METHOD FOR THE TREATMENT OF A COMPOSITION COMPRISING NATURAL VANILLIN.

Abstract

The invention relates to a method for treating a composition comprising natural vanillin by separating a compound of formula (I). (see Formula).

Description

METHOD FOR THE TREATMENT OF A COMPOSITION COMPRISING NATURAL VANILLIN This application claims priority over the patent application filed on July 30, 2019 in France under number 1908644, the content of which is incorporated in full by reference. Field of invention The present invention relates to a process for treating a composition comprising natural vanillin by separating a compound of formula (I). Previous technique Vanillin, or 4-hydroxy-3-methoxybenzaldehyde, can be obtained by various methods known to a person skilled in the art, in particular by the following three routes: - A natural pathway based on a biotechnological process comprising, in particular, the cultivation of a microorganism capable of bioconverting a fermentation substrate into vanillin. Such a process, in which the fermentation substrate is ferulic acid, is known, in particular, from application EP 0 885 968. The ferulic acid used can be of various origins, in particular, derived from rice bran or corn bran. These processes result in the preparation of a vanillin called natural vanillin. - A synthetic route involving conventional chemical reactions starting with guaiacol that do not involve a microorganism. This process results in the preparation of a vanillin called synthetic vanillin. Finally, vanillin can also be prepared according to a pathway described as biologically based in which the vanillin is derived from lignin; in particular, we can mention documents US 2745796, DE 1132113 and the article entitled Preparation of lignin from wood dust as vanillin source and comparison of different extraction methods by Azadbakht et al. in International Journal of Biology and Biotechnology, 2004, Vol. 1, No. 4, pp. 535-537, starting from eugenol. When the natural process is used for the industrial production of vanillin, several side reactions can occur, leading to the formation of numerous byproducts that can negatively affect the organoleptic properties of natural vanillin. These byproducts are also capable of reacting, particularly with vanillin. As a result, the purification yield of natural vanillin, and the overall production yield of natural vanillin, is reduced. The organoleptic properties of natural vanillin are also susceptible to degradation. Furthermore, natural vanillin can be purified. For example, WO 2018 / 146210 describes a process for purifying natural vanillin comprising at least one stage of separating a liquid stream comprising natural vanillin with a carrier gas and / or a vaporized liquid. Although this process makes it possible to satisfactorily purify natural vanillin, vanillic alcohol is not satisfactorily removed. The present invention aims to provide an effective solution to avoid side reactions with natural vanillin, to improve the overall performance of natural vanillin purification, while maintaining, or even improving, its organoleptic properties. Brief description Therefore, a first object of the present invention relates to a process for treating a composition (C) resulting from a process for producing natural vanillin comprising natural vanillin and vanillic alcohol, comprising: a step (i) of forming a compound of formula (I) from vanillic alcohol: [Chemical formula 1] where n equals 0 or 1, and R is chosen from a linear or branched, saturated or unsaturated alkyl group, optionally substituted with at least one hydroxyl, alkoxy, or amine group, or R is a group of formula -(WO)mX, where W is a linear or branched alkyl chain comprising 1 to 4 carbon atoms and the average molecular weight of the -(WO)m- group is between 200 and 3000 g / mol and X is chosen from H and a unit of formula (II) [Chemical formula 2] where step (i) is carried out in the presence of natural vanillin and allows the formation of a composition (Cl) or (C2); a step (ii) of natural vanillin recovery and / or a step of recovery of a compound of formula (I), which are present in composition (Cl) or (C2). Another aspect relates to a process for purifying a composition comprising natural vanillin and vanillic alcohol by separating a compound of formula (I) · The present invention also relates to a process for preparing a compound of formula (I) in the presence of natural vanillin. Finally, the present invention relates to the use of a natural vanillin composition as a flavoring agent in the field of human and animal nutrition, in pharmaceuticals, and as a fragrance in the cosmetics, perfumery, and detergent industries. Detailed description In the context of the present invention, unless otherwise stated, the expression between ... and ... includes the limits. Unless otherwise stated, percentages and ppm are percentages and ppm by weight. In the context of the present invention, unless otherwise stated, the term ppm means parts per million. This unit represents a weight fraction: 1 ppm = 1 mg / kg. In the context of the present invention, unless otherwise indicated, the term "natural vanillin" may denote a flavoring substance in accordance with Article 9.2(c) of Regulation (EC) No 1334 / 2008, that is, a flavoring substance obtained by physical, enzymatic, or microbiological processes from materials of plant, animal, or microbiological origin, taken as is or after conversion for human consumption by one or more of the conventional processes for the preparation of foodstuffs. A natural flavoring substance corresponds to a substance that is naturally occurring and has been identified in nature. Definitions provided by regulations in force in other countries or regions may also apply. Preferably, the term "natural vanillin" according to the present invention denotes vanillin obtained by a biotechnological process.According to another alternative, the term "natural vanillin" denotes vanillin obtained by a microbiological process, in particular, comprising the cultivation of a microorganism capable of converting a fermentation substrate into vanillin. According to the invention, the microorganism may be wild-type or genetically modified, in particular, to improve performance, for example, to enhance vanillin yield, to limit or prevent the formation of byproducts, or to increase productivity. Most preferably, this is a process for the fermentation of ferulic acid, as described in patent application EP 0 885 968. The ferulic acid may be of any origin, in particular, derived from rice bran, beet pulp, wheat bran, bagasse, sugarcane, or corn, in particular, corn bran or corn fibers, in particular, from starch mills or nixtamalization units. In the context of the present invention, the term alkyl represents a linear or branched, saturated or unsaturated chain. Preferably, an alkyl group comprises from 1 to 10 carbon atoms, preferably from 1 to 8 carbon atoms, and more preferably from 1 to 6 carbon atoms. An alkyl group may preferably be selected from the group consisting of methyl, ethyl, propyl, isopropyl, n-butyl, s-butyl, and tert-butyl. According to one particular aspect, the alkyl group may be substituted with at least one hydroxyl group. For example, the alkyl group substituted with at least one hydroxyl group may be -CH₂-CH(OH)-CH₂-OH. Therefore, a first object of the present invention relates to a process for treating a composition (C) resulting from a process for producing natural vanillin comprising natural vanillin and vanillic alcohol, said treatment process comprising: a step (i) of forming a composition C1 comprising natural vanillin and a compound of formula (I) from said vanillic alcohol present in composition (C): [Chemical formula 3] where n equals 0 or 1, and R is chosen from a linear or branched, saturated or unsaturated alkyl group, optionally substituted with at least one hydroxyl, alkoxy, or amine group, or a group of formula -(WO)mX, where W is a linear or branched alkyl chain comprising 1 to 4 carbon atoms and the average molecular weight of the (WO)m- group is between 200 and 3000 g / mol and X is chosen from H and a unit of formula (II) [Chemical formula 4] Formula (Π) a step (ii) of recovery of natural vanillin and / or a step of recovery of a compound of formula (I), which are present in composition (Cl) or (C2). Preferably, n is equal to 0 and / or R is a butyl group. Therefore, the invention relates, in particular, to a process for treating a composition (C) comprising natural vanillin and vanillic alcohol in which - the composition (C) is derived from a process for producing natural vanillin - vanillic alcohol is converted into the compound of formula I above, and in which a natural vanilla composition is purified. According to the present invention, the weight concentration of natural vanillin in composition (C) is between 0.50% and 99%, preferably between 0.50% and 60%, preferably between 5% and 40% and even more preferably between 10% and 35% with respect to the weight of the natural vanillin composition resulting from a process for producing natural vanillin. According to the present invention, the composition (C) resulting from a process for producing natural vanillin comprises vanillic alcohol. Generally, the weight concentration of vanillic alcohol is between 0.1% and 5%, preferably between 0.5% and 4%, and even more preferably between 1% and 2.5% with respect to the weight of the natural vanillin composition (C) resulting from a process for producing natural vanillin. According to the present invention, composition (C) may also comprise at least one compound selected from vanillic acid, acetovanillone, guaiacol, and vinylguaiacol. Preferably, when composition (C) comprises acetovanillone, guaiacol is also present. The present invention may further comprise a preliminary fermentation step of a substrate, preferably ferulic acid, for the production of a composition resulting from a process for producing natural vanillin comprising vanillic alcohol. The fermentation may be carried out as described in EP 0 885 968. The fermentation is generally carried out in an aqueous medium. Composition (C) may be obtained from the fermentation medium or after treatment of the aqueous medium obtained directly at the end of the fermentation, making it possible, in particular, to remove the fermentation biomass. The composition (C) used according to the treatment process of the present invention is generally obtained at the end of the fermentation stage and, optionally, from the treatment of the aqueous medium obtained directly at the end of fermentation. Composition (C) may be in aqueous solution or in a water / solvent mixture, preferably a water / organic solvent mixture. The organic solvent is generally a food-grade solvent, in particular, a solvent listed on the FEMA GRAS list. Examples include ethanol, isopropanol, butanol, isobutyl alcohol, glycols, and acetates such as ethyl acetate and propyl acetate. Stage (i): According to the present invention, step (i) is a step for forming a compound of formula (I) according to the following formula: [Chemical formula 5] EITHER iviA / a / ¿u¿¿ / uui io i where n equals 0 or 1, and R is chosen from a linear or branched, saturated or unsaturated alkyl group, optionally substituted with at least one hydroxyl, alkoxy or amine group, or a group of formula -(WO)mX, wherein W is a linear or branched alkyl chain comprising 1 to 4 carbon atoms and the average molecular weight of the -(W-O)m- group is between 200 and 3000 g / mol and X is chosen from H and a formula unit (II) In general, the average molecular weight of the -(WO)m15 group is between 200 and 3000 g / mol, preferably greater than or equal to 300 g / mol, and more preferably greater than or equal to 350 g / mol. The average molecular weight of the -(WO)m- group is generally less than or equal to 2000 g / mol, preferably less than or equal to 1500 g / mol. The average molecular weight of the -(WO)m- group can be 400 g / mol or 600 g / mol. According to a preferred aspect, step (i) is a compound formation step of formula (la) according to the following formula: [Chemical formula 7] Formula (la) wherein R is chosen from a linear or branched, saturated or unsaturated alkyl group, optionally substituted 10 with at least one hydroxyl, alkoxy or amine group, or a group of formula -(WO)mX, wherein W is a linear or branched alkyl chain comprising 1 to 4 carbon atoms and the average molecular weight of the -(WO)m- group is between 200 and 3000 g / mol and X is chosen from H and a unit of formula (II) [Chemical formula 8] Formula (Π) According to another preferred aspect, step (i) is a compound formation step of formula (Ib) according to the following formula: [Chemical formula 9] ινΐΛ / a / zuzz / uu 1 idí Formula (Ib) wherein R is chosen from a linear or branched, saturated or unsaturated alkyl group, optionally substituted with at least one hydroxyl, alkoxy or amine group, or a group of formula -(WO)mX, wherein W is a linear or branched alkyl chain comprising 1 to 4 carbon atoms and the average molecular weight of the -(W-O)m~ group is between 200 and 3000 g / mol and X is chosen from H and a unit of formula (II) [Chemical formula 10] Formula (Π) According to the present invention, the R group is preferably selected from ethyl, n-butyl, n-propyl, i-propyl, i-butyl, optionally substituted with a hydroxyl group. Advantageously, the R group can be chosen from ethyl, n-butyl, OH-CH2-CH2-, OH-CH2-CH (CH3) -. In one variant, the R group is chosen from the above groups and further comprises CH2-CH(OH)-CH2-OH. According to a preferred aspect, the compound of formula (la) is chosen from the group consisting of compounds of formulas A to D: [Chemical formula 11] Formula (A) Formula (C) According to a formula (Ib), compounds are chosen from Formula (B) Formula (D) aspect between formulas E to H: [Chemical formula 12] preferred group that the compound consists of Formula (F) Formula (H) According to the present invention, step (i) is an etherification or esterification reaction of the vanillyl alcohol present in composition (C). The etherification or esterification reaction is carried out in the presence of natural vanillin. Advantageously, the etherification or esterification reaction is selective with respect to vanillin alcohol. The etherification or esterification reaction is advantageously carried out without degradation of the natural vanillin. In particular, less than 10% by weight of the natural vanillin present in composition (C) is degraded, preferably less than 5%, more preferably less than 1%, and even more preferably less than 0.1%. The amount of natural vanillin degraded can be calculated according to the following formula: (amount of natural vanillin initially in composition (C) - amount of natural vanillin remaining after step (i)) / (amount of natural vanillin initially in composition (C)). According to the present invention, the etherification or esterification reaction is carried out in the presence of a compound chosen from the group consisting of ROH, RCOOH and HO-(WO)mH, wherein R is chosen from a linear or branched, saturated or unsaturated alkyl group, optionally substituted with at least one hydroxyl, alkoxy or amine group and W is a linear or branched alkyl chain comprising 1 to 4 carbon atoms and the average molecular weight of the compound HO-(WO)mH is between 200 and 3000 g / mol. For example, the etherification reaction may comprise contacting the vanillic alcohol present in composition (C) with a compound of formula ROH, R being defined above. In particular, the esterification reaction may comprise contacting the vanillic alcohol with a compound of formula RCOOH, R being as defined above. Advantageously, the primary alcohol group of vanillyl alcohol reacts selectively with the compound of formula ROH or RCOOH in order to form the corresponding ether or ester of formula (I). Therefore, the invention relates in particular to a process for treating a composition (C) wherein a composition Cl is formed, the composition (C) comprising natural vanillin and vanillic alcohol, said treatment process comprising: - a step (i) in which composition (C) is brought into contact with a compound of formula ROH or RCOOH, R having the above definition, in order to form a compound of formula (I) as defined above and in order to obtain composition (Cl), said composition (Cl) comprising the compound of formula (I) and / or natural vanillin, and - a step (ii) of recovery and / or purification of a natural vanillin composition and / or a compound of formula (I) present in the composition of formula (I). Preferably, the treatment process according to the invention is a process in which step (i) is an etherification reaction carried out in the presence of a compound of formula ROH, R being a butyl group, and in which step (ii) is a step of recovering natural vanillin and / or recovering a compound of formula (I) having n = 0 and R being a butyl group. In general, the average molecular weight of the compound HO(WO)mH is between 200 and 3000 g / mol, preferably greater than or equal to 300 g / mol, and more preferably greater than or equal to 350 g / mol. The average molecular weight of the HO-(WO)mH group is generally less than or equal to 2000 g / mol, preferably less than or equal to 1500 g / mol. The average molecular weight of the HO-(WO)m~H group can be 400 g / mol or 600 g / mol. According to one particular aspect, the etherification or esterification reaction is carried out in the presence of a compound that can be used in the agri-food industry. According to the present invention, the reaction is carried out in the presence of an acid. The acid may be a strong acid. Preferably, the acid is selected from the group consisting of HCl, H₂SO₄, and para-toluenesulfonic acid (p-TsOH). The acid may also be a Lewis acid. Advantageously, sulfuric acid makes it possible to avoid the chlorination reaction of vanillin that can be observed with HCl. According to the present invention, the reaction can be carried out in the presence of a mineral compound that is in solid form and exhibits acidic properties, such as a zeolite, in particular, titanosilicate, silicalite, or oxides of silica, aluminum, titanium, or zirconium. In particular, the reaction can be carried out in the presence of the zeolites described in Angew. Chem. Int. Ed. 2007, 46, 298300. The reaction can also be carried out in the presence of a cation exchange resin, in particular, of the Amberlite type as described in document CN101165038. According to another particular aspect, the etherification or esterification reaction can be carried out enzymatically. According to the present invention, the acid is generally used in a catalytic amount. In general, the amount of acid used is between 0.001 equivalents and 0.9 equivalents with respect to the amount of vanillic alcohol present in the composition (C). According to the present invention, the reaction can be carried out at a temperature between 10 °C and 100 °C, preferably between 20 °C and 80 °C, preferably at a temperature less than or equal to 50 °C and more preferably at a temperature between 25 °C and 40 °C. According to the present invention, the reaction is generally carried out at atmospheric pressure. According to the present invention, at the end of step (i), a composition (Cl) is obtained comprising natural vanillin and a compound of formula (I). According to the present invention, the composition (Cl) may also comprise at least one compound selected from vanillic acid, vanillic alcohol, acetovanillone, guaiacol, and vinylguaiacol. Advantageously, the composition (Cl) comprises between 0.1 ppm and 500 ppm of vanillic alcohol, preferably the composition comprises less than 200 ppm of vanillic alcohol, more preferably less than 100 ppm and even more preferably less than 50 ppm. Advantageously, the weight ratio of vanillyl alcohol to vanillin in the composition (Cl) is less than or equal to 0.5, preferably less than or equal to 0.2, very preferably less than or equal to 0.1 and even more preferably less than or equal to 0.01. According to a particular aspect of the present invention, step (i) also allows the formation of a compound of formula (III), according to the following formula, from the vanillic acid present in composition (C): ML / a / ZUZZ / UU I Oí [Chemical formula 13] where n equals 0 or 1, and R is chosen from a linear or branched, saturated or unsaturated alkyl group, optionally substituted with at least one hydroxyl, alkoxy, or amine group, or a group of formula -(WO)mX, where W is a linear or branched alkyl chain comprising 1 to 4 carbon atoms and the average molecular weight of the -(WO)m- group is between 200 and 3000 g / mol and X is chosen from H and a formula unit (IV) [Chemical formula 14] The formation of compound (III) occurs in the presence of natural vanillin. The formation of compound (III) can be simultaneous with the formation of compound (I). According to one particular aspect, at the end of step (i), a composition (C2) is obtained comprising natural vanillin, a compound of formula (I) and / or a compound of formula (III). According to the present invention, the composition (C2) may also comprise at least one compound selected from vanillic acid, vanillic alcohol, acetovanillone, guaiacol and vinylguaiacol. Advantageously, composition (C2) comprises between 0.1 ppm and 500 ppm of vanillic alcohol, preferably comprising less than 200 ppm of vanillic alcohol, more preferably less than 100 ppm, and even more preferably less than 50 ppm. Advantageously, the weight ratio of vanillyl alcohol to vanillin in composition (C2) is less than or equal to 0.5, preferably less than or equal to 0.2, very preferably less than or equal to 0.1 and even more preferably less than or equal to 0.01. Advantageously, the weight ratio of vanillic acid to vanillin in composition (C2) is less than or equal to 0.5, preferably less than or equal to 0.2, very preferably less than or equal to 0.1, and even more preferably less than or equal to 0.01. Stage (ii): According to the present invention, step (ii) is a step of recovering natural vanillin and / or recovering a compound of formula (I), which are present in composition (Cl) or (C2). According to a first aspect, step (ii) allows for the recovery of natural vanillin. The natural vanillin obtained at the end of step (ii) is purified natural vanillin. In one variant, the natural vanillin obtained at the end of step (ii) is a composition comprising purified natural vanillin. According to the present invention, the natural vanillin obtained at the end of step (ii) comprises between 0.1 ppm and 500 ppm of vanillic alcohol, preferably the composition comprises less than 200 ppm of vanillic alcohol, more preferably less than 100 ppm and even more preferably less than 50 ppm. According to the present invention, the natural vanillin obtained at the end of step (ii) comprises between 0 and 200 ppm of 4-((4-hydroxy-3-methoxybenzyl)oxy)-3-methoxybenzaldehyde or 4-hydroxy-3-(4-hydroxy-3-methoxybenzyl)5-methoxybenzaldehyde. Preferably, the content of 4-((4-hydroxy-3-methoxybenzyl)oxy)-3-methoxybenzaldehyde or 4-hydroxy3-(4-hydroxy-3-methoxybenzyl)-5-methoxybenzaldehyde is less than or equal to 100 ppm, preferably less than or equal to 50 ppm, and more preferably less than or equal to 20 ppm. Preferably, the content of 4-((4-hydroxy-3-methoxybenzyl)oxy)-3-methoxybenzaldehyde or 4-hydroxy-3-(4-hydroxy-3-methoxybenzyl)-5-methoxybenzaldehyde is greater than or equal to 0.01 ppm and more preferably greater than or equal to 0.1 ppm. Advantageously, the treatment process according to the present invention also makes it possible to improve the overall performance of the treatment process compared to conventional purification methods. According to the present invention, the process may comprise an additional step (iii) in which the natural vanillin obtained at the end of step (ii) is shaped, preferably in the form of crystals, powder, beads or pearls. According to the present invention, the natural vanillin content at the end of step (ii) or (iii) is greater than or equal to 95%, preferably greater than or equal to 97%, very preferably greater than or equal to 99%, and even more preferably greater than or equal to 99.5%. Very preferably, the natural vanillin content at the end of step (ii) or (iii) is greater than or equal to 99.95%. According to the present invention, the natural vanillin at the end of step (ii) or (iii) is weakly colored. Preferably, the natural vanillin at the end of step (ii) or (iii) has a color of less than or equal to 400. Hazen, preferably less than or equal to 200 Hazen, more preferably less than or equal to 100 Hazen, very preferably less than or equal to 50 Hazen, and most preferably less than or equal to 20 Hazen. The color is measured in a 10 wt% ethanolic solution. Color measurements are performed using a Konica Minolta CM-5 spectrophotometer with a cuvette having an optical path length of 10 mm. Advantageously, the natural vanillin at the end of step (ii) or (iii) has conforming organoleptic properties, particularly in terms of visual appearance, texture, taste, or fragrance. Advantageously, the composition according to the present invention does not exhibit any off-flavors. Preferably, the organoleptic profile of the composition according to the present invention is at least equivalent to the organoleptic profile of natural vanillin extracted from pods. According to another aspect, step (ii) allows the recovery of the compound of formula (I). According to the present invention, the natural vanillin content in the compound of formula (I) is less than or equal to 200 ppm, preferably less than or equal to 100 ppm. According to the present invention, the natural vanillin content in the compound of formula (I) is greater than or equal to 0.1 ppm. According to another aspect, step (ii) allows for the recovery of natural vanillin, while the compound of formula (I) is not recovered. The compound of formula (I) may degrade during step (ii). According to another aspect, step (ii) comprises the recovery of natural vanillin and the recovery of the compound of formula (I). The steps for recovering natural vanillin and the compound of formula (I) can be carried out simultaneously or sequentially in any order. In particular, step (ii) allows the recovery of a compound of formula (I) in which n = 0 and R is a butyl group. According to the present invention, the purification yield of natural vanillin is greater than or equal to 75%, preferably greater than or equal to 80%, preferably greater than or equal to 90%, even more preferably greater than or equal to 95%, and very preferably greater than or equal to 99%. The purification yield of natural vanillin corresponds to the ratio between the amount of natural vanillin isolated at the end of step (ii) and the amount of natural vanillin in the composition (C). Step (ii) can be carried out by vacuum distillation, in particular in a falling film evaporator or a wet film evaporator in order to avoid thermal degradation phenomena. Step (ii) may be carried out, in particular, under the conditions described in document WO 2018 / 146210 or WO ιнΐЛ / a / zuzz / uu i idí 2014 / 114590. In one variant, step (ii) can be carried out in accordance with the conditions described in document EP 2 791 098. Preferably, when step (i) is carried out in the presence of an acid, the process according to the present invention may comprise an optional neutralization step at the end of step (i) and before step (ii). In one embodiment, the neutralization step is not optional and / or may be carried out during step (ii). The neutralization may be carried out in the presence of a weak base or a strong base. Preferably, the neutralization may be carried out with NaOH or KOH, in solid form or in aqueous solution. Alternatively, the neutralization may be carried out in the presence of NaHCO3, KHCO3, or Na2CO3, in solid form or in aqueous solution. Finally, the present invention relates to a process for purifying a composition comprising natural vanillin and vanillic alcohol by separating a compound of formula (I). The present invention also relates to a process for preparing a compound of formula (I) in the presence of natural vanillin. Natural vanillin obtainable according to the process of the present invention is also the subject of the present invention. The compound of formula (I) obtainable according to the process of the present invention is also the subject of the present invention. For this purpose, the invention relates to a compound of formula (I) as described above, wherein n = 0 and R = butyl, and wherein the compound of formula (I) is naturally occurring. Advantageously, such a compound is considered natural under applicable legislation, particularly in the United States. The compound of formula (I) as described above, wherein n = 0 and R = butyl, can be obtained according to step (i) defined above from a naturally occurring compound of formula ROH and a naturally occurring vanillin alcohol, R being butyl. At the end of step (i), a step (ii) as defined above can be performed to recover and / or isolate the naturally occurring compound of formula (I) wherein n = 0 and R = butyl. The expression "natural compound" is understood to mean a compound that corresponds to the definition provided by legislation; for example, in the United States this means that the compound must be obtained through physical, enzymatic, or microbiological processes and only from materials of plant or animal origin. The invention also relates to a composition comprising a compound of formula (I) as described above, wherein n = 0 and R = ethyl or butyl, the compound of formula (I) being a naturally occurring compound, the composition further comprising less than 200 ppm of 4-((4-hydroxy-3-methoxybenzyl)oxy)-3-methoxybenzaldehyde and / or 4-hydroxy-3-(4-hydroxy-3-methoxybenzyl)-5-methoxybenzaldehyde. For example, the composition comprises between 0 and 200 ppm of 4-((4-hydroxy-3-methoxybenzyl)oxy)-3-methoxybenzaldehyde or 4-hydroxy-3-(4-hydroxy-3-methoxybenzyl)-5-methoxybenzaldehyde. Preferably, the content of 4-((4-hydroxy-3-methoxybenzyl)oxy)-3-methoxybenzaldehyde or 4-hydroxy-3-(4-hydroxy-3-methoxybenzyl)-5-methoxybenzaldehyde is less than or equal to 100 ppm, preferably less than or equal to 50 ppm, and more preferably less than or equal to 20 ppm. Preferably, the content of 4-((4-hydroxy-3-methoxybenzyl)oxy)-3-methoxybenzaldehyde or 4-hydroxy-3-(4-hydroxy-3-methoxybenzyl)-5-methoxybenzaldehyde is greater than or equal to 0.01 ppm, and more preferably greater than or equal to 0.1 ppm. Finally, the present invention relates to the use of a natural vanillin composition as a flavoring agent in the field of human and animal nutrition, in pharmaceuticals, and as a fragrance in the cosmetics, perfumery, and detergent industries. The process according to the invention will be better understood by reading the following example, which is a particular embodiment of the process. This example is provided for illustrative purposes only and shall not be construed as limiting the invention. In the event that the disclosure of patents, patent applications, and publications cited herein by reference contradicts the description in this application to the point of risking the indeterminacy of a term, the description in this application shall prevail. Example Materials The ethanol, sulfuric acid, sodium hydroxide solution, and solvents used for the analyses were all from Merck and were used without prior purification. High-performance liquid chromatography (HPLC) was performed using an Agilent 1260 analytical line with a C18 column. A composition (C) comprising natural vanillin, vanillin alcohol, and solvent SI was obtained after treatment of the aqueous phase resulting from the fermentation of ferulic acid by a microorganism. The microorganism was cultured according to the conditions described in EP 0 885 968, and the solvent SI was ethyl acetate. Composition (C) was analyzed by HPLC, and the results are presented in Table 1. In step (i), 349.5 g of composition (C), 21 g of ethanol (ROH), and 0.5 g of 96% H2SO4 were introduced into a reactor. The mixture was stirred for 1 hour at room temperature to form a compound of formula I with R = ethyl, n = 0. A composition (Cl) comprising said compound of formula I and natural vanillin was thus obtained and analyzed by HPLC. The results are presented in Table 1. Table 1 Composition C Composition Cl Vanillin (mmol) 505 505 Vanillyl alcohol (mmol) 50.8 2.1 Compound of formula I (mmol) 0 37.4 Composition CI also included solvent SI and heavy impurities, i.e., impurities with a relative volatility lower than that of natural vanillin under the considered pressure and temperature conditions. Vanillin and vanillic alcohol were identified by comparison with commercial standards. Therefore, due to the treatment process according to the invention, the vanillyl alcohol was selectively converted into ether. In fact, no loss of vanillin was observed: the content in composition (C) was the same as the content in composition (Cl), and only the vanillyl alcohol was converted into ether, specifically, vanillyl ethyl ether. In step (ii), the composition (Cl) was concentrated by evaporating a portion of the solvent SI. A concentrated composition (Cl) of approximately 270 g was thus obtained. The concentrated Cl medium was adjusted to pH 7 with a sodium hydroxide solution. The resulting mixture was washed with water. The organic phase was then removed using a rotary evaporator, and the residue was purified in a wet film evaporator to obtain natural vanillin with a purity greater than 99% and a Hazen 19 color. It is hereby stated that, as of this date, the best method known to the applicant for putting the aforementioned invention into practice is the one that is clear from the present description of the invention.

Claims

1. A process for treating a composition (C) resulting from a process for producing natural vanillin comprising natural vanillin and vanillic alcohol, said treatment process comprising: a step (i) of forming a composition (Cl) comprising natural vanillin and a compound of formula (I) from said vanillic alcohol present in the composition (C): [Chemical formula 15] wherein n equals 0 or 1, and R is selected from a linear or branched, saturated or unsaturated alkyl group, optionally substituted with at least one hydroxyl, alkoxy or amine group, or a group of formula -(WO)mX,wherein W is a linear or branched alkyl chain comprising 1 to 4 carbon atoms and the average molecular weight of the (WO)m- group is between 200 and 3000 g / mol and X is selected from H and a unit of formula (II) [Chemical Formula 16] Formula (Π) a recovery step (ii) of said natural vanillin and / or a recovery step of said compound of formula (I) present in composition (Cl)., 2. The treatment process according to claim 1, wherein step (i) is carried out in the presence of a compound selected from the group consisting of ROH, RCOOH and HO-(WO)mH, wherein R is selected from a linear or branched, saturated or unsaturated alkyl group, optionally substituted with at least one hydroxyl, alkoxy or amine group and W is a linear or branched alkyl chain comprising 1 to 4 carbon atoms and the average molecular weight of the compound HO-(WO)mH is between 200 and 3000 g / mol.

3. The treatment process according to any one of the preceding claims, wherein step (i) also allows the formation of a compound of formula (III), according to the following formula, from the vanillic acid present in composition (C): [Chemical formula 17] wherein n is equal to 0 or 1, and R is selected from a linear or branched, saturated or unsaturated alkyl group, optionally substituted with at least one hydroxyl, alkoxy or amine group, or a group of formula -(WO)mX, wherein W is a linear or branched alkyl chain comprising 1 to 4 carbon atoms and the average molecular weight of the (WO)m- group is between 200 and 3000 g / mol and X is selected from H and a unit of formula (IV) 10 [Chemical formula 18] 4. The treatment process according to claim 1 or 2, wherein step (i) is an etherification reaction carried out in the presence of a compound of formula ROH, R being a butyl group, and wherein step (ii) is a natural vanillin recovery step and a compound of formula (I) having n = 0 and R being a butyl group.

5. The treatment process according to any one of the preceding claims, wherein the natural vanillin obtained at the end of step (ii) comprises less than 500 ppm of vanillic alcohol.

6. The treatment process according to any one of the preceding claims, wherein the composition of the natural vanillin obtained at the end of step (ii) comprises less than 200 ppm of 4-((4-hydroxy-3-methoxybenzyl)oxy)-3-methoxybenzaldehyde or 4-hydroxy-3-(4-hydroxy-3-methoxybenzyl)5-methoxybenzaldehyde.

7. The treatment process according to any one of the preceding claims, comprising an additional step (iii) wherein the natural vanillin obtained at the end of step (ii) is shaped, in particular, into crystals, beads, pearls or powder.

8. The treatment process according to any one of the preceding claims, having a purification yield greater than or equal to 90% with respect to the amount of natural vanillin in the composition (C).

9. The treatment process according to any one of the preceding claims, wherein the vanillin content in the natural vanillin composition obtained at the end of step (ii) or (iii) is greater than or equal to 95%, preferably greater than or equal to 97%, very preferably greater than or equal to 99%, even more preferably greater than or equal to 99.5%.

10. The treatment process according to any one of the preceding claims, wherein the natural vanillin obtained at the end of step (ii) or (iii) has a color of less than or equal to 400 Hazen, preferably less than or equal to 200 Hazen, more preferably less than or equal to 100 Hazen, very preferably less than or equal to 50 Hazen and even more preferably less than or equal to 20 Hazen.

11. A compound of formula (I) below 0 Formula (I) Ul where n = 0 and R = butyl and where the compound of formula (I) is natural.

12. A composition comprising a compound of formula (I) according to claim 11 and further comprising less than 200 ppm of 4-((4-hydroxy-3-methoxybenzyl)oxy)-3-methoxybenzaldehyde and / or 4-hydroxy-3-(4-hydroxy-3-methoxybenzyl)-5-methoxybenzaldehyde.