FI63056B - FLYTANDE TVAETTMEDELSBLANDNING SOM SAERSKILT LAEMPAR SIG FOER DISKNING - Google Patents

Abstract

of the Invention An aqueous liquid detergent composition especially adapted for dishwashing, comprising 5-60% by weight of an organic synthetic surfactant system of at least two surfactants, and 5-50% by weight of a citrus juice, said organic synthetic surfactant system consisting of1) from about 30-90 parts by weight of the surfactant system of a Ca-sensitive first surfactant selected from the group consisting Water-soluble C8-16 alkyl benzene sulphonates; alkane sulphonates having 8-20 car-bon atoms; olefin sulphonates having from 8-20 carbon atoms; di-C8-20-alkyl sulpho-succinates; di-C6-12-alkyl phenol sulphosuccinates; primary and secondary alkyl suphates having 8-20 carbon atoms; C8-20 alkyl polyethoxy sulphates having 1-25 ethoxy groups and mixtures thereof, and2) from about 70-10 parts by weight of said system of a less Ca-sensitive second surfactant selected from the group consisting of water-soluble nonionic condensation products obtained by condensing from 5-30 moles of an alkylene oxide, preferably ethylene or propylene oxide with one mole of an organic hydrophobic compound, aliphatic or alkyl aromatic in nature, having 8 to 24 carbon atoms and at least one reactive hydrogen atom, particularly a reactive hydroxyl, amino, amido or carboxyl group; C8-20-alkylsulphobetaines; amines oxides containing one long chain alkyl moiety of from 10-28 carbon atoms and two moieties which can be either alkyl radicals or hydroxyalkyl radicals having from 1-4 carbon atoms; C8-20 alkyl-polyethoxy sulphates having from 1-25 ethoxy groups, and mixtures thereof, said surfactants of group (1) and the ion-active surfactants of group (2) being present in the form of their alkalimetal salts, ammonium salts, or mixtures thereof. The composition is an effective liquid dishwashing composition with improved cleaning performance on difficult soils.

Description

Ε3? * 1 ΓβΊ mviCONDUCT PUBLICATION. , nc, l J (11) UTLÄGGININCSSKRIFT 6 3 0 5 6 (¢ 45) Patent granted 11 0-1 1933 (51) Kv.lk.3 / lnt.CI.3 C 11 D 1/831 FINLAND —FINLAND (21) Pwnttttakmu »-Pmnttn» 6thanks 783879 (22) HUamlipiivi - An «öknkipd» j 18.12.78 (23) AlkupUvt — GlltiftMCadif 18.12.78 (41) Tullut JulklMlcsl - MMt offaMlig 23.06.79 ]. kwd + muUun, * m.- ratant- och regitterstyrelten 7 AmMuut utiagd odi utUkrtftM p «bMc« nd 31.12.32 (32) (33) (31) Pnr * · *** tcuellwM · —BegW priorityM 22.12 -77

England-England (GB) 53 ^ 72/77 (71) Unilever N.V., Burgemeester s’Jacobplein 1, Rotterdam, Holland-Holland (NL) (72) John Thomas Reilly, Wirral, Merseyside, Roy Baxter Hobson, Clwyd,

North Wales, Gordon John Abdey, Wirral, Merseyside, England-England (GB) (7 * 0 Leitzinger Ltd (5 * 0 Aqueous detergent mixture particularly suitable for dishwashing -

The present invention relates to an aqueous detergent composition which is particularly suitable for dishwashing and which contains 5 to 60% by weight of an organic synthetic surfactant system of at least two different surfactants and 5 to 50% by weight of citrus juice. .

Liquid detergent compositions containing lemon juice are known in the art. U.S. Patent 3,650,968 discloses cleaning compositions for removing fish odors comprising 30 to 80% by weight of detergent and 0.1 to 15% by weight of citrus juice. However, these liquid detergent compositions have very poor dishwashing properties and therefore cannot be satisfactorily used for washing dishes, glasses, kitchen utensils, cutlery and the like.

It is an object of the present invention to provide an effective liquid dishwashing detergent composition even for heavy stains.

In particular, in order to remove severe stains from containers,

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2 63056 parasites and pans and other kitchen utensils.

By "severe stains" is meant herein the difficult steps of dishwashing, for example, evaporated proteins and starch stains.

These and other objects of the invention, which will become apparent below, are achieved by combining an organic synthetic surfactant system of at least two surfactants as defined below with citrus juice in an amount of 5% by weight and above of the total mixture. Any citrus fruit juice belonging to the general class of citrus fruits may be used, for example: Sweet oranges (citrus sinensis); sour or bitter oranges (citrus auranticum); mandarins (citrus reticulata); grapefruit (citrus paradisi); pomelos (citrus grandis); lemons (citrus limon); limes (citrus aurantifolia); lemons (citrus medica); papeda (citrus hystrix) and trifoliate oranges (citrus trifoliata), although lemon juice is preferred in this invention due to its well-established and accepted market position.

Unless otherwise indicated, the percentages of fruit juices given in this specification refer to fruit juices of individual strength. The term "single strength" is used herein to mean the average strength of fruit juice squeezed from the fruit. If fortified juices have been used, they are shown separately by indicating the strength factor, for example "4 x concentrate".

For this reason, the compositions of the invention are particularly intended for general use in conventional dishwashing and can be used in concentrated aqueous form or in conventional very dilute dishwashing, providing good cleaning performance combined with consumer-accepted foam height and foam stability.

Accordingly, the liquid detergent composition of the invention comprises about 5-60% by weight of an organic synthetic surfactant system of at least two surfactants as defined below and at least 5% by weight of citrus juice.

3 63056

The composition of the invention is characterized in that the organic synthetic surfactant system comprises: 1) about 30 to 90 parts by weight of the weight of the system of a Ca-sensitive first surfactant selected from the group consisting of water-soluble C 1-6 alkylbenzenesulfonates; alkanesulfonates having 8 to 20 carbon atoms; olefin sulfonates having from 8 to 20 carbon atoms; di-Cg_2Q-alkyylisulfosukki-phosphonates; di-Cg_12-alkyylifenolisulfosukkinaatteja; primary and secondary alkyl sulfates having from 8 to 20 carbon atoms; c8-20 "alkyl polyethoxysulphates" having 1 to 25 ethoxy groups and mixtures thereof; and 2) about 70 to 10 parts by weight of the system of a less Ca-sensitive second surfactant selected from the group consisting of water-soluble nonionic condensation products obtained by condensing 5 to 30 moles of alkylene oxide, preferably ethylene or propylene oxide with one mole of an organic hydrophobic compound which is aliphatic or alkyl aromatic and has 8 to 24 carbon atoms and at least one reactive hydrogen atom, in particular a reactive hydroxyl, amino, amido or carboxyl group; Cg_20-alkylsulfobetaines; amine oxides containing one long chain alkyl moiety having from 10 to 28 carbon atoms and two moieties which may be either alkyl radicals or hydroxyalkyl radicals having from 1 to 4 carbon atoms; C 1-20 alkyl polyethoxy sulfates having 1 to 25 ethoxy groups and mixtures thereof, wherein the surfactants of group (1) and the nonionic surfactants of group (2) are present as their alkali metal salts, ammonium salts, lower alkanolamine salts , as lower alkylamine salts or mixtures thereof.

Examples of non-ionic aqueous condensation products obtained by condensing 5 to 30 moles of alkylene oxide with one mole of an organic hydrophobic compound include: a) Ethylene oxide condensates having an aliphatic straight chain or branched chain, primary or secondary alcohols having more than 8 carbon atoms for example, those obtained from tallow or coconut fatty acids and containing 5 to 20 ethylene oxide groups, as well as branched alcohols condensed with M.

4 with 5 to 20 ethylene oxide groups. 6 3056 b) Condensates obtained with alkylphenols of ethylene oxide, in which the phenols may be mono- or polyalkylated and the total number of carbon atoms in the side chain or chains is 5 to 18. Specific examples are condensates of one mole of nonylphenol. containing 5 to 15 moles of ethylene oxide.

c) Ethylene oxide condensates with fatty acid esters, preferably mono-fatty acid esters of sugar alcohols, sorbitol and monitol.

c) Polyethenoxy esters obtained by reacting ethylene oxide with carboxylic acids, the latter being natural fatty acids or synthetic fatty acids prepared from oxidised paraffin wax having 8 to 20 carbon atoms or alkylbenzoic or naphthenic acids having 5 to 18 carbon atoms.

e) Condensation products of C7-17 alkyl-Co-NHC2H2OH, alkyl-CO-N (C1-4H4OH) 2 type fatty acylalkanolamides with ethylene oxide.

f) condensation products of C 1-18 alkyl, alkenyl and C 1-6 alkylarylamines with ethylene oxide.

A specific example is the condensation product of one mole of oodecylamine with 9 to 12 moles of ethylene oxide.

Specific examples of amine oxides include dimethyldodecylamine oxide, diethyltetraoecylamine oxide, bis- (2-hydroxyethyl) -odecylamine oxide, and dimethyl-2-hydroxydodecylamine oxide.

It has been found that the surfactant system as defined above can be effectively used in combination with citrus juice, especially lemon juice in the above relative amounts, to provide a beneficial combined effect or potency of good washability, good foam behavior and improved removal of difficult stains. especially evaporated or dried proteins or starch stains, wherein the pH range of the system is wide, ranging from virtually 5,63056 acidic to basic pH, for example 4-10. The preferred pH range of the composition of the invention is about 5.5 to 9, especially 6 to 8.5, more preferably 7 to 8.5.

Any combination of the first and second surfactants described above can be used to form an organic synthetic surfactant system in the composition of the invention.

Typical examples of surfactant systems are alkyl benzene sulfonate / alkyl polyethoxysulfate mixtures; alkylbenzenesulfonate / alkyl polyethoxysulfate / nonionic mixtures; alkyl sulfate / alkyl benzene sulfonate / alkyl polyethoxysulfate mixtures and alkyl sulfate / alkyl polyethoxysulfate / amine oxide mixtures.

As explained above, any type of citrus juice can be used in the present invention with a lower limit of 5% by weight, the commonly used juices being lemon, lignet, orange and grapefruit juices. The minimum amount of citrus juice has been taken as 5 <x> sole, because with smaller amounts the effect is insignificant to virtually zero. Although any citrus juice can in any case be used in excess of 5%, it has been found that large amounts are not necessary to achieve the desired result. Moreover, since when the juice content exceeds 10%, the performance improves slowly and the performance improvement drops rapidly, especially at even higher percentages, the use of large amounts of juice is not advantageous due to the high additional costs involved. 50%, preferably 25% can be taken as a suitable upper limit for monohydric citrus juice in the mixture according to the invention, because at concentrations above these percentages the citrus juice does not offer such additional advantages that would compensate for the high cost of the extra citrus juice.

The amount of citrus juice most preferably used in the liquid detergent composition of the invention is from 5 to about 10% by weight.

Accordingly, the invention provides an aqueous liquid detergent composition which is particularly suitable for dishwashing and has improved cleaning performance, especially with respect to heavy stains, wherein the composition comprises from 5 to 60% by weight of an organic synthetic 6 6 3 O 5 6 surfactant system having at least two of the above surfactant, and in addition the mixture contains 5 to 50% by weight of a citrus menu.

Citrus juices are commonly available. They are usually either mono-strength juices or concentrates of different strengths, i.e. from 2x concentrates to 10x concentrates. Lemon juice contains several different categories of chemical compounds including acids, sugars, amino acids, oils and additives. Analytical data on citrus juices can be found in the following literature references: a) "Chemical Constituents of Citrus Fruits", Supp. 2 (1970),

Keffora and Chandler; b) "Biochemistry of Fruits and their Products", Vol. 1 (1970)

Ed. A. C. Hulme.

Each category has several different ingredients, each of which can be individually identified analytically. The main acid in citrus juice is citric acid, which is present in about 5-6% by weight.

It is not known exactly which ingredients present in the citrus juice are responsible for the improvement in cleaning efficiency, but it is believed that the synergistic effect is provided by a combination of one or more ingredients present in the citrus juice and the active system used in the composition of the invention.

Alternatively, in addition to the essential ingredients described above, the liquid detergent composition of the invention may contain other non-essential ingredients. Such alternative materials include additional surfactants defined as the first and second surfactants of the organic synthetic surfactant system; structural salts that can be added to improve the cleaning and stain removal performance of surfactants in the mixture, including, for example, phosphates, polyphosphates, phosphonates, carbonates, polyacetates, and polycarboxylates; foaming agents, for example coconut fatty acid diethanolamide, hydrotropes and solubilizing agents, for example lower alcohols containing 2 to 4 carbon atoms, in particular ethanol, urea, sodium or potassium toluenesulphonate and sodium or potassium xylene sulphonate, which are generally added to improve

, A

7 6305 6 phase stability of mixtures with high concentrations of surfactants; preservatives; fragrances and dyes. In addition, acidic or basic substances for adjusting the pH, as well as cleaning agents, can be included in the detergent composition according to the invention, if desired.

Preferred compositions are those containing 10 to 50% by weight of the organic synthetic surfactant system described above, 5 to 25% by weight of lemon juice and about 15 to 75% by weight of water. Particularly preferred are those with an active detergent content of more than 35% by weight.

The invention is illustrated by the following examples:

Examples I to III

The following mixtures were prepared:

Seos I II III A B

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Sodium dodecylbenzenesulfonate 29.0 29.0 29.0 29.0 29.0

Sodium lauryl (ethoxy) sulphate 14.0 14.0 14.0 14.0 14.0

Sodium citrate - - - - 1,0

Lemon juice (quadruple concentrate) 1.25 2.5 5.0 0.25 0.25

Ethanol 5.5 5.5 5.5 8.0 7.0

Urea 5.5 5.5 5.5 7.5 8.0

Water + preservatives 44.75 43.5 41.0 41.25 40.75

To determine the ease of swelling of mantle stains from substrates after watering, the following half-plate comparison test method was used:

Stained substrates (10 x 10 cm) in the form of square enamel tiles are immersed in solutions of test products (1 liter) at concentrations of 0.15%. At the beginning of the experiment, the temperature of the solution is 45 ° C and it is reheated as the temperature drops to 40 ° C (using a small immersion coil). The tiles are checked for the first signs that the stain in one of them has softened and then, 8 63056, all tiles are removed from the test solution and cleaned (immersion time varies between 5 and 50 minutes). Purification is performed for 30 seconds using a Brillo Swish sponge soaked in a suitable test solution.

Stain and staining method:

The experiments were performed using a fruit pie filling (cherry and apricot) and a mixture of flour and fruit pie filling (1: 4). The pie filling is finely milled by squeezing it through a 240 micron sieve and a fine paste is obtained from the flour / pie filling mixture.

The stain is applied to the substrate by schematic printing using two steps. The stain is then baked in the middle of a large oven (Gallenkainp Oven Model 0V330) for 4 minutes. The temperature should be 250 ° C before the stained substrates are introduced into the oven and should preferably be introduced into the oven at such a rate that the temperature does not fall below 220 ° C.

Results: These are presented in full in Table 1 below.

During the evaluations, the expert panel performed the stain removal as follows: 0 = completely clean; 1 = still slightly stained 2 = fairly stained 3 = markedly stained 4 = no visible cleaning effect.

Results were averages of 8 different outcomes and comparisons for each product. Product A was used as a control.

9

Table 1 63056

Average result Difference (reference sample)

Product in 5 ° hard 26 ° hard 5 ° hard 26 ° hard water in water in water in water I 2.13. 2.93 + 0.81 + 0.81 comparison (A) 2.94 3.74 II 1.25 3.31 + 0.44 + 0.32 comparison (A) 1.69 3.63 III 1.00 2.18 + 0.88 + 0.44 comparison (A) 1.88 2.62 B 0.75 2.62 - 0.12 - 0.37 comparison (A) 0.63 2.25

It is clear from the above results that the lemon juice mixtures I, II and III according to the invention are clearly better than the mixtures A and B outside the invention.

Example IV

The effect of pH was studied by evaluating the performance of the next liquid mixture in a dissolution test.

Mixture

Sodium radododyl benzene sulphonate 29.0%

C1-2 alkyl ether sulfate containing 3 ethylene oxides 14.0%

Lemon juice 10.0%

Ethanol 5.5%

Urea 5.5%

Water + preservatives 36.0%

Comparisons were performed by running standard size (10 x 10 cm) enamel plates stained with apricot pie filling / rovings and heated as in Examples I-III. Half-plate comparisons in 11.3 ° German Hardness water were performed at 45 ° C.

10 63056

The test products were tested at random and all experiments were repeated.

pH adjustments were made at 45 ° C using dilute sulfuric acid (0.1 M) and dilute sodium hydroxide (0.1 M) solutions, and pH was also measured at the end of each experiment.

The product of the nominal mixture described above without lemon juice was used as a comparator.

During the evaluation, a panel of experts performed the remaining staining on each half-plate of the evaluations as follows: 0 = completely clean 1 = still slightly stained 2 = fairly stained 3 = significantly stained 4 = no noticeable cleaning effect.

These results have been averaged (6 results per test product and comparator at each pH) and the staining difference between comparator and test product was calculated.

Table I

63056 11

Dissolution test results - comparison of a product with and without 10% lemon juice.

pH Product Results Mean Difference, reference value red sample 5.5 Lemon 1.5 2.5 1, 0.5 1, 0.5 1.17 + 0.75

Comparator 2.5 3, 1.5 1.5 2, 1, 1.92 7.0 Lemon 3, 3.5 2.5 0 0 0 1.5 + 0.67

Comparator 3.5 4, 3, 0.5 1, 0.5 2.17 8.5 Lemon 0.5 0.5 0.5 0.5 1, 0.5 0.58 + 1.42

Comparator 1.5 2, 1, 2.5 3, 2, 2.0 10.0 Lemon 1.5 2.5 1, 1.5 2.5 1, 1.67 + 0.50

Comparator 3, 3, 1.5 2, 2.5 1, 2.17

The table above shows that the mixture according to the invention is consistently clearly better at pH values of 5.5, 7.0, 8.5 and 10.0, the results obtained at pH 8.5 being particularly good.

Example V

The following mixtures were evaluated: weight percent

Seos C V1 V2 V3 V4 V5 V6

Sodium dodecylbenzenesulphonate 29.0 29.0 29.0 29.0 29.0 29.0 29.0

Lauryl 3-ethoxy sulfate 14.0 14.0 14.0 14.0 14.0 14.0 14.0

Lemon juice (quadruple concentrate) 0.25 1.25 2.5 3.75 5.0 6.25 12.5

Ethanol 10.0 10.0 10.0 10.0 10.0 10.0 10.0

Urea 10.0 10.0 10.0 10.0 10.0 10.0 10.0

Water + preservative to 100 to 100 to 100 to 100 to 100 to 100. Dilute amount of lemon juice 1 5 10 15 20 25 50 The method used was as follows: 12 63056 1. The egg dressing was prepared by thorough mixing dried egg powder and water in a ratio of 1: 1.

2. A 5 cm stain strip was diagrammatically printed on the center of a 30 x 25 cm glass plate.

3. The plates were heated for 30 minutes at 200 ° C.

Five evaluations could then be performed for each tile. At least two comparative assessments were performed on each tile.

4. Five 5 cm recesses were built across the slab using plastic strips. 6 ml of solution (0.15%) was placed in the well. Using a piece coated with a J-cloth and a weight of 1.5 kg, the amount of abrasion required to clean the 5 cm stain strip was recorded.

5. The test solution results were calculated as a percentage of the performance of the nearest comparator on the plate.

The results of the experiments using 5 ° hard water are tabulated below.

Mixture of% lemon juice Average performance% - _ _ for comparison_

Comparator (C) 1,100 νχ 5 89 V2 10 61 V3 15 70 V4 20 73 V5 25 68 V6 50 60.5

The above results clearly show the superiority of the V1 to Vg blends of the invention containing 5 to 50% lemon juice in the purification of a fried egg over a comparator.

Example VI

The dishwashing performance of the following mixtures was compared in a standard plate wash experiment as well as in an experiment to determine the ease of cleaning fried stains from substrates after dissolution using the test method described in Examples I-III.

m 63056 13

Seos VI Seos D

10% sodium dodecylbenzene / sulfonate 15% Empilan ^ LP 10 * 5% sodium lauryl (ethoxy) sulphate 30% glycerin 5% lemon juice 5% lemon juice 2% urea 2% urea remaining water remaining water * Empilan LP10 is a non-ionic fatty amide condensate comparable to Nopco 1179 by Nopco Chemical Company.

Empilan is a registered trademark of Marchon Products Ltd.

Standard plate washing experiments were performed using the following experimental conditions:

Product contents: 0.15 and 0.45%

Solution temperature: 45 ° C

Standard sauce stain 5 g / plate: fat, starch, oleic and stearic acids.

The results are tabulated below:

Table 3 _Number of plates washed_

Water hardness 5 ° H ^ 26¾

Product concentration 0.15% 0.45% 0.15% 0.45%

Mixture VI (pH 7) 30 63 27 59

Mixture D (pH 5.8) 3 7 2 4

Results of experiments to determine the ease of cleaning frying stains from substrates. Mean results were obtained from five results for each product used at 0.75% concentrations.

Λ

Table 4 6 305 6 14

Average Difference

Mixture _ 5 ° H in water 26 ° H in water 5 ° H in water 26 ° H in water VI (pH 7) 0/2 2,4 D (pH 5,8) 0,7 2,4 + 0,5 + ° '° VI (pH 7) 0.7 3.0 D. (pH 7) 1.1 3.3 +0.4 +0.3 VI ipH 7) 2.4 D (pH 5.8) 2.7 "+0.3 VI (pH 7) 1.5 D ( pH 7) 2.1 ”+0.6

The above results clearly show the superior properties of the mixture VI according to the invention compared to the known mixture D both in dishwashing and in the removal of frying stains.

Examples VII to IX

The following liquid dishwashing formulations are within the scope of the invention:

Mixture VII Percent by weight

Sodium dodecylbenzenesulphonate 16.0

Nonylphenol-7 ethylene oxide 7.0

Ethanol 2.0

Urea 4.0

Lemon juice 8.0

Water + preservatives to 100.0 15 63056

Mixture VIII% by weight

Ammonium ciodecylbenzenesulphonate 32.0

Nonylphenol-10 ethylene oxide 8.0

Ethanol 3.0

Urea 3.0

Sodium xylene sulfonate 9.0

Lemon juice 7.5

Magnesium sulphate 1,2

Water + preservatives to 100.0

Mixture IX Percent by weight

Sodium lauryl (ethoxy) sulphate 24.0

Dimethyldodecylamine oxide 5.0

Lemon juice 10.0

Sodium citrate 1/0

Urea 3.0

Ethanol 3.0

Water + preservatives to 100.0.

. ”·> *

Claims (8)

16 63056 Aqueous detergent composition which is particularly suitable for dishwashing and which contains from 5 to 60% by weight of an organic synthetic surfactant system of at least two different surfactants and from 5 to 50% by weight of citrus juice, characterized in that the organic synthetic surfactant system comprises: 1. about 30 to 90 parts by weight of the weight of the system of a Ca-sensitive first surfactant selected from the group consisting of water-soluble C 1-6 alkyl benzene sulfonates; alkanesulfonates having 8 to 20 carbon atoms; olefin sulfonates having from 8 to 20 carbon atoms; di-Cg_20 "a ^ * cyy ^^ su ^^ osuk, t ^" naates; di-Cg ^ - alkyylifenolisulfosukkinaatteja.; primary and secondary alkyl sulfates having from 8 to 20 carbon atoms; C8-20 "alkyl polyethoxysulfates having 1 to 25 ethoxy groups and mixtures thereof; and 2. about 70 to 10 parts by weight of the weight of the system of a less Ca-sensitive second surfactant selected from the group consisting of water-soluble nonionic condensation products obtained by condensing 5 to 30 moles of alkylene oxide, preferably ethylene or propylene oxide with one mole of an organic hydrophobic compound which is aliphatic or alkyl aromatic and has 8 to 24 carbon atoms and at least one reactive hydrogen atom, in particular a reactive hydroxyl, amino, amido or carboxyl group; C8-C20 alkylalkyl amine oxides containing one long chain alkyl moiety having from 10 to 28 carbon atoms and two moieties which may be either alkyl radicals or hydroxyalkyl radicals having from 1 to 4 carbon atoms; C 8-20 alkyl "P <> ly" ethoxy sulfates having 1 to 25 ethoxy groups and mixtures thereof, wherein the surfactants of group (1) and the nonionic surfactants of group (2) are present as their alkali metal salts, anunium salts , lower alkanolamine salts, lower alkylamine salts or mixtures thereof. A mixture according to claim 1, characterized in that said organic synthetic surfactant system is present in 10 to 50% of the mixture. 17 63056 Mixture according to Claim 1, characterized in that the citrus juice is present in an amount of 5 to 25% by weight of the mixture. Mixture according to Claim 3, characterized in that the citrus juice is present in an amount of 5 to 10% by weight of the mixture. Mixture according to one of Claims 1 to 4, characterized in that the citrus juice is lemon juice. Mixture according to Claim 5, characterized in that it has a pH of 5.5 to 9. Mixture according to Claim 6, characterized in that it has a pH of 6 to 8.5. Mixture according to one of the preceding claims, characterized in that more than 35% by weight of the organic surfactant system is present in the mixture. ·,> 63056 18