SK16942001A3 - Utilization of microemulsions in fermentation processes - Google Patents

Abstract

The invention relates to the utilization of O/W emulsions in fermentation processes, said emulsions containing at least water, emulsifying agents and an oil phase that contains one or more compounds selected from the group consisting of: a) fatty acid alkyl ester and/or b) triglycerides of vegetable origin, wherein the emulsions have an average drop size ranging from 1 to 100 nm.

Description

Technical field

The present invention relates to the use of microemulsions in a fermentation process.

BACKGROUND OF THE INVENTION

Microbiological processes are increasingly used in the synthesis of complex natural substances or other organic compounds, such as antibiotics. This is a matter of metabolism under anaerobic or aerobic conditions in which microorganisms or parts of microorganisms, in particular bacteria or fungi, are involved. For these processes, various, not always mutually limited terms such as "bioconversion", "biotransformation" or "fermentation" are used in the scientific world. The latter term is also used in the present application for processes in which microorganisms, preferably bacteria, are used for the conversion or synthesis of chemical compounds.

In developing and optimizing fermentation processes, the reaction medium in which the microbiological exchange takes place is particularly important. The reaction medium, almost always an aqueous solution or dispersion, affects in particular the yield and efficiency of the process. To enable successful metabolism to the desired products, microorganisms such as nutrients need carbon, nitrogen and certain trace elements in bound form, for example calcium, iron, phosphorus or zinc. Furthermore, it is necessary to regularly maintain a certain, mostly narrow temperature range and pH. For more details, see the textbook by W. Crueger / A. Crueger, Biotechnology - Lehrbuch der angewandten Microbiology,

2nd edition 1984, R. Oldenbourg Verlag. In particular, Chapter 5 of this work deals with the basics of fermentation techniques. This part of the literature is therefore also expressly included in the publication of the present application. In addition to energy-rich sugars or derivatives thereof, natural fats or oils are used as nutrients for microorganisms in many processes, as well as derivatives of these classes of compounds, such as glycerin, glycerides, fatty acids or fatty acid esters. Of course

- The culture media must not contain any substances which could adversely affect the metabolism of the micro-organism.

For example, DE 37 38 812 A1 discloses a microbial process for the preparation of alpha-omega-dicarboxylic acids, wherein the bacteria of the Candida tropicalis strain convert methyl laurane into the desired dicarboxylic acids. The conversion is carried out in aqueous medium at pH 6.0 and 30 ° C. In addition to microorganisms, the medium contains, as an energy source, glucose, as an emulsifier, ethoxylated sorbitan monooleate, yeast extract, soaking water as well as sources of inorganic nitrogen and phosphorus. Methyl lauran is then added to the medium. The type of emulsion which is produced in a fermenter or in which methyl laurane is added to the medium is not apparent from the specification. EP 0 535 939 A1 discloses a process for the production of omega-9 multiply unsaturated fatty acids, wherein in the aqueous culture medium the desired multiply unsaturated fatty acids produce suitable microorganisms in the presence of sugar as a source of energy and inorganic or organic nitrogen sources as well as methyl esters. of fatty acids.

However, it is also known to use only fatty substances of the type mentioned above as energy sources. This is of particular interest from an economic point of view, since such fatty substances are generally cheaper than sugars, starches and the like. Park et al. (Park et al., Journal of Fermentation and Bioengineering, Vol. 82, No. 2, 183-186, 1996) discloses a fermentation process for the production of tylosin using microorganisms of the strain Streptomyces fradiae in an aqueous medium containing as the sole carbon source rapeseed oil in the starting amount of about 60g / l.

In the fermentation process, among other things, the oxygen content of the medium or of the fermentation mixture plays a decisive role. Oxygen plays a role of substrate in aerobic processes. It is critical whether oxygen can be transferred from the gaseous to the liquid phase containing the microorganisms that is sufficient for the process. An important parameter is the specific exchange surface, which is usually determined by the oxygen exchange coefficient Ka (cf. section of the Crueger literature, chapter 5, page 71 et seq.). The adjustment of the optimum oxygen supply is typically carried out by stirring the fermentation mixture, whereby oxygen or air is mixed into the liquid and thus at the boundary surface r e

-3the gas is being exchanged. Naturally, considerable mechanical energy input by vigorous mixing, as reported by Park et al., Can also disrupt a portion of the culture and thus reduce the yield of the process. In addition, dead microorganisms are themselves further degraded and can cause the formation of degradation products by poisoning a culture that prevents economical production. It is known from the work of Goma and Rols (G. Goma, JL Rols, Biotech. Let, Vol. 13, No. 1, pp. 7-12, 1991) that the use of soybean oil in the fermentation process of antibiotic production leads to an improved exchange rate. of oxygen to _La , which can lead to an increase in the yield of the whole process with the same energy input (mixing).

It is an object of the present invention to improve the fermentation process so that, on the one hand, the use of cost-effective carbon sources is possible and, on the other hand, a sufficient oxygen supply of the microorganisms is ensured without impermissible mechanical loading of the microorganisms by stirring. A method should be found to minimize mechanical energy input in the fermentation process without reducing the yield. More preferably, it should be possible to increase the yield despite reduced energy input.

The use of special, fine oil-in-water (O / W-emulsions) emulsions has been found to solve the above task.

SUMMARY OF THE INVENTION

The object of the invention was solved by using oil-in-water (O / W-emulsions) emulsions in the fermentation process, which emulsions contain at least water, emulsifiers as well as an oil phase, the oil phase comprising one or more compounds from the group:

(a) alkyl esters of fatty acids; and / or

b) triglycerides of vegetable origin, the emulsions having a droplet size in the range of 1 to 100 nm.

The emulsions according to the invention are characterized in particular by their fineness. These are the so-called microemulsions, which are defined as macroscopic homogeneous, optically clear, often low-viscosity, thermodynamically stable mixtures of two immiscible liquids and at least one nonionic or one β P

The 4-ionic surfactant, which preferably contains two hydrophobic residues. The formation of a microemulsion requires a situation in which the oil-water surface tension approaches zero. In order to achieve this special form of emulsion, it is generally necessary to add additional additional surfactants to the at least one nonionic surfactant. To this end, compare the section of the literature entitled "Introduction to Colloid and Surface Chemistry, DJ Shaw, Butterworth, 1992, pages 269 and 270". The droplet size of the emulsions used according to the invention ranges from 1 to 100 nm. More preferably, the droplet size is in the range of 10 to 80 nm, most preferably in the range of 10 to 30 nm. The fineness of the oil droplets leads to a larger surface area between the oil phase and the aqueous phase and allows for faster contact between the microorganisms contained in the aqueous phase and the nutrients contained in the oil phase. Large surfaces will also facilitate the exchange of gases, especially oxygen and CO ₂ . Additionally, the viscosity of the emulsion and thus the total fermentation medium is also reduced. As a result, it is possible to significantly reduce the agitation rate of the fermentation medium, thereby allowing the yield of the fermentation process to be increased.

According to the invention, the microemulsions are metered into an aqueous fermentation medium containing microorganisms and optionally further auxiliaries and additives. The details of this process, in particular the speed and amount of the emulsion to be metered, result from the type of microorganisms and the fermentation process chosen and can be adapted to those of skill in the art.

The microemulsions contain, in addition to water, an oil phase containing compounds selected from the group of alkyl esters of fatty acids a) or vegetable oils and derivatives thereof b). Groups (a) and (b) are hydrophobic, water-insoluble or sparingly soluble compounds which may also serve as nutrients, ie energy sources, for the bacteria used in the fermentation process, but may also be the starting substances (substrates) for the desired products bioconversion.

Preferred methyl esters of group a) are derived from, in particular, saturated, unsaturated, linear or branched fatty acids having a total of 7 to 23 carbon atoms. They are therefore compounds of formula I

R ¹ -COO-R ² (I)

Where R ¹ is an alkyl radical of 6 to 22 carbon atoms and R ² is an alkyl radical of 1 to 4 carbon atoms. Methyl and ethyl are preferred. Particularly preferred is the use of methyl esters as component a). Esters of formula (I) or methyl esters may be obtained in a conventional manner, for example by esterification of triglycerides with methanol and subsequent distillation. Suitable fatty acids are caproic acid, heptanoic acid, caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, nonadecanoic acid, arachic acid and arachic acid. behenic. Unsaturated representatives are, for example, lauroeleic acid, myristoleic acid, palmitoleic acid, petrozelaidic acid, oleic acid, elaidic acid, ricinoleic acid, linoleic acid, linolaidic acid, linolenic acid, gadoleic acid, arachidonic acid and erucic acid. Also suitable are mixtures of the methyl esters of these acids. Particularly preferred is the use of such microemulsions which comprise a methyl ester selected from the group consisting of methyl oleate, methyl palmitate, methyl stearate and / or methylpelargonate. However, it is also possible to "use" methyl esters based on natural fatty acid mixtures such as those obtained from linseed oil, coconut oil, palm oil, palm kernel oil, olive oil, castor oil, rapeseed oil, sesame oil, soybean oil or sunflower oil ( for rapeseed oil and sunflower oil, always new and old cultivation).

Suitable compounds of group b) are natural oils of vegetable origin. In essence, they are mixtures of triglycerides, wherein the glycerin is always completely esterified with long-chain fatty acids. Particularly suitable are vegetable oils selected from the group of peanut oil, coconut oil, linseed oil, palm oil, olive oil, palm kernel oil, castor oil, rapeseed oil, sesame oil, soybean oil and sunflower oil.

Peanut oil contains on average (based on fatty acids) 54% by weight. % oleic acid, 24 wt. % linoleic acid, 1 wt. % linolenic acid, 1 wt. % arachic acid, 10 wt. palmitic acid as well as 4% stearic acid. Melting point: 2 to 3 ° C.

Linseed oil contains mostly 5 wt. % palmitic acid, 4 wt. % stearic acid, 22 wt. % oleic acid, 17 wt. linoleic acid and

-652 wt. Linolenic acid. The iodine number ranges from 155 to 205. The saponification number is from 188 to 196 and the melting point is about -20 ° C.

The coconut oil contains from about 0.2 to 1 wt.% Of fatty acids. % hexanoic acid, from 5 to 8 wt. % octanoic acid, from 6 to 9 wt. % decanoic acid, from 45 to 51 wt. % lauric acid, from 16 to 19 wt. % myristic acid, from 9 to 11 wt. % palmitic acid, from 2 to 3 wt. % stearic acid, less than 0.5 wt. % of behenic acid, from 8 to 10% oleic acid and up to 1% wt. Linoleic acid. The iodine number ranges from

7.5 to 9.5; saponification number from 0.88 to 0.9. The melting point is in the range of 20 to 23 ° C.

Olive oil predominantly contains oleic acid (cf. Lebensmittelchem. Gerichtl. Chem., 39, 112-114, 1985). Palm oil contains about 2% myristic acid, 42% palmitic acid, 5% wt. % stearic acid, 41 wt. % oleic acid, 10 wt. Linoleic acid. Palm kernel oil typically has the following composition relative to the fatty acid spectrum: 9 wt. % caproic / caprylic / capric acid, 50 wt. % lauric acid, 15 wt. % myristic acid, 7 wt. % palmitic acid, 2 wt. % stearic acid, 15 wt. % oleic acid and 1 wt. Linoleic acid.

Rape oil typically contains about 48 wt. % erucic acid, 15 wt. % oleic acid, 14 wt. % linoleic acid, 8 wt. % linolenic acid, 5 wt. % of icosenoic acid, 3 wt. % palmitic acid, 2 wt. % decenoic acid and 1 wt. docosadienoic acid. Rapeseed oil from the new variety is enriched with unsaturated proportions. Typical proportions of fatty acids are erucic acid 0.5% by weight, oleic acid 63% by weight, linoleic acid 20% by weight, linolenic acid 9% by weight, icosenic acid 1% by weight, palmitic acid 4% by weight, % hexadecenic acid 2 wt. and docosadienoic acid 1 wt.

Castor oil is comprised of from 80 to 85% of ricinoleic acid glyceride; % of oleic acid glycerides, up to 3% linoleic acid glycerides, and up to about 2% by weight; glycerides of palmitic acid and stearic acid.

Soybean oil contains from 55 to 65 wt. % of the total fatty acid content of polyunsaturated acids, in particular linoleic acid and linolenic acid. A similar situation is also in sunflower oil, the typical fatty acid spectrum of which, based on the total fatty acid content, is as follows: about 1% myristic acid, from 3 to 10% by weight of the fatty acid; % palmitic acid, from 14 to 65 wt. % oleic acid and from 20 to 75 wt. Linoleic acid.

All of the above data on the amounts of fatty acids in triglycerides are, as is known, dependent on the quality of the raw materials and can therefore fluctuate quantitatively. Particularly preferred are those microemulsions that contain nutrients of group b) selected from the group of coconut oil, sunflower oil and / or rapeseed oil.

Important components of the microemulsions used according to the invention are emulsifiers or emulsifier systems. It is preferred to use nonionic emulsifiers as emulsifiers, especially ethoxylated fatty alcohols and fatty acids.

The fatty alcohol ethoxylates according to the invention correspond to the general formula II

R ³ -O- (CH ₂ CH ₂ O) _n -H (II) wherein R ³ represents a linear or branched, saturated or unsaturated alkyl radical of 6 to 24 carbon atoms and is a number from 1 to 50. Particularly preferred are such compounds Particularly preferred are furthermore those compounds of formula II in which R ^{3 is an} alkyl radical of 16 to 22 carbon atoms.

The compounds of the formula II are obtained in a known manner by reacting fatty alcohols with ethylene oxide under pressure, optionally in the presence of acidic or basic catalysts. Typical examples are capro alcohol, caprylalcohol, 2-ethylhexyl alcohol, caprile alcohol, lauryl alcohol, isotridecyl alcohol, myristyl alcohol, cetyl alcohol, palmoleyl alcohol, stearyl alcohol, isostearyl alcohol, oleyl alcohol, elaidyl alcohol, petrozelinyl alcohol, linolyl alcohol, linolyl alcohol, linol alcohol, linol alcohol, linol alcohol, their technical mixtures resulting from the high-pressure hydrogenation of technical methyl esters based on fats and oils or aldehydes from Roelen oxosynthesis as well as the monomer fraction in the dimerization of unsaturated fatty alcohols.

Preferred are industrial fatty alcohols having 12 to 18 carbon atoms, such as coconut alcohol, palm alcohol, palm kernel alcohol or tallow alcohol.

Fatty acid ethoxylates which are also suitable as emulsifier or emulsifier component preferably correspond to formula III

R ⁴ CO ₂ (CH ₂ CH ₂ O) _m H (III) wherein R ⁴ represents a linear or branched alkyl radical having 12 to 22 carbon atoms and a number of from 5 to 50, more preferably from 15 to 35. Typical examples are addition products 20 to 30 moles of ethylene oxide on lauric acid, isotridecanoic acid, myristic acid, palmitic acid, palmoleic acid, stearic acid, isostearic acid, oleic acid, elaidic acid, petrozelic acid, linoleic acid, linolenic acid, glaeoste acid, elaeoste acid , behenic acid and erucic acid, as well as their technical mixtures, which are formed, for example, by pressure digestion of natural fats and oils or by reduction of aldehydes from Roelen oxosynthesis. The use of 20 to 30 moles of ethylene oxide on fatty acids having 16 to 18 carbon atoms is preferred.

The partial glycerides which are also suitable as emulsifiers correspond more preferably to the general formula IV

CH ₂ O (CH ₂ CH ₂ O) _X -COR ⁵ CH-O (CH ₂ CH ₂ O) _y -H (IV)

CH ₂ O (CH ₂ CH ₂ O) _from -H wherein COR ⁵ is a linear or branched acyl radical having 12 to 22 carbon atoms and x, and z are in total 0 or a number from 1 to 50, more preferably from 15 to 35. Typical examples of partial glycerides useful in the context of the invention are lauric acid monoglyceride, coconut monoglyceride, palmitic acid monoglyceride, stearic acid monoglyceride, isostearic acid monoglyceride,

C f (- * f _rr , ^r c · rr 'rf ^r Γ ¾)

Oleic acid monoglyceride and tallow monoglyceride, as well as adducts thereof with from 5 to 50 and more preferably from 20 to 30 moles of ethylene oxide. The use of monoglycerides or technical mixtures of monoglycerides / diglycerides with a predominant proportion of monoglycerides of the formula IV in which COR ^{5 is a} linear acyl radical having 16 to 18 carbon atoms is preferred.

Other suitable emulsifiers are, for example, nonionic surfactants from one of the following groups:

(I) Addition products of 2 to 30 moles of ethylene oxide and / or 0 to 5 moles of propylene oxide to linear fatty alcohols having 8 to 22 carbon atoms;

(II) Glycerol monoesters and glycerine diesters and sorbitan monoesters and sorbitan diesters of saturated and unsaturated fatty acids having 6 to 22 carbon atoms and their ethylene oxide addition products;

(III) Alkyl monoglycosides and C 8 -C 22 alkyl oligoglycosides and their ethoxylated analogs;

(IV) Addition products of 15 to 60 moles of ethylene oxide on castor oil and / or hardened castor oil;

(V) Polyol esters and especially polyglycerol esters such as polyglycerol polyyricinoleate or polyglycerol poly-12-hydroxystearate. Mixtures of compounds of several of these classes of substances are also suitable;

(VI) Addition products of from 2 to 15 moles of ethylene oxide on castor oil and / or hardened castor oil;

(VII) Partial esters based on linear, branched, unsaturated or saturated C12 / 22-fatty acids, ricinoleic acid and 12-hydroxystearic acid and glycerol, polyglycerol, pentaerythritol, dipentaerythritol, sugar alcohols (eg sorbitol) as well as polyglucosides such as cellulose);

(VIII) Lanolin alcohols;

(IX) Polyalkylene glycols.

Ethylene oxide and / or propylene oxide addition products on glycerine monoesters and glycerine diesters as well as sorbitan monoesters and sorbitan fatty acid esters or on castor oil are known, commercially available products. These are mixtures of homologues whose mean degree of alkoxylation corresponds

- the ratio of the amounts of substance amounts of ethylene oxide and / or propylene oxide and the substrate with which the addition reaction was carried out.

Especially preferred is the use of Group III emulsifiers, i.e. alkyl glycosides. Alkyloligoglycosides and alkenyloligoglycosides are known nonionic surfactants which correspond to the general formula V

R 'O- [G] _P (V) wherein R ^{6 is an} alkyl and / or alkenyl radical having 4 to 22 carbon atoms, G is a sugar radical having 5 or 6 carbon atoms, and is a number from 1 to 10. obtained by appropriate preparative organic chemistry procedure. For a large-scale work, reference is made to Biermann et al. In Starch / Stärke 45, 281 (1993), B. Salka in Cosm. Toil. 108, 89 (1993) as well as J. Kahre et al. In SOFWJournal, Book 8, 598 (1995).

The alkyloligoglycosides and / or alkenyloligoglycosides may be derived from aldoses or ketoses having 5 or 6 carbon atoms, more preferably glucose. Thus preferred alkyloligoglycosides and / or alkenyloligoglycosides are alkyloligoglucosides and / or alkenyloligoglucosides. The index number p in the general formula V is the degree of oligomerization (DP), ie the distribution of monoglycosides and oligoglycosides and is a number from 0 to 10. While p in a given compound must always be an integer and here may have values in particular from 1 to 6, the p value for a particular alkyloligoglycoside is an analytically calculated calculated value, which is usually a fraction. Preference is given to using alkyloligoglycosides and / or alkenyloligoglycosides with a mean degree of oligomerization of p from 1.1 to 3.0. From an application point of view, alkyloligoglycosides and / or alkenyloligoglycosides whose oligomerization degree is less than 1.7 and most preferably in the range of 1.2 to 1.4 are preferred. The alkyl or alkenyl radical R ⁶ can be derived from primary alcohols having 4 to 11, more preferably 8 to 10, carbon atoms. Typical examples are butanol, capro alcohol, caprylalcohol, caprinal alcohol and undecyl alcohol as well as technical mixtures thereof, such as are obtained, for example, in the hydrogenation of industrial fatty acid methyl esters or during the hydrogenation of aldehydes from Roelen oxosynthesis. Preferred are C8-C10 alkyloligoglucosides (DP = 1 to 3) which are formed as the front fraction at rr

-11 by distillation separation of the technical C8-C-i-coconut alcohol and which may be contaminated with less than 6 wt. C12-alcohol and alkyl oligo-glucosides based on C8 / n-oxoalcohol (DP = 1 to 3). The alkyl or alkenyl radical R ⁶ can furthermore be derived from primary alcohols having 12 to 22, preferably 12 to 14, carbon atoms. Typical examples are lauryl alcohol, myristyl alcohol, cetyl alcohol, palmoleyl alcohol, stearyl alcohol, isostearyl alcohol, oleyl alcohol, elaidyl alcohol, petrozelinyl alcohol, arachyl alcohol, gadoleyl alcohol, behenyl alcohol, erucyl alcohol, brazidyl alcohol as well as the technical mixtures thereof described above. Preferred are C-12/14-coconut alcohol-based alkyl oligoglucosides having a DP of from 1 to 3. When emulsifiers of the formula V are used as emulsifiers, it may be advantageous to use small amounts of polyhydroxycarboxylic acids, for example citric acid, as formulation auxiliaries. Typically, the polyhydroxy acids are then used in amounts of from 0.1 to 3.0% by weight, more preferably in amounts of from 0.1 to 1.0% by weight.

Preferred microemulsions used according to the invention contain from 20 to 90 wt. % water, more preferably from 30 to 80 wt. % and most preferably from 30 to 60 wt. The residue up to 100 wt. it comprises the oil phase as well as emulsifiers and optionally other auxiliaries and additives. The oil phase itself is preferably present in amounts of from 10 to 80 wt%, more preferably from 20 to 70 wt%. % and most preferably from 25 to 55 wt. The oil phase comprises only component a) or component b) or a mixture of these components. Particularly preferred is the use of such emulsions which contain an oil phase and an aqueous phase in a ratio of 1: 1. The emulsifiers or emulsifier systems are preferably present in amounts of from 10 to 50% by weight, more preferably in amounts of from 15 to 45% by weight. % and most preferably in amounts of from 20 to 40 wt.

The microemulsions described can be used according to the invention in fermentation processes of all types. It is possible to use all process arrangements known to the person skilled in the art, for example in batches, semi-continuous as well as continuous fermentation. All fermentation systems known to those skilled in the art are also applicable. For details, see Crueger, pages 50 to 70. The use of microemulsions is not even limited to certain microorganisms, but emulsions can be used to

The production or conversion of all compounds by fermentation known to those skilled in the art. In addition to conventional fermentation processes which are mainly used for the synthesis of antibiotics (cf. Crueger, pages 197 to 242), the emulsions described are also suitable for use in microbial transformation ("bioconversion"), for example for transformation of stereides and sterins, antibiotics and pesticides or vitamins (cf. Crueger, pages 254-273). However, it is preferred to use in the fermentation process for the production of antibiotics, for example chefalosporine, tylosin or erythromycin.

As a rule, the microemulsions are metered in an appropriate manner into an aqueous fermentation mixture which contains microorganisms as well as a nitrogen source and trace elements and optionally other auxiliaries, in particular antifoams. Possible sources of nitrogen are, for example: peptone, yeast and malt extract, steep water, urea or lecithins. The trace elements may be present in the form of inorganic salts, for example sodium or potassium nitrate, ammonium nitrate, ammonium sulfate, iron sulfate, and the like. It may also be advantageous if the microemulsions themselves contain other additives, such as antifoams or nitrogen sources.

DETAILED DESCRIPTION OF THE INVENTION

Various microemulsions were produced by mixing the starting materials. The compositions are shown in Table 1. Droplet size was measured using a Malvern Mastersitzer 2000. Emulsions are suitable, for example, as separate nutrient sources in the fermentation process and can be directly added to the aqueous fermentation broth.

Table 1a

% wt. % wt. % wt. % wt. metylolejan 32.44 methyl laurate 30.95 metylpelargonan 29.61 rapeseed fatty acid methyl ester oil 32.35

r .- 13-

Water 34.27 32,04 30.24 34.18 alkyl glycoside 25.22 32.55 30.95 25.3 glycerínolejan 7.91 6.55 7.62 7.84 citric acid 0.25 0.24 0.24 0.24 appearance limpid limpid limpid limpid drop size <80 nm <80 nm <80 nm <80 nm

Claims (9)

PATENT CLAIMS Use of oil-in-water emulsions in a fermentation process comprising at least water, emulsifiers as well as an oil phase comprising one or more compounds selected from the group consisting of: (a) alkyl esters of fatty acids; and / or b) triglycerides of vegetable origin, the emulsions having a droplet size in the range of 1 to 100 nm. The use according to claim 1, wherein component a) is a fatty acid methyl ester. Use according to claim 1 or 2, wherein the emulsions have a mean droplet size in the range from 10 to 80 nm, more preferably from 10 to 50 nm. Use according to claims 1 to 3, wherein the emulsions contain water in amounts of from 20 to 90% by weight, more preferably from 30 to 80% by weight. % and most preferably from 30 to 60 wt. Use according to claims 1 to 4, wherein the emulsions comprise the oil phase in amounts of from 10 to 80% by weight, more preferably from 20 to 70% by weight. % and most preferably from 25 to 55 wt. Use according to claims 1 to 5, wherein the emulsions comprise a fatty acid methyl ester of the formula I in the oil phase R ¹ -COO-R ² (I) wherein R ¹ is an alkyl radical of 6 to 22 carbon atoms and R ² is a methyl radical. The use according to claims 1 to 6, wherein the emulsions comprise methyl oleate, methyl palmitate, methyl stearate and / or methylpelargonate in the oil phase. Use according to claims 1 to 7, wherein the emulsions comprise coconut oil, sunflower oil and / or rapeseed oil in the oil phase. The use according to claims 1 to 8, wherein the emulsions comprise alkyloligoglycosides as an emulsifier. Use according to claims 1 to 9, wherein the emulsions comprise emulsifiers in amounts of from 10 to 50% by weight, more preferably in amounts of from 15 to 40% by weight. % and most preferably in amounts of from 20 to 35 wt.