EP4359496A1

EP4359496A1 - Aroma or fragrance compositions, comprising 4-methylheptan-3-one, and methods for producing them

Info

Publication number: EP4359496A1
Application number: EP21737352.1A
Authority: EP
Inventors: Jekaterina ONGOUTA; Michael Backes; Nadine HEINEMEIER; Thomas Riess; Volkmar Koppe; Caroline Brinkmann
Original assignee: Symrise AG
Current assignee: Symrise AG
Priority date: 2021-06-21
Filing date: 2021-06-21
Publication date: 2024-05-01
Also published as: WO2022268285A1

Abstract

The present invention relates to novel aroma/flavour or fragrance compositions comprising 4-methylheptan-3-on, a method for preparing said compositions and their use. Furthermore, the invention relates to foodstuff, luxury food, food supplements, semi-finished products, pet foods, aroma or fragrances, comprising the aroma or fragrance composition according to the present invention. Finally, the present invention pertains to the use of 4-methylheptan-3-one as aroma/flavour or odorant.

Description

Aroma or fragrance compositions, comprising 4-methylheptan-3-one, and methods for producing them

Field of the invention

[0001] The present invention relates to novel aroma/flavour or fragrance compositions comprising 4-methylheptan-3-on. The invention also relates to methods for preparing 4- methylheptan-3-one and the 4-methylheptan-3-one obtained by this method. In addition, the invention pertains to a method for producing, enhancing or modifying one or more nutty, sweet, chemical-fruity, mushroom and/or roasted taste or odour impression(s) in a finished formulation. The invention also relates to the use of such aroma or fragrance compositions for imparting, enhancing or modifying one or more of a nutty, sweet, chemical-fruity, mushroom or roasted taste or odour in a finished formulation. Furthermore, the invention relates to foodstuff, luxury food, food supplements, semi finished products, pet foods, or fragrances, comprising the aroma or fragrance composition according to the present invention. Finally, the present invention pertains to the use of 4-methylheptan-3-one as aroma/flavour or odorant.

State of the art

[0002] There is sustained interest within the flavour industry in developing new flavour substances in order to enable the creation of new aromas or fragrances. Compounds with a nutty, sweet, fruity or roasted flavour/aroma or odour are indispensable components in the food or fragrance industry. Especially naturally occurring substances, which can be produces by green, environmentally friendly methods, are of great interest.

[0003] During the screening of flavour compounds 4-methylheptan-3-one was surprisingly identified as a very powerful flavour compound with characteristic nutty, sweet, chemical-fruity and/or roasted profile. These typical nutty, sweet, chemical-fruity and/or roasted notes are very useful for the development of authentic flavours or fragrances having particular notes and aspects. [0004] 4-Methylheptan-3-one is a natural product, which was first isolated from the mandibular glands of Pogonomyrmex barbatus. Later 4-methylheptan-3-one was also determined in defensive secretions of other species of ants, other insects and also in urine of different animals. This volatile compound functions as an alarm pheromone and assists by the communication between animals and insects. That is why, 4-methylheptan- 3-one is used for pest control, especially against the codling moth ( Laspeyresia pomonella), false codling moth ( Cryptophlebia leucotreta) and fruit fly ( Pterandrus rosa).

[0005] 4-Methylheptan-3-one was also identified in different plants and also in food, like in guava, apple, melon, black tee, cow's and goat's milk yoghurt, almond nuts, aronia and broccoli.

[0006] However, the naturally occurring small amounts of 4-methylheptan-3-one (for example, 2.48 mg/kg in nuts) are not enough to achieve the invented effects in flavour applications.

[0007] 4-Methylheptan-3-one exists in form of two isomers (-)-(4R)-methylheptan-3-one and (+)-(4S)-methylheptan-3-one. Comparison of the biological activity of both isomers in insects showed that the naturally occurring S-isomer is 100 to 400 times stronger.

[0008] To date, many methods for the preparation of 4-methylheptan-3-one were published. Also, the synthesis starting from 3-pentanone is already known. One method comprises a three-step synthesis including an aldol-reaction between 3-pentanone and propionaldehyde, subsequent water elimination and reduction of the double bond. The aldol reaction is catalysed by potassium hydroxide in methanol. The subsequent water elimination can be achieved using phosphor pentoxide or oxalic acid and the following reduction of the double bond using hydrogen catalysed by Raney Nickel or palladium. One of the disadvantages of this process for the preparation of 4-methylheptan-3-one is the use of toxic methanol.

[0009] The reduction of the double bond can be also realized stereoselectively using microorganisms or enzymes to generate enantiomerically enriched 4-methylheptan-3- one. Examples thereof were published. Using microorganism Beauveria sulfurescens selectively (-)-(4R)-methylheptan-3-one could be obtained. In addition, using old yellow enzyme (OYE 3) from Saccharomyces pastorianus or old yellow enzyme (OYE 1 ) from Saccharomyces cerevisiae, (+)-(4S)-methylheptan-3-one or respectively (-)-(4 R)- methylheptan-3-one could be synthesized selectively. The use of the isolated enzymes provides very good yields and enantioselectivities. However, the addition of stoichiometric amounts of expensive cofactors such as NADPH or application of other enzymes to regenerate NADPH is necessary. The use of commercially available baker’s yeast for generation of 4-methylheptan-3-one was not published until now.

[0010] Other methods for production of 4-methylheptan-3-one include either the addition of organometallic compounds to carbonic acid derivatives or to aldehydes, followed by oxidation, or a-alkylation of linear ketones or use of the photocatalysis. However, these strategies require either strictly anhydrous conditions or the use of stoichiometric amounts of oxidation agents or generate toxic waste, and thus, severely limiting their industrial potential.

[0011 ] For the generation of enantiomer enriched 4-methylheptan-3-one, chiral starting materials or the use of expensive chiral auxiliary components are necessary. Therefore, a sustainable, environmentally friendly and cost-effective approach towards the synthesis of 4-methylheptan-3-one is clearly needed.

[0012] The object of the present invention is thus to provide an aroma/flavour or fragrance composition comprising a sensory effective amount of 4-methylheptan-3-one having a rich and balanced aroma/flavour or odour profile and a method for the preparation of 4-methylheptan-3-one based on green environmentally friendly methods, avoiding the use of halogenated or toxic reagents and/or reducing or completely avoiding the solvents for the aldol reaction to minimize the waste production.

[0013] The invention is based, inter alia on the surprising finding, that 4-methylheptan- 3-one is suitable as aroma/flavour or odour substance. Surprisingly, it was found that 4- methylheptan-3-one produced according to the present invention has one or more nutty, chemical-fruity, sweet, and/or roasted aroma/flavour and odour characteristics causing it to be particularly useful for generation of authentic aromas/flavours or fragrances. It was found that the aroma/flavour or fragrance compositions containing 4-methylheptan-3-one, generated according to invention, are particularly more rich and more balanced and have a pronounced natural and intense aroma/flavour or odour and produce excellent aroma or fragrances. Additionally, the aroma/flavour or fragrance compositions containing 4- methylheptan-3-one are particularly useful to give other flavouring or perfuming compounds a more complex, natural and intensified taste or odour impression from the group consisting of nutty, sweet, fruity, mushroom and/or roasted notes.

[0014] Further aspects of the invention emerge from the attached patent claims and the following description.

Summary of the invention

[0015] In a first aspect, the present invention relates to an aroma/flavour or fragrance composition, comprising a sensory effective amount of 4-methylheptan-3-one.

[0016] In a second aspect, the present invention relates to a method for preparing 4- methylheptan-3-one, comprising the following steps:

(a) performing an acid catalysed aldol condensation between pentan-3-one and propionaldehyde to obtain a mixture comprising 4-methylhept-4-en-3-one;

(b) separating 4-methylhept-4-en-3-one from the mixture from step (a) by extraction and subsequent distillation;

(c) treating the isolated 4-methylhept-4-en-3-one from step (b) with a chemical-type reducing agent to reduce the double bond to obtain the chemically generated product 4-methylheptan-3-one; or treating the isolated 4-methylhept-4-en-3-one from step (b) with a biochemical-type reducing agent to reduce the double bond to obtain the biological generated product 4-methylheptan-3-one; and

(d) separating the product 4-methylheptan-3-one from step (c) by optionally filtration and/or by distillation. [0017] In a third aspect, the present invention relates to an aroma/flavour or fragrance composition comprising a sensory effective amount of 4-methylheptan-3-one, obtained or obtainable by a method according to the present invention

[0018] In a fourth aspect, the present invention relates to a method of producing, enhancing or modifying of one or more nutty, sweet, fruity, mushroom and/or roasted taste or odour impression(s), comprising the following steps:

(a1 ) providing 4-methylheptan-3-one; and

(a2) mixing a sensory effective amount of 4-methylheptan-3-one with one or more of further aroma or fragrance substance(s) to obtain a nutty, sweet, fruity, mushroom and/or roasted aroma/flavour or odour in the finished aroma composition or fragrance composition; or (b1 ) providing 4-methylheptan-3-one; and

(b2) mixing a sensory effective amount of 4-methylheptan-3-one with an aroma, an orally consumable preparation or a fragrance to obtain a nutty, sweet, fruity, mushroom or roasted taste or odour in the finished preparation.

[0019] In another aspect, the present invention relates to the use of the aroma/flavour or fragrance composition according to the present invention for producing, enhancing or modifying of a nutty, sweet, fruity, mushroom or roasted taste or odour.

[0020] In yet another aspect, the present invention relates to foodstuff, luxury food, food supplements, semi-finished products for the preparation of foodstuffs or food supplements, pet food, or fragrances, comprising the aroma/flavour or fragrance composition according to the present invention.

[0021 ] Still further, the present invention relates to flavoured or perfumed products, such as foodstuff, luxury food, food supplements, semi-finished products for the preparation of foodstuffs or food supplements, pet food, aroma or fragrances, comprising the aroma/flavour or fragrance composition according to the present invention, in an effective amount. [0022] In a final aspect, the present invention pertains to the use of 4-methylheptan-3- one as aroma/flavour or odorant.

Detailed description of the invention

[0023] In accordance with the present invention, the above object is achieved by an aroma/flavour or fragrance composition comprising a sensory effective amount of 4- methylheptan-3-one, also designated as 4-methyl-3-heptanone, and represented by the formula (I):

[0024] Within the context of the present invention, an aroma/flavour composition in general is a composition comprising an individual chemical compound or class of chemical compounds to impart a flavour or a taste.

[0025] Within the context of the present invention, a fragrance composition in general is a composition comprising an individual chemical compound or class of chemical compounds to impart an odour or smell.

[0026] Flavours affect both the sense of taste and smell, whereas fragrances affect only smell.

[0027] The composition according to the present invention can be both, either an aroma/flavour composition or a fragrance composition.

[0028] Additionally, in the context of the present invention, the terms “aroma” or “flavour” are used interchangeable and in an equivalent sense. [0029] Within the context of the present invention, a sensory effective amount of 4- methylheptan-3-one is such an amount that is sufficient to impart a perceptible flavour or odour in the aroma/flavour or fragrance composition. When applied to a combination of flavour or fragrance substances, the term refers to the total amount of the combination of flavour or fragrance substances resulting in the flavour or odour.

[0030] It is known that 4-methylheptan-3-one according to the above formula comprises a chiral centre and, thus, can occur in different stereoisomeric forms, and as such may exist as enantiomerically pure forms or in any mixture of its stereoisomers, in particular enantiomers. The stereoisomeric forms are (-)-(4R)-methylheptan-3-one and (+)-(4S)- methylheptan-3-one.

[0031] Consequently, whenever reference is made in the present description to 4- methylhetpan-3-one without any further indication, this is deemed to refer to the compound in general, i.e. including all stereoisomers, in particular all enantiomers, i.e. the (-)-(4R)-methylheptan-3-one enantiomer and the (+)-(4S)-methylheptan-3-one enantiomer.

[0032] When referring to 4-methylheptan-3-one with a particular stereo-structure, this typically means either the pure (-)-(4R)-methylheptan-3-one enantiomer or the pure (+)- (4S)-methylheptan-3-one enantiomer, or any mixture of said enantiomers similarly, as long as not described otherwise.

[0033] Thus, the 4-methylheptan-3-one stereoisomers are preferably present in the form of:

(a) a pure optically active enantiomer, either the (-)-(4R)-methylheptan-3-one enantiomer or the (+)-(4S)-methylheptan-3-one enantiomer;

(b) a racemic mixture of the enantiomers; or

(c) any optically active mixture of the enantiomers.

[0034] For economic reasons it is preferred to use the compounds as any mixture of their enantiomers. [0035] In a preferred variant according to the first aspect of the present invention, the aroma/flavour or fragrance composition comprises the 4-methylheptane-3-one as an isomeric mixture of the (-)-(4R)-methylheptan-3-one enantiomer and the (+)-(4S)- methylheptan-3-one enantiomer.

[0036] In a more preferred variant according to the first aspect of the present invention, the aroma/flavour or fragrance composition comprises the racemic mixture of the (-)-(4 R)- methylheptan-3-one enantiomer and the (+)-(4S)-methylheptan-3-one enantiomer, i.e. the (-)-(4R)-methylheptan-3-one enantiomer and the (+)-(4S)-methylheptan-3-one enantiomer are present in the isomeric mixture in a ratio of 50 : 50.

[0037] In a still more preferred variant according to the first aspect of the present invention, the aroma/flavour or fragrance composition comprises an isomeric mixture of the (-)-(4R)-methylheptan-3-one enantiomer and the (+)-(4S)-methylheptan-3-one enantiomer, in which the (-)-(4R)-methylheptan-3-one enantiomer is enriched.

[0038] In a most preferred variant according to the first aspect of the present invention, the (-)-(4R)-methylheptan-3-one enantiomer is present in the isomeric mixture in an amount of more than 50 % by weight, relative to the total content of 4-methylheptan-3- one in the isomeric mixture.

[0039] In a still more preferred variant according to the first aspect of the present invention the (-)-(4R)-methylheptan-3-one enantiomer and the (+)-(4S)-methylheptan-3- one enantiomer are present in the isomeric mixture in a ratio of > 2 : 1, preferably in a ratio of 2 : 1.

[0040] In a more preferred variant, the isomeric mixture in the aroma/flavour or fragrance composition comprises the (-)-(4R)-methylheptan-3-one enantiomer in an amount of at least 60 to 65 % by weight, more preferably at least 70 to 75 % by weight, still more preferred at least 80 to 85 % by weight, and particularly preferred at least 90 to 95 % by weight, relative to the total weight of 4-methylheptan-3-one present in the isomeric mixture. [0041] In a most preferred variant, the aroma/flavour or fragrance composition comprises the (-)-(4R)-methylheptan-3-one enantiomer as pure optically active enantiomer.

[0042] The 4-methylheptan-3-one, namely the (-)-(4R)-methylheptan-3-one enantiomer or the (+)-(4S)-methylheptan-3-one enantiomer itself, or the racemic mixture of (-)-(4 R)- methylheptan-3-one enantiomer and (+)-(4S)-methylheptan-3-one enantiomer or an isomeric mixture of the (-)-(4R)-methylheptan-3-one enantiomer and the (+)-(4S)- methylheptan-3-one enantiomer, as described above, unexpectedly possess one or more strong nutty, sweet, chemical-fruity or roasted aroma/flavour or odour properties. The 4- methylheptan-3-one, namely the (-)-(4R)-methylheptan-3-one enantiomer or the (+)-(4S)- methylheptan-3-one enantiomer itself, or the racemic mixture or an isomeric mixture of the (-)-(4R)-methylheptan-3-one enantiomer and the (+)-(4S)-methylheptan-3-one enantiomer thus have an organoleptically, i. e. gustatory and/or olfactory, highly valuable, intense, natural nutty, sweet, chemical-fruity or roasted aroma/flavour or odour notes combined with a surprisingly elevated tenacity.

[0043] Said properties are pronounced for the (-)-(4R)-methylheptan-3-one enantiomer. The (-)-(4R)-methylheptan-3-one enantiomer has a natural, strongest nutty, sweet, fruity, roasted and slightly rummy aroma/flavour or odour.

[0044] It is thus preferred that the aroma/flavour or fragrance composition according to the present invention comprises the (-)-(4R)-methylheptan-3-one enantiomer. It is more preferred that the aroma/flavour or fragrance composition according to the present invention comprises predominantly the (-)-(4R)-methylheptan-3-one enantiomer, i.e. the (-)-(4R)-methylheptan-3-one enantiomer is present in the aroma/flavour or fragrance composition according to the present invention in excess.

[0045] However, the (+)-(4S)-methylheptan-3-one enantiomer likewise has a valuable and distinct aroma profile in the nutty, sweet, fruity, and/or roasted range which is thus alternatively advantageous. [0046] It is thus preferred that the aroma/flavour or fragrance composition comprises (+)- (4S)-methylheptan-3-one.

[0047] The above described organoleptic properties are particularly distinctive either for the racemic mixture of (-)-(4R)-methylheptan-3-one enantiomer and (+)-(4S)- methylheptan-3-one enantiomer or for any isomeric mixture of (-)-(4R)-methylheptan-3- one enantiomer and (+)-(4S)-methylheptan-3-one enantiomer.

[0048] The above described organoleptic properties are particularly distinctive for an isomeric mixture of (-)-(4R)-methylheptan-3-one enantiomer and (+)-(4S)-methylheptan- 3-one enantiomer, in which the (-)-(4R)-methylheptan-3-one enantiomer is enriched.

[0049] It is thus particularly preferred that the aroma/flavour or fragrance composition according to the present invention comprises both enantiomers, i.e. (-)-(4 R)- methylheptan-3-one enantiomer and (+)-(4S)-methylheptan-3-one enantiomer, either as racemic mixture or as an isomeric mixture as described above.

[0050] Due to the outstanding properties, still more preferred is an aroma/flavour or fragrance composition according to the present invention comprising an isomeric mixture of the (-)-(4R)-methylheptan-3-one enantiomer and the (+)-(4S)-methylheptan-3-one enantiomer, in which the (-)-(4R)-methylheptan-3-one enantiomer is enriched, i.e. an isomeric mixture, in which the (-)-(4R)-methylheptan-3-one enantiomer is present in an amount of more than 50 % by weight, preferably at least 60 to 65 % by weight, more preferably at least 70 to 75 % by weight, still more preferred at least 80 to 85 % by weight, and particularly preferred at least 90 to 95 % by weight, relative to the total weight of the isomeric mixture.

[0051] Advantageously, the aroma/flavour or fragrance composition containing the 4- methylheptan-3-one are particularly useful to give other flavouring compounds or odorants a more complex, naturally and intensified taste or odour impression(s) of the group consisting of nutty, sweet, fruity, mushroom or roasted notes.

[0052] Preferably, the (-)-(4R)-methylheptan-3-one enantiomer is particularly beneficial in imparting, enhancing or modifying one or more nutty, preferably hazelnut, sweet, fruity, mushroom, and/or roasted taste or odour in mixture with one or more aroma or fragrance substances, preferably having a nutty, preferably, hazelnut, sweet, fruity, mushroom and/or roasted note.

[0053] However, due to its above described properties, alternatively, the (+)-(4S)- methylheptan-3-one enantiomer is likewise advantageously in imparting, enhancing or modifying one or more nutty, preferably hazelnut, sweet, fruity, mushroom, and/or roasted taste or odour in mixture with one or more aroma or fragrance substances, preferably having a nutty, preferably, hazelnut, sweet, fruity, mushroom and/or roasted note.

[0054] Due to its above described advantageous properties, the racemic mixture of (-)- (4R)-methylheptan-3-one enantiomer and (+)-(4S)-methylheptan-3-one enantiomer or any isomeric mixture of (-)-(4R)-methylheptan-3-one enantiomer and (+)-(4S)- methylheptan-3-one enantiomer is deemed to impart, enhance or modify one or more nutty, preferably hazelnut, sweet, fruity, mushroom, and/or roasted taste or odour in mixture with one or more aroma or fragrance substances, preferably having a nutty, preferably, hazelnut, sweet, fruity, mushroom and/or roasted note, and is thus preferred.

[0055] Due to said beneficial properties, the 4-methylheptan-3-one, namely the (-)-(4 R)- methylheptan-3-one enantiomer or the (+)-(4S)-methylheptan-3-one enantiomer itself, or the racemic mixture of (-)-(4R)-methylheptan-3-one enantiomer and (+)-(4 S)- methylheptan-3-one enantiomer or an isomeric mixture of the (-)-(4R)-methylheptan-3- one enantiomer and the (+)-(4S)-methylheptan-3-one enantiomer, can either be used as individual substance or in mixtures with at least one other known aroma/flavour or odorant/fragrance substance selected from an extensive range of natural and synthetic substances available in a large number of aroma or fragrance mixtures. The olfactory properties of the 4-methylheptane-3-one harmonise with a multitude of natural or synthetic aroma/flavour or fragrance substances.

[0056] In particular, the 4-methylheptan-3-one harmonises particularly well with all nutty, sweet, fruity, mushroom and roasted aroma/flavour or odour notes.

[0057] Thus, it is advantageous to combine the 4-methylheptan-3-one with at least one other aroma/flavour or odour/fragrance substance in order to form a novel aroma or fragrance composition or in order to round off and refine the flavour or odour of an aroma/flavour or odour/fragrance substance. Interesting and natural novel and original flavour or fragrance notes may be created in this manner.

[0058] Hence, the present invention relates to an aroma or fragrance composition, comprising 4-methylheptan-3-one or its (-)-(4R)-methylheptan-3-one enantiomer or its (+)-(4S)-methylheptan-3-one enantiomer or the racemic mixture of (-)-(4 R)- methylheptan-3-one enantiomer and (+)-(4S)-methylheptan-3-one enantiomer or any isomeric mixture of the (-)-(4R)-methylheptan-3-one enantiomer and the (+)-(4S)- methylheptan-3-one enantiomer, and at least one further aroma/flavour or odour/fragrance substance.

[0059] The following specified aroma/flavour or odour/fragrance substances can be used, either as individual substances or in mixtures with at least one, two, three or even more aroma/flavour or odour/fragrance substances in combination with 4-methylheptan-

3-one, or at least one 4-methylheptan-3-one isomer or mixtures thereof, selected from an extensive range of natural and synthetic substances.

[0060] Aroma/flavour substances with are advantageously suitable for combining with

4-methylheptan-3-one are selected from the group consisting of: organic acids: acetic acid, butyric acid, 2- or, respectively 3-methyl butyric acid, caprinic acid, capronic acid, phenylacetic acid; alcohols: ethanol, propylene glycol, 1,3-octenol, c/s-3-hexenol, linalool, benzyl alcohol, p-cresol, 2,6-dimethylthiophenol, guajacol, eugenol; sulfides/thiols: dimethyl sulfide, difurfuryl disulfide, methyl thiopropanal, 2-methyl-3- methyldithiofuran and bis(2-methyl-3-furyl)disulfide, methylfuranthiol, 2-(4-methyl- 1 ,3-thiazol-5-yl)ethanol (sulfurol), methyltetrahydrofuranthiol, 3-methyl-2-buten-1- thiol, 3-thio-2-methylpentanol, 2-furfurylthiol, thiophenol, 2-methylthiophenol and 2- mercaptobutanone; pyridines: 2-acetylpyridine; pyrazines: methylpyrazine, 2,5-methylethylpyrazine, 2,3,5-trimethylpyrazine, acetylpyrazine, 2,3-diethyl-5-methylpyrazine, 2-ethyl-3,5-dimethylpyrazine and 2- isopropyl-3-methoxy-pyrazine; thiazoles/thiazoline: 2-acetylthiazol, 2-acetyl-2-thiazoline; pyrrolines: 2-propionyl-1-pyrroline and 2-acetyl-1-pyrroline; aldehydes: acetaldehyde, frans-4,5-epoxy-(2E)-decenal, c/s-4,5-epoxy-(2E)- decenal, (E,E)-2,4-undecadienal, (E,E)-2,4-decadienal, (E,Z)-2,4-decadienal, (E,E,Z)-2,4,6-nonathenal, (E,E)-2,4-nonadienal, (E)-2-undecenal, (Z)-2-decenal, (E)-2-decenal, (E)-2-nonenal, (Z)-2-nonenal, (E,Z)-2,6-nonadienal, (E,E)- 2,4- nonadienal, 3-methylthiopropanal (methional), vanillin und phenylacetaldehyde; ketones: 3,4-dimethylcyclopentan-1 ,2-dione, 3-hydroxy-4,5-dimethylfuran-2(5H)-on (sotolon), 2-aminoacetophenone, 3-hydroxy-4,5-dimethyl-2(5H)-furanone, 2,5- dimethyl-4-hydroxy-3-[2H]-furanone (furaneol©), tetrahydrothiophen-3-one und 3- thiobutan-2-one; esters and lactones: methylbutanoate, ethyl-3-methylbutanoate, propyl-2- methylbutanoate, (Z)-6-dodecen-y-lactone, 4-hydroxy-2-nonenic acid lactone, d- undecalactone, y-nonalactone und y-octalactone; and mixtures of the above substances.

[0061] Preferred aroma/flavour substances which are advantageously suitable for combining with 4-methylheptan-3-one are selected from the group consisting of: difurfuryl disulfide, bis(2-methyl-3-furyl)disulfide, methylfuranthiol, methylpyrazine, 2,5- methylethylpyrazine, 2,3,5-trimethylpyrazine, acetylpyrazine, 2,3-diethyl-5- methylpyrazine, 2-ethyl-3,5-dimethylpyrazine and 2-isopropyl-3-methoxy-pyrazine; 2- acetyl-2-thiazolin, 2-propionyl-1-pyrrolin and 2-acetyl-1-pyrrolin; (E,E)-2,4-decadienal, (E,Z)-2,4-decadienal, 3-hydroxy-4,5-dimethylfuran-2(5H)-on (sotolon), 2,5-dimethyl-4- hydroxy-3-[2H]-furanone (furaneol®); and mixtures of the above substances.

[0062] Fragrance substances which are advantageously suitable for combining are listed for example in S. Arctander, Perfume and Flavor Materials, volumes I and II, Montclair, N.J. 1969, private publication, and/or in H. Surburg, J. Panten, Common Fragrance and Flavor Materials, 6^th edition, Wiley-VCFI, Weinheim 2016. The following list comprises examples of known odorant substances: extracts of natural raw materials such as essential oils, concretes, absolutes, resins, resinoids, balsams, tinctures such as for example: ambergris tincture; amyris oil; angelica seed oil; angelica root oil; anise oil; valerian oil; basil oil; tree moss absolute; bay oil; artemisia oil; benzoin resin; bergamot oil; beeswax absolute; birch tar oil; bitter almond oil; savory oil; buchu leaf oil; cabreuva oil; cade oil; calamus oil; camphor oil; cananga oil; cardamom oil; cascarilla oil; cassia oil; cassie absolute; castoreum absolute cedar leaf oil; cedarwood oil; cistus oil; citronella oil; lemon oil; copaiba balsam; copaiba balsam oil; coriander oil; costus root oil; cumin oil; cypress oil; davana oil; dill weed oil; dill seed oil; eau de brouts absolute; oak moss absolute; elemi oil; tarragon oil; eucalyptus citriodora oil; eucalyptus oil; fennel oil; pine-needle oil; galbanum oil; galbanum resin; geranium oil; grapefruit oil; guaiac wood oil; gurjun balsam; gurjun balsam oil; helichrysum absolute; helichrysum oil; ginger oil; iris root absolute; iris root oil; jasmine absolute; calamus oil; blue camomile oil; Roman camomile oil; carrot seed oil; cascarilla oil; pine-needle oil; spearmint oil; caraway oil; labdanum oil; labdanum absolute; labdanum resin; lavandin absolute; lavandin oil; lavender absolute; lavender oil; lemongrass oil; lovage oil; distilled lime oil; pressed lime oil; linaloe oil; Litsea cubeba oil; bay leaf oil; mace oil; marjoram oil; mandarin oil; massoia bark oil; mimosa absolute; ambrette oil; musk tincture; muscatel sage oil; nutmeg oil; myrrh absolute; myrrh oil; myrtle oil; clove leaf oil; clove bud oil; neroli oil; olibanum absolute; olibanum oil; opopanax oil; orange blossom absolute; orange oil; origanum oil; palmarosa oil; patchouli oil; perilla oil; Peru balsam oil; parsley leaf oil; parsley seed oil; petitgrain oil; peppermint oil; pepper oil; pimento oil; pine oil; pennyroyal oil; rose absolute; rosewood oil; rose oil; rosemary oil; Dalmatian sage oil; Spanish sage oil; sandalwood oil; celery seed oil; spike lavender oil; star anise oil; styrax oil; tagetes oil; fir needle oil; tea tree oil; terpentine oil; thyme oil; Tolu balsam; tonka absolute; tuberose absolute; vanilla extract; violet leaf absolute; verbena oil; vetiver oil; juniper berry oil; cognac oil; wormwood oil; wintergreen oil; ylang ylang oil; hyssop oil; civet absolute; cinnamon leaf oil; cinnamon bark oil, and fractions thereof or constituents isolated therefrom; individual fragrance substances from the group comprising hydrocarbons, such as for example 3-carene; alpha- pinene; befa-pinene; alpha- terpinene; gamma- terpinene; p-cymene; bisabolene; camphene; caryophyllene; cedrene; famesene; limonene; longifolene; myrcene; ocimene; valencene; (E,Z)-1 ,3,5-undecatriene; styrene; diphenylmethane; aliphatic alcohols such as for example hexanol; octanol; 3-octanol; 2,6- dimethylheptanol; 2-methyl-2-heptanol; 2-methyl-2-octanol; (E)-2-hexenol; (E)- and (Z)-3-hexenol; 1-octen-3-ol; mixtures of 3,4,5,6,6-pentamethyl-3,4-hepten-2-ol and 3,5,6,6-tetramethyl-4-methyleneheptan-2-ol; (E,Z)-2,6-nonadienol; 3,7-dimethyl-7- methoxyoctan-2-ol; 9-decenol; 10-undecenol; 4-methyl-3-decen-5-ol; aliphatic aldehydes and the acetals thereof such as for example hexanal; heptanal; octanal; nonanal; decanal; undecanal; dodecanal; tridecanal; 2-methyloctanal; 2-methylnonanal; (E)-2-hexenal; (Z)-4-heptenal; 2,6-dimethyl-5-heptenal; 10-undecenal; (E)-4-decenal; 2-dodecenal; 2,6,10-trimethyl-9-undecenal; 2,6,10-trimethyl-5,9-undecadienal; heptanal diethylacetal; 1 ,1 -dim ethoxy-2, 2, 5- trimethyl-4-hexene; citronellyloxyacetaldehyde; 1 -(1 -methoxypropoxy)-(E,Z)-3- hexene; aliphatic ketones and the oximes thereof such as for example 2-heptanone;

2-octanone; 3-octanone; 2-nonanone; 5-methyl-3-heptanone; 5-methyl-3- heptanone oxime; 2,4,4,7-tetramethyl-6-octen-3-one; 6-methyl-5-hepten-2-one; aliphatic sulphur-containing compounds such as for example 3-methylthio-hexanol;

3-methylthiohexyl acetate; 3-mercaptohexanol; 3-mercaptohexyl acetate; 3-mercaptohexyl butyrate; 3-acetylthiohexyl acetate; 1-menthen-8-thiol; aliphatic nitriles such as for example 2-nonenoic acid nitrile; 2-undecenoic acid nitrile; 2-tridecenoic acid nitrile; 3,12-tridecadienoic acid nitrile; 3,7-dimethyl-2,6- octadienoic acid nitrile; 3,7-dimethyl-6-octenoic acid nitrile; esters of aliphatic carboxylic acids such as for example (E)- and (Z)-3-hexenyl formate; ethyl acetoacetate; isoamyl acetate; hexyl acetate; 3,5,5-trimethylhexyl acetate; 3-methyl-2-butenyl acetate; (E)-2-hexenyl acetate; (E)- and (Z)-3-hexenyl acetate; octyl acetate; 3-octyl acetate; 1-octen-3-yl acetate; ethyl butyrate; butyl butyrate; isoamyl butyrate; hexyl butyrate; (E)- and (Z)-3-hexenyl-isobutyrate; hexyl crotonate; ethyl isovalerate; ethyl-2-methyl pentanoate; ethyl hexanoate; allyl hexanoate; ethyl heptanoate; allyl heptanoate; ethyl octanoate; ethyl-(E,Z)-2,4- decadienoate; methyl-2-octinate; methyl-2-noninate; allyl-2-isoamyloxyacetate; methyl-3, 7-dimethyl-2,6-octadienoate; 4-methyl-2-pentyl-crotonate; acyclic terpene alcohols such as for example: citronellol; geraniol; nerol; linalool; lavandulol; nerolidol; farnesol; tetrahydrolinalool; tetrahydrogeraniol; 2,6-dimethyl- 7-octen-2-ol; 2,6-dimethyloctan-2-ol; 2-methyl-6-methylene-7-octen-2-ol; 2,6- dimethyl-5,7-octadien-2-ol; 2,6-dimethyl-3,5-octadien-2-ol; 3,7-dimethyl-4,6- octadien-3-ol; 3,7-dimethyl-1 ,5,7-octatrien-3-ol; 2,6-dimethyl-2,5,7-octatrien-1 -ol; and the formates, acetates, propionates, isobutyrates, butyrates, isovalerates, pentanoates, hexanoates, crotonates, tiglinates and 3-methyl-2-butenoates thereof; acyclic terpene aldehydes and ketones such as for example geranial; neral; citronellal; 7-hydroxy-3,7-dimethyloctanal; 7-methoxy-3,7-dimethyloctanal; 2,6,10- trimethyl-9-undecenal; geranyl acetone; and the dimethyl and diethyl acetals of geranial, neral, 7-hydroxy-3,7-dimethyloctanal; cyclic terpene alcohols such as for example: menthol; isopulegol; alpha- terpineol; terpinenol-4; menthan-8-ol; menthan-1-ol; menthan-7-ol; borneol; isoborneol; linalool oxide; nopol; cedrol; ambrinol; vetiverol; guaiol; and the formates, acetates, propionates, isobutyrates, butyrates, isovalerates, pentanoates, hexanoates, crotonates, tiglinates and 3-methyl-2-butenoates thereof; cyclic terpene aldehydes and ketones such as for example menthone; isomenthone; 8-mercaptomenthan-3-one; carvone; camphor; fenchone; a/p/?a-ionone; beta- ionone; a/p/ia-n-methyl ionone; Jbefa-n-m ethyl ionone; a/p/ia-isomethyl ionone; beta- isomethyl ionone; alpha- irone; alpha- damascone; Jbefa-damascone; beta- damascenone; delta- damascone; gamma- damascone; 1-(2,4,4-trimethyl-2- cyclohexen-1 -yl)-2-buten-1 -one; 1 ,3,4,6,7,8a-hexahydro-1 , 1 ,5,5-tetramethyl-2H- 2,4a-methanonaphthalen-8(5H)-one; 2-methyl-4-(2,6,6-trimethyl-1 -cyclohexen-1 - yl)-2-butenal; nootkatone; dihydronootkatone; 4,6,8-megastigmatrien-3-one; alpha- sinensal; Jbefa-sinensal; acetylated cedarwood oil (methylcedryl ketone); cyclic alcohols such as for example: 4-fe/f-butylcyclohexanol; 3,3,5- trimethylcyclohexanol; 3-isocamphylcyclohexanol; 2,6,9-trimethyl-Z2,Z5,E9- cyclododecatrien-1-ol; 2-isobutyl-4-methyltetrahydro-2H-pyran-4-ol; cycloaliphatic alcohols such as for example a/p/?a-3,3-trimethylcyclohexylmethanol; 1 -(4-isopropylcyclohexyl)ethanol; 2-methyl-4-(2,2,3-trimethyl-3-cyclopent-1 - yl)butanol; 2-methyl-4-(2,2,3-trimethyl-3-cyclopent-1 -yl)-2-buten-1 -ol; 2-ethyl-4- (2,2,3-trimethyl-3-cyclopent-1 -yl)-2-buten-1 -ol; 3-methyl-5-(2,2,3-trimethyl-3- cyclopent-1 -yl)-pentan-2-ol; 3-methyl-5-(2,2,3-trimethyl-3-cyclopent-1 -yl)-4-penten- 2-ol; 3,3-dimethyl-5-(2,2,3-trimethyl-3-cyclopent-1-yl)-4-penten-2-ol;

1 -(2,2,6-trimethylcyclohexyl)pentan-3-ol; 1 -(2,2,6-trimethylcyclohexyl)hexan-3-ol; cyclic and cycloaliphatic ethers such as for example: cineole; cedryl methyl ether; cyclododecyl methyl ether; 1 ,1-dimethoxycyclododecane;

(ethoxymethoxy)cyclododecane; a/p/ia-cedrene epoxide; 3a, 6, 6,9a- tetramethyldodecahydronaphtho[2, 1 -b]furan; 3a-ethyl-6,6,9a-trimethyldodeca- hydronaphtho[2,1-b]furan; 1 ,5,9-trimethyl-13-oxabicyclo[10.1 0]trideca-4, 8-diene; rose oxide; 2-(2,4-dimethyl-3-cyclohexen-1-yl)-5-methyl-5-(1-methylpropyl)-1 ,3- dioxane; cyclic and macrocyclic ketones such as for example 4-fe/f-butylcyclohexanone; 2,2,5-trimethyl-5-pentylcyclopentanone; 2-heptylcyclopentanone; 2-pentylcyclo- pentanone; 2-hydroxy-3-methyl-2-cyclopenten-1 -one; 3-methyl-c/s-2-penten-1 -yl-2- cyclopenten-1 -one; 3-methyl-2-pentyl-2-cyclopenten-1 -one; 3-methyl-4- cyclopentadecenone; 3-methyl-5-cyclopentadecenone; 3- methylcyclopentadecanone; 4-(1-ethoxyvinyl)-3,3,5,5-tetramethylcyclohexanone; 4-fef-pentylcyclohexanone; 5-cyclohexadecen-1 -one; 6,7-dihydro-1 , 1 ,2,3,3- pentamethyl-4(5H)-indanone; 8-cyclohexadecen-1 -one; 9-cycloheptadecen-1 -one; cyclopentadecanone; cyclohexadecanone; cycloaliphatic aldehydes such as for example 2,4-dimethyl-3-cyclohexene carbaldehyde; 2-methyl-4-(2,2,6-trimethyl-cyclohexen-1 -yl)-2-butenal; 4-(4- hydroxy-4-methylpentyl)-3-cyclohexene carbaldehyde; 4-(4-methyl-3-penten-1 -yl)- 3-cyclohexene carbaldehyde; cycloaliphatic ketones such as for example 1-(3,3-dimethyl-cyclohexyl)-4-penten-1- one; 2,2-dimethyl-1 -(2,4-dimethyl-3-cyclohexene-1 -yl)-1 -propanone; 1 -(5,5- dimethyl-1 -cyclohexen-1 -yl)-4-penten-1 -one; 2,3,8,8-tetramethyl-1 , 2, 3, 4, 5, 6,7,8- octahydro-2-naphthalenyl methyl ketone; methyl-2,6, 10-trimethyl-2, 5,9- cyclododecatrienyl ketone; fe f-butyl-(2,4-dimethyl-3-cyclohexen-1-yl) ketone; esters of cyclic alcohols such as for example 2-fe/f-butylcyclohexyl acetate; 4-tert- butylcyclohexyl acetate; 2-fe/f-pentylcyclohexyl acetate; 4-fe/f-pentylcyclohexyl acetate; 3,3,5-trimethylcyclohexyl acetate; decahydro-2-naphthyl acetate; 2- cyclopentylcyclopentyl crotonate; 3-pentyltetrahydro-2H-pyran-4-yl acetate; decahydro-2,5,5,8a-tetramethyl-2-naphthyl acetate; 4,7-methano-3a,4,5,6,7,7a- hexahydro-5- or 6-indenyl acetate; 4,7-methano-3a,4,5,6,7,7a-hexahydro-5- or 6- indenyl propionate; 4,7-methano-3a,4,5,6,7,7a-hexahydro-5- or 6-indenyl isobutyrate; 4,7-methanooctahydro-5- or 6-indenyl acetate; esters of cycloaliphatic alcohols such as for example 1 -cyclohexylethyl crotonate; esters of cycloaliphatic carboxylic acids such as for example allyl-3-cyclohexyl propionate; allylcyclohexyl oxyacetate; c/s- and frans-methyl dihydrojasmonate; c/s and frans-methyl jasmonate; methyl-2-hexyl-3-oxocyclopentane carboxylate; ethyl- 2-ethyl-6,6-dimethyl-2 -cyclohexene carboxylate; ethyl-2, 3,6, 6-tetramethyl-2- cyclohexene carboxylate; ethyl-2-methyl-1 ,3-dioxolane 2-acetate; araliphatic alcohols such as for example benzyl alcohol; 1-phenylethyl alcohol;

2-phenylethyl alcohol; 3-phenylpropanol; 2-phenylpropanol; 2-phenoxyethanol;

2,2-dimethyl-3-phenylpropanol; 2,2-dimethyl-3-(3-methylphenyl)propanol;

1 ,1-dimethyl-2-phenylethyl alcohol; 1 ,1-dimethyl-3-phenylpropanol; 1 -ethyl-1 - methyl-3-phenylpropanol; 2-methyl-5-phenylpentanol; 3-methyl-5-phenylpentanol;

3-phenyl-2-propen-1-ol; 4-methoxybenzyl alcohol; 1-(4-isopropylphenyl)ethanol; esters of araliphatic alcohols and aliphatic carboxylic acids such as for example benzyl acetate; benzyl propionate; benzyl isobutyrate; benzyl isovalerate; 2- phenylethyl acetate; 2-phenylethyl propionate; 2-phenylethyl isobutyrate; 2- phenylethyl isovalerate; 1-phenylethyl acetate; a/p/ia-trichloromethylbenzyl acetate; a/p/?a,a/p/?a-dimethylphenylethyl acetate; a/p/?a,a/p/?a-dimethylphenyl-ethyl butyrate; cinnamyl acetate; 2-phenoxyethyl isobutyrate; 4-methoxybenzyl acetate; araliphatic ethers such as for example: 2-phenyl ethyl methyl ether; 2-phenyl ethyl isoamyl ether; 2-phenyl ethyl 1 -ethoxyethyl ether; phenylacetaldehyde dimethylacetal; phenylacetaldehyde diethylacetal; hydratropaldehyde dimethylacetal; phenylacetaldehyde glycerol acetal; 2,4,6-trimethyl-4-phenyl-1 ,3- dioxane; 4,4a,5,9b-tetrahydroindeno[1 ,2-d]-m-dioxin; 4,4a,5,9b-tetrahydro-2,4- dimethylindeno[1 ,2-d]-m-dioxin; aromatic and araliphatic aldehydes such as for example: benzaldehyde; phenylacetaldehyde; 3-phenylpropanal; hydratropaldehyde; 4-methylbenz- aldehyde; 4-methylphenylacetaldehyde; 3-(4-ethylphenyl)-2,2-dimethylpropanal; 2- methyl-3-(4-isopropylphenyl)propanal; 2-methyl-3-(4-fe/f-butylphenyl)propanal; 2- methyl-3-(4-isobutylphenyl)propanal; 3-(4-fe/f-butylphenyl)propanal; cinnamaldehyde; a/p/ia-butylcinnamaldehyde; a/p/7a-amylcinnamaldehyde; alpha- hexylcinnamaldehyde; 3-methyl-5-phenylpentanal; 4-methoxybenzaldehyde; 4- hydroxy-3-methoxybenzaldehyde; 4-hydroxy-3-ethoxybenzaldehyde; 3,4- methylenedioxybenzaldehyde; 3,4-dimethoxybenzaldehyde; 2-methyl-3-(4- methoxyphenyl)propanal; 2-methyl-3-(4-methylenedioxyphenyl)propanal; aromatic and araliphatic ketones such as for example: acetophenone; 4-methyl- acetophenone; 4-methoxyacetophenone; 4-fe/f-butyl-2,6-dimethylacetophenone; 4- phenyl-2-butanone; 4-(4-hydroxyphenyl)-2-butanone; 1 -(2-naphthalenyl)ethanone; 2-benzofuranylethanone; (3-methyl-2-benzofuranyl)ethanone; benzophenone; 1 ,1 ,2,3,3, 6-hexamethyl-5-indanyl methyl ketone; 6-fe/f-butyl-1 ,1-dimethyl-4-indanyl methyl ketone; 1-[2,3-dihydro-1 ,1 ,2,6-tetramethyl-3-(1-methylethyl)-1 H-5- indenyl]ethanone; 5',6',7',8'-tetrahydro-3',5',5',6',8',8'-hexamethyl-2- acetonaphthone; aromatic and araliphatic carboxylic acids and the esters thereof such as for example: benzoic acid; phenylacetic acid; methyl benzoate; ethyl benzoate; hexyl benzoate; benzyl benzoate; methylphenyl acetate; ethylphenyl acetate; geranylphenyl acetate; phenylethylphenyl acetate; methyl cinnamate; ethyl cinnamate; benzyl cinnamate; phenylethyl cinnamate; cinnamyl cinnamate; allyl phenoxy acetate; methyl salicylate; isoamyl salicylate; hexyl salicylate; cyclohexyl salicylate; c/s-3-hexenyl salicylate; benzyl salicylate; phenylethyl salicylate; methyl- 2, 4-dihydroxy-3,6-dimethylbenzoate; ethyl-3-phenyl glycidate; ethyl-3-methyl-3- phenyl glycidate; nitrogenous aromatic compounds such as for example: 2,4,6-trinitro-1 ,3-dimethyl-5- fe/f-butylbenzene; 3,5-dinitro-2,6-dimethyl-4-fe/f-butyl aceto-phenone; cinnamonitrile; 3-methyl-5-phenyl-2-pentenoic acid nitrile; 3-methyl-5- phenylpentanoic acid nitrile; methyl anthranilate; methyl-/V-m ethyl anthranilate; Schiff bases of methyl anthranilate with 7-hydroxy-3,7-dimethyloctanal, 2-methyl-3- (4-fe/f-butylphenyl)propanal or 2,4-dimethyl-3-cyclohexene carbaldehyde 6- isopropyl quinoline; 6-isobutyl quinoline; 6-sec-butyl quinoline; 2-(3- phenylpropyl)pyridine; indole; skatole; 2-methoxy-3-isopropylpyrazine; 2-isobutyl-3- methoxypyrazine; phenols, phenyl ethers and phenyl esters such as for example: estragole; anethole; eugenol; eugenyl methyl ether; isoeugenol; isoeugenyl methyl ether; thymol; carvacrol; diphenyl ether; beta- naphthyl methyl ether; beta- naphthyl ethyl ether; beta- naphthyl isobutyl ether; 1 ,4-dimethoxybenzene; eugenyl acetate; 2-methoxy-4-methylphenol; 2-ethoxy-5-(1-propenyl)phenol; p-cresyl phenyl acetate; heterocyclic compounds such as for example: 2,5-dimethyl-4-hydroxy-2H-furan-3- one; 2-ethyl-4-hydroxy-5-methyl-2H-furan-3-one; 3-hydroxy-2-methyl-4H-pyran-4- one; 2-ethyl-3-hydroxy-4H-pyran-4-one; lactones such as for example: 1 ,4-octanolide; 3-methyl-1 ,4-octanolide; 1 ,4- nonanolide; 1 ,4-decanolide; 8-decen-1 ,4-olide; 1 ,4-undecanolide; 1 ,4-dodecan- olide; 1 ,5-decanolide; 1 ,5-dodecanolide; 4-methyl-1 ,4-decanolide; 1 ,15-penta- decanolide; c/s- and trans- 11 -pentadecen-1 , 15-olide; c/s- and trans- 12-pentadecen- 1 , 15-olide; 1 ,16-hexadecanolide; 9-hexadecen-1 ,16-olide; 10-oxa-1 ,16- hexadecanolide; 11 -oxa-1 , 16-hexadecanolide; 12-oxa-1 , 16-hexadecanolide; ethylene 1 ,12-dodecanedioate; ethylene 1 ,13-tridecanedioate; coumarin; 2,3- dihydrocoumarin; octahydrocoumarin; and mixtures of the above substances.

[0063] In such aroma/flavour or fragrance compositions according to the present invention, the 4-methylheptan-3-one exhibit a positive action over the entire aroma or fragrance chord by distinctly enhancing the nutty, preferably hazelnutty, sweet, fruity, mushroom and/or roasted nature of the composition. In the mixtures/blends with 4- methylheptan-3-one and other aroma/flavour or fragrance substances the aroma/flavour or odour of other aroma/flavour or odorants/fragrance is intensified, resulting in more rich, balanced and authentic flavour or odour profiles in the finished product, as it is demonstrated by the sensory tests in the following examples.

[0064] Surprisingly, it was found that, even at low concentrations up to 0.01 ppm, preferably up to 2 ppm, 4-methylheptan-3-one can greatly intensify the nutty, preferably hazelnut, fruity, sweet, mushroom and/or roasted notes in such blends.

[0065] According to a more preferred variant, the aroma/flavour or fragrance compositions according to the invention, comprising 4-methylheptan-3-one or its (-)-(4 R)- methylheptan-3-one enantiomer or its (+)-(4S)-methylheptan-3-one enantiomer or the racemic mixture or an isomeric mixture of the enantiomers, may further comprise at least one aromatic substance(s), preferably at least one volatile aromatic substance(s). [0066] Preferably, the aroma/flavour or fragrance compositions may comprise one or more aromatic substance(s) selected from the group consisting of volatile hydrocarbons, organic acids, aliphatic alcohols, aliphatic aldehydes and their acetales, aliphatic ketones and their oximes, sulfur containing compounds such as thiols, disulfides, aliphatic nitriles, aliphatic carbonic acids esters, acyclic terpene alcohols, acyclic terpene aldehydes and ketones, cyclic terpene alcohols, cyclic terpene aldehydes and ketones, cyclic alcohols, esters of cycloaliphatic carbonic acids, aromatic hydrocarbones, araliphatic alcohols, esters of araliphatic alcohols and aliphatic carbonic acids, araliphatic and aliphatic ethers and acetales or ketales, carbonic acid amides, carbonates and ureas, aromatic and araliphatic aldehydes, aromatic and araliphatic ketones, aromatic and araliphatic carbonic acids and their esters, nitrogen containing aroma compounds, phenoles, phenyl ethers and phenyl esters, heterocyclic compounds, preferably pyridines, pyrazines, pyrrolines, thiazoles and thiazolines, lactones, and mixtures thereof.

[0067] Particularly the aromatic substances are selected from the group, consisting of the following groups of substances: hydrocarbons: 3-carene; alpha- pinene; befa-pinene; alpha- terpinene; gamma- terpinene; p-cymol; bisabolene; camphene; caryophyllene; cedrene; farnesene; limonene; longifolene; myrcene; ocimene; valencene; (E,Z)-1 ,3,5-undecatriene; organic acids: acetic acid; butyric acid; 2- or, respectively 3-methyl butyric acid; caprinic acid; capronic acid; phenylacetic acid; aliphatic alcohols: ethanol, propylene glycol; hexanol; octanol; 3-octanol; 2,6- dimethyl-heptanol; 2-methylheptanol, 2-methyloctanol; (E)-2-hexenol; (E)- und (Z)- 3-hexenol; 1-octen-3-ol; mixture of 3,4,5,6,6-pentamethyl-3/4-hepten-2-ol and 3,5,6,6-tetramethyl-4-methyleneheptan-2-ol; (E,Z)-2,6-nonadienol; 3,7-dimethyl-7- methoxyoctan-2-ol; 9-decenol; 10-undecenol; 4-methyl-3-decen-5-ol; aliphatic aldehydes and their acetales: hexanal; heptanal; octanal; nonanal; decanal; undecanal; dodecanal; tridecanal; 2-methyloctanal; 2-methylnonanal; (E)- 2-hexenal; (Z)-4-heptenal; 2,6-dimethyl-5-heptenal; 10-undecenal; (E)-4-decenal;

2-dodecenal; 2,6,10-trimethyl-5,9-undecadienal; heptanaldiethylacetal; 1,1- dimethoxy-2,2,5-trimethyl-4-hexene; acetaldehyde; frans-4,5-epoxy-(2E)-decenal; c/s-4,5-epoxy-(2E)-decenal; (E,E)-2,4-undecadienal; (E,E)-2,4-decadienal; (E,Z)- 2,4-decadienal; (E,E,Z)-2,4,6-nonatrienal; (E,E)-2,4-nonadienal; (E)-2-undecenal; (Z)-2-decenal; (E)-2-decenal; (E)-2-nonenal; (Z)-2-nonenal; (E,Z)-2,6-nonadienal; (E,E)-2,4-nonadienal; aliphatic ketones and their oximes: 2-heptanone; 2-octanone; 3-octanone; 2- nonanone; 5-methyl-3-heptanone; 5-methyl-3-heptanonoxime; 2,4,4,7-tetramethyl- 6-octen-3-one; 3,4-dimethylcyclopentan-1 ,2-dione; sulfur containing compounds: 3-methylthiohexanol; 3-methylthiohexylacetate; 3- mercaptohexanol; 3-mercaptohexylacetate; 3-mercaptohexylbutyrate; 3- acetylthiohexylacetate; 1-Menthen-8-thiol; dimethyl sulphide; difurfuryl disulphide; methyl thiopropanal; 2-methyl-3-methyldithiofuran and bis(2-methyl-3- furyl)disulphide; methylfuranthiol; 2-(4-methyl-1 ,3-thiazol-5-yl)ethanol (sulfurol); methyltetrahydrofuranthiol; 3-methyl-2-buten-1 -thiol; 3-thio-2-methylpentanol; 2- furfurylthiol; thiophenol; 2-methylthiophenol and 2-mercaptobutanone; tetrahydrothiophen-3-one; 2,6-dimethylthiophenol; aliphatic nitriles: 2-nonenic acid nitril; 2-tridecenic acid nitril; 2,12-tridecadienic acid nitril; 3,7-dimethyl-2,6-octadienic acid nitril; 3,7-dimethyl-6-octenic acid nitril; aliphatic carbonic acid esters: methylbutanoate, ethyl-3-methylbutanoate, propyl-2- methylbutanoate; (E)- und (Z)-3-hexenylformiate; ethylacetoacetate; isoamylacetate; hexylacetate; 3,5,5-trimethylhexylacetate; 3-methyl-2- butenylacetate; (E)-2-hexenylacetate; (E)- und (Z)-3-hexenylacetate; octylacetate;

3-octylacetate; 1 -octen-3-ylacetate; ethylbutyrate; butylbutyrate; isoamylbutyrate; hexylbutyrate; (E)- und (Z)-3-hexenylisobutyrate; hexylcrotonate; ethylisovalerianate; ethyl-2-methylpentanoate; ethylhexanoate; allylhexanoate; ethylheptanoate; allylheptanoate; ethyloctanoate; ethyl-(E,Z)-2,4-decadienoate; methyl-2-octinate; methyl-2-noninate; allyl-2-isoamyloxyacetate; methyl-3, 7- dimethyl-2,6-octadienoate; menthyllactate (FEMA GRAS 3748); monomethylsuccinate (FEMA GRAS 3810); monomenthylglutarate (FEMA GRAS 4006); acyclic terpene alcohols: citronellol; geraniol; nerol; linalool; lavadulol; nerolidol; farnesol; tetrahydrolinalool; tetrahydrogeraniol; 2,6-dimethyl-7-octen-2-ol; 2,6- dimethyloctan-2-ol; 2-methyl-6-methylen-7-octen-2-ol; 2,6-dimethyl-5,7-octadien-2- ol; 2,6-dimethyl-3,5-octadien-2-ol; 3,7-dimethyl-4,6-octadien-3-ol; 3,7-dimethyl- 1 ,5,7-octatrien-3-ol; 2,6-dimethyl-2,5,7-octatrien-1-ol; as well as their formiates, acetates, propionates, isobutyrates, butyrates, isovalerianates, pentanoates, hexanoates, crotonates, tiglinate, 3-methyl-2-butenoates; acyclic terpene aldehydes and ketones: geranial; neral; citronellal; 7-hydroxy-3,7- dimethyloctanal; 7-methoxy-3,7-dimethyloctanal; 2,6, 10-trimethyl-9-undecenal; geranylaceton; as well as dimethyl- and diethylacetale from geranial, neral, 7- hydroxy-3,7-dimethyloctanal; cyclic terpene alcohols: menthol; isopulegol; alpha- terpineol; terpinenol-4; menthan- 8-ol; menthan-1-ol; menthan-7-ol; borneol; isoborneol; linalooloxid; nopol; cedrol; ambrinol; vetiverol; as well as their formiates, acetates, propionates, isobutyrates, butyrates, isovalerianates, pentanoates, hexanoates, crotonates, tiglinates, 3- methyl-2-butenoates; cyclic terpene aldehydes and ketones: menthone; isomenthonell; 8- mercaptomenthan-3-one; carvone; campher; fenchone; a/pba-ionone; befa-ionone; a/pba-n-methylionone; befa-n-methylionone; a/pba-isomethylionone; beta- isomethylionone; alpha- irone; alpha- damascone; beta- damascone; beta- damascenone; delta- damascone; gamma- damascone; 1-(2,4,4-trimethyl-2- cyclohexen-1 -yl)-2-buten-1 -one; 1 ,3,4,6,7,8a-hexahydro-1 , 1 ,5,5-tetramethyl-2FI- 2,4a-methanonaphthalen-8(5FI)-one; nootkatone; dihydronootkatone; a/pba- sinensal; beta- sinensal; cyclic alcohols: 4-te/f-butylcyclohexanol; 3,3,5-trimethylcyclo-hexanol; 3- isocamphylcyclohexanol; 2,6,9-trimethyl-Z2,Z5,E9-cyclododecatrien-1 -ol; 2- isobutyl-4-methyltetrahydro-2H-pyran-4-ol; a/p/7a-3,3-trimethylcyclohexyl-methanol; 2-methyl-4-(2,2,3-trimethyl-3-cyclopent-1-yl)butanol; 2-methyl-4-(2,2,3-trimethyl-3- cyclopent-1 -yl)-2-buten-1 -ol; 2-ethyl-4-(2,2,3-trimethyl-3-cyclopent-1 -yl)-2-buten-1 - ol; 3-methyl-5-(2,2,3-trimethyl-3-cyclopent-1 -yl)-pentan-2-ol; 3-methyl-5-(2,2,3- trimethyl-3-cyclopent-1-yl)-4-penten-2-ol; 3,3-dimethyl-5-(2,2,3-trimethyl-3- cyclopent-1 -yl)-4-penten-2-ol; 1 -(2,2,6-trimethylcyclohexyl)pentan-3-ol; 1 -(2,2,6- trimethylcyclohexyl)hexan-3-ol; esters of cycloaliphatic carbonic acids: allyl-3-cyclohexylpropionate; allylcyclohexyloxyacetate; methyldihydrojasmonate; methyljasmonate; methyl-2- hexyl-3-oxocyclopentancarboxylate; ethyl-2 -ethyl-6, 6-dimethyl-2- cyclohexencarboxylate; ethyl-2, 3, 6, 6-tetramethyl-2-cyclohexencarboxylate; ethyl-2 - methyl-1 ,3-dioxolan-2-acetate; aromatic hydrocarbones: styrol and diphenylmethan; araliphatic alcohols: benzylalkohol; p-cresol;1-phenylethylalkohol; 2- phenylethylalkohol; 3-phenylpropanol; 2-phenylpropanol; 2-phenoxyethanol; 2,2- dimethyl-3-phenylpropanol; 2,2-dimethyl-3-(3-methylphenyl)propanol; 1 , 1 -dimethyl- 2-phenylethylalkohol; 1 , 1 -dimethyl-3-phenylpropanol; 1 -ethyl-1 -methyl-3- phenylpropanol; 2-methyl-5-phenylpentanol; 3-methyl-5-phenylpentanol; 3-phenyl- 2-propen-1 -ol; 4-methoxybenzylalkohol; 1 -(4-isopropylphenyl)ethanol; esters of araliphatic alcohols and aliphatic carbonic acids: benzylacetate; benzylpropionate; benzylisobutyrate; benzylisovalerianate; 2-phenylethylacetate; 2- phenylethylpropionate; 2-phenylethylisobutyrate; 2-phenylethylisovalerianate; 1- phenylethylacetate; a/p/ia-trichlormethylbenzylacetate; alpha, alpha- dimethylphenylethylacetate; a/p/?a,a/p/?a-dimethylphenylethylbutyrate; cinnamylacetate; 2-phenoxyethylisobutyrate; 4-methoxybenzylacetate; araliphatic and aliphatic ethers and acetales or ketales: 2-phenyl ethyl methyl ether; 2-phenyl ethyl isoamyl ether; 2-phenyl ethyl-1 -ethoxyethyl ether; phenylacetaldehyde dimethylacetal; phenylacetaldehyde diethylacetal; hydratropaaldehyde dimethylacetal; phenylacetaldehyde glycerinacetal; menthyl methyl ether; menthone glyceryl acetal (FEMA GRAS 3807); menthone glyceryl ketal (FEMA GRAS 3808); menthoxy-1 ,2-propandiol (FEMA GRAS 3784); menthoxy-2-methyl-1 ,2-propandiol (FEMA GRAS 3849); carbonic acid amides: WS-3 (FEMA GRAS 3455), WS-5 (FEMA GRAS 4309), WS- 12 (Frescolat® SC-1 , FEMA GRAS 4681 ), WS-23 (FEMA GRAS 3804), (E)-3- benzo[1 ,3]-dioxol-5-yl-N,N-diphenyl-2-propenamide (FEMA GRAS 4788) and 2-(4- methylphenoxy)-N-(1 FI-pyrazol-3-yl)-N-(thiophen-2-ylmethyl)acetamide (FEMA GRAS 4809); N-(2-isopropyl-5-methylcyclohexyl)cyclopropancarbox-amide (FEMA GRAS 4558), 3-(3,4-dimethoxyphenyl)-N-[2-(3,4-dimethoxyphenyl)-ethyl]- acrylamide (FEMA GRAS 4310); (E)-N-[2-(1 ,3-benzodioxol-5-yl)ethyl]-3-(3,4- dimethoxyphenyl)prop-2-enamide (FEMA GRAS 4773); carbonates and ureas: menthol ethylene glycol carbonate (FEMA GRAS 3805); menthol propylenglycol carbonate (FEMA GRAS 3806); 3-[3-(2-isopropyl-5-methyl- cyclohexyl)ureido]butyric acid ethyl ester (FEMA GRAS 4766); aromatic and araliphatic aldehydes: benzaldehyde; phenylacetaldehyde; 3- phenylpropanal; hydratropaaldehyde; 4-methylbenzaldehyde; 4-me- thylphenylacetaldehyde; 3-(4-ethylphenyl)-2,2-dimethylpropanal; 2-methyl-3-(4- isopropylphenyl)propanal; 2-methyl-3-(4-fe/f-butylphenyl)propanal; 3-(4-fe/f-butyl- phenyl)propanal; cinnamicaldehyde; alpha- butylzimtaldehyde; alpha- amylzimtaldehyde; alpha- hexylzimtaldehyde; 3-methyl-5-phenylpentanal; 4- methoxybenzaldehyde; 4-hydroxy-3-methoxybenzaldehyde; 4-hydroxy-3- ethoxybenzaldehyde; 3,4-methylendioxybenzaldehyde; 3,4- dimethoxybenzaldehyde; 2-methyl-3-(4-methoxyphenyl)propanal; 2-methyl-3-(4- methylendioxyphenyl)propanal; vanillin; aromatic and araliphatic ketones: acetophenone; 4-methylacetophenone; 4- methoxyacetophenone; 4-fe/f-butyl-2,6-dimethylacetophenone; 4-phenyl-2- butanone; 4-(4-hydroxyphenyl)-2-butanone; 1 -(2-naphthalenyl)ethanone; benzophenone; aromatic and araliphatic carbonic acids and their esters: benzoic acid; phenylacetic acid; methylbenzoate; ethylbenzoate; hexylbenzoate; benzylbenzoate; methylphenylacetate; ethylphenylacetate; geranylphenylacetate; phenylethyl- phenylacetate; methylcinnamate; ethylcinnamate; benzylcinnamate; phenylethylcinnamate; cinnamylcinnamate; allylphenoxyacetate; methylsalicylate; isoamylsalicylate; hexylsalicylate; cyclohexylsalicylate; c/s-3-hexenylsalicylate; benzylsalicylate; phenylethylsalicylate; methyl-2, 4-dihydroxy-3,6-dimethylbenzoate; ethyl-3-phenylglycidate; ethyl-3-methyl-3-phenylglycidate; nitrogen containing aroma compounds: 2,4,6-trinitro-1 ,3-dime-thyl-5-fe/f- butylbenzol; 3,5-dinitro-2,6-dimethyl-4-fe/f-butylacetophenone; cinnamic acid nitril; 5-phenyl-3-methyl-2-pentenic acid nitril; 5-phenyl-3-methylpentanic acid nitril; methylanthranilate; methyl-N-methylanthranilate; Schiff bases of methylanthranilate with 7-hydroxy-3,7-dimethyloctanal, 2-methyl-3-(4-fe/f-butylphenyl)propanal or 2,4- dimethyl-3-cyclohexen-carbaldehyde; 6-lsopropylchinoline; 6-isobutylchinoline; 6- sec-butylchinoline; indole; skatole; 2-methoxy-3-isopropylpyrazine; 2-isobutyl-3- methoxypyrazine; 2-aminoacetophenone; phenoles, phenyl ethers and phenyl esters: estragole; anethole; genole; eugenyl methyl ether; guajacol; eugenol; isoeugenole; isoeugenyl methyl ether; thymol; carvacrol; diphenyl ether; beta- naphthyl methyl ether; beta- naphthyl ethyl ether; beta- naphthyl isobutyl ether; 1 ,4-dimethoxybenzol; eugenylacetate; 2-methoxy-4- methylphenol; 2-ethoxy-5-(1 -propenyl)phenol; p-kresylphenylacetate; heterocyclic compounds: 3-hydroxy-4,5-dimethylfuran-2(5H)-on (sotolon); 3- hydroxy-4,5-dimethyl-2(5H)-furanone; 2,5-dimethyl-4-hydroxy-3-[2H]-furanone (furaneol©); 2-ethyl-4-hydroxy-5-methyl-2H-furan-3-one; 3-hydroxy-2-methyl-4H- pyran-4-one; 2-ethyl-3-hydroxy-4H-pyran-4-one; 2-acetylpyridine; methylpyrazine; 2,5-methylethylpyrazine; 2,3,5-trimethylpyrazine; acetylpyrazine; 2,3-diethyl-5- methylpyrazine; 2-ethyl-3,5-dimethylpyrazine and 2-isopropyl-3-methoxy-pyrazine; 2-acetylthiazol; 2-acetyl-2-thiazoline; pyrrolines: 2-propionyl-1-pyrroline and 2- acetyl-1-pyrroline; lactones: (Z)-6-dodecen-y-lactone, 4-hydroxy-2-nonenic acid lactone, d- undecalactone, g-nonalactone and y-octalactone; 1 ,4-octanolide; 3-methyl-1 ,4- octanolide; 1 ,4-nonanolide; 1 ,4-decanolide; 8-decen-1 ,4-olide; 1 ,4-undecanolide; 1 ,4-dodecanolide; 1 ,5-decanolide; 1 ,5-dodecanolide; 1 ,15-pentadecanolide; c/s and frans-11 -pentadecen-1 ,15-olide; c/s- and frans-12-pentadecen-1 ,15-olide; 1 ,16-hexadecanolide; 9-hexadecen-1 ,16-olide; 10-oxa-1 ,16-hexadecanolide; 11- oxa-1 , 16-hexadecanolide; 12-oxa-1 , 16-hexadecanolide; ethylen-1 , 12- dodecandioate; ethylen-1 ,13-tridecandioate; coumahn; 2,3-dihydrocoumahn; octahydrocoumahn; and mixtures of the above aromatic substances.

[0068] The above-described aroma/flavour or fragrance substance(s) and further aromatic substances may be used e.g. in the form of reaction flavours (Maillard-products), extracts or respectively, essential oils of plants or plant parts or, respectively, fractions thereof, smoke flavours or other flavour providing compositions (e.g. protein [part] hydrolysates), grill-like flavours, plant extracts, spices, spice compositions, vegetables types and/or vegetable compositions.

[0069] From the above specified aroma/flavour or fragrance substances and further aromatic substances such are at most preferred, which have a nutty, preferably hazelnut, fruity, sweet, mushroom or roasty taste or odour impression.

[0070] In such aroma/flavour or fragrance compositions according to the present invention, the 4-methylheptan-3-one exhibit a positive action over the entire aroma or fragrance chord by distinctly enhancing the nutty, preferably hazelnutty, sweet, fruity, mushroom and/or roasted nature of the composition. In the mixtures/blends with 4- methylheptan-3-one and other aromatic substance(s) the aroma/flavour or odour of other aroma/flavour or odorants/fragrance is intensified, resulting in more rich, balanced and authentic flavour or odour profiles in the finished product.

[0071] Surprisingly, it was found that, even at low concentrations up to 0.01 ppm, preferably up to 2 ppm, 4-methylheptan-3-one can greatly intensify the nutty, preferably hazelnut, fruity, sweet, mushroom and/or roasted notes in such blends.

[0072] In the aroma/flavour or fragrance compositions according to the present invention, the amount of 4-methylheptan-3-one used is preferably 0.0001 % by weight to 90 % by weight, preferably 0.01 % by weight to 70 % by weight and particularly preferably 0.1 % by weight to 50 % by weight, relative to the total amount of the aroma/flavour or fragrance composition. If the aroma/flavour or fragrance composition comprises a blend of 4-methylheptan-3-one and one or more flavour or fragrance substances, the above weight ranges are related to the blend.

[0073] Aroma/flavour or fragrance compositions according to the present invention which contain 4-methylheptan-3-one may be used for flavouring or perfuming in liquid form, undiluted or diluted with a solvent.

[0074] Solvents suitable for this purpose are for example ethanol, isopropanol, diethylene glycol monoethyl ether, glycerol, propylene glycol, 1 ,2-butylene glycol, dipropylene glycol, diethyl phthalate, triethyl citrate, isopropyl myristate, triacetin, vegetable oils, etc.

[0075] Moreover, aroma/flavour or fragrance compositions according to the invention which contain 4-methylheptan-3-one may be adsorbed on a carrier which ensures both a fine distribution of the aroma/flavour or fragrance substances in the product and controlled release on use. Such carriers may be porous inorganic materials such as sodium sulphate, silica gels, zeolites, gypsums, clays, clay granules, aerated concrete etc., or organic materials such as woods, cellulose-based substances, sugars, dextrins (for example maltodextrin), or plastics such as PVC, polyvinyl acetates or polyurethanes. [0076] Aroma/flavour or fragrance compositions according to the invention may also be spray-dried, be provided as inclusion complexes or as extrusion products or in microencapsulated form.

[0077] Spray-dried flavour or fragrance compositions may be produced for example by spray-drying an emulsion or dispersion containing the flavour or fragrance composition, wherein modified starches, proteins, dextrin and vegetable gums may be used as carriers. Inclusion complexes may be produced for example by introducing dispersions of the flavour or fragrance substance composition and cyclodextrins or urea derivatives into a suitable solvent, for example water.

[0078] Extrusion products may be produced by melting the flavour or fragrance substance compositions with a suitable waxy substance and extruding with subsequent solidification, optionally in a suitable solvent, for example isopropanol.

[0079] Optionally, the properties of the compositions modified in this way may be further optimised with regard to a more targeted flavour or fragrance release by “coating” with suitable materials, for which purpose waxy plastics such as for example polyvinyl alcohol are preferably used.

[0080] The flavour or fragrance compositions according to the invention may be encapsulated, for example, by coacervation methods with the assistance of capsule materials made for example from polyurethane-type substances or soft gelatine.

[0081] All of the above-described resultant product variants are aroma/flavour or fragrance compositions according to the invention.

[0082] In a second aspect, the present invention also relates to a method for preparing 4-methlyheptan-3-one, comprising the following steps:

(b) separating 4-methylhept-4-en-3-one from the mixture from step (a) by extraction and subsequent distillation; (c) treating the isolated 4-methylhept-4-en-3-one from step (b) with a chemical-type reducing agent to reduce the double bond to obtain the chemically generated product 4-methylheptan-3-one; or treating the isolated 4-methylhept-4-en-3-one from step (b) with a biochemical-type reducing agent to reduce the double bond to obtain the biological generated product 4-methylheptan-3-one; and

(d) separating the product 4-methylheptan-3-one from step (c) by optionally filtration and/or by distillation.

[0083] The specific synthetic methods followed for preparing the 4-methylheptan-3-one are based on the application of conventional discrete reaction steps. The details of these processes are given in the description which follows. Reagents or reaction conditions may be modified from those given in the following, the originality of the described process residing in the specific choice of the different reaction steps and the reaction sequence adopted.

[0084] All of the possible reaction routes in the method for synthesising 4-methylheptan- 3-one according to the present invention start from pentan-3-one.

[0085] As starting materials for step (a) in the method according to the present invention, either pure pentan-3-one, or pentan-3-one containing mixtures, such as solutions with organic solvents or fermentation broth can be used. Preferred is the use of single pentan- 3-one.

[0086] In step (a) in the method according to the present invention, the pentan-3-one is reacted with propionaldehyde by an acid catalysed aldol condensation according to the following reaction scheme: pentan-3-one propionaldehyde 4-methylhept-4-en-3-one

[0087] For the reaction, the propionaldehyde can either be used as single substance or in a mixture with a solvent or fermentation broth. Preferred is the use of single propionaldehyde.

[0088] The pentan-3-one and the propionaldehyde are used in a mol ratio of pentan-3- one to propionaldehyde in a range from 5 : 1 to 1 : 5. Preferred is the ratio of pentan-3- one to propionaldehyde in a rage from 3 : 1 to 1 : 3 and more preferred is the ratio of pentan-3-one to propionaldehyde in a range from 2 : 1 to 1 : 2.

[0089] An aldol condensation is a condensation reaction in which the pentan-3-one reacts with the carbonyl compound to form a b-hydroxyketone, followed by dehydration to give a conjugated enone, as illustrated in the above reaction scheme.

[0090] The aldol condensation in step (a) of the method according to the present invention is catalysed by using mineral/inorganic or organic acids.

[0091 ] Acid catalysed aldol reactions with reactive aldehydes are mentioned in literature only few times. The self-condensation of aldehyde is a big limitation of this reaction. That is why, usually instead of reactive aldehydes, protected intermediates, which slowly release the aldehyde in the reaction media, are used. For example, for the aldol condensation of 3-pentanone with acetaldehyde, catalysed with sulfuric acid, instead of acetaldehyde paraldehyde is used. Flowever, for propionaldehyde such a protected intermediate, like paraldehyde, is not a common reagent for industrial scale synthesis. The use of free propionaldehyde in acid catalysed aldol condensation was reported only using dry hydrogen chloride. Flowever, the use of hydrogen chloride for large-scale production is limited due to difficult handling of gaseous chemicals and possible corrosion. [0092] The inorganic or mineral acid for the aldol condensation in step (a) is selected from the group consisting of hydrochloric acid, phosphoric acid, sulfuric acid, and mixtures thereof.

[0093] Preferred inorganic acids are selected from the group consisting of sulfuric acid, phosphoric acid, and mixtures thereof.

[0094] The organic acid for the aldol condensation in step (a) is preferably a carboxylic acid. Preferred organic acids are selected from the group consisting of acetic acid, oxalic acid, tartaric acid, citric acid, lactic acid, malic acid, malonic acid, formic acid, and mixtures thereof.

[0095] Particularly preferred are oxalic acid, tartaric acid, citric acid or mixtures thereof.

[0096] The use of naturally occurring, i.e. organic, acids such as oxalic acid, tartaric acid and citric acid is especially advantageous for the preparation of 4-methylheptane-3-one, because the resulting products do not contain any chemical side-products and can be used for food production without any concerns.

[0097] However, with the use of sulfuric acid, the aldol condensation reaction can be accelerated; this leads to a shorter reaction time and thus to a reduction of process costs. It is thus preferred, that the acid catalysed aldol reaction is performed using sulfuric acid.

[0098] According to the present invention the acid is used either in catalytically amounts, in less than equivalent amounts, in equivalent amounts or in excess to the amount of pentan-3-one.

[0099] Whenever reference is made in the present description to “equivalent(s)” without any further indication, this is deemed to refer to “mol equivalent(s)”. An equivalent (in the following abbreviated eq) is the amount of a substance A that reacts with an arbitrary amount, e.g. 1 mole, of another substance B in a given chemical reaction. In our example, if a substance A is used in an amount of 0.05 to 1 eq to the amount of substance B, this is deemed that the substance A is used in an amount of 0.05 to 1 mol equivalents relative to 1 mol of the substance B. [0100] The mineral/inorganic acid, such as hydrochloric acid, phosphoric acid, sulfuric acid, or mixtures thereof is preferably used in the acid catalysed aldol condensation in an amount of up to 0.05 to 1 eq to the amount of pentan-3-one. More preferred is the use of sulfuric acid in an amount of 0.1 to 0.7 eq to the amount of pentan-3-one, and particularly preferred is the use in an amount of 0.2 to 0.5 eq to the amount of pentan-3-one.

[0101] Sulfuric acid is preferably used in the acid catalysed aldol condensation in an amount of 0.05 to 1 eq to the amount of pentan-3-one. More preferred is the use of sulfuric acid in an amount of 0.1 to 0.7 eq to the amount of pentan-3-one, and particularly preferred is the use in an amount of 0.2 to 0.5 eq to the amount of pentan-3-one.

[0102] Phosphoric acid is preferably used in the acid catalysed aldol condensation in an amount of 0.05 to 1 eq to the amount of pentan-3-one. More preferred is the use of phosphoric acid in an amount of 0.1 to 0.7 eq to the amount of pentan-3-one, and particularly preferred is the use in an amount of 0.2 to 0.5 eq to the amount of pentan-3- one.

[0103] The organic acid, such as acetic acid, oxalic acid, tartaric acid, citric acid, lactic acid, malic acid, malonic acid, formic acid, or mixtures thereof, is preferably used in the acid catalysed aldol condensation in an amount of up to 0.5 to 3 eq to the amount of pentan-3-one. More preferred, the organic acid is used in an amount of 0.5 to 2 eq to the amount of pentan-3-one and particularly preferred is the use of the organic acid in an amount of 0.7 to 1 .5 eq to the amount of pentan-3-one.

[0104] According to the present invention the acid can be used as pure substance or can be used in the form of an aqueous solutions. Using aqueous solutions, the concentration of the acid may vary from about 20 % by weight to 100 % by weight with a preferred concentration of acid being about 50 % by weight to 100 % by weight. The use of the concentrated acid > 70 % by weight, preferably > 80 % by weight, more preferably > 90 % by weight, was found to be particularly advantageous to generate selectively the desired product, to reduce the side reaction, and to reduce self-condensation of propionaldehyde. [0105] In a preferred variant of the method according to the present invention, in the aldol condensation step (a) a stepwise addition of the acid was found to be particularly advantageous to reduce the formation of side products and to improve the yield. In a preferred embodiment, the acid can be added in 2 to 8 steps, particularly preferred in 2 to 4 steps.

[0106] In a preferred variant of the method according to the present invention, the aldol condensation in step (a) is carried out without the addition of any solvent to the reaction mixture. This is especially favourable for the development of sustainable, environmentally friendly processes.

[0107] In a further preferred variant of the method according to the present invention, in the aldol condensation reaction in step (a) the addition of the aldehyde is slowed down, thereby improving the selectivity. The addition of propionaldehyde within a period of 2 to 10 h was found to be especially beneficial. Preferably, the addition of propionaldehyde is added to the reaction mixture within a period of 3 to 9 h, more preferred within a period of 4 to 8 h.

[0108] In accordance with the present invention, the aldol condensation in step (a) is carried out at a temperature in a range between 0 °C and 180 °C and a reaction time between 1 to 30 hours.

[0109] In a preferred variant, the aldol condensation in step (a) using sulfuric acid as the catalyst the reaction is carried out at a temperature in a range from 0 °C to 100 °C and a reaction time between 1 to 20 h, more preferred at a temperature in a range from 20 °C to 80 °C and a reaction time between 2 to 15 h, and especially preferred at a temperature in a range from 35 °C to 60 °C for 3 to 12 h.

[0110] In an alternative variant, the aldol condensation in step (a) using oxalic acid, tartaric acid or citric acid as catalyst, the reaction is carried out at a temperature in a range from 80 °C to 180 °C and a reaction time between 8 to 24 h, more preferred at a temperature in a range from 100 °C to 150 °C and a reaction time between 10 to 16 h. [0111] In cases, where the reaction temperature is higher than 50 °C the use of an autoclave is necessary, because of the low boiling points of the reagents.

[0112] The acid catalysed aldol condensation between pentan-3-on and propionaldehyde results in a mixture comprising the intermediate 4-methylhept-4-en-3- one.

[0113] In the next step (b) of the method according to the present invention, the 4- methylhept-4-en-3-one intermediate is separated from the mixture obtained in step (a) by extraction and subsequent distillation.

[0114] After the reaction in step (a) is completed, the reaction mixture comprising the intermediate 4-methylhept-4-en-3-one is diluted with water and washed with a basic solution (e. g. aqueous KOH, aqueous NaOH, aqueous NaHCCb) to remove inorganic or organic acid from the reaction mixture. In order to reduce the production of waste, the phase separation can be realized without using additional organic solvents. The organic phase containing the 4-methylhept-4-en-3-one intermediate can then be distilled under a pressure of 1 to 50 mbar and a temperature in a range from 50 to 150 °C, preferably at a pressure of 5 to 15 mbar and a temperature in a range from 80 to 100 °C.

[0115] In the next step (c) of the method according to the present invention, the isolated 4-methylhept-4-on-3-one obtained in step (b) is treated with a chemical-type reducing agent in order to reduce the double bond to obtain the chemically generated product 4- methylheptan-3-one; or alternatively is treated with a biochemical-type reducing agent in order to reduce the double bond to obtain the biologically or biochemically generated product 4-methylheptan-3-one, according to the following reaction scheme:

h i l t

4-methylhept-4-en-3-one 4-methyl heptan-3-one

[0116] The reduction of the double bond of the 4-methylhept-4-on-3-one in step (c) of the method according to the present invention can be realized by using either a transition- metal catalyst, or a lithium or boron-based hydride transfer reagent as chemical-type reducing agent or alternatively by using a biocatalyst as biochemical-type reducing agent.

[0117] Transition-metal catalyst play a vital role in modern organic and organometallic chemistry due to their inherent properties like variable oxidation state (oxidation number), complex ion formation and catalytic activity.

[0118] Preferably, the transition metal of the transition metal catalyst used in step (c) of the method according to the present invention (involving a chemical-type reducing agent) is selected from the group consisting of palladium, platinum, copper, nickel, ruthenium, iridium and rhodium on a supporting material, for example carbon or organic polymer, or as soluble complexes, for example Pd(OAc)2, N1CI2, rhodium(l) complexes, Cu(OAc)2, (lrCI(cod))2 and ruthenium(ll) complexes and addition ligands e.g. phosphines.

[0119] Also, lithium or boron-based hydride transfer reagent as chemical-type reducing agent can be used for the reduction of the double bond of the 4-methylhept-4-on-3-one in step (c) of the method according to the present invention. The lithium or boron-based hydride transfer reagent is preferably selected from the group consisting of LiBhU, NaBhU, and Na(OAc)₃BH.

[0120] According to a preferred variant, the reduction or hydrogenation in step (c) of the method according to the present invention is carried out using a chemical-type reducing agent under the following conditions: 1 eq of 4-methylhept-4-en-3-one from step (b) is diluted in ethyl acetate and treated with catalytic amounts of 0.01 to 0.2 eq, preferably 0.03 to 0.15 eq, of a transition-metal catalyst, in the presence of hydrogen atmosphere at a temperature in a range from 10 °C to 40 °C, preferably at a temperature in a range from 20 °C to 30 °C, and under normal pressure. According to a preferred embodiment, the preferred reaction time is between 1 and 15 h, particularly preferred is reaction time between 5 and 10 h.

[0121] According to a further preferred embodiment in step (c) instead of hydrogen, ammonium formate can be used. Preferred is the use of ammonium formate in excess, more preferred in an amount of 1 to 10 eq of ammonium formate to the amount of 4- methylhept-4-on-3-one, especially preferred in an amount of 2 to 6 eq of ammonium formate to the amount of 4-methylhept-4-on-3-one.

[0122] Alternatively, a biocatalyst as biochemical-type reducing agent can be used for the reduction of the double bond of the 4-methylhept-4-on-3-one in step (c) of the method according to the present invention in order to obtain the biochemically generated product 4-methylheptan-3-one.

[0123] In general, a biocatalyst is a substance, that initiates or increases the rate of a (bio)chemical reaction.

[0124] The biocatalyst which is favourably used is selected from the group of enzymes and yeast. More preferred is yeast of the Saccharomyces species, selected from the group consisting of baker’s yeast, beer yeast and wine yeast.

[0125] According to a further preferred variant, the reduction in step (c) of the method according to the present invention is carried out using biochemical-type reducing agent under the following conditions: 1 eq of the of 4-methylhept-4-en-3-one intermediate from step (b) is treated with a baker’s yeast ( Saccharomyces cerevisiae) solution containing 25 g/L to 400 g/L, preferably 50 to 300 g/L baker’s yeast (calculated on the anhydrous yeast) and 0.1 to 2.5 % by weight, preferably 0.5 to 1.5 % by weight glucose. In accordance with the present invention, the yeast solution is prepared by suspension of yeast in normal tap water, in NaCI solution (0.9 %) or in a buffer. According to a preferred embodiment, the concentration of 4-methylhept-4-en-3-one from step (c) may vary from 0.5 g/L to 5.0 g / L, preferably from 1.0 g/L to 2.5 g/L. Preferably the reduction or fermentation is carried out at a temperature in a range from 15 to 40 °C for a period of 8 to 48 h, more preferably at a temperature in a range from 20 to 35 °C for 20 to 30 h.

[0126] The product obtained in step (c) of the method according to the present invention is either a chemically generated product 4-methylheptan-3-one (by the use of a chemical- type reducing agent) or a biochemically generated product 4-methylheptan-3-one (by the use of a biochemical-type reducing agent).

[0127] In the next step (d) of the method according to the present invention, the 4- methylhept-3-one product is separated from the reaction mixture obtained in step (c) by optionally filtration and/or by (subsequent) distillation.

[0128] The reaction mixture resulting in step (c) of the method involving the chemical- type reducing agent is first filtered to separate the catalysts. Subsequently, the solvent is then evaporated under reduced pressure and the product 4-methylheptan-3-one is then distilled under a pressure of 10 to 80 mbar and a temperature in a range from 50 to 140 °C, preferably under a pressure of 20 to 60 mbar and a temperature in a range from 80 to 120 °C, to obtain the chemically generated 4-methylheptan-3-one. The distilled solvent obtained in step (d) can be used for the reaction again, making the process more sustainable and environmentally friendly.

[0129] The reaction mixture from step (c) in the method involving the biochemical-type reducing agent can be directly distilled, preferably using steam distillation. The distillate contains water and the product 4-methylheptan-3-one. The product can be then isolated using simple phase separation or extraction with organic solvent. Particularly preferred is the extraction with low-boiling solvents such as ethyl acetate or methyl tert- butyl ether, especially preferred is fermentatively produced ethyl acetate, followed by removal of the solvent at 30 °C under reduced pressure up to 50 mbar. According to a preferred embodiment, the separated solvent can be recycled and reused, making the process more sustainable and environmentally friendly. The product is then distilled under a pressure of 10 to 80 mbar and a temperature in a range from 50 to 140 °C, preferably under a pressure of 20 to 60 mbar and a temperature in a range from 80 to 120 °C, to obtain the biochemically generated 4-methylheptan-3-one.

[0130] The 4-methylheptan-3-one obtained in step (d) of the method according to the present invention contains at least 50 % by weight of (-)-R-isomer of 4-methylheptan-3- one, i.e. (-)-(4R)-methylheptan-3-one, preferably at least 60 % by weight, more preferably at least 70 % by weight, still more preferred at least 80 % by weight, and particularly preferred at least 90 % by weight, relative to the total weight of 4-methylheptan-3-one present in the product.

[0131] Advantageously, in the method according to the present invention, involving the chemical-type reducing agent, the R-isomer and the S-isomer of the 4-methylheptan-3- one, i.e. (-)-(4R)-methylheptan-3-one enantiomer and (+)-(4S)-methylheptan-3-one enantiomer, are obtained as racemic mixture in a ratio of 50 : 50, making said method particularly beneficial.

[0132] Preferably, in the method according to the present invention involving the biochemical-type reducing agent, the R-isomer of the 4-methylheptan-3-one, i.e. (-)-R- isomer of 4-methylheptan-3-one, is obtained in excess. The 4-methylheptan-3-one obtained in step (d) contains more than 50 % by weight of the (-)-R-isomer of 4- methylheptan-3-one, preferably at least 60 to 65 % by weight, more preferably at least 70 to 75 % by weight, still more preferred at least 80 to 85 % by weight, and particularly preferred at least 90 to 95 % by weight, relative to the total weight of 4-methylheptan-3- one present in the final product.

[0133] In another aspect, the present invention relates to an aroma/flavour or fragrance composition obtained or obtainable by the method according to the present invention.

[0134] The aroma/flavour or fragrance composition comprising a sensory effective amount of 4-methylheptan-3-one and/or the 4-methylheptan-3-one itself obtained or obtainable by the method according to the present invention is characterized itself by an intense nutty, chemical-fruity, sweet, and/or roasted aroma/flavour and odour characteristics causing it to be particularly useful for generation of authentic aromas/flavours or fragrances. Additionally, the aroma/flavour or fragrance composition comprising a sensory effective amount of 4-methylheptan-3-one and/or the 4- methylheptan-3-one itself obtained or obtainable by the method according to the present invention are particularly useful to give other flavouring or perfuming compounds a more complex, natural and intensified taste or odour impression from the group consisting of nutty, sweet, fruity, mushroom and/or roasted notes.

[0135] Further, the aromatic or scented aroma/flavour or fragrance composition comprising a sensory effective amount of 4-methylheptan-3-one and/or the 4- methylheptan-3-one itself obtained or obtainable by the method as described above, are particularly advantageous as they can be obtained in an environmentally friendly manner without the use of halogenated or toxic reagents. Especially as the preferred natural organic solvent ethyl acetate can be recycled and reused.

[0136] In another aspect, the present invention thus relates to a method for producing, enhancing or modifying of one or more nutty, chemical-fruity, sweet, mushroom and/or roasted taste or odour impression(s), comprising the following steps:

(a1) providing 4-methylheptan-3-one; and

(a2) mixing a sensory effective amount of 4-methylheptan-3one with one or more further aroma/flavour or fragrance substance(es) to obtain a nutty, preferably hazelnut, chemical-fruity, sweet, mushroom and/or roasted aroma/flavour or odour in the finished aroma or fragrance preparation; or (b1) providing 4-methylheptan-3-one; and

(b2) mixing a sensory effective amount of 4-methylheptan-3-one with an aroma, an orally consumable preparation to obtain a nutty, chemical-fruity, sweet, mushroom and/or roasted aroma/flavour or odour in the finished preparation.

[0137] Due to its immanent remarkable gustatory and/or olfactory properties the 4- methylheptan-3-one according to the present invention or an aroma/flavour or fragrance composition comprising the 4-methylheptan-3-one enables nutty, preferably hazelnut, chemical-fruity, sweet, mushroom and/or roasted notes to be obtained in the resulting preparations, even at a low rate of addition. [0138] In another aspect, the present invention thus relates to the use of the aroma/flavour or fragrance composition according to the present invention, for imparting, enhancing, or modifying of a nutty, chemical-fruity, sweet, mushroom and/or roasted taste or odour in an aroma/flavour composition, orally consumable preparations or fragrances. With regard to the preferred variants of the aroma/flavour or fragrance compositions according to the invention, the comments made above of course apply correspondingly.

[0139] The aroma/flavour or fragrance compositions according to the invention which contain 4-methylheptan-3-one may be incorporated into products which are flavoured or perfumed or are intended to be flavoured or perfumed, preferably foodstuff, luxury food, food supplements, semi-finished products for the preparation of foodstuff or food supplements, pet food, fragrance or formulations serving for personal hygiene such as cleaning agents, laundry agents.

[0140] In accordance with a preferred development, the flavoured or perfumed products according to the invention containing the aroma/flavour or fragrance composition according to the invention which contain 4-methylheptan-3-one are produced by incorporating the aroma/flavour or fragrance composition according to the invention which contain 4-methylheptan-3-one as the substance, without a solvent, as a solution or in the form of a mixture with a solid or liquid carrier and optionally other auxiliaries and/or stabilisers to form a base preparation for preparing foodstuff, luxury food, food supplements, semi-finished products for the preparation of foodstuff or food supplements, pet food, fragrance or formulations serving for personal hygiene such as cleaning agents, laundry agents, etc.

[0141] The present invention therefore also provides flavoured or perfumed products, preferably foodstuff, luxury food, food supplements, semi-finished products for the preparation of foodstuff or food supplements, pet food, fragrance or formulations serving for personal hygiene such as cleaning agents, laundry agents, etc., comprising the aroma/flavour or fragrance composition according to the present invention, which contains 4-methylheptan-3-one in an effective amount. [0142] Flavoured products in the light of the present invention are for example baked goods (e.g. bread, dry cookies, cake, other baked goods), sweets (e.g. chocolates, chocolate bar products, other bar products, fruit gum, hard and soft caramels, chewing gums), alcoholic or non-alcoholic drinks (e.g. cocoa, coffee, green tea, black tea, (black, green) tea drinks enriched with (green, black) tea extracts, rooibos-tea, other herbal teas, wine, drinks containing wine, beer, drinks containing beer, liqueurs, schnapps, brandies, lemonades containing fruits, isotonic drinks, refreshing-drinks, nectars, fruit and vegetable juices, fruit or vegetable juice preparations), instant drinks (e.g. instant cocoa drinks, instant tea drinks, instant coffee drinks), meat products (e.g. ham, fresh sausage or raw sausage compositions, spiced or marinated fresh or salt meat products), eggs or egg products (dry egg, protein, yolk), wheat products (e.g. breakfast cereals, muesli bars, precooked finished-rice products), dairy products (e.g. full fat or fat-reduced or fat-free milk drinks, rice pudding, yoghurt, pudding, kefir, cream cheese, soft cheese, hard cheese, dry milk powder, whey, butter, buttermilk, partly or completely hydrolyzed milk protein containing products), products made of soy protein or other soy bean fractions (e.g. soy milk and products made thereof, isolated or enzymatically treated soy protein containing drinks, soy flour containing drinks, soya lecithin containing compositions, fermented products such as tofu or tempeh or products made thereof and mixtures with fruit compositions and facultative fragrances), fruit compositions (e.g. jams, sorbets, fruit sauces, fruit fillings), vegetable compositions (e.g. ketchup, sauces, dry vegetables, frozen vegetables, pre-cooked vegetables, boiled down vegetables), snacks (e.g. baked or fried potato chips or potato dough products, extrudates based on corn or peanut), products based on fat and oil or emulsions of the same (e.g. mayonnaise, remoulade, dressings, each full fat or fat-reduced), other finished-products and soups (e.g. dry soups, instant soups, pre-cooked soups), spices, spice compositions as well as particularly seasonings, which are e.g. used in the field of snacks, sweetener compositions, sweetener tablets or sweetener sachets, other compositions for sweetening or whitening of drinks or other food.

[0143] The products according to the invention may also be semi-finished products comprising the aroma/flavour or fragrance composition according to the present invention which contains 4-methylheptan-3-one in an effective amount. [0144] Perfumed products according to the invention are for example perfume extracts, eaux de parfum, eaux de toilette, shaving lotions, eaux de cologne, pre-shave products, splash colognes and perfumed tissue wipes, including for perfuming acidic, alkaline and neutral cleaning agents such as for example floor cleaners, window cleaners, dishwashing detergents, bath and sanitary cleaners, scouring creams, solid and liquid toilet cleaners, pulverulent and foam carpet cleaners, textile fresheners, ironing aids, liquid detergents, pulverulent detergents, laundry pre-treatment agents such as bleaches, soaking agents and stain removers, laundry rinse conditioners, laundry soaps, laundry tablets, disinfectants, surface disinfectants as well as air fresheners in liquid or gel form or those applied to a solid carrier, aerosol sprays, waxes and polishes such as furniture polishes, floor waxes and shoe polishes as well as body care products such as for example solid and liquid soaps, shower gels, shampoos, shaving soaps, shaving foams, bath oils, cosmetic emulsions of the oil-in-water, water-in-oil and water-in-oil-in-water type such as for example skin creams and lotions, face creams and lotions, sunscreen creams and lotions, after-sun creams and lotions, hand creams and lotions, foot creams and lotions, depilatory creams and lotions, after-shave creams and lotions, tanning creams and lotions, hair care products such as for example hair sprays, hair gels, strengthening hair lotions, hair rinses, permanent and semi-permanent hair dyes, hair styling agents such as cold waving and hair straightening agents, hair tonics, hair creams and lotions, deodorants and antiperspirants such as for example underarm sprays, roll-ons, deodorant sticks, deodorant creams, decorative cosmetic products such as for example eyeshadow, nail varnish, make-up products, lipstick, mascara, as well as candles, lamp oils, incense sticks, insecticides, repellents and fuels or oral and/or dental care products such as toothpastes, tooth gels, tooth powders, mouthwashes, chewing gum and other oral care products.

[0145] The percentages at which the aroma/flavour or fragrance composition according to the present invention comprising 4-methylheptan-3-one is used may vary within wide limits ranging from a few parts per thousand in mass market products such food stuff, food supplements, pet food, products for personal care up to a few per cent in alcoholic extracts for fine perfumery. However, even small amounts of the aroma/flavour or fragrance composition which contains 4-methylheptan-3-one according to the invention provide nutty, chemical-fruity, sweet, roasted aroma/flavour or odour notes. Preferably, the aroma/flavour or fragrance composition which contains 4-methyhept-3-one is used in an amount of 0.0001 to 90 % by weight, preferably 0.01 to 70 % by weight and particularly preferably 0.1 to 50.0 % by weight, based on the total weight of the final product/formulation.

[0146] Due to its remarkable gustatory and/or olfactory properties of the 4-methylheptan- 3-one as described above, the present invention relates in a final aspect to the use of 4- methylheptan-3-one as aroma/flavour or odorant.

[0147] In a preferred variant of the use according to the present invention the 4- methylheptane-3-one is an isomeric mixture of the (-)-(4R)-methylheptan-3-one enantiomer and the (+)-(4S)-methylheptan-3-one enantiomer.

[0148] In a more preferred variant of the use according to the present invention, the (-)- (4R)-methylheptan-3-one enantiomer and the (+)-(4S)-methylheptan-3-one enantiomer are used as racemic mixture, i.e. the (-)-(4R)-methylheptan-3-one enantiomer and the (+)-(4S)-methylheptan-3-one enantiomer are present in the isomeric mixture in a ratio of 50 : 50.

[0149] In a particular preferred variant of the use according to the present invention, in the isomeric mixture the (-)-(4R)-methylheptan-3-one enantiomer is enriched.

[0150] In a further preferred variant of the use according to the present invention, the (- )-(4R)-methylheptan-3-one enantiomer is present in the isomeric mixture in an amount of more than 50 % by weight, relative to the total content of 4-methylheptan-3-one in the isomeric mixture.

[0151 ] In a particular preferred variant of the use according to the present invention, the (-)-(4R)-methylheptan-3-one enantiomer and the (+)-(4S)-methylheptan-3-one enantiomer are present in the isomeric mixture in a ratio of > 2 : 1 , preferably in a ratio of 2 : 1. [0152] In a more preferred variant of the use according to the present invention, the isomeric mixture comprises the (-)-(4R)-methylheptan-3-one enantiomer in an amount of at least 60 to 65 % by weight, more preferably at least 70 to 75 % by weight, still more preferred at least 80 to 85 % by weight, and particularly preferred at least 90 to 95 % by weight, relative to the total weight of 4-methylheptan-3-one present in the isomeric mixture.

[0153] In a most preferred variant, the 4-methylheptan-3-one comprises the (-)-(4 R)- methylheptan-3-one enantiomer as pure optically active enantiomer.

[0154] In a most preferred variant of the use, the 4-methylheptan-3-one comprises the (-)-(4R)-methylheptan-3-one enantiomer, since it is characterized by a natural, strongest nutty, preferably hazelnut, chemical-fruity, sweet, slightly rummy, and/or roasted aroma/flavour or odour.

[0155] In a still more preferred variant, in the use according to the present invention, the racemic mixture of the (-)-(4R)-methylheptan-3-one enantiomer and the (+)-(4S)- methylheptan-3-one enantiomer is particular beneficial, since it is distinguished by a natural, strongest nutty, preferably hazelnut, chemical-fruity, sweet, and/or roasted aroma/flavour or odour.

[0156] In the use according to the present invention, at most preferred is an isomeric mixture which comprises the (-)-(4R)-methylheptan-3-one enantiomer in excess as described above. Such mixtures are characterized by a significant natural, strongest nutty, preferably hazelnut, chemical-fruity, sweet, slightly rummy, and/or roasted aroma/flavour or odour.

[0157] The present invention shall now be described in detail with reference to the following examples, which are merely illustrative of the present invention, such that the content of the present invention is not limited by or to the following examples. Examples

[0158] The following examples have the purpose of clarifying the invention, without limiting it thereby.

[0159] Example 1 (aldol reaction)

[0160] 4.4 g (0.5 eq) of concentrated sulfuric acid were added to 7.7 g (1 eq) of 3- pentanone under stirring. The resulting reaction mixture was then heated to 50 °C and 10.5 g (2 eq) of propionaldehyde was added slowly (within 5 h). After 6 h the reaction mixture was cooled to room temperature and washed with water and NaHCCb solution to get rid of acid. The product was distilled under reduced pressure (10 mbar, 90 °C) to give 2.85 g of 4-methyl-4-hepten-3-one. Yield: 25 %.

[0161] Example 2 (aldol reaction)

[0162] 2.2 g (0.25 eq) of concentrated sulfuric acid were added to 7.7 g (1 eq) of 3- pentanone under stirring. The resulting reaction mixture was then heated to 50 °C and 5.25 g (1 eq) of propionaldehyde was added slowly (within 5 h). Subsequently, additional 2.2 g (0.25 eq) of concentrated sulfuric acid were added to the reaction mixture. The resulting reaction mixture was then again treated with 5.25 g (1 eq) of propionaldehyde slowly (within 5 h). After 11 h the reaction mixture was cooled to room temperature and washed with water and NaHCCb solution to get rid of acid. The product was distilled under reduced pressure (10 mbar, 90 °C) to give 4.6 g of 4- methyl-4-hepten-3-one. Yield: 36 %.

[0163] Example 3 (aldol reaction)

[0164] 1.6 g (0.2 eq) of concentrated sulfuric acid were added to 7.7 g (1 eq) of 3- pentanone under stirring. The resulting reaction mixture was then heated to 50 °C and 10.5 g (2 eq) of propionaldehyde was added slowly (within 5 h). After 6 h the reaction mixture was cooled to room temperature and washed with water and NaHCCb solution to get rid of acid. The product was distilled under reduced pressure (10 mbar, 90 °C) to give 2.28 g of 4-methyl-4-hepten-3-one. Yield: 20 %.

[0165] Example 4 (aldol reaction)

[0166] 23.3 g (1 eq) of 3-pentanone were treated under stirring with 12.3 g (0.5 eq) of oxalic acid and subsequently with 31.4 g (2 eq) of propionaldehyde. The resulting reaction mixture was then heated to 120 °C for 16 h in closed autoclave. After 16 h the reaction mixture was cooled to room temperature and washed with water and NaHCCb solution to get rid of acid. The product was distilled under reduced pressure (10 mbar, 90 °C) to give 5.12 g of 4-methyl-4-hepten-3-one. Yield: 15 %.

[0167] Example 5 (reduction of the double bond with palladium)

[0168] 22.7 g (1.0 eq) of 4-methyl-4-hepten-3-one were dissolved in ethyl acetate (300 ml_) and treated under stirring with 2.27 g of palladium on carbon (5 %). The resulting reaction mixture was then stirred under hydrogen atmosphere at room temperature for 8 h. The reaction mixture was filtered through celite to get rid of catalyst and the filtrate was evaporated under reduced pressure. The product was distilled under reduced pressure (60 mbar, 100 °C) to give 20.8 g of 4-methylheptan-3-one as racemic mixture (4 R : 4S = 50 : 50). Yield: 92 %.

[0169] Example 6 (reduction of the double bond with baker’s yeast)

[0170] To a Baker’s yeast solution (400 g of Baker’s yeast suspension (containing 150 g yeast) in 600 g water) 80 g glucose and 3.0 g of 4-methyl-4-hepten-3-one were added. The resulting reaction mixture was then stirred at room temperature for 24 h. After 24 h the reaction mixture was distilled at 120 °C under normal pressure. The distillate was extracted with MTBE and the product was distilled under reduced pressure (60 mbar, 100 °C) to give 1 .9 g of mixture of 4-methylheptan-3-one (4 R : 4S = 2 : 1 ) and 4-methyl-4-hepten-3-one (4-methylhept-4-en-3-one) in a ratio of 1 : 1. Yield: 63 % for the mixture and 29 % for 4-methylheptan-3-one. [0171] Example 7 Synthesis of (-)-4/?-methylheptan-3-one

[0172] (-)-4R-methylheptan-3-one was synthesized from 3-pentanone using RAMP- auxiliar according to ENDERS procedure. Starting from 0.7 g (8 mmol, 1.1 eq) of 3- pentanone and 1.0 g (7.3 mmol, 1 eq) of (R)-1-amino-2-methoxymethylpyrrolidine (RAMP) 0.3 g (2.3 mmol) of (-)-4R-methylheptan-3-one were obtained in a ratio of 96 : 3 (4 R -. 4 S). Yield: 29 %.

[0173] Example 8 Sensory evaluation of 4-methylheptan-3-one

[0174] 50 g sugar and 0.001 g of 4-methylheptan-3-one from Example 5 were dissolved in 1000 ml_ water. When tested by a panel of skilled test persons, the composition according to the invention was described as intensive, nutty, roasted, green, and fresh.

[0175] Example 9 Sensory evaluation of (-)-4/?-methylheptan-3-one

[0176] 50 g sugar and 0.001 g of (-)-4R-methylheptan-3-one from Example 7 were dissolved in 1000 ml_ water. When tested by a panel of skilled test persons, the composition ((-)-4R-methylheptan-3-one) in comparison with the composition from Example 5 (racemic mixture) was described as slightly more nutty and rummy.

[0177] Aroma compositions

[0178] In the following application examples, the aroma/flavour compositions, containing 4-methylheptan-3-one, are preferably prepared by using either 4- methylheptan-3-one as pure material or as a mixture with a solvent. The thus obtained solutions are preferably solutions of 0.1 to 20 % 4-methylheptan-3-one, particularly preferred solutions of 1 to 10 % 4-methylheptan-3-one, in triacetine or triethylcitrate. Alternatively, said solutions are used in spray dried form. [0179] Application example 1 - Hazelnut flavour

[0180] Table 1 :

A = compositions of comparison B = compositions according to the invention

[0181] Sensory evaluation: 50 g sugar and 0.5 g of hazelnut flavour were dissolved in 1000 ml_ water. When tested by a panel of skilled persons on a scale from 1 to 9 the composition according to the invention B is assessed as clearly more nutty especially more reminding hazelnuts and more pyrazine-like with regard to its aroma and taste than the composition of comparison A.

[0182] Table 2:

[0183] This aromatic blend is used in the subsequently described application examples.

[0184] Application example 2 - Mushroom flavour

[0185] Table 3:

A = compositions of comparison B = compositions according to the invention

[0186] Sensory evaluation: 0.1 g of mushroom flavour was dissolved in 1000 ml_ of a 0.3 % salt solution. When tested by a panel of skilled persons, the composition according to the invention B is assessed as clearly more mushroom like especially more forest mushroom like with regard to its aroma and taste than the composition of comparison A. [0187] This aromatic blend is used in the subsequently described application examples.

[0188] Application example 3 - Beef flavour, type grill

[0189] Table 4:

A = composition of comparison B = composition according to the invention

[0190] Sensory evaluation: 0.25 g of beef flavour was dissolved in 1000 mL of a 0.3 % salt solution. When tested by a panel of skilled persons, the composition according to the invention B is assessed as clearly more rich, balanced and the roasted notes are intensified with regard to its aroma and taste than the composition of comparison A.

[0191] This aromatic blend is used in the subsequently described application examples. [0192] Application example 4 - Beef flavour, type grill for spray dried compositions

[0193] Table 5:

[0194] Application example 5 - Spray dried aroma composition

[0195] Spray dried aroma compositions - starting from the previously described application examples 1 to 3 - are prepared.

[0196] Table 6:

[0197] The ingredients are dissolved in demineralized water and subsequently spray dried to obtain aroma compositions A to F.

[0198] These aroma compositions are used in the subsequent application examples.

[0199] Application example 6 - Hazelnut Pudding

[0200] Table 7:

A = composition of comparison B = composition according to the invention

[0201] The ingredients are dissolved in milk warmed to 95 °C for 2 minutes while stirring well, and subsequently cooled to 5 - 8 °C.

[0202] By the use of the inventive flavour compositions according to invention, a clearly nutty, authentic taste is achieved.

[0203] Application example 7 - Hazelnut Chocolate

[0204] Table 8:

A = composition of comparison B = composition according to the invention [0205] When tested by a panel of skilled test persons, the hazelnut notes according to the invention B are assessed more rich and more balanced in comparison with composition A.

[0206] Application example 8 - Chocolate-Hazelnut Ice Cream

[0207] Table 9:

A = composition of comparison B = composition according to the invention

[0208] By the use of the inventive flavour compositions according to invention, a clearly nutty, authentic taste is achieved.

[0209] Application Example 9 - Beef Seasoning Mixture for (Instant) Noodles

[0210] Table 10:

A = composition of comparison B = composition according to the invention

[0211] All ingredients are mixed, until a homogeneous mixture is obtained.

[0212] By the use of the inventive flavour compositions according to invention, a more balanced and stronger taste is achieved.

[0213] Application Example 10 - Brown Sauce

[0214] Table 11:

A = composition of comparison B = composition according to the invention

[0215] 90 g of the sauce mixture is infused with 1000 ml of hot water and stirred vigorously with the wire whisk.

[0216] During the tasting by a panel of trained test persons, the inventive preparation B is evaluated as significantly richer, more balanced, stronger and longer-lasting than the comparative preparation A with regard to their flavour and taste.

[0217] Application Example 11 - Instant mushroom cream soup

[0218] Table 12: A = composition of comparison B = composition according to the invention

[0219] All ingredients are mixed, until a homogeneous mixture is obtained. The soup was prepared by stirring 140 g of the instant soup in 1 L water and boiling for 1 min.

[0220] During the tasting by a panel of trained test persons, the inventive preparation B is evaluated as significantly richer, more balanced, clearly more mushroom like especially more forest mushroom than the comparative preparation A with regard to their flavour and taste.

[0221] Application Example 12 - Bouillon

[0222] Table 12:

A, C = composition of comparison B, D = composition according to the invention

[0223] 15 g of the powder mixture are infused with 1000 mL of hot water.

[0224] When tasted by a panel of skilled test persons, the composition according to the invention B and D are assessed as clearly more rich, balanced and authentic.

Claims

1. An aroma/flavour or fragrance composition comprising a sensory effective amount of 4-methylheptan-3-one.

2. The aroma/flavour or fragrance composition according to claim 1 , wherein the 4- methylheptane-3-one is an isomeric mixture of:

(-)-(4R)-methylheptan-3-one, and (+)-(4S)-methylheptan-3-one.

3. The aroma/flavour or fragrance composition according to claim 2, wherein the isomeric mixture comprises the (-)-(4R)-methylheptan-3-one enantiomer and the (+)-(4S)-methylhetpan-3-one enantiomer in a ratio of 50 : 50.

4. The aroma/flavour or fragrance composition according to any one of claims 1 to

3, wherein the isomeric mixture comprises the (-)-(4R)-methylheptan-3-one enantiomer in an amount of more than 50 % by weight, relative to the total content of 4-methylheptan-3-on in the isomeric mixture.

5. The aroma/flavour or fragrance composition according to any one of claims 1 to

4, further comprising at least one further aroma/flavour substance or at least one fragrance substance or at least one further aromatic substance.

6. The aroma/flavour or fragrance composition according to claim 5, wherein the at least one further aroma substance is selected from the group consisting of:

Organic acids: acetic acid, butyric acid, 2- or, respectively 3-methyl butyric acid, caprinic acid, capronic acid, phenylacetic acid;

Alcohols: ethanol, propylene glycol, 1,3-octenol, c/s-3-hexenol, linalool, benzyl alcohol, p-cresol, 2,6-dimethylthiophenol, guajacol, eugenol; Sulfides/thiols: dimethyl sulfide, difurfuryl disulfide, methyl thiopropanal, 2- methyl-3-methyldithiofuran and bis(2-methyl-3-furyl)disulfide, methylfuranthiol, 2-(4-methyl-1 ,3-thiazol-5-yl)ethanol (sulfurol), methyltetrahydrofuranthiol, 3-methyl-2-buten-1 -thiol, 3-thio-2- methylpentanol, 2-furfurylthiol, thiophenol, 2-methylthiophenol and 2- mercaptobutanone;

Pyridines: 2-acetylpyridine;

Pyrazines: methylpyrazine, 2,5-methylethylpyrazine, 2,3,5- trimethylpyrazine, acetylpyrazine, 2,3-diethyl-5-methylpyrazine, 2-ethyl-3,5- dimethylpyrazine and 2-isopropyl-3-methoxy-pyrazine;

Thiazoles/thiazoline: 2-acetylthiazol, 2-acetyl-2-thiazoline;

Pyrrolines: 2-propionyl-1-pyrroline and 2-acetyl-1-pyrroline;

Aldehydes: acetaldehyde, frans-4,5-epoxy-(2E)-decenal, c/s-4,5-epoxy- (2E)-decenal, (E,E)-2,4-undecadienal, (E,E)-2,4-decadienal, (E,Z)-2,4- decadienal, (E,E,Z)-2,4,6-nonathenal, (E,E)-2,4-nonadienal, (E)- 2- undecenal, (Z)-2-decenal, (E)-2-decenal, (E)-2-nonenal, (Z)-2-nonenal, (E,Z)-2,6-nonadienal, (E,E)-2,4-nonadienal, 3-methylthiopropanal (methional), vanillin und phenylacetaldehyde;

Ketones: 3,4-dimethylcyclopentan-1 ,2-dione, 3-hydroxy-4,5-dimethylfuran- 2(5H)-on (sotolon), 2-aminoacetophenone, 3-hydroxy-4,5-dimethyl-2(5H)- furanone, 2,5-dimethyl-4-hydroxy-3-[2H]-furanone (furaneol©), tetrahydrothiophen-3-one und 3-thiobutan-2-one;

Esters and lactones: methylbutanoate, ethyl-3-methylbutanoate, propyl-2- methylbutanoate, (Z)-6-dodecen-y-lactone, 4-hydroxy-2-nonenic acid lactone, d-undecalactone, y-nonalactone und y-octalactone; and mixtures of the above substances; and/or wherein the at least one further aromatic substance(s) is selected from the group consisting of volatile hydrocarbons, organic acids, aliphatic alcohols, aliphatic aldehydes and their acetales, aliphatic ketones and their oximes, sulfur containing compounds such as thiols, disulfides, aliphatic nitriles, aliphatic carbonic acids esters, acyclic terpene alcohols, acyclic terpene aldehydes and ketones, cyclic terpene alcohols, cyclic terpene aldehydes and ketones, cyclic alcohols, esters of cycloaliphatic carbonic acids, aromatic hydrocarbones, araliphatic alcohols, esters of araliphatic alcohols and aliphatic carbonic acids, araliphatic and aliphatic ethers and acetales or ketales, carbonic acid amides, carbonates and ureas, aromatic and araliphatic aldehydes, aromatic and araliphatic ketones, aromatic and araliphatic carbonic acids and their esters, nitrogen containing aroma compounds, phenols, phenyl ethers and phenyl esters, heterocyclic compounds, preferably pyridines, pyrazines, pyrrolines, thiazoles and thiazolines, lactones, and mixtures thereof.

7. Method for preparing 4-methylheptane-3-one, comprising the following steps:

(a) performing an acid catalysed aldol condensation between pentan-3-one and propionaldehyde to obtain a mixture comprising 4-methylhept-4-en-3- one;

(c) treating the isolated 4-methylhept-4-en-3-one from step (b) with a chemical- type reducing agent to reduce the double bond to obtain the chemically generated product 4-methylheptan-3-one; or treating the isolated 4-methylhept-4-en-3-one from step (b) with a biochemical-type reducing agent to reduce the double bond to obtain the biochemically generated product 4-methylheptan-3-one; and

8. The method according to claim 7, wherein the ratio of pentan-3-one to propionaldehyde is from 5 : 1 to 1 : 5, in particular from 2 : 1 to 1 : 2.

9. The method according to claim 7 or claim 8, wherein the acid for the aldol condensation is selected from the group consisting of mineral/inorganic acid or organic acid; wherein the inorganic/mineral acid is selected from the group consisting of hydrochloric acid, phosphoric acid, sulfuric acid, and mixtures thereof; and/or wherein the organic acid is selected from the group consisting of acetic acid, oxalic acid, tartaric acid, citric acid, lactic acid, malic acid, malonic acid, formic acid, and mixtures thereof.

10. The method according to any one of claims 7 to 9, wherein the mineral/inorganic acid is used in an amount of 0.05 to 1 eq to the amount of pentan-3-one or wherein the organic acid is used in an amount of 0.5 to 3 eq to the amount of pentan-3-one.

11. The method according to any one of claims 7 to 10, wherein the chemical-type reducing agent is selected from the group consisting of a transition-metal catalyst, or a lithium or boron-based hydride transfer reagent; or the biochemical-type reducing agent is selected from the group consisting of enzymes and yeasts.

12. Aroma/flavour or fragrance composition comprising a sensory effective amount of 4-methylheptan-3-one obtained or obtainable by the method according to any one of claims 7 to 11.

13. A method for producing, enhancing or modifying of one or more nutty, sweet, fruity, mushroom, and/or roasted taste or odour impression(s), comprising the following steps:

(a1) providing 4-methylheptan-3-one; and

(a2) mixing a sensory effective amount of 4-methylheptan-3-one with one or more of further aroma or fragrance substance(es) to obtain a nutty, sweet, fruity, mushroom, and/or roasted aroma/flavour or odour in the finished aroma or fragrance composition; or (b1) providing 4-methylheptan-3-one; and

14. Use of the aroma or fragrance composition according to any one of claims 1 to 6, for producing, enhancing or modifying of a nutty, sweet, fruity, mushroom and/or roasted taste or odour.

15. Foodstuff, luxury food, food supplements, semi-finished products for the preparation of foodstuff or food supplements, pet food, aroma or fragrances, comprising the aroma/flavour or fragrance composition according to any one of claims 1 to 6 and claim 12.

16. Foodstuff, luxury food, food supplements, semi-finished products for the preparation of foodstuffs or foods supplements, petfood, or fragrances according to claim 15, comprising the aroma/flavour or fragrance composition in an amount of 0.0001 to 90 % by weight, based on the total weight of the final product/formulation.

17. Use of 4-methylheptan-3-one as aroma/flavour or as odorant.