Formulation for aromatizing a food product

Abstract

The present invention relates to a process for producing a formulation for aromatizing a product, in particular a food product, a semi-luxury product, cosmetic or pharmaceutical product and food supplement, which contains preferably at least one (alkyl)pyrazine of the formula (Ia) and / or at least one (alkyl)pyrazine of the formula (Ib), wherein R1, R2 and R3 represent the groups defined in the claims.

Description

[0001] Formulation for flavoring a food product

[0002] The invention relates to a formulation for flavoring a food, luxury food, cosmetic or pharmaceutical product as well as a food supplement, and to a process for producing this formulation.

[0003] Pyrazines substituted with one or more alkyl or cycloalkyl groups are known to be naturally occurring, highly potent flavorings, some of which have a very low odor threshold. These alkylpyrazines, such as 2-ethyl-3,5-dimethylpyrazine or 2,3-diethyl-5-methylpyrazine, have an earthy odor. Corylon-pyrazine (also known as 5-methyl-6,7-dihydrocyclopentapyrazine or nutty pyrazine) is a flavoring compound with a strong odor. This odor can be described as sweet, nutty, roasted, rusty, earthy, as well as cereal-, coffee-, and popcorn-like. Corylon-pyrazine is found in natural flavors of coffee and numerous nuts. In the flavoring industry, this compound is used, for example, to enhance the aroma of popcorn.

[0004] It is known from the prior art that the addition of an alkyl-substituted pyrazine, alone (US 3,579,353) or in combination with other compounds (GB1401096A), to food or delicatessen products leads to an improvement in the product flavor. US 3,579,353 describes three reactions for the preparation of alkyl-substituted pyrazines: diketone plus ethylenediamine; alkyllithium plus dialkylpyrazines; and sodium amide plus alkylpyrazines.

[0005] Various approaches for the preparation of pyrazines have been described in the literature (Ong et al., Borneo Journal of Resource Science and Technology, 2017, 7(2), pp. 60-75). The classic synthetic routes involve the use of various metal compounds. For example, pyrazines can be prepared by condensation of 1,2-diaminoalkane with 1,2-dicarbonyl compounds, using copper(II) oxide and manganese oxide as oxidants.

[0006] 1,2-Dicarbonyl 1,2-Diaminoethane Dihydropyrazine Pyrazine

[0007] Pyrazines can also be obtained by condensation of two molecules of an α-amino ketone or an α-amino aldehyde. The resulting dihydropyrazines are converted into pyrazines using an oxidizing agent, such as divalent mercury salts:

[0008] Dihydropyrazines

[0009] Amino aldehyde Pyrazine

[0010] US 4,097,478A describes a process for the preparation of pyrazines in a gas-phase contact reaction at 300-600 °C in the presence of a zinc-containing catalyst, using diols and diamines as starting compounds:

[0011] Pyrazines

[0012] DE 695 18 206 T2 (Firmenich SA) discloses the use of two different hydroxyketones for the preparation of asymmetrically substituted alkylpyrazines. Reaction of 1,3-dihydroxypropan-2-one with an acyloin of formula (III) yields substituted pyrazines as shown in the following scheme.

[0013] a) Ammonium acetate, solvent

[0014] However, the hydroxyketones and dihydroxyketones used are relatively unstable and expensive.

[0015] Pyrazines can be produced by various synthetic routes, but all currently known methods have certain disadvantages. These include the use of solvents and metal compounds, some of which are highly toxic, as well as low yields of the target product and high reaction temperatures.

[0016] The toxic properties of catalysts and solvents can lead to environmental and health risks and must be considered in occupational safety during both the production and use of these catalysts. Complex and costly measures are necessary to ensure the necessary safety in the face of toxicological and health problems that primarily arise in the workplace. Furthermore, some of the catalysts used are very expensive compounds, so the purchase, disposal, or recycling of these catalysts can have a negative impact on the price of the final product.

[0017] Another possibility for obtaining pyrazines involves isolating these compounds from animal material using known separation processes such as steam distillation of cooked pork liver. It is known that pyrazines, such as alkylpyrazines, acetylpyrazines, cyclopentapyrazines and quinoxalines, represent the largest group of aroma substances in cooked pork liver (Mussinan CJ and Walradt JP (1974) Volatile Constituents of Pressure Cooked Pork Liver, J. Agrc. Food Chem., 22, No. 5, 827-831). Pyrazines belong, among other things, to the so-called reaction aromas. These aroma-active compounds are formed during heating, cooking, frying and / or baking and are among the substances responsible for the typical aroma of processed foods. According to the Aromas Regulation (EC) No.According to Regulation (EC) No 1334 / 2008, heating for the preparation of reaction flavorings used as food additives may only take place for a maximum of 15 minutes at a maximum temperature of 180°C. This limitation is intended to approximate the typical cooking conditions for food processing.

[0018] In the meat sector, the formation of reaction flavorings, such as unsubstituted, mono-, or polysubstituted pyrazines, from flavor precursors during the Maillard reaction and the Strecker degradation of amino acids has already been extensively researched (see, for example: Belitz, H.-D., Grosch, W., Schieberle, P. (2007): Textbook of Food Chemistry. 6th Edition!.. Springer Verlag, Heidelberg, pp. 378-382; and R. Wilhelm (2015), Comparative Studies on Volatile Aroma Substances from Roasting Beef and Sham Liver as well as from Roasted Goose and Foie Gras, Dissertation, Hannover University of Veterinary Medicine). Pyrazines are formed during the dimerization of α-aminoketones, which are formed during the oxidative deamination and decarboxylation of α-amino acids with α-dicarbonyl compounds. However, the use of animal material as a raw material is questionable for animal welfare reasons and is also undesirable from a consumer perspective.Furthermore, the quantities obtained are very small and therefore not economical.

[0019] The closest prior art to the present invention can be considered to be document DE 20 2021 104 269 U1, which describes a process for preparing a formulation containing at least one (alkyl)pyrazine. This known process allows a natural corylonepyrazine (CP) to be prepared from cyclotene and L-serine with acetic acid, without the use of metal compounds or animal starting materials. A disadvantage of the known process is that L-serine must be used in excess: the ratio of cyclotene to L-serine is preferably 1:3. Furthermore, the known process uses a highly flammable solvent such as diethyl ether to isolate the desired product.

[0020] Therefore, there continues to be a need for a process for producing a formulation containing at least one (alkyl)pyrazine that does not have any of the above-mentioned disadvantages and that furthermore does not use metal catalysts or material of animal origin. A further object of the invention is to proceed as economically and resource-efficiently as possible.

[0021] This problem could be solved surprisingly simply by a process for preparing a formulation. This process comprises the following steps: (a) providing at least one compound of formula (II) or (III) or (IIIa), preferably a compound of formula (II) or (III),

[0022] R 2 -C(O)-C(O)-R 3 (II) or R 2 -C(O)-C(OH)=R 3 (III) or R 2 -C(O)-CH(OH)-R 3 (Illa), wherein

[0023] R 2 and R 3are the same or different and independently represent hydrogen or C1-4 alkyl or

[0024] R 2 and R 3 are connected to each other and together form a group of the formula represent, where

[0025] A, B, C and D independently represent hydrogen or Ci-4-alkyl,

[0026] (b) Providing an alpha-amino acid

[0027] (c) bringing into contact at least one compound of formula (II) or formula (III) or formula (IIIa), preferably at least one compound of formula (II) or formula (III), and at least one alpha-amino acid from step (b), wherein at least one solvent suitable for the production of foodstuffs which has a boiling point of at least 140 °C, preferably propylene glycol, glycerol, triethyl citrate, diacetin, monoacetin and / or triacetin, is used, and wherein the solvent is added before step (c) and / or in step (c).

[0028] According to the invention, the reaction is therefore carried out in solution, using the solvent or solvent mixture described herein. It is particularly preferred to use a solvent mixture comprising a solvent suitable for food production that has a boiling point of at least 140°C. The term "boiling point" used here is the boiling point at atmospheric pressure (1013.25 mbar).

[0029] It is therefore also possible to use a solvent combination in which at least one of the solvents has a boiling point of at least 140 °C. The solvent with a boiling point of at least 140 °C is preferably selected from the group consisting of propylene glycol, glycerol, diacetin, monoacetin, triacetin, triethyl citrate, or mixtures thereof. Water, ethanol, and / or propanol can be added as additional solvents.

[0030] The chemical transformation shown below takes place.

[0031] For the preparation of an (alkyl)pyrazine of formula (Ia), any alpha-amino acid can be used, with proteinogenic alpha-amino acids being preferred. The proteinogenic alpha-amino acid is selected from the group consisting of alanine, arginine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, selenocysteine, threonine, tryptophan, tyrosine, valine, and mixtures thereof.

[0032] The process according to the invention allows the production of previously commercially unused pyrazines, such as 2,5(6)-diethyl-3,6(5)-dimethylpyrazine, obtained from acetylpropionyl (10) with an amino acid. The isolated isomer mixture possesses a potent peanut aroma even at low doses of 10 ppm in a product. The product can be selected from the group consisting of food, luxury goods, cosmetic or pharmaceutical products, and dietary supplements.

[0033] (10) (1a) In the process according to the invention, it is particularly preferred if at least one of the solvents used has at least one hydroxyl group. This hydroxyl-containing solvent can be selected from the group consisting of propylene glycol (PG), glycerol (also glycerol or glycerin), diacetin, monoacetin, triethyl citrate, and mixtures thereof. These hydroxyl-containing solvents can be mixed with at least one other solvent, such as triacetin or water.

[0034] If only one diketone of formula (II) or (III) is contacted with at least one alpha amino acid according to the process of the invention, at least one "symmetric" (alkyl)pyrazine of formula (Ia) can be obtained in both regioisomers. For example, the following "symmetric" (alkyl)pyrazines of formula (Ia) can be obtained in the process of the invention:

[0035] 2,5-Diethyl-3,6-dimethyl pyrazine

[0036] Pyrazine

[0037] 2,3,5,6-Tetraethylpyrazine ,12-dimethyl-2,8-diazatricyclo[7.3.0.03,7]dodeca-l,3(7),8-triene ,10-dimethyl-2,8-diazatricyclo[7.3.0.03,7]dodeca-l(9),2,7-triene ,2,3,4,6,7,8,9-octahydrophenazine ,5 (6)-Diethylpyrazine ,5 (6)-Dimethylpyrazine When two or more different diketones of formula (II) or (III) are brought into contact in the presence of at least one alpha amino acid according to the process of the invention, at least one "asymmetric" (alkyl)pyrazine of formula (Ia') can be obtained. An "asymmetric" (alkyl)pyrazine of formula (Ia') is understood to mean a pyrazine in which the pyrazine ring is formed from two different diketones of formula (II) or (III).

[0038] Wherein in the (alkyl)pyrazine of formula (Ia')

[0039] R 2 and R3 are the same or different and independently represent hydrogen or C 1-4 alkyl or

[0040] R 2 and R 3 are connected to each other and together form a group of the formula o er represent, wherein A, B, C and D independently of one another represent hydrogen or C 1 - alkyl.

[0041] In the process according to the invention, for example, the following “asymmetric” (alkyl)pyrazines of the formula (Ia') can be obtained: -methylpyrazine -Ethylpyrazine ,3-Dimethylpyrazine ,3-Diethylpyrazine ixr ^ -Ethyl-3-methylpyrazine 2-Ethyl-5(6)-dimethylpyrazine (Cocoa Pyrazine)

[0042] 2,3-Diethyl-5-methylpyrazine

[0043] Corylone Pyrazine (or 5-methyl-6,7-dihydro-5H-cyclopentapyrazine)

[0044] 2(3),5-Dimethyl-6,7-dihydro-5H-cyclopentapyrazine

[0045] 2,3,5-Trimethyl-6,7-5H-dihydrocyclopentapyrazine 2-Ethyl-3,5,6-trimethylpyrazine

[0046] 2,3,5-trimethylpyrazine

[0047] 5 , 6,7, 8 -tetrahy droquinoxaline (Cyclohexapyrazine)

[0048] Methyl-5,6,7,8-tetrahydroquinoxaline

[0049] Surprisingly, it was found that when using a compound of formula (II) or (III) in combination with at least one alpha-amino acid, preferably an alpha-amino acid of formula (IV), a second (alkyl)pyrazine of formula (Ib) is formed in addition to (Ia).

[0050] (II) / (III) (IV) (la) (Ib)

[0051] In the alpha-amino acid of formula (IV), E stands for S or O and R 1 stands for hydrogen or methyl.

[0052] The alpha-amino acids of formula (IV) include serine, cysteine, threonine and mixtures thereof.

[0053] For the (alkyl)pyrazine of formula (lb), the alpha-amino acid, preferably the alpha-amino acid of formula (IV), plays a crucial role, as its carbon skeleton is incorporated into the (alkyl)pyrazine. This means that the alpha-amino acid of formula (IV) functions not only as a nitrogen source, as described in the literature (J. AGR. FOOD CHEM., VOL. 20, NO. 5, 1972, 1081), but also as a reducing agent in the Strecker degradation.

[0054] In a preferred embodiment of the invention, no organic acid, such as acetic acid or propionic acid, is used in the process, with the exception of the alpha amino acid^). In a further preferred embodiment of the invention, the formulations contain no organic acids, such as acetic acid or propionic acid, with the exception of the alpha amino acid(s).

[0055] Influence of the solvent on the ratio of the two (alkyl)pyrazines (Ia) and (Ib) in the reaction with the amino acid, preferably the amino acid of formula (IV):

[0056] As already mentioned above, the production of (alkyl)pyrazines of formula (Ib) is highly preferred when using amino acids of formula (IV), since the carbon skeleton of the amino acid is incorporated into the pyrazine. The process described in the present invention allows the ratio of the two pyrazines, such as (alkyl)pyrazine (Ia) and (alkyl)pyrazine (Ib), to be significantly influenced by selective choice of reaction parameters in order to obtain the desired (alkyl)pyrazine in high yield.

[0057] It has surprisingly been found that the choice of solvent in the process according to the invention, in particular the addition of solvents carrying hydroxyl groups, preferably propylene glycol, glycerol (also glycerol or glycerin), monoacetin, triethyl citrate and / or diacetin, can have an influence on the ratio of the two pyrazines of the formula (Ia) and (Ib) as well as their overall yield.

[0058] When a solvent bearing(s) hydroxyl group(s), preferably glycerol or propylene glycol, is used as the sole solvent, it has been found that the (alkyl)pyrazine of formula (Ia) is formed particularly preferentially and in short reaction times. If the proportion of the solvent bearing(s) hydroxyl group(s) is reduced (and the proportion of triacetin is increased accordingly), the proportion of (alkyl)pyrazine of formula (Ib) formed increases. However, since this also has a negative effect on the reaction rate, the overall yield, consisting of (alkyl)pyrazine (Ia) and (Ib), can decrease when the solvent bearing(s) hydroxyl group(s) is omitted, as well as cause additional costs due to long reaction times. It has been observed that the addition of catalytic amounts of at least one solvent bearing(s) hydroxyl group(s), such as glycerol or propylene glycol, i.e.of 0.01-5 mol% based on the compound of formula (II) or (III), shows the greatest yield-increasing effect.

[0059] This solvent-dependent product selectivity now also enables cost-efficient access to new, previously commercially unused pyrazines, such as 2,5(6)-diethyl-3,6(5)-dimethylpyrazine obtained from acetylpropionyl (10) with an amino acid of formula (IV). The isolated isomer mixture (i.e., the mixture of 2,5-diethyl-3,6-dimethylpyrazine and 2,6-diethyl-3,5-dimethylpyrazine) possesses a potent peanut aroma even at low doses of 10 ppm in a product such as a food product. As shown in the table below, a larger ratio of 2,5(6)-diethyl-3,6(5)-dimethylpyrazine (Ia) to (alkyl)pyrazine of formula (Ib) can be formed by choosing the solvent.

[0060]

[0061] If a higher proportion of (alkyl)pyrazines of formula (Ib) is desired in the reaction with the alpha-amino acid of formula (IV), triacetin or a combination of solvents containing triacetin should be used. A mixture of triacetin and at least one solvent containing at least one hydroxyl group is preferred. This hydroxyl-containing solvent can be selected from the group consisting of propylene glycol, glycerol, diacetin, monoacetin, triethyl citrate, water, and mixtures thereof. The reaction time in a combination of solvents containing triacetin is shorter than the reaction time in pure triacetin as solvent. Particular preference is given to a mixture of triacetin and diacetin or a mixture of triacetin and glycerol.

[0062] Triacetin (or glycerol triacetate, E 1518) is an ester of glycerol and acetic acid. In the food industry, it is used, among other things, as a plasticizer for chewing gum and as a flavoring agent. Triacetin is a natural ingredient in papayas.

[0063] For the yield of the (alkyl)pyrazine of formula (Ib), it is particularly advantageous if, in step (c), the reaction mixture has a ratio of triacetin to diacetin in the range from 99:1 to 1:1, preferably in the range from 20:1 to 5:1, particularly preferably 19:1. Surprisingly, it has been found that glycerol has an effect just as pronounced as that of diacetin, even in smaller amounts. It is particularly advantageous if, in step (c), the reaction mixture has a ratio of triacetin to glycerol in the range from 99:1 to 99.99:0.01, preferably in the range from 99.5:0.5 to 99.9:0.1, particularly preferably 99.84:0.16.

[0064] The mixture obtained by the process according to the invention, which contains (alkyl)pyrazines of the formula (Ia) and (alkyl)pyrazines of the formula (Ib), can be used for the production of products such as foodstuffs, luxury foods, cosmetic or pharmaceutical products and food supplements.

[0065] The (alkyl)pyrazines of formula (Ia) and (alkyl)pyrazines of formula (Ib) can be separated from one another. For this purpose, any separation method known to the person skilled in the art can be used. Examples of separation methods that can be used include distillation, crystallization, or chromatography. The (alkyl)pyrazines of formula (Ia) or (alkyl)pyrazines of formula (Ib) isolated by these separation processes can be used for the production of products such as food, luxury goods, cosmetic or pharmaceutical products, and dietary supplements.

[0066] For example, in the reaction of 2,3-pentanedione with L-threonine in a solvent mixture containing triacetin and glycerol (in catalytic amounts), at least two different pyrazine fractions could be isolated or separated from each other. The first pyrazine fraction contains (alkyl)pyrazines of formula (Ib), namely cocoa pyrazine, which is composed of two isomers (2-ethyl-3,5-dimethylpyrazine and 2-ethyl-3,6-dimethylpyrazine). It was found that the isomer ratio in the cocoa pyrazine product produced by the process according to the invention differs significantly from the isomer ratio in the commercially available cocoa pyrazine product. While the commercially available product has a ratio of cocoa pyrazine isomer 1 (2-ethyl-3,5-dimethylpyrazine) to cocoa pyrazine isomer 2 (2-ethyl-3,6-dimethylpyrazine) of approx.40:60, the ratio of cocoa-pyrazine isomer 1 to cocoa-pyrazine isomer 2 in the fraction produced by the process according to the invention is approximately 60:40 or higher. Surprisingly, it was found that the ratio of cocoa-pyrazine isomers has a strong impact on the sensory potency of the overall cocoa-pyrazine product. The cocoa-pyrazine fraction produced by the process according to the invention is significantly more potent than the commercially available variant (such as ethyldimethylpyrazine from Riverside Aromatics), for example, with approximately 20% more flavor. This makes the cocoa-pyrazine product according to the invention more economically viable (lower cost of use).Therefore, in a preferred embodiment, the invention relates to a formulation containing 2-ethyl-3,5-dimethylpyrazine and 2-ethyl-3,6-dimethylpyrazine in a molar ratio of at least 50:50, preferably at least 55:45, particularly preferably at least 60:40. Particularly preferred is a formulation containing 2-ethyl-3,5-dimethylpyrazine and 2-ethyl-3,6-dimethylpyrazine in a molar ratio of between 50:50 and 70:30, preferably between 55:45 and 65:35. In a further preferred embodiment, the invention relates to a formulation containing 2-ethyl-3,6-dimethylpyrazine and 2-ethyl-3,5-dimethylpyrazine in a molar ratio of at least 50:50, preferably at least 55:45, particularly preferably at least 60:40. Particularly preferred is a formulation which contains 2-ethyl-3,6-dimethylpyrazine and 2-ethyl-3,5-dimethylpyrazine in a molar ratio of between 50:50 and 70:30, preferably between 55:45 and 65:35.The invention also relates to a product, in particular a food, luxury food, cosmetic or pharmaceutical product, or dietary supplement, containing such a formulation. Furthermore, the present invention relates to a process for producing a formulation containing 2-ethyl-3,5-dimethylpyrazine and 2-ethyl-3,6-dimethylpyrazine, wherein the process comprises reacting 2,3-pentanedione with an alpha amino acid, preferably L-threonine, in a solvent mixture containing at least one solvent containing at least one hydroxyl group, wherein the solvent mixture preferably contains triacetin and glycerol.

[0067] The second pyrazine fraction obtained was the (alkyl)pyrazines of formula (Ia), namely the isomer mixture of 2,5-ethyl-3,6-dimethylpyrazine and 2,6-ethyl-3,5-dimethylpyrazine. In a further aspect, the present invention relates to a process for preparing a formulation comprising the following steps:

[0068] (a) providing at least one compound of formula (II) or (III) or (IIIa)

[0069] R 2 -C(O)-C(O)-R 3 (II) or R 2 -C(O)-C(OH)=R 3 (III) or R 2 -C(O)-CH(OH)-R 3 (Illa), wherein

[0070] R 2 and R 3 are the same or different and independently represent hydrogen or C1-4 alkyl or

[0071] R 2 and R 3 are connected to each other and together form a group of the formula represent, where

[0072] A, B, C and D independently represent hydrogen or Ci-4-alkyl,

[0073] (b) providing an alpha amino acid, in particular a proteinogenic alpha amino acid,

[0074] (c) Contacting at least one compound of formula (II) or formula (III) or formula (IIIa) with at least one alpha-amino acid, wherein at least one solvent containing at least one hydroxy group is added before step (c) and / or in step (c). According to the invention, the reaction is thus carried out in solution, using the solvent or solvent mixture described herein.

[0075] The solvent containing at least one hydroxy group is preferably selected from the group consisting of propylene glycol, glycerol (also glycerin or glycerine), monoacetin, triethyl citrate, diacetin and mixtures thereof.

[0076] It is preferred that the solvent containing at least one hydroxyl group is part of a solvent mixture added before step (c) and / or in step (c). In a preferred embodiment, the solvent containing at least one hydroxyl group makes up between 0.01 and 10 percent by weight of the solvent mixture. In a particularly advantageous embodiment, the solvent mixture comprises a solvent that does not contain a hydroxyl group, preferably triacetin.

[0077] In a preferred embodiment, the solvent containing at least one hydroxy group is used in a ratio of 0.01-5 mol%, based on the compound of formula (II) or (III) or (IIIa).

[0078] In a further aspect, the invention relates to the use of a solvent containing at least one hydroxy group to increase the yield in a process for producing

[0079] (Alkyl-)pyrazine, in particular (alkyl-)pyrazine of formula (Ia), and / or (alkyl)pyrazine of formula (Ib) wherein

[0080] R 1 represents hydrogen or methyl,

[0081] R 2 and R 3 are the same or different and independently represent hydrogen or C 1-4 alkyl or

[0082] R 2 and R 3 are connected to each other and together form a group of the formula where A, B, C and D independently represent hydrogen or Ci-4-alkyl.

[0083] Particularly preferably, said process for preparing (alkyl)pyrazine is the process described above, in which at least one solvent containing at least one hydroxy group is added before step (c) and / or in step (c).

[0084] In a further aspect, the invention relates to the use of a solvent containing at least one hydroxy group for regulating the molar ratio of the (alkyl)pyrazines of the formula

[0085] (la) and the formula (Ib) in a process for the preparation of (alkyl)pyrazines, wherein

[0086] R 1 represents hydrogen or methyl,

[0087] R 2 and R 3 are the same or different and independently represent hydrogen or C 1-4 alkyl or

[0088] R 2 and R 3 are connected to each other and together form a group of the formula wherein A, B, C, and D independently represent hydrogen or C 1-4 -alkyl. Particularly preferably, said process for preparing (alkyl)pyrazine is the process described above, in which at least one solvent containing at least one hydroxy group is added before step (c) and / or in step (c).

[0089] In a further aspect, the invention relates to a process for producing a formulation comprising the following steps:

[0090] (a) Providing at least one compound of formula (II) or (III)

[0091] R 2 -C(O)-C(O)-R 3 (II) or R 2 -C(O)-C(OH)=R 3 (III), wherein

[0092] R 2 and R 3 are the same or different and independently represent hydrogen or C1-4-

[0093] alkyl or

[0094] R 2 and R 3are connected to each other and together form a group of the formula represent, where

[0095] A, B, C and D independently represent hydrogen or Ci-4-alkyl,

[0096] (b) providing an alpha amino acid, in particular a proteinogenic alpha amino acid,

[0097] (c) Contacting at least one compound of formula (II) or formula (III) with at least one alpha-amino acid, wherein the reaction is carried out in solution, and wherein at least one solvent suitable for the production of foodstuffs and having a boiling point above 140°C is used. The features of the embodiments of various aspects of the invention can also be combined.

[0098] Addition of ammonium salt

[0099] Due to the relatively high cost of natural quality amino acids, in particular L-serine, which was used as the sole nitrogen source in the process according to claim 1, a more cost-effective alternative was sought.

[0100] This problem could be solved surprisingly simply by a process according to claim 2. The process comprises the additional addition of at least one ammonium salt. It is particularly advantageous if at least one ammonium salt is added in one portion in step (c).

[0101] It has been found that by using an ammonium salt, the amount of an alpha-amino acid, preferably an alpha-amino acid of formula (IV), can be reduced by 50%, while the yield of the target product—(alkyl)pyrazine of formula (Ib)—remains the same. If the amount of amino acid is not reduced, i.e., the molar ratio of the compound of formula (II) or (III) or (IIIa) to the alpha-amino acid remains 1:2, a significant increase in yield is achieved upon addition of an ammonium salt, preferably 2 equivalents of the ammonium salt. Furthermore, it can also be observed that fewer by-products are formed during purification, which considerably simplifies the process.

[0102] The ammonium salt used is preferably an inorganic or organic ammonium salt. An ammonium salt is particularly preferably selected from the group consisting of ammonium halide, ammonium phosphates, ammonium sulfates, ammonium carbonate, ammonium bicarbonate, ammonium carbamate, ammonium salt of an organic acid, and mixtures thereof. Ammonium chloride is most preferred.

[0103] Ammonium salt is added here in a molar ratio to the amino acid, preferably to the amino acid of formula (IV), the ratio being in a range from 4:1 to 0.1:1, preferably in the range from 2:1 to 0.5:1, most preferably in a ratio of 1:1.

[0104] The solvent, preferably at least one organic solvent, particularly preferably triacetin, can be added before step (c) and / or in step (c). In particular, the solvent can be added before step (c) to the compound of formula (II) or (III) or (IIIa) and / or to an alpha-amino acid, preferably an alpha-amino acid of formula (IV). In an advantageous embodiment, the process according to the invention comprises, before step (c), a further step c1) adding at least one solvent to the compound of formula (II) or (III) or (IIIa), to obtain a solution in which the amount of compound of formula (II) or (III) or (IIIa) depends on the solubility of this compound(s) in the solvent used.

[0105] Solvent combination is dependent. A solution maximally saturated with the compound of formula (II) or (III) or (IIIa) is preferred. The amount of the compound of formula (II) or (III) or (IIIa) in the solvent is particularly preferably up to 40 wt.%, very particularly preferably approximately 2 to 10 wt.%, based on the total weight of this solution.

[0106] In step (c), the solution obtained in step (c1) is added to the alpha-amino acid either dropwise or in one portion with constant stirring. The mixture is heated to a maximum temperature of approximately 180 °C, preferably approximately 100 to 140 °C, and particularly preferably 110 to 130 °C.

[0107] It has been found that it is particularly advantageous if, before step (c), the solution obtained in step (cl) is divided into two portions, the ratio of the first portion to the second portion being in the range from 1:10 to 1:4, preferably in the range from 1:7 to 1:3, particularly preferably 1:4.

[0108] In a further advantageous embodiment, the process according to the invention comprises, after step (cl), a further step c2) mixing the first portion of the solution obtained in step (cl) with the alpha-amino acid, preferably with the alpha-amino acid of the formula (IV), and heating this mixture to maximum temperatures of about 180 °C, preferably to about 100 to 140 °C, particularly preferably to 110 to 130 °C.

[0109] In step (c), the second portion of the solution obtained in step (c1) is added dropwise to the mixture obtained in step (c2) with continuous stirring.

[0110] In a further advantageous embodiment of the invention, water, especially distilled water, is used as a solvent in addition to triacetin. It has been found that the amount of water can influence the yield. It is particularly advantageous if, in step (c), the reaction mixture has a ratio of water to the compound of formula (II) or (III) or (IIIa) in the range from 40:1 to 10:1, preferably in the range from 30:1 to 20:1, particularly preferably 21:1.

[0111] The process according to the invention may additionally comprise the addition of water in step (c). The water may be added in one portion to the mixture containing the alpha amino acid and the solution obtained in step (c1) with at least one compound of formula (II) or (III) or (IIIa).

[0112] Furthermore, it was found that particular advantages in increasing the yield and shortening the reaction time are achieved by the addition of a solvent mixture, such as triacetin and diacetin, in combination with the addition of at least one ammonium salt.

[0113] Furthermore, it was discovered that the gained reaction control with the addition of an ammonium salt also allows the amount of solvent or solvent mixture to be reduced. The total reaction volume can be halved without a significant loss of yield (less than 4 mol%), which was not possible without the addition of an ammonium salt. This not only increases the economic efficiency of the process, but also leads to simplified purification, comparably higher yield, and, last but not least, a more environmentally friendly alternative with half the amount of waste.

[0114] In an alternative embodiment of the invention, in step (c), water is added dropwise to the mixture obtained in step (c2) with continuous stirring. The addition of water takes place simultaneously with the addition of the solution obtained in step (c1). However, the water is added separately, i.e., without mixing with the second portion of the solution obtained in step (c1). The rate of water addition is comparable to the rate of addition of the solution obtained in step (c1).

[0115] In the context of the present invention, the radical “Ci-4-alkyl” in the compound of formula (II) or (III) or (IIIa) is methyl, ethyl, propyl or butyl, preferably methyl.

[0116] The compound of formula (II) or (III) or (IIIa) is preferably selected from the group consisting of (1) 2-hydroxy-3-methyl-2-cyclopenten-l-one (also known as Cycloten or MCP)

[0117] (2) Glyoxal

[0118] (3) 2-Oxopropanal

[0119] (4) Diacetyl

[0120] (5) 2-Hydroxycyclopentanon (2-Hydroxycyclopent-2-en-l-on)

[0121] (6) 2-Hydroxy-3-methyl-cyclopentanon (7) 2-Hydroxy-3 ,4-dimethylcyclopentanon (2-Hydroxy-3 ,4-dimethylcyclopent-2-en- 1 -on)

[0122] (8) 3,5-Dimethylcyclopentandion (2 -Hydroxy-3, 5-dimethyl-2-cyclopenten- 1-on)

[0123] (9) 2-Hydroxycyclohexanon (2-hydroxycyclohex-2-en-l-on)

[0124] (10) Acetylpropionyl (acetyl propionyl oder 2,3-pentanedion)

[0125] (11) 3,4-Hexanedion besteht, wobei

[0126] (1) 2-Hydroxy-3-methyl-2-cyclopenten-l-on (Cycloten) oder

[0127] (10) Acetylpropionyl (acetyl propionyl oder 2,3-pentanedion) besonders bevorzugt wird.

[0128] The alpha-amino acid of formula (IV) is selected in particular from the group consisting of L- / D- / (RS)-serine, L- / D- / (7S)-cysteine, L- / D- / (7S)-thyroxine, and mixtures thereof, preferably L- / D- / (7S)-serine and L- / D- / (7S)-cysteine. Particularly preferably L-serine or L-cysteine, most preferably L-serine. The amino acids used can be obtained, for example, by the enzymatic hydrolysis of vegetable protein if the flavoring end products / final substances obtained from these amino acids are desired to be of natural quality.

[0129] The molar ratio of a compound of formula (II) or (III) or (IIIa) to the alpha-amino acid, preferably to the alpha-amino acid of formula (IV), can range from 1:1 to 1:5. In the process known from DE 202021104269 U1, the preferred ratio of a compound of formula (II) or (III) or (IIIa) to the alpha-amino acid of formula (IV) is 1:3. Surprisingly, it has been found that in the process according to the invention, this ratio can be as low as 1:2, for example 1:1 to 1:2. This leads to economic advantages of the process according to the invention. The reaction in step (c) takes place at maximum temperatures of approximately 180°C, preferably at temperatures in the range of approximately 100 to 140°C, more preferably in the range of approximately 110 to 130°C, most preferably 125°C. During the reaction, it was observed that water was produced.The reaction in step (c) takes place in particular over a period of up to 40 hours, preferably over a period of up to 24 hours, preferably from 1 to 12 hours, particularly preferably up to 6 hours.

[0130] The progress of the reaction in step (c) can be monitored by GC analysis. When no more compounds of formula (II) or (III) can be detected, the reaction is stopped, e.g., by cooling the reaction mixture to room temperature and, if necessary, neutralizing it with a basic solution. A solution of alkali hydroxides, such as sodium or potassium hydroxide solution, can preferably be used as the basic solution.

[0131] The method may additionally comprise a further step after step (c)

[0132] (cl) isolating the resulting (alkyl)pyrazine of formula (la) and / or (b) from the crude product obtained after step (c).

[0133] The isolation in step (cl) is preferably carried out by rectification, optionally under reduced pressure. Alternatively, after adjusting the pH, the crude product can be concentrated and purified by solid-phase extraction (SPE). The fraction(s) containing (alkyl)pyrazine of formula (Ia) and / or (Ib) can be obtained with a purity of at least 95% by weight. The fractions obtained by the process according to the invention can contain one or more (alkyl)pyrazines. The fraction containing multiple (alkyl)pyrazines can optionally be further used as formulation(s). For example, a fraction can be isolated which contains both trimethylpyrazine and tetramethylpyrazine.

[0134] Further recovery of the crude product from the reaction mixture can be achieved by co-distillation with propylene glycol (PG). A mixture of glycerol and PG (3:2) is added to the reaction mixture at room temperature and then distilled under reduced pressure. The PG thus distilled serves as an entrainer for the pyrazine formed. In a particularly preferred embodiment of the process, triacetin or triacetin-containing mixtures are added as solvent, using 2-hydroxy-3-methyl-2-cyclopenten-l-one (cyclotene) as the compound of formula (II) or (III) and L-serine as the alpha-amino acid of formula (IV). Triacetin can not only dissolve cyclotene but also offer enormous advantages in the isolation of the desired product, such as corylonepyrazine. Triacetin has a higher boiling point than corylonepyrazine, so that corylonepyrazine, as the target product, can be isolated to a desired purity by rectification.

[0135] Further improvement of the process in yield, selectivity and atom economy is observed with the addition of a solvent mixture containing triacertin and diacetin in combination with the addition of ammonium chloride.

[0136] The closest prior art—document DE 20 2021 104 269 U1—describes the isolation of the desired product, such as corylonepyrazine, by extraction in a Likens-Nickerson apparatus with diethyl ether. Diethyl ether forms highly flammable vapor-air mixtures, making its use undesirable in industry. By using triacetin as a solvent, it is possible to avoid the use of diethyl ether.

[0137] Surprisingly, an increase in the yield of the target product was also observed compared to the process known from DE 20 2021 104 269 U1. The yield of corylonepyrazine can be up to approximately 30 mol% in the present inventive process, whereas, in contrast, the yield of corylonepyrazine in the process described in DE 20 2021 104 269 U1 is only approximately 6 mol%. The corylonepyrazine-containing fraction obtained after purification or isolation can have a purity of at least 95 wt%.

[0138] A further subject of the present invention is the formulation which is prepared in particular by the process according to the invention and which contains at least one (alkyl)pyrazine of the formula (Ia) contain, in which

[0139] R 2 and R 3 are the same or different and independently represent hydrogen or C 1-4 alkyl or

[0140] R 2 and R 3are connected to each other and together form a group of the formula where A, B, C and D independently represent hydrogen or C 1 - alkyl.

[0141] The formulation according to the invention may additionally contain at least one (alkyl)pyrazine of the formula (Ib) contain, in which

[0142] R 1 represents hydrogen or methyl,

[0143] R 2 and R 3 are the same or different and independently represent hydrogen or C 1-4 alkyl or

[0144] R 2 and R 3 are connected to each other and together form a group of the formula where A, B, C and D independently represent hydrogen or C 1-4 -alkyl. The (alkyl)pyrazines of formula (Ia) and (alkyl)pyrazines of formula (Ib) can be separated from one another. For this purpose, any separation method known to the person skilled in the art can be used. Distillation, crystallization or chromatography can be used as a separation method, for example. The (alkyl)pyrazines of formula (Ia) or (alkyl)pyrazines of formula (Ib) isolated by these separation processes can be used for the production of products such as food, luxury goods, cosmetic or pharmaceutical products and dietary supplements.

[0145] This (alkyl)pyrazine of formula (Ib) can be prepared from at least one alpha-amino acid as the sole nitrogen source. It is preferred that a combination comprising at least one alpha-amino acid and at least one ammonium salt be used as the sole nitrogen source for the preparation of at least one (alkyl)pyrazine of formula (Ib). It is particularly preferred that a combination consisting of at least one alpha-amino acid and at least one ammonium salt be used as the sole nitrogen source for the preparation of at least one (alkyl)pyrazine of formula (Ib).

[0146] The formulation preferably contains at least about 99.9% by weight, preferably at least about 95% by weight, of at least one (alkyl)pyrazine of formula (Ib). Furthermore, the minimum amount of at least one (alkyl)pyrazine of formula (Ib) in the formulation according to the invention is about 0.01% by weight. The formulation according to the invention can preferably contain at least about 0.1% by weight of at least one (alkyl)pyrazine of formula (Ib) in one or more solvents suitable for the production of a food. For example, in the case of isolation of the formulation by means of SPE, in which ethanol is used as the solvent, a product can be obtained which contains at least about 0.1 to about 0.2% by weight of at least one (alkyl)pyrazine of formula (Ib). In the case of co-distillation with PG, a product can be obtained which contains at least about 2 to about 3 wt.% of at least one (alkyl)pyrazine of formula (Ib).

[0147] Particularly preferred are the (alkyl)pyrazines of formula (Ib) in which

[0148] R 1 stands for hydrogen and

[0149] R 2 and R 3 are connected to each other and together form a group of the formula where A is methyl and B and C are hydrogen.

[0150] Very particular preference is given to the (alkyl)pyrazines of formula (Ia) or (Ib) which are selected from the group consisting of

[0151] 5-Methyl-6,7-dihydro-cyclopentapyrazine (Corylon-Pyrazine)

[0152] Pyrazine

[0153] 2-Methylpyrazine

[0154] 2,5-Dimethylpyrazine ,5,6-Trimethylpyrazine -Ethyl-3,6-dimethylpyrazine -Methyl-6,7-dihydro-5H-cyclopenta[b]pyrazine ,6,7,8-Tetrahydroquinoxaline (Cyclohexapyrazine) 2-Methyl-5,6,7,8-tetrahydroquinoxaline

[0155] 2,5-Diethyl-3,6-dimethyl pyrazine

[0156] 2,6-Diethyl-3,5-dimethyl pyrazine

[0157] consists.

[0158] The formulation according to the invention is preferably free from alcohol, particularly preferably free from ethanol.

[0159] A formulation for flavoring a product, such as food, luxury food, cosmetic or pharmaceutical product as well as food supplement, which contains at least 95 wt.% of 5-methyl-6,7-dihydro-cyclopentapyrazine (Corylon-pyrazine), represents a preferred subject matter of the invention.

[0160] A formulation for flavoring a product, such as food, luxury food, cosmetic or pharmaceutical product as well as food supplement, which contains at least 95 wt.% of 2,5(6)-diethyl-3,6(5)-dimethylpyrazine, represents a preferred subject matter of the invention.

[0161] The present invention further relates to the product, in particular food, luxury food, cosmetic or pharmaceutical product, and dietary supplement, containing a formulation according to the invention. The proportion of the formulation according to the invention in this product is up to approximately 1000 ppm, preferably approximately 10' 3 ppm up to approx. 750 ppm, particularly preferably from approx. 0.1 up to 150 ppm.

[0162] The formulation according to the invention can be used to flavor a product, in particular a food, luxury food, cosmetic or pharmaceutical product, or a dietary supplement. For this purpose, the product, in particular a food, luxury food, cosmetic or pharmaceutical product, or a dietary supplement, is brought into contact with the formulation according to the invention. Furthermore, the present invention relates to a process for producing a product, in particular a food, luxury food, cosmetic or pharmaceutical product, or a dietary supplement, in which the formulation according to the invention is brought into contact with the product.

[0163] The invention will be explained using the attached example, but is not limited to the specifically described embodiment. The invention also applies to all combinations of preferred embodiments, provided they are not mutually exclusive. The terms "about" or "approx." in conjunction with a numerical value mean that values ​​that are at least 10% higher or lower, or 5% higher or lower, and in any case 1% higher or lower, are included.

[0164] Example 1

[0165] Raw materials:

[0166] L-Serine (500 mmol, 52.5 g),

[0167] Cyclotene (250 mmol, 28 g) as a 5% solution in triacetin (560 g) distilled water (95 g)

[0168] L-serine (500 mmol, 52.5 g) is mixed with 112 g of cyclotene solution (5% solution in triacetin) and the mixture is heated to approximately 110 °C.

[0169] The remaining cyclotene solution (448 g) and the distilled water are each placed in a dropping funnel and added only when the mixture temperature reaches 110 °C. The mixture is stirred at 110-120 °C. The reaction progress is monitored by GC analysis. When no more cyclotene is detected in the reaction mixture, the reaction is stopped (e.g., by cooling to room temperature) and the mixture is purified using a rectification apparatus to obtain corylonepyrazine with a purity of at least 95 wt.%.

[0170] The obtained product was analyzed by GC-FID.

[0171] Example 2

[0172] L-serine (105 mmol, 11.1 g) is mixed with 116 g of cyclotene solution (5% solution in triacetin) and 20 g of distilled water. The mixture is heated to 120 °C with continuous stirring. The reaction progress is monitored by GC analysis. When no more cyclotene is detected in the reaction mixture, the reaction is stopped, and the mixture is purified using a rectification apparatus to obtain corylonepyrazine with a purity of at least 95 wt. %.

[0173] Example 3

[0174] L-serine (2500 mmol; 263 g) is mixed with 600 g of cyclotene solution (5% solution in triacetin) and heated to approximately 110 to 120 °C. A further cyclotene solution (2280 g) and distilled water are placed in dropping funnels and added only when the mixture temperature reaches 110 °C. The mixture is stirred at 110 to 120 °C. The reaction progress is monitored by GC analysis. If no cyclotene is detected in the mixture, the reaction is stopped, and the mixture is adjusted to pH 12 using 30% NaOH solution. The resulting mixture is passed through an SPE column and then eluted with ethanol. This ethanolic extract contains 10,000 to 12,000 ppm of corylonpyrazine and can be declared as a natural flavor extract.

[0175] Example 4

[0176] L-serine (121 mmol; 13.9 g) is mixed with cyclotene (121 mmol; 13.9 g), 138 g of glycerol, 91.8 g of propylene glycol, and 45.9 g of water. The mixture is heated to 120 °C. The reaction progress is monitored by GC analysis. When no cyclotene is detected in the mixture, the reaction is stopped. The mixture is distilled under reduced pressure (40 mbar) by slowly heating the mixture to 160 °C and reducing the pressure to 10 mbar. The collected fraction contains 1000 to 5000 ppm of corylonepyrazine in PG.

[0177] Example 5

[0178] L-serine (420 mmol, 44.2 g) is added to a triacetin / diacetin mixture with a triacetin to diacetin ratio of 9:1 (1 L). The mixture is heated to 125 °C with continuous stirring. The reaction progress is monitored by GC analysis. When no more cyclotene is detected in the reaction mixture and approximately 19 mol% corylonepyrazine has been reached, which occurs after approximately 72 h, the reaction is stopped, and the mixture is rectified to obtain corylonepyrazine with a purity of at least 95 wt. %. Example 6

[0179] Raw materials:

[0180] L-serine (420 mmol, 44.1 g);

[0181] Cyclotene (210 mmol, 24.3 g);

[0182] ammonium chloride (420 mmol, 22.5 g);

[0183] Triacetin (463 g) and diacetin (24.0 g).

[0184] L-serine (2 eq.), ammonium chloride (2 eq.), and cyclotene (1 eq.) are placed together with triacetin (10 eq.) and diacetin (0.6 eq.) in a 1-liter, three-neck flask equipped with a reflux condenser and a precision glass stirrer bar. The mixture is heated to 125 °C with continuous stirring. The reaction progress is monitored by GC analysis. When no more cyclotene is detectable in the reaction mixture (after approximately 32 hours), the reaction is stopped. The yield was determined by GC analysis and is approximately 29.3 mol%, based on the molar amount of cyclotene used. The crude mixture was purified using a rectification apparatus.

[0185] Examples 7-11

[0186] Example 7 was carried out analogously to Example 5, except that in Example 5 the ratio of triacetin to diacetin in Example 7 was 19:1.

[0187] Examples 8 to 12 were carried out analogously to Example 6. Compared to Example 6, the components, such as L-serine, ammonium chloride and solvent, as well as their amounts were varied (see Table 1).

[0188] Table 1: As can be seen from Table 1, the addition of ammonium chloride leads to an increase in yield. By using ammonium chloride in combination with a solvent mixture such as triacetin and diacetin (see Example 10), the amount of L-serine can be reduced by 50%, compared to the reaction without ammonium chloride and diacetin (see Example 11).

[0189] 8) a comparable yield of the target product - corylonepyrazine - is achieved within a shorter reaction time.

[0190] If the amount of L-serine is not reduced, a significant increase in yield and a further reduction in reaction time are observed after adding an ammonium salt in combination with a solvent mixture such as triacetin and diacetin (see Example 6). Furthermore, it can be observed that fewer byproducts are formed during purification, which considerably simplifies the process.

[0191] It was also found that the amount of solvent or solvent mixture can be reduced (see Example 12). The total reaction volume can be halved without significant loss of yield, which was not possible without the addition of an ammonium salt. This not only increases the economic efficiency of the process, but also leads to simplified purification, comparably higher yields, and, last but not least, a more environmentally friendly alternative with half the amount of waste.

[0192] Example 12

[0193] Raw materials:

[0194] L-threonine (22 mol, 2.62 kg);

[0195] 2,3-pentadione (11 mol, 1.1 kg);

[0196] ammonium chloride (22 mol, 1.12 kg);

[0197] Triacetin (55 mol, 12.1 kg) and glycerol (8.8 mmol 0.8 g).

[0198] L-threonine (2 eq.), ammonium chloride (2 eq.), and 2,3-pentadione (1 eq.) are placed together with triacetin (5 eq.) and glycerol (0.0008 eq.) in a 20-liter, three-neck flask equipped with a reflux condenser and a KPG stirrer bar. The mixture is heated to 140 °C with continuous stirring. The reaction progress is monitored by GC analysis. When no more 2,3-pentadione can be detected in the reaction mixture (after approximately 8 hours), the reaction is stopped. The yield was determined by GC analysis and is approximately 40 mol% for the isomer mixture of 2-ethyl-3,5(6)-dimethylpyrazine ((alkyl)pyrazine of formula (Ib)) and 20 mol% for the isomer mixture of 2,5-diethyl-3,6(5)-dimethylpyrazine ((alkyl)pyrazine of formula (Ia)), based on the molar amount of 2,3-pentadione used. The crude mixture was purified using a rectification apparatus.

[0199] Examples 13-17

[0200] The reactions described in Examples 13-17 were carried out in 20 mL crimp vials. The objective was to investigate the different influence of the solvents and the ammonium salt on the ratio of pyrazine of formula (Ia) and (Ib). For this purpose, 0.5 g of 2,3-pentadione (2 mmol) and 1.0 g of serine (10 mmol) were dissolved in 5 mL of the respective solvents. The reaction mixture was then heated to 140°C with stirring for 24 h. After cooling, the ratios of pyrazine Ia and Ib were determined by GC-FID.

[0201] Table 2:

[0202] As can be seen from Table 2, the addition of ammonium chloride leads to an increase in the overall yield of pyrazines. This is particularly evident in Example 16, where the overall yield of only 25.6% is significantly lower than the overall yields of 55.2-66.7% achieved in Examples 13-15 and 17.

[0203] As can be seen from the comparison of Example 13 with Examples 14-17, the addition of hydroxyl-containing solvents such as glycerol and propylene glycol can increase the ratio of pyrazine of formula (Ia) obtained. In catalytic amounts (Examples 14+15, glycerol 0.15%), this increases the overall yield, whereas when used as the sole solvent (Example 17), the selectivity is strongly shifted toward pyrazine of formula (Ia).

Claims

Claims 1. A process for preparing a formulation comprising the following steps: (a) providing at least one compound of formula (II) or (III) or (IIIa) R 2 -C(O)-C(O)-R 3 (II) or R 2 -C(O)-C(OH)=R 3 (Ill)or R 2 -C(O)-CH(OH)-R 3 (Illa), wherein R 2 and R 3 are the same or different and independently represent hydrogen or C1-4 alkyl or R 2 and R 3 are connected to each other and together form a group of the formula represent, where A, B, C and D independently represent hydrogen or Ci-4-alkyl, (b) providing an alpha amino acid, in particular a proteinogenic alpha amino acid, (c) bringing into contact at least one compound of formula (II) or formula (III) or formula (IIIa) and at least one alpha-amino acid, using at least one solvent suitable for the production of foodstuffs and having a boiling point of at least 140 °C, in particular propylene glycol, glycerol, triethyl citrate, diacetin, monoacetin and / or triacetin, and adding the solvent before step (c) and / or in step (c).

2. The process according to claim 1, wherein the process is carried out in the presence of at least one ammonium salt.

3. The process according to claim 1 or 2, wherein the alpha-amino acid in step (b) is an alpha-amino acid of formula (IV), where E stands for O or S and R 1represents hydrogen or methyl. Process according to any one of the preceding claims, characterized in that the compound of formula (II) or (III) or (IIIa) is selected from the group consisting of (1) 2-Hydroxy-3-methyl-2-cyclopenten-l-one (cyclotene) (2) Glyoxal (3) 2-Oxopropanal (4) Diacetyl (5) 2-Hydroxycyclopentanone (2-Hydroxycyclopent-2-en-l-one) (6) 2-Hydroxy-3-methylcyclopentanone (7) 2-Hydroxy-3,4-dimethylcyclopentanone (2-Hydroxy-3,4-dimethylcyclopent-2-en-1-one) (8) 3,5-Dimethylcyclopentanedione (2-Hydroxy-3,5-dimethyl-2-cyclopenten-l-one) and (9) 2-Hydroxycyclohexanone (2-hydroxycyclohex-2-en-l-one) (10) Acetylpropionyl (2,3-pentanedione) (11) 3,4-Hexanedione (12) Methylglyoxal exists, whereby (1) 2-Hydroxy-3-methyl-2-cyclopenten-l-one (cyclotene) (10) Acetylpropionyl (2,3-pentanedione) is preferred. . Process according to one of the preceding claims, characterized in that the alpha amino acid in step (b) is selected from the group consisting of L- / D- / (7?,S')-Scrin. L- / D- / (RS)-cysteine, L- / D- / (7?.S')-thyroxine and mixtures thereof, preferably L- / D- / (7?.S)-serine and L- / D- / (7?.S)-cystine. particularly preferably L-serine or L-cysteine, very particularly preferably L-serine. . Process according to one of the preceding claims, characterized in that the molar ratio of a compound of the formula (II) or (III) or (IIIa) to the alpha amino acid is 1:1 to 1:5, preferably 1:

2. . Process according to one of claims 2 to 6, characterized in that the molar ratio of ammonium salt to at least one amino acid is in a range from 4:1 to 0.1:1, preferably in the range 2:1 to 0.5:1, very particularly preferably in a ratio 1:

1. .Process according to one of the preceding claims, characterized in that the solvent is selected from the group consisting of propylene glycol, glycerol, diacetin, monoacetin, triacetin, triethyl citrate, or mixtures thereof, wherein water, ethanol, or propanol can additionally be added as solvent. Process according to one of the preceding claims, characterized in that the reaction in step (c). at maximum temperatures of approximately 180 °C, preferably in the range of approximately 100 to 140 °C, particularly preferably at temperatures in the range of approximately 110 to 130 °C and in particular over a period of up to 40 hours, preferably over a period of up to 24 hours, preferably from 1 to 12 hours, particularly preferably up to 6 hours. Process according to one of the preceding claims, characterized in that the resulting formulation contains at least one (alkyl)pyrazine of the formula (Ia) contains, in which R 2 and R 3 are the same or different and independently represent hydrogen or C 1-4 alkyl or R 2 and R 3 are connected to each other and together form a group of the formula where A, B, C and D independently represent hydrogen or Ci-4-alkyl. Process according to one of the preceding claims, characterized in that the formulation obtained comprises at least one (alkyl)pyrazine of formula (Ia) and at least one (alkyl)pyrazine of formula (Ib) contains, in which R 1 represents hydrogen or methyl, R 2 and R 3 are the same or different and independently represent hydrogen or C1-4 alkyl or R 2 and R 3 are connected to each other and together form a group of the formula ABC or ABCD where A, B, C and D independently represent hydrogen or C 1-4 -alkyl. A formulation, in particular prepared by a process according to one of the preceding claims, containing at least one (alkyl)pyrazine of the formula (Ia), and / or at least one (alkyl)pyrazine of formula (Ib) wherein R 1 represents hydrogen or methyl, R 2 and R 3 are the same or different and independently represent hydrogen or C 1-4 alkyl or R 2 and R 3 are connected to each other and together form a group of the formula wherein A, B, C and D independently of one another represent hydrogen or Ci-4-alkyl. Formulation according to claim 12, which contains at least one (alkyl)pyrazine of the formula (Ia) and at least one (alkyl)pyrazine of the formula (Ib). Formulation according to claim 13, characterized in that the (alkyl)pyrazine of the formula (Ia) and (Ib) is preferably selected from the group consisting of 5-Methyl-6,7-dihydro-cyclopentapyrazine (Corylon-Pyrazine), Pyrazine, 2-Methylpyrazine, 2.6-Dimethylpyrazine 2,5-dimethylpyrazine 2,3-dimethylpyrazine, 2.5.6-Trimethylpyrazine, 2-Methyl-6,7-dihydro-5H-cyclopenta[b]pyrazine, 2,5-Dimethyl-6,7-dihydro-5H-cyclopenta[b]pyrazine, 5,6,7,8-tetrahydroquinoxaline (cyclohexapyrazine) and 2-methyl-5,6,7,8-tetrahydroquinoxaline 2-ethyl-3-methylpyrazine 2-ethyl-3,5-dimethylpyrazine 2-Ethyl-3,6-dimethylpyrazine 2-Ethyl-3,5,6-trimethylpyrazine 2,3-Diethyl-5-methylpyrazine 2-Ethylpyrazin, 2.5-Diethyl-3,6-dimethyl pyrazin, 2.6-Diethyl-3,5-dimethyl pyrazin, 2.3-Diethyl-5,6-dimethyl pyrazin, Tetraethyl pyrazin und 2,3-Diethylpyrazine, with 5-methyl-6,7-dihydrocyclopentapyrazine (Corylonpyrazine) or 2,5(6)-diethyl-3,6(5)-dimethylpyrazine being particularly preferred. Formulation according to any one of claims 12-14, characterized in that it contains 2-ethyl-3,5-dimethylpyrazine and 2-ethyl-3,6-dimethylpyrazine in a molar ratio of at least 50:50, preferably at least 55:45, particularly preferably at least 60:

40. A product, in particular food, luxury food, cosmetic or pharmaceutical product, and dietary supplement, which contains a formulation according to any one of claims 12-15. A product, in particular food, luxury food, cosmetic or pharmaceutical product, and dietary supplement, which contains at least one (alkyl)pyrazine of the formula (Ib) produced by a process according to any one of claims 1-11. Formulation, in particular prepared by a process according to any one of claims 1-11, containing at least one (alkyl)pyrazine of the formula (Ib),。 wherein R 1 represents hydrogen or methyl, R 2 and R 3 are the same or different and independently represent hydrogen or C1-4- alkyl or R 2 and R 3 are connected to each other and together form a group of the formula where A, B, C and D independently represent hydrogen or Ci-4-alkyl.

19. A process for preparing a formulation comprising the following steps: (a) providing at least one compound of formula (II) or (III) or (IIIa) R 2 -C(O)-C(O)-R 3 (II) or R 2 -C(O)-C(OH)=R 3 (Ill)or R 2 -C(O)-CH(OH)-R 3 (Illa), wherein R 2 and R 3 are the same or different and independently represent hydrogen or C1-4 alkyl or R 2and R 3 are connected to each other and together form a group of the formula represent, where A, B, C and D independently represent hydrogen or Ci-4-alkyl, (b) providing an alpha amino acid, in particular a proteinogenic alpha amino acid, (c) bringing into contact at least one compound of formula (II) or formula (III) or formula (IIIa) and at least one alpha-amino acid, wherein at least one solvent containing at least one hydroxy group is added before step (c) and / or in step (c). The process according to claim 19, wherein the solvent containing at least one hydroxy group is propylene glycol, glycerol (also glycerol or glycerin), monoacetin, triethyl citrate and / or diacetin. The process according to claim 19 or 20, wherein the solvent containing at least one hydroxy group is part of a solvent mixture which is added before step (c) and / or in step (c). The process according to claim 21, wherein the solvent containing at least one hydroxy group makes up between 0.01 and 10% by weight of the solvent mixture, preferably between 0.05 and 1% by weight. The process according to claim 21 or 22, wherein the solvent mixture comprises a solvent which does not contain a hydroxy group, preferably triacetin. The process according to any one of claims 19-23, wherein the solvent containing at least one hydroxy group is added in a ratio of 0.01-5 mol.-%, based on the compound of formula (II) or (III) or (IIIa). Use of a solvent containing at least one hydroxy group to increase the yield in a process for preparing (alkyl)pyrazine, in particular in a process according to any one of claims 19-24, in particular (alkyl)pyrazine of formula (Ia). and / or (alkyl)pyrazine of formula (Ib) wherein R 1 represents hydrogen or methyl, R 2 and R 3 are the same or different and independently represent hydrogen or C 1-4 alkyl or R 2 and R 3 are connected to each other and together form a group of the formula where A, B, C and D independently represent hydrogen or Ci-4-alkyl. . Use of a solvent containing at least one hydroxy group for regulating the molar ratio of the (alkyl)pyrazines of formula (Ia) and formula (Ib) in a process for preparing (alkyl)pyrazines, in particular in a process according to one of the Claims 19-24, wherein R 1 represents hydrogen or methyl, R 2 and R 3 are the same or different and independently represent hydrogen or C 1-4 alkyl or R 2 and R 3 are connected to each other and together form a group of the formula where A, B, C and D independently represent hydrogen or Ci-4-alkyl.

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