CA2170238A1 - A process for differentiating organic food residues on hard surfaces - Google Patents

Abstract

A process is disclosed for differentiating organic foodstuff residues according to their type on hard surfaces by applying a solution that contains a combination of at least two dyes, of which at least one is hydrophilic and at least one is hydrophobic, on the hard surface, then optically determining the residue type thanks to their specific colouring. Also disclosed are liquid compositions of dye mixtures and their use.

Description

` -- 2170238 A process for differentiating organic food residues on hard surface~

This invention relates to a process for differenti-ating organic food residues according to type on hard surfaces by suitable dye combinations. The invention also relates to liquid formulations of dye mixtures and to their use in the process according to the invention.
The production and processing of foods or other materials containing organic components of animal or vegetable origin results in the soiling of equipment, work surfaces and rooms. Such soiling can lead to the formation and growth of bacteria, fungi and micro-organisms. Since this can have a considerable influence on the quality of the process products and, accordingly, must be avoided, high standards of hygiene are necessary.
Regular cleaning and disinfection are essential for establishing high standards of hygiene in any food-producing factory. In addition to inorganic salts, organic contaminants, such as proteins, fats, low molecu-lar weight and high molecular weight carbohydrates which are mostly present alongside one another, are generally encountered in any food factory.
Cleaning formulations varying in composition are used to remove these contaminants. The choice of a suitable cleaning formulation is generally determined by the type of contaminant to be removed. If the type of contaminant is known, the cleaning formulation can be selected accordingly. However, the various combinations of cleaning components lead to a difference in cleaning performance with respect to protein, fat and carbohy-drates. Small soil residues can remain behind after cleaning and, although barely visible, nevertheless represent a microbiological risk.

~17~23g Hitherto, hygiene standards have been tested solely by bacteriological methods in which a culture is applied.
Unfortunately, methods such as these for testing hygiene standards are unsuitable because they can only be used to determine living microorganisms (bacteria and fungi). It is not possible with bacteriological methods to determine the organic contaminants which have been responsible for the bacterial growth. Accordingly, the success of the cleaning operation cannot be directly determined by bacteriological methods. In addition, bacteriological methods are time-consuming and can take a few hours or even a few days until a definitive result is obtained.
Furthermore, the monitoring of hygiene standards by bacteriological methods can be falsified by disinfection lS which does not rule out the accumulation of organic contaminants which, ultimately, are responsible for the growth of resistant microorganisms. In addition, there is nothing in spot sampling to guarantee that even entire machines and relatively large surfaces can be tested for their hygiene standards.
Published PCT application WO 90/14591 describes a process for cleaning and, at the same time, monitoring the cleaning result and hygiene standards by applying a solution of a mixture of a cleaning formulation and a dye or dye combination to the surfaces to be cleaned. The organic contaminant remaining behind on the surface after cleaning is made visible by coloration. However, it is only possible by this method to determine whether resi-dues have remained on the surface after cleaning. It is not possible by this method to determine the nature of the residues, i.e. to tell whether they are fats, carbo-hydrates or proteins.
BP-A-o 347 494 describes a process for detecting contaminants on an article by treatment of the article with a dye solution and then with a developer solution.

217023~

This process, too, only enables the contaminants to be detected, but not differentiated according to type.
A process for determining leakages of organic material from containers or pipes using a suitable dye solution is described in US-A-4,745,797.
The coloring of food residues by indicators (ery-throsine) is known from odontology. In this case, the indicators are used to show up coatings on teeth. Once again, it is only possible to tell that food residues are present on the teeth, but not what the residues are.
However, there is a considerable demand for a process which would enable the type of organic residues present on the surface after cleaning to be determined so that special-purpose cleaners could be used for any aftercleaning necessary or so that cleaners or cleaner combinations suitable for the future could be used, thus avoiding the need for aftercleaning.
Equally, it should be possible to tell what type of organic residues are present on the surface before the actual cleaning process so that a suitable cleaning composition can be used from the outset.
This demand for a rapid method for determining the organic soil residues before or after cleaning exists not only for the entire food-producing industry, but also for all sectors where cleaning is necessary on hygiene and/
or aesthetic grounds, more particularly in meat, fish, delicatessen and beverage factories, breweries, milk-processing and agricultural operations, the starch and sugar industries, kitchens, hospitals, swimming baths, the cosmetics industry and the pharmaceutical industry.
Accordingly, one of the problems addressed by the present invention was to provide a process which would enable organic contaminants to be differentiated accord-ing to type, i.e. fat, protein or carbohydrate (low molecular weight and high molecular weight), before or ~17~238 after a cleaning operation. The process according to the invention would be easy to carry out and would enable the contaminants to be differentiated as fat, protein or carbohydrate on the hard surface itself.
According to the invention, this problem has been solved by a process for differentiating organic food residues according to type on hard surfaces by applica-tion of a solution containing a combination of at least two dyes, of which at least one is hydrophilic and at least one hydrophobic in character, to the hard surface and subsequent visual determination of the nature of the residues through their specific coloration.
A definition of the terms "hydrophilic" and "hydro-phobic" as used in the present specification in reference to dyes of hydrophilic or hydrophobic character can be found, for example, in "Rompp Chemie Lexikon" 9th Edi-tion, Vol. 3 (1990), Georg Thieme Verlag, pages 1892 and 1893. The definitions read as follows (after transla-tion): "The hydrophobic character of a substance is determined by its tendency to penetrate into water and to remain therein." and "The hydrophobic character of a substance is determined by its tendency not to penetrate into water and remain therein.". Accordingly, "dyes of hydrophilic character" in the context of the present invention are understood to be dyes which are "water-friendly" and which dissolve readily and thoroughly in water (at room temperature). On the other hand, "dyes of hydrophobic character" in the context of the invention are understood to be dyes which are "water-repellent", i.e. are insoluble or sparingly soluble in water (at room temperature). Corresponding characterizations of the dyes suitable for use in accordance with the invention can be found, for example, in the following standard works:
- "Rosmetische Farbemittel~, 3rd Edition, 1991, published by the Farbstoffkommission der Deutschen ~orschungsgemeinschaft (DFG), VCH Verlagsgesell-schaft mbH, and - "Color Index~' Third Edition, Vol. 1 to 9, published by The Society of Dyers and Colourists.
The organic residues are fats, proteins and/or carbohydrates which may be present alongside one another or even on their own. In the process according to the invention, the nature of the residue can be determined with a single solution.
By means of this method, the user 1. can determine the nature of the organic contaminant and also the most heavily contaminated areas before the actual cleaning process so that the type of cleaner can be selected in advance and the most heavily contaminated areas can be more intensively treated, 2. can check the result of the cleaning process on its completion, 3. can readily determine the weaknesses of the cleaning formulation with respect to the individual soil compo-nents so that the right cleaner can be selected for future cleaning operations and 4. after determining the organic contaminants remaining behind after a cleaning operation, can remove these contaminants with special-purpose cleaners.
The process according to the invention represents a simple method of qualitatively determining the perfor-mance of cleaning formulations, especially in the devel-opment of a cleaning product, by treating a test soil (fat/protein/starch) first with the cleaner ~to be tested and then with the formulation according to the invention by a standardized method. Through the differences in the coloration of the individual soil components it is possible to tell which component is easier or more difficult to remove with the cleaning formulation. The formulation may then be improved with greater purpose.
The process according to the invention enables a suitable cleaning formulation to be selected by detection of the particular type of soil present before cleaning.
After cleaning, it is possible on the one hand to monitor the result of the cleaning operation and, on the other hand, to select a suitable special-purpose cleaner for the soil component which was not removed. In the clean-ing of large production units or plants, for example, critical points can be defined on the HACCP principle (Hazard Analysis of Critical Control Points). To this end, the critical points are sprayed with the formulation according to the invention after cleaning and appropriate measures are taken according to the result.
The formulation according to the invention may be applied to the hard surfaces to be investigated by known methods, but especially by spraying, brushing, pouring or dabbing of the formulation according to the invention onto the surface. This may optionally be done with the prerinse water.
Dyes of hydrophilic or hydrophobic character suit-able for use in accordance with the invention are listed by way of example in the following. The "color index number C.I.", the "DFG name", "synonyms" and "EEC num-bers" can be found in the two standard works cited above:

Dyes of hydrophilic character:

Colour DFG Name Synonyms EEC
Index Number C.I.

10020 C-ext. Grun 6 Naphtolgrun B, L-ext. Grun 1 13015 C-Gelb 9 Echtgelb 14270 C-Gelb 12 Chrysoin S
14700 C-Rot 57 Ponceau SX, FD & C Red 4 14720 C-Rot 54 Azorubin, Carmoisine, L-Rot 1 E 122 14815 C-Rot 49 Scharlach GN, Scarlet GN E 125 15510 C-ext. Orange 8 Orange II, D & C Orange 4 15620 C-WR Rot 13 15980 C-Orange 9 Orange GGN E 111 15985 C-Orange 10 Gelborange S, Sunsett Yellow E 110 FCF, FD & C Yellow 6, L-Orange 2 16035 C-Rot 60 Allura Red AC, FD & C Red 40 16185 C-Rot 46 Amaranth, L-Rot 3 E 123 16230 C-ext. Orange 11 Orange GG
16255 C-Rot 47 Ponceau 4R, L-Rot 4, Chochen- E 124 illerot A
16290 C-Rot 48 Ponceau 6R E 126 17200 C-Rot 58 Fast Acid Magenta B, D&C
Red 33 18050 C-ext. Rot 63 Amidonaphtolrot G, Red 2G, L-Rot 12 18130 C-WR Rot 4 Supranolbrilliantrot 3B
18690 C-WR Orange 9 Zaponechtgelb R, Perln Fast Yellow G

18736 C-WR Orange 8 Palantinechtrot RN
18820 C-WR Gelb 9 Flavazin L

217~2:~

Dyes of hydrophilic character (continued):

Colour DFG Name Synonyms EEC
Index Number C.I.

18965 - Yellow 2G
19140 C-Gelb 10 Tartrazin, FD & C Yellow 5, E 102 L-Gelb 2, Permanentgelb NCG
20170 C-ext. Braun 4 Resorcinbraun, D & C Brown 1 20470 C-WR Schwarz 1 Amidoschwarz 10 B
24790 C-WR Rot 18 Supranolrot BR
27290 - Brillantcrocein MOD
27755 C-Schwarz 7 Schwarz 7984 E 152 28440 C-Schwarz 6 Brillantschwarz BN, Brilliant E 151 Black PN, L-Schwarz 1 40215 C-WR Orange 1 42045 C-ext. Blau 13 Patentblau VF
42051 C-Blau 20 Patentblau V, Patent blue V, E 131 L-Blau 3 42053 C-Grun 12 Fast Green FCF, FD & C Green 3 -42080 C-WR Blau 11 Patentblau A
42090 C-Blau 21 Patentblau AE, Brilliant Blue FCF, FD & C Blue 1, L-Blau 4 42100 C-WR Grun 5 42170 C-ext. Grun 10 Alkaliechtgrun 10 G, L-ext.
Grun 2 42510 C-WR Violett 8 Fuchsin, Magenta 42520 - Neufuchsin, New Magenta 42735 C-ext. Blau 14 BriIlantwollblau FFR
44045 C-WR Blau 8 ~ Victoriablau B

44090 C-Grun 4 Wollgrun S, Brillantsauregrun E 142 BS, L-Grun 3 17~23~

Dyes of hydrophilic character (continued):

Colour DFG Name Synonyms EEC
Index Number C.I.

45100 - Sulforhodamin B
45190 C-WR Violett 5 Echtsaureviolett ARR, L-ext.
Violett 2 45220 C-WR Rot 16 Sulforhodamin G
45350 C-ext. Gelb 16 Fluorescein, Uranin, D & C
Yellow 7/8 45380 C-Rot 30 Eosin, Eosine, D & C Red 21/22 -45430 C-Rot 38 Erythrosin, Erythrosine, FD & E 127 C Red 3, L-Rot 11 47005 C-Gelb 11 Chinolingelb, Quinoline yel- E 104 low, L-Gelb 3 50325 C-WR Violett 10 Wollechtviolett B
50420 - Nigrosin GF wasserloslich 59040 C-ext. Gelb 24 Pyranin, Pyranine 60730 C-ext. Violett Anthralanviolett 3B, Ext.
21 D & C Violet 2 61570 C-Grun 11 Alizarincyaningrun G, D&C
Green 5 61585 C-WR Blau 10 73015 C-Blau 19 Indigotin, Indigocarmin, E 132 FD & C Blue 2, L-Blau 2 74180 C-WR Blau 12 Heliogenblau SBL, Siriuslicht- -turkisblau GL
75815 C-Grun 8 Chlorophyllin-Cu-Komplex E 141 - C-Rot 53 Beetenrot, Beetroot red E 162 - C-Rot 52 Anthocyane, Anthocyans E 163 - 217023~

Dyes of hydrophobic character:

Colour DFG Name Synonyms EEC
Index Number C.I.

11920 C-Orange 1 Sudanorange G
12150 C-Rot 2 Solvent Red 1, Food Red 16 12700 - Sudangelb 3G
21230 C-ext. Gelb 21 Sudangelb GRN, L-ext. Gelb 1 26100 C-ext. Rot 56 Sudan Red BK, D & C Red 17 40800 C-Orange 11 ~-Carotin, L-Orange 3 E 160a 40820 C-Orange 16 Apocarotinal, L-Orange 8 E 160e 40825 C-Orange 17 Apocarotinsaure-ethylester, L- E 160f Orange 9 40850 C-Orange 15 Canthaxanthin E 161g 45370 C-Rot 27 D & C Orange 5 4700 C-ext. Gelb 23 Chinolingelb A Spritl. ~ & C
Yellow 11 56238 C-WR Gelb 16 Hostasolgelb 3G
61554 - Solvent Blue 35, Fettblau B, Sudanblau II
61565 C-Grun 10 Alizarincyaningrun fettl., D & C Green 6 60725 C-ext. Violett Irisol spritl., D & C Vio-18 let 2 69800 C-Blau 18 Indanthrenblau RS, Indan- E 130 throne 7300 C-Blau 22 Indigo, D & C Blue 6 75120 C-Orange 12 Annatto, Orlean, Bixin, Nor- E 160b Bixin, L-Orange 4 75125 C-Orange 14 Lycophin, L-Orange 6 E 160d 75130 C-Orange 11 Carotin, Carotene, L-Orange 3 E 160a 217~2~8 Dyes of hydrophobic character (continued):

Colour DFG Name Synonyms EEC
Index Number C.I.

75135 C-Orange 15d Xanthophylle, L-Orange 7d, E 161d Rubixanthin 75170 - Guanine 75300 C-Gelb 15 Kurkumin, Curcumin, Turmeric, E 100 L-Gelb 7 75810 C-Grun 8 Chlorphyll-Cu-Komplex, L- E 140 Grun 2 - C-Gelb 14 Riboflavin, Lactoflavin, E 101 Vitamin B2, L-Gelb 6 - C-WR Grun 3 Bromkresolgrun, Bromcresol green - C-WR Grun 3 Bromthymolblau, Bromthymol blue C-Orange 13 Capsanthin, Capsorubin, L- E 160c Orange 5 - - Solvent Blue 97, Ceres Blau RR

- 217023~

In one preferred embodiment of the present inven-tion,~erythrosine (C.I. 45 430; E 127) and Ponceau 4 R
(C.I. 16255; E 124) are used as dyes of hydrophilic character. According to the invention, curcumin (C.I.
75300; E 100), B-carotene (C.I. 40800; E 160a), ribo-flavin (E 101) and Ceres Blau RR are preferably used as dyes of hydrophobic character.
Another preferred embodiment of the present inven-tion is characterized by the use of dye combinations of two different dyes (binary system), of which one is hydrophilic in character and the other hydrophobic in character. In this embodiment, one component of the binary dye combinati`on is preferably erythrosine and the second component is preferably curcumin or B-carotene.
In addition, the present invention encompasses dye combinations of three different dyes (ternary system), of which at least one is hydrophilic in character and at least one other is hydrophobic in character. For systems such as these, it is immaterial in principle whether the third additional dye is hydrophilic or hydrophobic in character. According to the present invention, however, the dyes mentioned above for binary dye combinations are preferably used for the ternary systems with Ceres Blau RR as the additional dye component.
In accordance with the foregoing observations, the present invention also encompasses dye combinations of four different dyes (quaternary system) or of more different dyes.
In another preferred embodiment of the invention, the dye combination of at least two dyes is present in the solution in a quantity of 0.05 to 3% by weight, preferably in a quantity of 0.05 to 2% by weight and more preferably in a quantity of 0.05 to 1% by weight.
The ratio of the dyes in binary systems is 1:10 to 10:1, preferably 1:5 to 5:1 and more preferably 1:2 to ~170238 2:1. In general, however, 1:1 mixtures give good re-sults.
So far as the ternary and quaternary systems are concerned, no dye may be present in more than a 10-fold and preferably 5-fold excess over the dye present in the smallest quantity. The same applies to combinations of more than four different dyes. In general, however, combinations in which the dyes are present in equal amounts are preferred.
The present invention also relates to liquid for-mulations containing - in addition to a suitable solvent - a combination of at least two dyes of which at least one is hydrophilic in character and at least one hydro-phobic in character. A dye combination such as this enables organic food residues on hard surfaces to be visually differentiated according to type.
According to the invention, particularly good results in regard to differentiation of the contaminants according to type through their specific respective colorations are obtained in particular if one component of the combination is erythrosine and the second com-ponent is curcumin or ~-carotene. For ternary dye systems, the dyes mentioned above are preferably used in accordance with the invention with Ceres Blau RR as the third component of the dye combination.
Water with a pH value of 2 8 may be used as solvent for the liquid formulation of the dye combination. The pH value suitable for the solubility of the dye combina-tion, which has to be individually determined, is es-tablished with suitable bases, more particularly alkalimetal hydroxides (NaOH, KOH) or alkali metal carbonates (sodium carbonate, potassium carbonate). Water corre-spondingly adjusted to alkaline pH values also enables the above-mentioned dyes of hydrophobic character to be dissolved.

~o 95/06241 14 PCT/EP94/02725 However, a mixture of water and a water-miscible organ c solvent as solubilizer is particularly suitable as a-further solvent for the dye combination. In this case, the water-miscible organic solvent is preferably used in a ratio by weight of water to water-miscible organic solvent of 20:1 to 1:20, preferably 10:1 to 1:10:
and, more preferably, 2:1 to 1:2. There is no need in this case to add bases to the solution.
Particularly suitable water-miscible organic sol-vents are monohydric and dihydric water-miscible alco-hols, particularly ethanol, propanol, isopropanol, butanol, ethylene glycol, propylene glycol, butyl glycol, methyl diglycol, ethylene diglycol, butyl diglycol or dipropylene glycol monoethyl ether. These water-miscible organic solvents act as a solubilizer. In this connec-tion, a 1:1 mixture of triethanolamine and caprylic acid or sodium cumene sulfonate, optionally in the form of aqueous solutions, is also mentioned as a solubilizer.
The dye combination may also be dissolved in a suitable pure organic solvent. Particularly suitable pure organic solvents are the water-miscible organic solvents mentioned above as solubilizers or mixtures thereof. In addition, a 1:1 mixture of triethanolamine and caprylic acid or sodium cumene sulfonate, optionally in the form of aqueous solutions, may also be used as solvent for the dye combination.
The solution of the dye combination may also contain the usual nonionic, cationic, anionic or amphoteric surfactants or mixtures thereof otherwise present in cleaning formulations in order to make any fat or protein layers present permeable to the dye combination so that underlying carbohydrates can be reached and colored.
Corresponding formulations may contain surfactants in a quantity of 0.05 to 2% by weight, preferably in a quan-tity of 0.05 to 0.5% by weight and, more preferably, in 217~238 a quantity of 0.05 to 0.15~ by weight.
m.he anionic surfactants used are, for example, those of the sulfonate and sulfate type, more particularly alkene and hydroxyalkane sulfonates or mixtures thereof, alkane sulfonates, ester sulfonates, sulfonated fatty acid glycerol esters/sulfotriglycerides, alkyl sulfates or alcohol sulfates or alk(en)yl sulfates/ether sulfates, alkyl sulfosuccinic acid, sulfosuccinates, isethionates, taurates, phosphate esters or mixtures thereof.
Preferred nonionic surfactants are ethoxylated and/
or propoxylated alcohols derived from primary alcohols preferably containing 9 to 18 carbon atoms and an average of 1 to 12 moles of ethylene oxide and/or propylene oxide. Alkyl glucosides may also be used.
Suitable cationic surfactants are, in particular, quaternary ammonium compounds (QUATS), quaternary phos-phonium compounds (QPCS) and amine oxides. Amphoteric compounds, particularly betaines, may also be mentioned in this regard.
Besides the dyes, surfactants or solubilizers, ty-pical preservatives may also be present in the solution.
Immediately after the surface in question has been treated with the solution containing the dye combination, fat, protein and carbohydrate (starch) may be differen-tiated through their different colorations. In general, the different colorations of these food residues can be visually determined with the naked eye in daylight.
However, the colorations may optionally be intensified or actually made visible by exposure of the treated surface to W light. Where a mixture of fat, protein and carbo-hydrates is present, mixed colorations can occur, one color or the other dominating according to the quantity ratio in which the food residues are present.
The solutions are stable in storage and can be stored for prolonged periods without losing their proper-` - 217~238 ties.
The following Examples are intended to illustrate the invention without limiting it in any way.

Examples 1. Deionized water, butyl diglycol as solubilizer, a C9_10 fatty alcohol-1,6-glucoside (Triton BG 10, a product of Union Carbide) and the particular dye or dye combina-tion were used in the following formulations (percentages = ~ by weight). The dye combination was then sprayed onto the surface to be investigated (white ceramic tiles) and the discoloration was analyzed by corresponding specific coloration of the soils previously applied in visible light and W light (366 nm).
Beef tallow was used as the fat, flour (10% by weight in water) as the starch and a mixture of whole milk with protein or casein as the protein.

Formulations 1 2 3 4 Water 47.30% 47.20% 47.10% 47.10%
Solubilizer 52.50% 52.50% 52.50% 52.50%
Surfactant 0.10% 0.10% 0.10% 0.10%
Curcumin 0.10% -- 0.10% 0.15%
Erythrosine -- 0.20% 0.20% 0.15%
Note: Formulations 1 and 2 are Comparison Examples Tests A) Coloring in daylight Formulations 1 2 3 4 Fat Red Yellow Yellow Light yellow Protein Red Yellow Orange Red 35 Starch Red Yellow Red Pink `` 2~7023~

B) Coloring in W light (366 nm) Formulations 1 2 3 4 Fat -- Green/ Green/ Green/
yellow yellow yellow Protein Orange Green/ Red/ Orange yellow orange Starch -- Green/ Orange Light yellow orange The same result is obtained for the erythrosine/
curcumin (2:1) dye combination if the water/solubilizer mixture is replaced by a single solvent (butyl diglycol, butyl glycol, methyl diglycol, ethylene glycol, dipro-pylene glycol monoethyl ether, ethanol, 40% by weightaqueous Na cumene sulfate solution or 66% by weight aqueous triethanolamine/caprylic acid (1:1) solution).
In the mixture with water, butyl diglycol may be replaced by butyl glycol, ethylene glycol, methyl diglycol, ethanol or an aqueous 1:1 mixture of triethanolamine and caprylic acid (67% by weight) without affecting the result.

2. 47.1% by weight of deionized water, 52.5% by weight of butyl diglycol as solubilizer, 0.1% by weight of Triton BG 10 as surfactant and a total of 0.3% by weight of the particular dye combination were used for the following formulations. The formulations were then sprayed onto the surface to be investigated (white ceramic tiles) and the coloration of the soils applied beforehand (as described above) was determined in visible light and in W light (366 nm).
The results are set out in Table 1 below.

`` ~ 2170238 ~ r ~ r t DJ r~ t r rt ~ r ~ r O
~ O
C~ : C ~ C ~ O
r - ~ r O r~ C ~~ C ~~ C J ~ I' C ~ cr~ PJ Ul r r 3 .. .. .. .. O
c ~ 2 Q Q Q Q Q Q Q Q
E~ 3 3 E~ ~ 3 3 3 - .. . - .. .. .. .-r Q
s 'O 'D O tt O ~^ O O
~: : ~D
o 1.
o r r ~ r ~ r P ~ ~Q Y
~ s ~ s ~ s O G O O

1) X
Cl tt t ~t W W
Q 1 ~ O
S J S
ID D D
rn n n ID O K: O ~ o ~ ~ Q ~ P~ It 'D O
O
~ o ~ ~4 o ' t lD ~ o lD ~ C D
~t O ~: ~1 0 pl ~ D '- ~t lD ~ O ~4 ID ~ lD
c ~ ~ ~ C E.
r rn n n ~ ~d a~ J t~ ~ ~ S a :1' ~ ~
ID lD lD D O
3 3 3 3 ~1 N

~n `` 2170238 -3. Other tests were carried out with the following formulations (binary and ternary dye combinations):

Binary dye Ternary dye comb. (l:1) comb. (1:1:1) Dye combination 0.4% by weight 0.6% by weight Surfactant 0.1% by weight 0.1% by weight (Triton BG 10) Solubilizer 5.0% by weight 5.0% by weight (methyl diglycol) Water (deionized) 94.5% by weight 94.3~ by weight The formulations were sprayed onto the surface to be investigated (white ceramic tiles), to which the soils described above had been applied beforehand - both indi-vidually and as ternary mixtures - and the colorations were viewed and determined in visible light (daylight).
The results are set out in Table 2 below.

(palnsea~ ~oN ~-N) ~-Ns~ods a~uelo s~ealls a~uelo pa~ ~-Ns~ods a~uelo a~n~XF~
~ ~olla~ 'pa~ ~ Molla~ 'pa~ ~ Molla~ 'pa~ ~leula~ _~
pa~ pa~/a~uelo a~uelo pa~ pa~a~uelo (uFase~
uFa~Old C~3 C~
pa~ pa~ pa~ pa~ pa~pa~ (Inol~) e~S
anl~ anlq ~ Molla~ Molla~ an~ olla~ (Molle~ ~aaq) e~oq ~e~
T 1:1:1 1:1:1 1:1 1:11:1 nel~ sala~ ~ nela sala~Ul~el~qF~
/uFAel~oqF~ aua~ole~-e~a~ /aua~o~e~-e~a~ ~ nel~ sala~ uFAel~oqF~ aua~ole~-e~a~
/auFso~ /auFsol~ /aulso~ /auFsol~ /auFso~ la /auFsol~

Lzo/~6aa/~ oz T~Z90/56 OM

Claims (19)

1. A process for differentiating organic food residues according to type on hard surfaces by application of a solution containing a combination of at least two dyes, of which at least one is hydrophilic in character and at least one is hydrophobic in character, to the hard surface and subsequent visual determination of the nature of the residues through their specific coloration.

2. A process as claimed in claim 1, characterized in that the organic residues are fats, proteins and/or carbohydrates.

3. A process as claimed in claim 1 or 2, characterized in that the dyes of hydrophilic character are selected from erythrosine and Ponceau 4 R while the dyes of hydrophobic character are selected from curcumin, .beta.-carotene, riboflavin and Ceres Blau RR.

4. A process as claimed in one or more of claims 1 to 3, characterized in that one component of the dye com-bination is erythrosine and the second component is curcumin or .beta.-carotene.

5. A process as claimed in claim 4, characterized in that an additional component of the dye combination is Ceres Blau RR.

6. A process as claimed in one or more of claims 1 to 5, characterized in that the combination of at least two dyes is present in the solution in a quantity of 0.05 to 3% by weight.

7. A process as claimed in one or more of claims 1 to 6, characterized in that water with a pH value of 2 is used as the solvent for the combination of at least two dyes.

8. A process as claimed in one or more of claims 1 to 6, characterized in that a mixture of water and a water-miscible organic solvent is used as solvent for the combination of at least two dyes.

9. A process as claimed in claim 8, characterized in that the ratio by weight of water to water-miscible organic solvent is in the range from 20:1 to 1:20, preferably in the range from 10:1 to 1:10 and more preferably in the range from 2:1 to 1:2.

10. A process as claimed in one or more of claims 1 to 6, characterized in that a water-miscible organic solvent is used as solvent for the combination of at least two dyes.

11. A process as claimed in one or more of claims 1 to 10, characterized in that the solution additionally contains at least one nonionic, anionic, cationic or amphoteric surfactant.

12. A process as claimed in claim 11, characterized in that the surfactant is present in the solution in a quantity of 0.05 to 2% by weight.

13. A liquid formulation containing - in addition to a suitable solvent - a combination of at least two dyes of which at least one is hydrophilic in character and at least one hydrophobic in character.

14. A liquid formulation as claimed in claim 13, charac-terized in that one component of the dye combination is erythrosine and the second component is curcumin or .beta.-carotene.

15. A liquid formulation as claimed in claim 14, charac-terized in that an additional component of the dye combination is Ceres Blau RR.

16. A liquid formulation as claimed in one or more of claims 13 to 15, characterized in that water with a pH
value of 8, a water-miscible organic solvent or a mixture of water with a water-miscible organic solvent is used as solvent.

17. A liquid formulation as claimed in one or more of claims 13 to 16, characterized in that the dye combina-tion makes up 0.05 to 3% by weight of the formulation.

18. A liquid formulation as claimed in one or more of claims 13 to 17, characterized in that it additionally contains 0.05 to 2% by weight of a surfactant.

19. The use of the liquid formulation claimed in one or more of claims 13 to 18 for differentiating organic food residues according to type on hard surfaces.