KR20020012580A - Utilization of microemulsions in fermentation processes - Google Patents

Abstract

The present invention relates to the use of an oil-in-water emulsion in a fermentation process, wherein the emulsion is at least one selected from the group consisting of water, emulsifiers, and a) fatty acid alkyl esters and / or b) triglycerides derived from plants. It contains an oil phase containing, the emulsion has a droplet size of 1 to 100 nm.

Description

UTILIZATION OF MICROEMULSIONS IN FERMENTATION PROCESSES

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

Microbial processes are increasingly used in the synthesis of complex natural products and other organic compounds. Such processes involve the transfer / conversion under anaerobic or aerobic conditions involving microorganisms, in particular bacteria or fungi. Various terms for microbiological processes—although not clearly distinguishable at all times (eg, biotransition, bioconversion, fermentation) —are used by the skilled person. The term "fermentation" is used herein for processes in which microorganisms, preferably bacteria, are used for the conversion or synthesis of chemical compounds.

An important factor in the generation and optimization of the fermentation process is in particular the reaction medium in which microbial transformation takes place. The reaction medium, which is usually an aqueous solution or an aqueous dispersion, first of all influences the yield and efficiency of the process. Microorganisms require carbon, nitrogen and certain trace elements in the combined form, such as calcium, iron, phosphorus or zinc, as nutrients that will enable successful metabolism to the desired product. In addition, the temperature and pH should be kept constant in a specific, generally narrow range. More specifically, W. Crueger / A. Crueger, Biotechnologie-Lehrbuch der angewandten Mikrobioliogie , 2nd edition, 1984, R. Ollbourg Verlag. In Chapter 5 of this document, in particular, the basics of fermentation are discussed. Thus, the above references also strictly belong to the description of the present invention. In addition to high energy sugars and derivatives thereof, natural fats and derivatives thereof such as glycerol, glycerides, fatty acids or fatty acid esters are further used as nutrients for microorganisms in many processes. Of course, the culture medium may not contain any additives that may adversely affect the metabolism of microorganisms.

For example, DE 37 38 812 A1 discloses a microbial process for the preparation of α, ω-dicarboxylic acids in which bacteria of the Candida tropicalis strain convert methyl laurate to the desired carboxylic acid. Described. The conversion is carried out in aqueous medium at pH 6.0 at 30 ° C. In addition to microorganisms, the medium contains glucose as an energy source, ethoxylated sorbitan monooleate as an emulsifier, yeast extract, corn steep liquor and inorganic N and P sources. Methyl laurate is then added to the medium. The document makes no mention of the type of emulsion formed in the fermentor or in which methyllaurate is added to the fermentation broth. EP 0 535 939 A1 discloses a process for producing ω-9-unsaturated fatty acids in which suitable microorganisms produce the desired polyunsaturated fatty acids in an aqueous culture medium in the presence of sugars and inorganic or organic nitrogen sources as energy sources, and fatty acid methyl esters. Described.

However, other known processes use only fatty compounds of the type described above as energy sources. Such fatty compounds are particularly economically beneficial as they are generally less expensive than sugars, starches and similar compounds. Park et al. (Park et al., Journal of Fermentation and Bioengineering, Vol. 82, No. 2, 183-186, 1996) reported that the rapeseed oil contained an intake of about 60 g / l of microorganisms of Streptomyces fradiae strains. A fermentation method for the production of tyrosine for use in an aqueous medium present as the sole carbon source is described.

In the fermentation process, the oxygen content in the medium or fermentation broth also plays an important role. In aerobic processes, oxygen serves as the substrate. The important point is whether the transfer of oxygen from the gas phase to the liquid phase containing the microorganisms can occur sufficiently for a particular process. An important parameter is the special exchange surface, which is usually measured indirectly via the oxygen transfer efficiency k _La (see Crueger, Chapter 5, p. 71, cf.). Adjustment of the optimum oxygen injection is typically achieved by stirring the fermentation broth, where oxygen or air is mixed with the liquid, and thus gas exchange takes place at the interface. However, as performed by Park et al., Significant mechanical input of energy by vigorous agitation can destroy part of the culture, reducing the yield of the process. In addition, dead microorganisms are further degraded by themselves, and the culture solution can be toxic through the formed degradation products, making economic production impossible. From the work of Goma and Rols (G.Goma, JLRols, Biotech. Let., Vol. 13, No. 1, pages 7 to 12, 1991), the use of soybean oil in the fermentation process for the preparation of antibiotics, oxygen transfer efficiency It is known that this results in an improvement in k _La , which can lead to an overall improvement in process yield for the same energy input (stirring).

At present, the problem to be solved by the present invention is to improve the fermentation process, on the one hand it is possible to use an inexpensive carbon source, and on the other hand it is sufficient for microorganisms without exposure to unacceptable extreme mechanical stress by agitation. To ensure an oxygen supply. A method has been found to minimize the mechanical input of energy in the fermentation process without reducing the yield. Preferably, the yield will increase despite the reduced energy input.

It has been found that the use of special micro-drop oil-in-water (o / w) emulsions can solve the above mentioned problems.

In a first embodiment, the invention relates to the use of an o / w emulsion in a fermentation process, said emulsion containing at least water, an emulsifier and an oil phase, wherein the oil phase is at least one compound from the group consisting of Contains:

a) fatty acid alkyl esters and / or

b) triglycerides derived from plants

The emulsion has a droplet size of 1 to 100 nm:

The emulsions according to the invention are particularly characterized by their droplet fineness. They are visually uniform, optically clear, often low viscosity, thermodynamic, of at least two immiscible liquids, and at least one nonionic surfactant or at least one ionic surfactant containing preferably two hydrophobic moieties. It is a so-called microemulsion that is defined as a stable mixture. Formation of the microemulsion involves the situation where the oil / water interface tension is close to the value zero. In addition to one or more nonionic surfactants, other co-surfactants are generally added to complete this particular type of emulsion [Ref. To "Introduction to Colloid and Surface Chemistry", D.J. Shaw, Butterworth, 1992, pp. 269-270]. The droplet size of the emulsions used according to the invention is in the range from 1 to 100 nm, preferably in the range from 10 to 80 nm, more preferably in the range from 10 to 30 nm. The fineness of the oil droplets results in a large surface between the oil and the water phases, providing a quick contact between the microorganisms present in the oil and aqueous phases containing the nutrient substances. The large surface also simplifies the exchange of gases, in particular oxygen and carbon dioxide. Moreover, the viscosity of the emulsion and thus the entire fermentation medium is reduced. As a result, the stirring speed of the fermentation medium can be significantly reduced, so that the yield of the fermentation process can be increased.

According to the invention, microemulsions are added to an aqueous fermentation medium containing microorganisms and optionally containing other auxiliaries and additives. The details of this process, more specifically the rate and amount of addition of the emulsion, are determined by the chosen microbial strain and fermentation process and can be adapted to the particular situation by the skilled person.

In addition to water, the microemulsions contain an oil phase containing compounds from the group of a) fatty acid alkyl esters and b) natural plant oils and derivatives thereof. Groups a) and b) are hydrophobic, water insoluble or substantially capable of serving as nutrients for the bacteria used in the fermentation process, ie energy sources, but may also be starting materials (substrates) for products obtained by bioconversion. It is a compound which is water insoluble.

Suitable methyl esters of group a) are especially derived from saturated, unsaturated, linear or branched fatty acids having 7 to 23 carbon atoms. In other words, it is a compound of formula

R ¹ -COO-R ²

[ _Wherein , R ¹ is a C _6-22 alkyl group and R ² is a C _1-4 alkyl group]. Methyl and ethyl groups are preferred. Methyl esters are particularly preferred as component a). Esters or methyl esters of formula I can be obtained by known methods, for example by transesterification of triglycerides with methanol followed by distillation. Suitable fatty acids include caproic acid, heptanoic acid, caprylic acid, pelagonic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, Nonadecanoic acid, arachic acid and behenic acid. Unsaturated representatives are, for example, lauroleic acid, myristoleic acid, palmitoleic acid, petroleic acid, oleic acid, oleic acid, ricinoleic acid, linoleic acid, linoleic acid, linolenic acid, gadoleic acid, arachidonic acid and Erucic acid. Mixtures of methyl esters of these acids are also suitable. Particular preference is given to using microemulsions containing methyl esters from the group consisting of methyl oleate, methyl palmitate, methyl stearate and / or methyl pelargonate. However, for example, obtainable 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, newborn and aging plants) Methyl esters based on natural fatty acid mixtures may also be used.

Suitable group b) compounds are plant-derived natural oils. These are essentially triglyceride mixtures in which glycerol is fully esterified with fatty acids which are always relatively long chains. Particularly suitable vegetable oils are selected from the group consisting 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, on average (based on fatty acids), contains 54% by weight of oleic acid, 24% by weight of linoleic acid, 1% by weight of linolenic acid, 1% by weight of arachic acid, 10% by weight of palmitic acid and 4% by weight of stearic acid. It has a melting point of 2-3 ℃. Flaxseed oil typically contains 5% by weight palmitic acid, 4% by weight stearic acid, 22% by weight oleic acid, 17% by weight linoleic acid and 52% by weight linolenic acid and has an iodine value of 155-205, It has a saponification value of 188 to 196 and a melting point of about -20 ° C. Coconut oil contains about 0.2 to 1 wt% hexanoic acid, 5 to 8 wt% octanoic acid, 6 to 9 wt% decanoic acid, 45 to 51 wt% lauric acid, 16 to 19 wt% myristic acid , 9-11 wt% palmitic acid, 2-3 wt% stearic acid, less than 0.5 wt% behenic acid, 8-10 wt% oleic acid and up to 1 wt% linoleic acid as fatty acid components. It has an iodine value of 7.5 to 9.5, a saponification value of 0.88 to 0.90 and a melting point of 20 to 23 ° C. Olive oil contains mainly oleic acid. See also Lebensmittelchem. Gerichtl. Chem., 39, 112-114, 1985). Palm oil contains about 2% by weight of myristic acid, 42% by weight of palmitic acid, 5% by weight of stearic acid, 41% by weight of oleic acid, and 10% by weight of linoleic acid as fatty acid components. Palm kernel oil typically has the following composition in relation to its fatty acid spectrum: 9% by weight of capro / capryl / capric acid, 50% by weight of lauric acid, 15% by weight of myristic acid, 7% by weight of palmitic acid , 2 wt% stearic acid, 15 wt% oleic acid and 1 wt% linoleic acid. Rapeseed oil is typically about 48% by weight erucic acid, 15% by weight oleic acid, 14% by weight linoleic acid, 8% by weight linolenic acid, 5% by weight eicosane acid, 3% by weight palmitic acid, 2% by weight % Of hexadecanoic acid and 1% by weight of docosadienoic acid are contained as fatty acid components. Rapeseed oil from young plants is rich in unsaturated components. Typical fatty acid components here are 0.5% by weight erucic acid, 63% by weight oleic acid, 20% by weight linoleic acid, 9% by weight linolenic acid, 1% by weight eicosane acid, 4% by weight palmitic acid, 2% by weight % Hexadecenoic acid and 1% docosadienoic acid. 80-85% by weight of castor oil consists of glycerides of ricinoleic acid. Castor oil also contains about 7% by weight of glycerides of oleic acid, 3% by weight of glycerides of linoleic acid and about 2% by weight of glycerides of palmitic and stearic acid. 55-65% by weight of total fatty acids in soybean oil are polyunsaturated acids, more specifically linoleic and linolenic acid. Similarly for sunflower oil, its typical fatty acid spectrum—total fatty acid basis—is as follows: about 1% by weight of myristic acid, 3 to 10% by weight of palmitic acid, 14 to 65% by weight of oleic acid and 20 To 75% by weight of linoleic acid.

All of the above value data for the fatty acid component of triglycerides depends on the quality of the raw material and can therefore vary. Particular preference is given to microemulsions containing b) a nutrient group selected from coconut oil, sunflower oil and / or rapeseed oil.

Important components of the microemulsion used according to the invention are the emulsifiers and emulsifier systems used. Nonionic emulsifiers, more specifically ethoxylated fatty alcohols and fatty acids, are preferably used as emulsifiers.

Fatty alcohol ethoxylates in the teachings according to the invention correspond to formula II:

R ³ -O- (CH ₂ CH ₂ O) _n -H

[Wherein, R ³ is a linear, branched, saturated or unsaturated alkyl group having 6 to 24 carbon atoms, n is a number from 1 to 50]. Particular preference is given to compounds of the formula II wherein n is 1 to 35, more particularly 1 to 15. Another particularly preferred compound of Formula (II) is one in which R ³ is an alkyl group having 16 to 22 carbon atoms.

Compounds of formula (II) are obtained in a known manner by reaction of fatty alcohols with ethylene oxide under pressure in the presence of an acidic or basic catalyst. Typical examples are caproic alcohol, capryl alcohol, 2-ethyl hexyl alcohol, capric alcohol, lauryl alcohol, isotridecyl alcohol, myristyl alcohol, cetyl alcohol, palmitole alcohol, stearyl alcohol, isostearyl alcohol , Oleyl alcohol, erylidyl alcohol, petroselinyl alcohol, linolyl alcohol, linoleyl alcohol, elaeostearyl alcohol, arachyl alcohol, gadoleyl alcohol, behenyl alcohol, erucyl alcohol and brassidyl alcohol, and examples Aldehydes from the oxosynthesis of Roelen or their industrial mixtures obtained as monomer fractions in high pressure hydrogenation of oil and fat based industrial methyl esters and in dimerization of unsaturated fatty alcohols. Industrial fatty alcohols having 12 to 18 carbon atoms are preferred, such as coconut oil, palm oil, palm kernel oil or resin fatty alcohols.

Fatty acid ethoxylates, which may also be used as emulsifiers or emulsifier components, preferably correspond to formula III:

R ⁴ CO ₂ (CH ₂ CH ₂ O) _m H

[Wherein, R ⁴ is a linear or branched alkyl group having 12 to 22 carbon atoms, and m is 5 to 50, preferably 15 to 35]. Typical examples include 20 to 30 moles of ethylene oxide such as lauric acid, isotridecanoic acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, isostearic acid, oleic acid, elideic acid, and petroleum acid. Obtained by linoleic acid, linolenic acid, elaostearic acid, arachic acid, gadoleic acid, behenic acid and erucic acid, and, for example, by pressurized hydrolysis of natural fats and oils or by reduction of aldehydes from the oxosynthesis of Roelen Product added to their industrial mixture. Preferably a product is used in which 20 to 30 moles of ethylene oxide are added to the C _16-18 fatty acid.

Partial glycerides which can also be used as emulsifiers preferably correspond to formula IV:

[Wherein, COR ⁵ is a linear or branched acyl group having 12 to 22 carbon atoms, and x, y and z together represent 0 or 1 to 50, preferably 15 to 35]. Typical examples of partial glycerides suitable for the purposes of the present invention include lauric acid monoglycerides, coconut fatty acid monoglycerides, palmitic acid monoglycerides, stearic acid monoglycerides, isostearic acid monoglycerides, oleic acid monoglycerides, and resin fatty acid monoglycerides. And addition products thereof with 5 to 50, preferably 20 to 30 moles of ethylene oxide. Preferably, the monoglyceride, or COR ⁵ is the industrially mono / diglyceride mixture containing mainly a lot of linear acyl monoglyceride IV with a carbon number of 16-18 is used.

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

(I) the product of adding 2 to 30 moles of ethylene oxide and / or 0 to 5 moles of propylene oxide onto a linear fatty alcohol having 8 to 22 carbon atoms;

(II) glycerol monoesters and diesters of saturated and unsaturated fatty acids having 6 to 22 carbon atoms, and sorbitan monoesters and diesters, and their ethylene oxide adducts;

(III) alkyl mono- and oligoglycosides having 8 to 22 carbon atoms of alkyl groups and their ethoxylated analogs;

(IV) the product of adding 15 to 60 moles of ethylene oxide onto castor oil and / or hydrogenated castor oil;

(V) polyol esters, in particular polyglycerol esters, such as polyglycerol polylysinoleate or polyglycerol poly-12-hydroxystearate. Mixtures of compounds from several of these classes are also suitable:

(VI) the product of adding 2 to 15 moles of ethylene oxide onto castor oil and / or hydrogenated castor oil;

(VII) linear, branched, unsaturated or saturated C _6-22 fatty acids, ricinoleic acid and 12-hydroxystearic acid with glycerol, polyglycerol, pentaerythritol, dipentaerythritol, sugar alcohols (e.g. sorbitol ) And partial esters based on polyglycosides (eg cellulose);

(VIII) wool wax alcohols;

(XI) polyalkylene glycols.

The product of the addition of ethylene oxide and / or propylene oxide onto glycerol mono- and diesters of fatty acids and sorbitan mono- and diesters or castor oil is a known commercial product. These are homogeneous mixtures in which the average alkoxylation degree corresponds to the ratio between the amount of ethylene oxide and / or propylene oxide and the base mass at which the addition reaction takes place.

Particular preference is given to using emulsifiers of group (III), ie alkyl glycosides. Alkyl and alkenyl oligoglycosides are known as nonionic surfactants corresponding to formula (V):

R ⁶ O- [G] _p

[Wherein R ⁶ is an alkyl and / or alkenyl radical having 4 to 22 carbon atoms, G is a sugar unit having 5 or 6 carbon atoms and p is a number of 1 to 10]. These can be obtained by methods relating to preparative organic chemistry. Biermann et al., Cosm. In Starch / Staerke 45, 281 (1993). Toil. B. Salka in 108, 89 (1993), and J. Kahre et al. In SOEFW-Journal, 8, 598 (1995), may be cited as representative documents of a wide range of literature available on this subject.

Alkyl and / or alkenyl oligoglycosides may be derived from aldose or ketose, preferably glucose, having 5 or 6 carbon atoms. Thus, preferred alkyl and / or alkenyl oligoglycosides are alkyl and / or alkenyl oligoglycosides. The index p in formula V represents the degree of oligomerization (DP), ie the distribution of mono- and oligoglycosides, and is a number from 1 to 10. P in a given compound must always be an integer, and in particular can represent 1 to 6, but the value p for a particular alkyl oligoglycoside is an analytically determined calculation which is generally a fraction. Preferably alkyl and / or alkenyl oligoglycosides having an average degree of oligomerization p of from 1.1 to 3.0 are used. Alkyl and / or alkenyl oligoglycosides having an oligomerization degree of less than 1.7, more particularly 1.2 to 1.4, are preferred in view of the present application. The alkyl or alkenyl radicals R ⁶ can be derived from primary alcohols having 4 to 11 carbon atoms, preferably 8 to 10 carbon atoms. Typical examples are butanol, caproic alcohol, caprylic alcohol, capric alcohol and undecyl alcohol, and their industrial mixtures obtained, for example, from hydrogenation of industrial fatty acid methyl esters or hydrogenation of aldehydes from the oxosynthesis of Roelen. to be. An alkyl glycoside having a chain length of C ₈ to C ₁₀ which is obtained by distillation as the first run of the separation of industrial C _8-18 coconut oil fatty alcohols and may contain less than 6% by weight of C ₁₂ alcohols as impurities. (DP = 1 to 3), and alkyl oligoglycosides based on industrial C _9/11 oxoalcohol (DP = 1 to 3) are preferred. In addition, alkyl or alkenyl radicals R ⁶ may be derived from primary alcohols having 12 to 22 carbon atoms, preferably 12 to 14 carbon atoms. Typical examples include lauryl alcohol, myristyl alcohol, cetyl alcohol, palmitole alcohol, stearyl alcohol, isostearyl alcohol, oleyl alcohol, ellidil alcohol, petrolininyl alcohol, aralkyl alcohol, gadoleyl alcohol, Behenyl alcohol, erucyl alcohol, brassidyl alcohol and their industrial mixtures obtainable as described above. Preference is given to alkyl oligoglucosides having 1 to 3 DPs based on hydrogenated C _{12/14 cocoalcohols} . If alkyl glycosides of the formula V are used as emulsifiers, it may be advantageous to use small amounts of polyhydroxycarboxylic acids, preferably citric acid, with them as formulation aids. In this case, the polyhydroxy acid is used in an amount of 0.1 to 3.0% by weight, preferably 0.1 to 1.0% by weight.

The microemulsions used according to the invention preferably contain 20 to 90% by weight of water, more preferably 30 to 80% by weight and most preferably 30 to 60% by weight of water. Matching 100% by weight is an oil phase and an emulsifier, and optionally other auxiliaries and additives. The oily phase itself is present in an amount of 10 to 80 weights, more preferably 20 to 70 weight percent, most preferably 25 to 55 weights. In a preferred embodiment, the oil phase contains solely component a) or b) or a mixture of components. Particular preference is given to using emulsions containing oil phase and water phase in a weight ratio of 1: 1. The emulsifier or emulsifier system is preferably present in an amount of 10 to 50% by weight, more preferably 15 to 45% by weight and most preferably 20 to 40% by weight.

According to the invention, the described microemulsions can be used in all kinds of fermentation processes. Any of various processes known to the skilled person can be used, such as batch or fed batches and continuous fermentation. In addition, any fermenter system known to the skilled person can be used. For details see [Crueger, pp. 50-70]. Furthermore, the use of microemulsions is not limited to specific microorganisms. In contrast, emulsions can be used for the preparation and conversion of any compound known to the skilled person through fermentation. In addition to conventional fermentation processes (cf. Crueger, pp. 197-242), which are mainly used for antibiotic synthesis, the described emulsions can also be used for microbial transformation (bioconversion), for example, steroids and sterols, antibiotics and pesticides, or vitamins. It is also suitable for use in manufacture (cf. Crueger, pp. 254-273). However, the described emulsions are preferably used in fermentation processes for the preparation of antibiotics, for example cephalosporins, tyrosine or erythromycin.

In general, microemulsions are suitably added to aqueous fermentation broths containing microorganisms and nitrogen sources and trace elements and optionally other auxiliaries, in particular antifoaming agents. Suitable nitrogen sources are, for example, peptone, yeast or malt extracts, corn steep liquor, urea or lecithin. Trace elements can be present in the form of inorganic salts such as sodium or potassium nitrate, ammonium nitrate, ammonium sulfate, iron sulfate and the like. It may also be advantageous to add other additives such as antifoams or nitrogen sources to the microemulsion itself.

Various microemulsions were prepared by mixing the starting materials. Their composition is shown in Table 1 below. Droplet size was measured with a Malvern Mastersizer 2000. The emulsion is suitable, for example, as a sole nutrient for the fermentation process and can be added directly to the aqueous fermentation broth.

weight% weight% weight% weight% Methyl oleate 32.44 Methyl laurate 30.95 Methyl pelargonate 29.61 Rapeseed oil fatty acid methyl ester 32.35 water 34.27 32.04 30.24 34.18 Alkyl glycosides 25.22 31.55 30.95 25.3 Glycerol Oleate 7.91 6.55 7.62 7.84 Citric acid 0.25 0.24 0.24 0.24 Exterior Sunny Sunny Sunny Sunny Droplet size <80 nm <80 nm <80 nm <80 nm

Claims (10)

Use in a fermentation process of an oil-in-water emulsion containing an oil phase containing at least water, an emulsifier, and at least one compound selected from the group characterized in that the emulsion has a droplet size of 1 to 100 nm: a) fatty acid alkyl esters and / or b) triglycerides derived from plants. Use according to claim 1, characterized in that the oil phase contains a fatty acid methyl ester as component a). Use according to claim 1 or 2, characterized in that emulsions with an average droplet size of 10 to 80 nm, preferably 10 to 50 nm are used. The emulsion according to any one of claims 1 to 3, wherein an emulsion containing water in an amount of 20 to 90% by weight, preferably 30 to 80% by weight and more preferably 30 to 60% by weight is used. Characteristic uses. The emulsion according to any one of claims 1 to 4, wherein an emulsion containing an oil phase is used in an amount of 10 to 80% by weight, preferably 20 to 70% by weight, more preferably 25 to 55% by weight. Use, characterized in that. Use according to any one of claims 1 to 5, characterized in that an emulsion is used which contains a fatty acid methyl ester of the general formula (I) in an oil phase: [Formula I] R ¹ -COO-R ² [ _Wherein , R ¹ is a C _6-22 alkyl group and R ² is a methyl group]. Use according to any one of claims 1 to 6, characterized in that an emulsion containing methyl oleate, methyl palmitate, methyl stearate and / or methyl pelargonate in the oil phase is used. Use according to any one of claims 1 to 7, characterized in that an emulsion containing coconut oil, sunflower oil and / or rapeseed oil in an oil phase is used. The use according to any one of claims 1 to 8, characterized in that an emulsion containing an alkyl oligoglycoside as an emulsifier is used. Use of an emulsion containing an emulsifier according to any one of the preceding claims in an amount of 10 to 50% by weight, preferably 15 to 40% by weight, more preferably 20 to 35% by weight. Characteristic uses.