / acetoxybenzaldehyde monomer, ethyl vanillin monomer, and 4-hydroxycinnamyl alcohol 4-β-D-glucoside dimer.

[0104] In a more preferred embodiment, the antioxidant composition of the present invention comprises about 6-8%, more preferably about 7.4%, of vanillyl lactate isomer 2, more preferably as a monomer, when derived from softwood.

[0105] In another preferred embodiment, the antioxidant composition of the present invention comprises about 3.5-5%, more preferably about 4%, of protocatechuic aldehyde, more preferably as a monomer, when derived from softwood.

[0106] In a more preferred embodiment, the amount of the compounds is determined by HPLC-ESI-QTOF-MS / MS. In one embodiment, the composition of the invention obtained from hardwood is characterized by containing the phenolic compounds shown in Table 1, each compound being present in a concentration (in % w / w) at least as great as the amount present in Table 1.

[0107] [Table 2-1] [Table 2-2]

[0108] In other preferred embodiments, the antioxidant composition of the present invention, when derived from hardwood, comprises one or more compounds selected from the group consisting of one or more compounds set forth in Table 2.

[0109] In a more preferred embodiment, the antioxidant composition of the present invention comprises methyl vainillate as a monomer. In another preferred embodiment, the antioxidant composition of the present invention comprises taxifolin as a dimer. In another preferred embodiment, the antioxidant composition of the present invention comprises 5-hydroxyguaiacyl-guaiacylbenzodioxane as a trimer.

[0110] In one embodiment, the softwood derived composition of the invention is characterized by containing the phenolic compounds shown in Table 2, each compound being present in a concentration (in % w / w) at least as great as the amount present in Table 2.

[0111] In another preferred embodiment, the antioxidant composition of the present invention obtained from hardwood comprises about 70-75%, preferably 71.9%, of monomer, about 35-30, preferably 27.4%, of dimer and about 1-2%, preferably 0.7%, of trimer.

[0112] In another preferred embodiment, the antioxidant composition of the present invention obtained from softwood is composed of about 80-85%, more preferably 81.6%, monomer, about 17-18%, preferably 17.3%, dimer and about 1-2%, preferably 1.1%, trimer.

[0113] The antioxidant compositions of the present invention may contain one or more additional ingredients. In some embodiments, the antioxidant compositions of the present invention do not contain additional ingredients that substantially affect the properties of the composition, particularly the antioxidant properties.

[0114] The antioxidant compositions obtained by the process of the present invention may be utilized in any application where inhibition of oxidation is required.

[0115] The skilled artisan will understand that the antioxidant composition of the present invention may be part of a food or feed, or part of a nutraceutical, pharmaceutical or cosmeceutical product or cosmetic composition, constituting an additional aspect of the present invention. Thus, a further aspect of the present invention relates to a food, feed, pharmaceutical, cosmeceutical, cosmetic or nutraceutical product comprising the antioxidant composition of the present invention. The product may be in liquid, semi-solid or solid form.

[0116] In a preferred embodiment, the antioxidant composition obtained by the method of the present invention is heavy metal free. In another preferred embodiment, the antioxidant composition obtained by the method of the present invention is pathogen free.

[0117] As used herein, "heavy metal" refers to any metallic chemical element that is relatively dense and toxic or poisonous even at low concentrations. Examples of heavy metals include mercury (Hg), cadmium (Cd), arsenic (As), chromium (Cr), thallium (Tl) and lead (Pb).

[0118] As used herein, a "pathogen" is an organism capable of causing disease in a host, particularly a human. The World Health Organization (WHO) lists potentially harmful bacteria, viruses, toxins and parasites among the hazards that may be present in food.

[0119] Thus, in one aspect, the present invention relates to an antioxidant composition of the present invention for use as an ingredient in a food or feed formulation.Furthermore, the present invention relates to a food or feed comprising the antioxidant composition of the present invention.

[0120] The term "food" as used herein is any substance or manufacture of any nature, solid or liquid, natural or processed, which, depending on its characteristics, use, constituents, preparation and storage conditions, can usually or ideally be used for some of the following purposes: a) as normal nutrition or as a pleasurable food for humans or animals; or b) as a dietary product, in particular as a food for humans or animals. The term "feed" encompasses natural materials of any origin and final products, separate or conveniently mixed together, suitable as food for animals.

[0121] A ready-to-eat food is one that does not require dilution, for example with an aqueous solution suitable for consumption. In principle, the ingredients present in a ready-to-eat food are balanced and no additional ingredients, as would be considered by a person skilled in the art, are required to make the food ready to consume. A concentrated food is one in which one or more ingredients are present in a higher concentration than in a ready-to-eat food and therefore requires dilution, for example with an aqueous solution suitable for consumption, in order to use it. Non-limiting examples of preferred food products provided by the present invention include both dairy products and secondary products, such as fermented milk, yogurt, kefir, curd, cheese, butter, ice cream, milk-based desserts, etc., as well as non-dairy products, such as baked products, cakes and pastries, cereals, chocolates, jams, fruit juices, other fruit-derived products, oils and margarines, prepared dishes, etc.

[0122] In another specific embodiment, the present invention is a nutraceutical product comprising the antioxidant composition of the present invention and a nutraceutical acceptable carrier. The present invention further relates to the use of the antioxidant composition of the present invention as an ingredient in a nutraceutical product.

[0123] The term "nutraceutical product" as used herein refers to a product suitable for human or animal use, comprising one or more natural products with therapeutic effects that provide health benefits or are related to the prevention or reduction of disease, and also includes dietary supplements, which are concentrates of biologically active natural products that are normally present (or not) in food, provided in non-food matrices (e.g. capsules, powders, etc.), and when taken in doses higher than those present in normal foods, have a positive health effect that is higher than that which such foods can provide.Thus, the term "nutraceutical product" includes, in addition to isolated or purified food products, additives or food supplements that are generally presented in dosage forms that are usually used orally, such as capsules, tablets, sachets, drinkable vials, etc.; such products provide physiological benefits or provide protection from diseases, generally chronic diseases. Optionally, the nutraceutical products provided by the present invention may contain, in addition to the antioxidant composition of the present invention, one or more nutraceuticals (products or substances related to the prevention or reduction of disease), such as flavonoids, omega-3 fatty acids, etc., and / or one or more prebiotics (non-digestible food ingredients that stimulate the activity and / or growth of probiotics), such as fructooligosaccharides, pectin, inulin, galactooligosaccharides, lactulose, human milk oligosaccharides, dietary fiber, etc.

[0124] In another particular embodiment, the product of the present invention is a cosmeceutical product comprising the antioxidant composition of the present invention and a cosmetically acceptable vehicle or carrier. The present invention further relates to the use of the antioxidant composition of the present invention as an ingredient in a cosmeceutical product.

[0125] The term "cosmeceutical product" as used herein refers to a product suitable for use on the human or animal body, comprising one or more cosmeceutical products (functional, dermatological or active), i.e. topical hybrid products that combine cosmetic and pharmaceutical characteristics, containing higher and more effective concentrations of active ingredients that provide benefits to the skin, hair and / or nails of the user, and thus are intermediate between cosmetics and medicines. Preferred examples of cosmeceutical products include essential oils, ceramides, enzymes, minerals, peptides, vitamins, etc.

[0126] The present invention relates to a cosmetic composition comprising the antioxidant composition of the present invention and a cosmetically acceptable carrier or medium. The present invention also relates to the use of the antioxidant composition of the present invention for use as a component of a cosmetic formulation.

[0127] As used herein, "cosmetic composition" refers to a composition comprising one or more products suitable for use in the personal hygiene of a human or animal, or for use in enhancing natural beauty or changing the appearance of the human or animal body without affecting its structure or function, and providing such an effect. Optionally, the cosmetic composition provided by the present invention can contain, in addition to the antioxidant composition of the present invention, one or more cosmetics or cosmetic products, i.e. substances or mixtures intended for contacting the external parts of the human or animal body (e.g., the epidermis, hair system, nails, lips, etc.), or the teeth and buccal mucosa, for the sole or main purpose of cleaning them, perfume them, modifying their appearance, protecting them, keeping them in good condition, or regulating body odor. Preferred examples of cosmetically acceptable vehicles include products listed in the INCI (International Nomenclature of Cosmetic Ingredients) list. The antioxidant compositions of the present invention can be added to a wide variety of products for use in cosmetic applications, such as make-up, creams for cleaning, protecting, treating or caring for the skin, particularly the face, hands and feet (e.g., day and night creams, make-up remover creams, cream foundations and sunscreens), liquid foundations, make-up remover lotions, body lotions for protection or skin care, sunscreen lotions, skin care lotions, gels or foams, such as cleansing, sunscreen and artificial tanning lotions, bath additives, deodorant compositions, aftershave gels or lotions, hair removal creams and compositions used to relieve insect bites and pain. The antioxidant compositions of the present invention can take any of a wide variety of forms, such as, for example, dressings, lotions, solutions, sprays, creams, gels, ointments or the like.

[0128] The present invention further relates to a pharmaceutical product comprising the antioxidant composition of the present invention and a vehicle or carrier suitable for oral, topical or parenteral administration. The present invention also relates to the use of the antioxidant composition of the present invention as a component of a pharmaceutical composition.

[0129] As used herein, "pharmaceutical composition" refers to physiologically acceptable compositions and molecular species.Preferably, the term "pharmaceutical acceptable" means approved by a state or federal regulatory agency or listed in the US Pharmacopoeia or other generally recognized pharmacopoeias for use in animals, more specifically in humans.

[0130] Pharmaceutically acceptable carriers or vehicles are known to those skilled in the art and are readily available to the public.

[0131] Depending on the particular mode of administration, the pharmaceutical products can be formulated into solid, liquid, injectable or topical dosage forms.

[0132] The solid dosage form for oral administration can include conventional capsules, sustained release capsules, conventional tablets, sustained release tablets, chewable tablets, sublingual tablets, effervescent tablets, pills, suspensions, powders, granules and gels.In these solid dosage forms, the active compound can be mixed with at least one inert excipient such as sucrose, lactose, starch, etc.This type of dosage form can also comprise additional substances other than inert diluents, such as magnesium stearate, as is commonly done.In the case of capsules, tablets, effervescent tablets and pills, the dosage form can also comprise a buffering agent.Tablets and pills can be formulated with enteric coating.

[0133] Liquid dosage forms for oral administration may include pharma- ceutically acceptable emulsions, solutions, suspensions, syrups, and elixirs, containing inert diluents, such as water, commonly used in this art. These compositions may also contain auxiliary agents, such as wetting agents, emulsifying and suspending agents, and sweeteners, flavoring agents, and perfuming agents.

[0134] Injectable preparations, for example, aqueous or oily suspensions, sterile injections can be formulated using suitable dispersants, wetting agents and / or suspending agents according to known techniques.Among acceptable vehicles and solvents that can be used, water, Ringer's solution and isotonic sodium chloride solution can be used.Sterile oils are also conventionally used as solvents or suspension media.

[0135] For topical administration, the pharmaceutical compositions of the present invention may be formulated as creams, gels, hydrogels, lotions, liquids, pomades, spray lotions, dispersions, solid bars, emulsions, microemulsions, and the like, in accordance with conventional methods using suitable excipients such as emulsifiers, surfactants, thickeners, colorants, and combinations of two or more of these.

[0136] Hydrocarbon fuels, gasoline, jet fuel and fuel oils are all susceptible to autoxidation. Antioxidants minimize lubricant deterioration by retarding viscosity increase, metal corrosion and the formation of acids, sludge, resins and lacquers. Commercial organic polymers such as thermoplastics, elastomers, synthetic fibers and adhesives are all susceptible to oxidation degradation during processing and end use. Thus, the present invention also relates to the use of the antioxidant composition of the present invention as an ingredient in plastic, rubber, latex, fuel or lubricant formulations. The present invention also relates to plastic, rubber, latex, fuel or lubricant formulations comprising the antioxidant composition of the present invention.

[0137] All particular embodiments of the method of the present invention are also applicable to this aspect of the invention.

[0138] The present invention is further illustrated by the following examples, which should not be construed in any way as limiting the scope of the invention. EXAMPLES

[0139] material All reagents used were of analytical grade. Most were supplied by SCHARLAB: NaOH, H 2 SO4, ethyl acetate, FCR, Na 2 CO 3 , DPPH, methanol, gallic acid, BHT, and poly(styrenesulfonic acid) sodium salt standard. Water was mQ grade (Milli Q Gradient; Millipore).

[0140] N 2 , O 2 Gases such as air (industrial grade) were provided by Nippon Gases.

[0141] Example 1 - Obtaining an antioxidant composition The feed to the reactor is a mixture of kraft lignin (typically 60 g / l) and sodium hydroxide (typically 60 g / l) using deionized water as the solvent.

[0142] The functionalization process is carried out by feeding the solution into a heated and pressurized reactor made of 316 stainless steel vessel with an internal volume of 2 L. The reaction process conditions are 240 °C and PT 3.8 MPa. The oxidant gas (air) is injected through a ceramic disperser placed 1 cm above the bottom of the vessel at a flow rate of 10-30 l / h, regulated by a mass flow controller. The internal temperature of the reactor is regulated by an internal thermocouple connected to an external ceramic heating jacket. The total pressure inside the reactor is controlled by a back pressure valve. The residence time of the feed (10-15 min) is manipulated by a peristaltic pump and the reactor filling control. The outlet streams (gas and liquid) are cooled by a water-cooled condenser.

[0143] After cooling to room temperature, the solution is fractionated by tangential flow filtration. The feed is pumped to a membrane module in which a membrane made of PES material with a cutoff size of 3000 Da is placed. The feed is pumped to a pressure of at least 0.5 MPa and a maximum of 1.5 MP, ensuring a minimum cross-flow velocity of at least 0.1 m / s. The feed is split into two streams by the membrane module. The permeate is the fraction of the feed that crosses the membrane and contains the lower molecular weight functionalized kraft lignin, i.e. the product (antioxidant). The other fraction, the retentate, is continuously recycled to the feed tank of the membrane module, with a volumetric concentration factor of up to 5-8 times. The final retentate is enriched in the high molecular weight fraction, while the entire permeate is collected for down-processing.

[0144] The pH of the permeate is adjusted to pH 2-5 with 2 M sulfuric acid. The next step is a liquid-liquid extraction using ethyl acetate as the organic solvent. The extraction is carried out in two stages in a countercurrent column (0.25 L) packed with glass spheres at a flow rate of 50-250 mL / min. The organic solvent is then recovered by distillation of the organic phase. For this purpose, a rotary evaporator (R-300; Buchi) is used, operated at a temperature of 75-80 °C and at normal pressure. The distillation temperature is 1000 mL / min, and the solvent is then removed by distillation. 2 The temperature can be reduced by applying a reduced pressure in an atmosphere or even in an air atmosphere. The organic solvent-free solids are characterized.

[0145] Example 2 - Effect of reaction temperature on the yield of functionalized lignin The residence time was set to approximately 10 minutes or less, and the effect of reaction temperature on the radical scavenging activity (%) measured by DPPH and the product yield (%) calculated against the lignin load was investigated. As shown in Figure 3, both the product yield and antioxidant activity increased with increasing reaction temperature.

[0146] The effect of reaction time at a reaction temperature of 240 °C on relignitonization (%) and polydispersity ((PD):Mw / Mn) is shown in Figure 4. Relignitonization (%) was calculated in terms of the percentage change in recombination or formation of lignin fractions with molecular weights above 2500 Da relative to the optimum (t = 10 min). Both relignitonization and polydispersity index increased as a function of residence time, with the effect becoming evident for residence times greater than 30 min.

[0147] Example 3 - Characterization of antioxidant compositions The resulting products are physicochemically characterized based on several analytical methods such as total organic matter, ash content, molecular size, chemical analysis, etc. The product yields are determined by mass balance based on the initial charge of kraft lignin in the reactor feed, and the characteristics of the volumetric fractionated streams are measured at each step along the procedure as follows: Total solids (dry matter) is determined by drying in a laboratory oven (ED-115; Binder) at 105°C until constant weight is reached. Similarly, the inorganic solids content (ash content) is determined by calcining in a ceramic crucible at 850 °C for 5 h in a muffle furnace (BWF 11 / 13; Carbolite). The organic matter (functionalized kraft lignin) content is calculated from the difference of the above mentioned parameters. · The molecular size distribution of the soluble solids and their polydispersity are determined by size exclusion chromatography (HP-SEC) (1260 Infinitty II; Agilent Technologies). Samples are diluted with 0.1 M NaOH and analyzed on a HPLC equipped with two PSS MCX GP-SEC columns (molar mass range: 100-70000 Da; dimensions 5 μm, 1000 Å) using a refractive index detector (RID). Calibration is set up using eight poly(styrenesulfonic acid) sodium salt standards ranging from 246 Da to 14900 Da. · Identification of the chemical structures of the compounds of the antioxidant composition and the ratio of monomers, dimers and trimers are evaluated by high performance liquid chromatography coupled with time-of-flight mass spectrometry (HPLC-ESI-QTOF-MS / MS) (Agilent 1260 HPLC equipped with a 4.6 x 150 mm Agilent Zorbax Eclipse Plus C18 column, 1.8 μm particle size; Agilent 650 UHD Accurate Mass Q-TOF, ESI Jet Dual Stream interphase). Samples are dissolved in methanol (10 mg / mL) and the mobile phase is water and acetonitrile with 0.1% formic acid. Other parameters used are: capillary voltage 4000 V, nebulizer pressure 20 psig, fragmentor voltage 130 V, nozzle voltage 500 V, skimmer voltage 45 V, octopole voltage 750 V.

[0148] Characterization of the antioxidant properties of the resulting products is performed by two spectrophotometric methods; Total Phenolic Content (TPC) (El Rayess et al., 2014 Wine: Phenolic Composition, Classification and Health Benefits (pp.71-102) Chapter: 3 pp 71-102) and DPPH free radical scavenging capacity (Brand-Williams et al., 1995 Food Science and Technology, 28(1), 25-30; Dizhbite et al., 2004 Bioresource Technology, 95(3), 309-317). Both are widely used spectrophotometric methods in the scientific literature on lignin derivatives and antioxidants. The TPC method measures the amount of phenolic groups in a sample based on its reaction with a Mo / W compound called Folin-Ciocalteau reagent (FCR). 2 CO 3The sample is added to the solution and after 1 h in the dark, the absorbance of the sample is measured at 765 nm using a spectrophotometer (Genesys 10UV, Thermo Spectronic). This value is correlated with the content of phenolic groups by a standard (e.g. gallic acid). The DPPH method measures the ability of a sample to scavenge model free radicals based on the degree of color change. The sample is diluted with methanol and 1 mL of a 0.16 mM solution of DPPH in methanol is added. After 2 hours, the absorbance at 517 nm is measured with a spectrophotometer (Genesys 10UV, Thermo Spectronic). The results are expressed as ARP or mM DPPH neutralized per mg of sample and compared with other commercially available antioxidants: BHT (E-321, CAS 128-37-0), TBHQ (E-319, CAS 1948-33-0), Irganox 1010 (CAS 6683-19-8), α-tocopherol (E-307, CAS 59-02-9) and rosemary extract (E-392, CAS 84604-14-8).

[0149] The antioxidant composition obtained using the method of the present invention is characterized by: The antioxidant activity evaluated by the DPPH method (RSA, radical scavenging activity) was 1.5 times higher than that of commercial BHT (synthetic antioxidant) and 2 times higher than that of kraft lignin. The antioxidant activity of the composition of the present invention is significantly higher than that of other natural antioxidants such as tocopherol and rosemary extract. The total phenol content, evaluated by the Folin-Ciocalteau method, is 2.25 times higher than that of kraft lignin. The Mw and PD measured by HPLC-RID using 0.1 M NaOH as the mobile phase are 715 Da and 2.

[0150] Example 4 - Further characterization of antioxidant compositions The identification of the compounds was carried out by high performance liquid chromatography coupled with electrospray ionization and quadrupole time-of-flight mass spectrometry (HPLC-ESI-QTOF-MS). Many of the identified compounds are known for their antioxidant effect and can be classified into monomeric, dimeric and trimeric molecules based on the number of aromatic rings. The products obtained from hardwood consisted of 71.9% monomer, 27.4% dimeric and 0.7% trimer, whereas the products obtained from softwood consisted of 81.6% monomer, 17.3% dimeric and 1.1% trimer.

[0151] Based on the identification of the monomeric, dimeric and trimeric moieties, the product mass distribution was determined for each wood (hardwood or softwood) from which the lignin originated, as shown in Tables 1 and 2, with an average molar mass corresponding to each component. The presence of phenolic OH in the samples was determined by the TPC method and expressed as milliequivalents of gallic acid per gram of sample, amounting to 685 and 770 mGAE / g for HW (hardwood) and SW (softwood).

Claims

1. 1. A method for producing an antioxidant composition from lignin, lignin liquor, or black liquor, comprising contacting the lignin, lignin liquor, or black liquor with an oxidizing agent, wherein the contacting is carried out at a temperature above 160°C under alkaline conditions, and wherein when the oxidizing agent is oxygen, a gas mixture comprising oxygen, or an oxygen-generating compound or composition, the agent is added such that the oxygen partial pressure is less than 0.3 MPa.

2. 10. The method of claim 1, wherein the residence time is less than 15 minutes.

3. 3. The method of claim 1 or 2, wherein the starting material is kraft lignin.

4. The method of claim 1, wherein the oxidizing agent is selected from the group consisting of oxygen, a gas mixture comprising oxygen, or an oxygen-generating compound or composition.

5. The gas mixture comprising oxygen is air, and / or the oxygen generating compound or composition is ozone, hydrogen peroxide, deionized water, O ２ 5. The method of claim 4, wherein the solvent is selected from the group consisting of plasma and alcohol.

6. 6. The method according to claim 5, wherein air is used as the oxygen-containing gas mixture.

7. 10. The method of claim 1, wherein the alkaline conditions are achieved with an Arrhenius base selected from the group consisting of sodium hydroxide and sodium carbonate.

8. 8. The method of claim 7, wherein the Arrhenius base is sodium hydroxide.

9. 9. The method of claim 8, wherein the concentration of sodium hydroxide is from 2 to 80 g / l.

10. 2. The method of claim 1, wherein the temperature is from 160 to 260°C.

11. 2. The method of claim 1, wherein the total pressure is 2 to 5.5 MPa.

12. 10. The method of claim 1, wherein the pH is greater than 10.

13. 2. The method of claim 1, wherein the starting material is kraft lignin at a concentration of 7 to 100 g / l.

14. 10. The method of claim 1, further comprising fractionating said composition based on the molecular weight of said compounds forming part of said composition.

15. 15. The method of claim 14, wherein the cutoff molecular weight of the fraction is at least 1000 Da.

16. 15. The method of claim 14, further comprising purifying one or more antioxidant products from the low molecular weight fraction obtained after said size fractionation.

17. 10. An antioxidant composition obtainable by the process of claim 1.

18. 18. The antioxidant composition of claim 17, having a molecular weight (Mw) of 650 to 850 Da and / or a polydispersity index of less than 2.

2.

19. 19. Use of the antioxidant composition of claim 17 or 18 as an ingredient in cosmetic, pharmaceutical, plastic, rubber, latex, fuel, lubricant or food formulations.

20. 19. A cosmetic, pharmaceutical, plastic, rubber, latex, fuel, lubricant, food formulation or feed formulation comprising the antioxidant composition of claim 17 or 18.

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