Method for cleaning hard surfaces

Abstract

To provide a washing method for a hard surface that can effectively wash stains containing protein deposited on a hard surface even in the regions having neutral to weakly alkaline liquid properties.SOLUTION: A washing method for a hard surface includes the step in which: a hard surface stained with protein and others is brought into contact with a washing liquid with a pH of 6 or more and 11 or less so that the cleavage rate of disulfide bonds in a protein molecule or between protein molecules becomes 20% or more and 100% or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for cleaning a hard surface.

Background Art

[0002] Dishwashers are used for cleaning dishes such as soiled plates, glasses, and cooking utensils in kitchens of homes, restaurants, cafes, etc., and for cleaning plastic containers for food ingredients and products used in food and beverage factories. The main target stains include protein, starch, oil and fat derived from food, and these stains are combined and adhered to dishes such as plates, glasses, and cooking utensils, and plastic containers. In addition, when these stains are thermally denatured during heat cooking, they may become strong stains and adhere firmly.

[0003] Normally, the cleaning by a dishwasher is performed in the order of a cleaning step and a rinsing step. The required time for these steps is very short, about 40 to 180 seconds for the cleaning step and about 5 to 20 seconds for the rinsing step in the case of business use and in terms of process design. However, in the case of strong stains, the cleaning may be insufficient within such a designed time, and it is not uncommon to spend several times the designed time in the cleaning step for sufficient cleaning.

[0004] [[ID=z19]] Patent Document 1 discloses a method for removing protein-containing stains from a fabric, which comprises treating the fabric with a cleaning solution containing an effective amount of protease and an effective amount of a reagent capable of cleaving disulfide bonds (disulfide cleavage reagent, DCR). Patent Document 2 discloses a method for cleaning a soiled contact lens, which comprises immersing the soiled contact lens in a cleaning solution containing thiocyanate and a reducing agent and heating it. Patent Document 3 discloses a method for cleaning a contaminated surface of an object to be cleaned, such as hair or skin waste, by incorporating a keratinase, which is one type of protease, and a phosphorus-based reducing agent, which is a non-sulfur-based reducing agent capable of reductively cleaving the S-S bonds of keratin constituting hair, into a cleaning agent composition. Patent Document 4 discloses a liquid detergent composition that contains a specific alkyl sulfosuccinate (A) and a protease (B), which can clean dirt from dishes or cooking utensils without applying significant mechanical force. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 62-265398 [Patent Document 2] Japanese Patent Application Publication No. 2-168226 [Patent Document 3] Japanese Patent Publication No. 2002-256294 [Patent Document 4] Japanese Patent Publication No. 2015-199941 [Overview of the project] [Problems that the invention aims to solve]

[0006] Various types of dirt adhere to hard surfaces, especially tableware, but protein-containing dirt is particularly difficult to remove with short washes in commercial dishwashers because it is prone to deterioration and hardening. Egg yolk, in particular, can become firmly attached and difficult to remove with short washes depending on how it has deteriorated over time due to drying and denaturation. Currently, in order to effectively remove protein-containing dirt with short washes, washing under strong alkaline conditions is unavoidable, but considering the impact on workers and the environment, it is desirable to use a neutral to weakly alkaline solution.

[0007] The present invention provides a method for cleaning hard surfaces that can effectively remove protein-containing dirt adhering to hard surfaces, even in a neutral to weakly alkaline solution. [Means for solving the problem]

[0008] The present invention relates to a method for cleaning hard surfaces, comprising contacting a hard surface to which protein-containing contaminants are attached with a cleaning solution (hereinafter referred to as "the cleaning solution of the present invention") with a pH of 6 to 11 such that the rate of disulfide bond cleavage in or between protein molecules is 20% to 100%. [Effects of the Invention]

[0009] The present invention provides a method for cleaning hard surfaces that can effectively remove protein-containing dirt adhering to hard surfaces, even in a neutral to weakly alkaline pH range. [Modes for carrying out the invention]

[0010] The reason why the present invention's method for cleaning hard surfaces can effectively clean protein-containing dirt attached to hard surfaces even when the solution is neutral to weakly alkaline is not entirely clear, but it is presumed to be as follows. The inventors analyzed difficult-to-clean protein stains such as dried egg yolk stains and found that disulfide bonds (-SS- bonds) within or between protein molecules stabilize the structure, making it difficult for existing detergents with surfactants as their basic composition to cause swelling or dispersion when the cleaning process is carried out in a neutral to weakly alkaline range. In the present invention, when more than 20% of the disulfide bonds in the proteins constituting difficult-to-clean protein stains are cleaved, it is believed that even if the pH of the cleaning solution is in the neutral to weakly alkaline range, the proteins swell due to the cleaning solution, and physical forces such as collisions of the cleaning solution are applied, making cleaning easy. There are no particular restrictions on the method of cleaving disulfide bonds in proteins in a neutral to weakly alkaline range of cleaning solution; for example, reduction reactions using reducing agents or enzymes can be considered. In particular, when using a reducing agent with an oxidation-reduction potential of +71mV or less, the cleavage of disulfide bonds in proteins proceeds easily. Furthermore, during the investigation of the present invention, it was found that protein structures stabilize by forming cross-linked structures consisting of anionic groups in the protein and calcium ions, for example, the phosphate groups of protein molecules forming calcium phosphate cross-linked structures within or between protein molecules via Ca ions. It is thought that by using a chelating agent with a phosphate / Ca dissociation constant greater than that of the dissociation constant to cleave the calcium phosphate cross-linked structure, the cleavage of disulfide bonds can be made easier. Furthermore, the effects of this invention are not limited to the mechanisms of action described herein.

[0011] <Method for cleaning hard surfaces> In the hard surface cleaning method of the present invention, the cleaning solution of the present invention is brought into contact with the hard surface to which protein-containing dirt is attached, such that the rate of disulfide bond cleavage in or between protein molecules is 20% or more, preferably 30% or more, more preferably 40% or more, and 100% or less, from the viewpoint of protein cleaning.

[0012] The rate of disulfide bond cleavage in protein molecules or between proteins in protein-containing contaminants is measured by the following method. To a pH 8 0.1 M borate buffer, 4-(Aminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole (ABD-F, for example, manufactured by Tokyo Chemical Industry Co., Ltd.) is added to prepare a 100 μM ABD-F solution (hereinafter referred to as solution (A)). To a pH 8 0.1 M borate buffer, disodium ethylenediaminetetraacetate (EDTA2Na) is added to prepare a 1 mM EDTA2Na solution. To this solution, 1000 ppm of a stain containing the target disulfide bond-containing protein (for example, egg yolk) and the disulfide bond-cleaving agent contained in the washing solution of the present invention are added in an amount twice the concentration in the washing solution to prepare solution (B). 500 μL each of solution (A) and solution (B) are placed in an Eppendorf tube and mixed. The mixture is heated to 50°C for 5 minutes using a block heater (e.g., WSC-2620, manufactured by Ato Co., Ltd.), and then cooled in ice water for 10 minutes. After cooling, 300 μL of 0.1 M hydrochloric acid is added to the mixture. 200 μL of the mixture is placed in a 96-well plate, and fluorescence measurement is performed using a fluorescence analyzer (e.g., SH-9000, manufactured by Corona Electric Co., Ltd.) (excitation wavelength / measurement wavelength = 389 / 513 nm, measurement sensitivity × 100). Next, 1000 ppm of a contaminant containing the target protein with disulfide bonds is added to an aqueous NaOH solution adjusted to pH 11 to prepare solution (B). This solution is then mixed with solution (A) to prepare a mixture using NaOH as a disulfide bond-clearing agent, and fluorescence measurement is performed in the same manner as described above. Next, in preparing solution (B), instead of the contaminants containing the target protein with disulfide bonds, glutathione (for example, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), a simple compound with disulfide bonds, is added at varying concentrations, and 1000 ppm of sodium sulfite is added as a disulfide bond-cleaving agent. Otherwise, solution (B) is prepared in the same manner as above, and then mixed with solution (A) to prepare each mixture with varying glutathione concentrations. Fluorescence measurements are performed in the same manner as above to create a calibration curve of glutathione concentration and fluorescence intensity. Based on this calibration curve and the fluorescence measurement results of stains containing proteins with disulfide bonds for each disulfide bond-cleaving agent, the amount of disulfide bond cleavage by each disulfide bond-cleaving agent is estimated. The fluorescence measurement results when NaOH is used as the disulfide bond-cleaving agent are set as 100% disulfide bond cleavage rate, and the disulfide bond cleavage rate for each disulfide bond-cleaving agent is calculated.

[0013] Methods for reducing the cleavage rate of disulfide bonds in or between protein molecules in protein-containing stains to 20% or more and 100% or less include, but are not particularly limited, redox reactions using reducing agents or disulfide oxidoreductases, thiol-disulfide exchange reactions with low molecular weight thiol compounds, and disulfide-disulfide exchange reactions with low molecular weight disulfide compounds. However, from the viewpoint of short cleaning time, temperature range, workability, and availability of the chemicals used, a method using a cleaning solution containing a reducing agent and / or disulfide oxidoreductase is preferred, and a method using a cleaning solution containing a reducing agent is more preferred.

[0014] The cleaning solution of the present invention may contain the following component (a) from the viewpoint of protein cleaning properties. (a) Ingredients: Reducing agent with an oxidation-reduction potential of +71mV or less (a) The oxidation-reduction potential of component (a) is preferably +71mV or less, more preferably +60mV or less, more preferably +55mV or less, and even more preferably +50mV or less, from the viewpoint of protein washing ability. Furthermore, the lower limit of the oxidation-reduction potential of component (a) is not particularly limited, and the lower the value, the better the effect can be expected, but from the viewpoint of availability, it is preferably 0mV or more, more preferably 3mV or more. (a) The oxidation-reduction potential of the component shall be the value obtained by the following method. Add distilled water to component (a) to a concentration of 0.016 mol / L, and add 1 mol / L hydrochloric acid and / or sodium hydroxide to adjust the pH to 7.5 to prepare a preparation solution. Adjust the temperature of the adjustment solution to 60 °C, and measure the oxidation-reduction potential using an oxidation-reduction potentiometer (for example, an ORP measuring instrument (ORP5 pen ORP meter) manufactured by Semic Corporation).

[0015] Component (a) is specifically one or more selected from sulfites, disulfates, thiosulfates, and iodide salts. Specifically, examples include sodium sulfite (+50 mV), potassium sulfite (+50 mV), sodium bisulfate (+17 mV), potassium bisulfate (+17 mV), potassium iodide (+28 mV), sodium iodide (+28 mV), sodium thiosulfate (+5 mV), and potassium thiosulfate (+5 mV). Component (a) is not particularly limited as long as its oxidation-reduction potential is +71 mV or less. From the perspective of protein detergency, it is preferably one or more selected from sodium sulfite, sodium bisulfate, potassium iodide, and sodium thiosulfate, and more preferably one or more selected from sodium sulfite, sodium bisulfate, and potassium iodide. The values in parentheses indicate the oxidation-reduction potential values.

[0016] From the perspective of protein detergency, the cleaning liquid of the present invention can contain component (a) preferably at 0.0001% by mass or more, more preferably at 0.0005% by mass or more, still more preferably at 0.001% by mass or more, even more preferably at 0.002% by mass or more, even more preferably at 0.005% by mass or more. From the perspectives of protein detergency and the stability of the properties as a preparation, it is preferably 30% by mass or less, more preferably 20% by mass or less, still more preferably 10% by mass or less, even more preferably 8% by mass or less, even more preferably 5% by mass or less, even more preferably 1% by mass or less, even more preferably 0.5% by mass or less, even more preferably 0.1% by mass or less, and even more preferably 0.5% by mass or less.

[0017] From the perspective of protein detergency, the cleaning solution of the present invention can contain the following component (b). Component (b): Chelating agent

[0018] From the perspective of protein detergency, the chelating agent for component (b) preferably has a conditional calcium stability constant pK’Ca of 2.6 or more at pH 7.5 and 60°C. From the perspective of protein detergency, the conditional calcium stability constant pK’Ca of component (b) at pH 7.5 and 60°C is preferably 2.6 or more, more preferably 2.7 or more. From the perspective of protein detergency, it is further preferably 3 or more, even more preferably 3.2 or more. From the perspective of easy availability, it is preferably 15 or less, more preferably 10 or less, and even more preferably 6 or less. For the conditional calcium stability constant pK’Ca of component (b) at pH 7.5 and 60°C, the value measured by the following method is used. Using a calcium ion selective electrode (for example, manufactured by HORIBA), 0.2 mL of a calcium chloride solution at 25°C and 2 g / L is dropped into 100 mL of distilled water at 60°C, and the potential at that time is measured. With the logarithm of the calcium ion concentration at each drop amount on the horizontal axis and the potential on the vertical axis, a first-order approximation formula is calculated. Subsequently, distilled water is added to component (b) to prepare a concentration of 1 g / L, and it is adjusted to pH 7.5 with 1N sodium hydroxide and / or 1N hydrochloric acid to prepare a chelating agent solution. 100 mL of the chelating agent solution is taken out, heated to 60°C, 3 mL of a calcium chloride solution at 25°C and 2 g / L is dropped, and the potential is measured using a calcium ion selective electrode (for example, manufactured by HORIBA). The potential at this time is substituted into the approximation formula to calculate the uncaught calcium concentration A (mol / L) in the chelating agent solution, and it is substituted into the following formula together with the concentration B (mol / L) of the chelating agent to calculate K’Ca, and the logarithm is taken to calculate pK’Ca. K’Ca=(5.4×10 -5 -A) / (A×(B-(5.4×10 -5 -A)

[0019] (b) Specifically, the components include ethylenediaminetetraacetic acid (pK'Ca 6.0), hexametaphosphate (pK'Ca 5.7), polyacrylic acid (pK'Ca 4.2), acrylic acid-maleic acid copolymer (pK'Ca approximately 4.6 (may vary depending on the monomer ratio)), citric acid (pK'Ca 3.4), tripolyphosphate (pK'Ca 3.8), nitrilotriacetic acid (pK'Ca 2.9), glutamine diacetate (pK'Ca 2.7), and one or more selected from these salts, and the protein washing properties are considered. From this viewpoint, the salt is preferably one or more selected from ethylenediaminetetraacetic acid, hexametaphosphate, polyacrylic acid, acrylic acid-maleic acid copolymer, citric acid, tripolyphosphate, nitrilotriacetic acid, glutamine diacetate, and salts thereof; more preferably one or more selected from ethylenediaminetetraacetic acid, hexametaphosphate, polyacrylic acid, acrylic acid-maleic acid copolymer, citric acid, and salts thereof; and even more preferably one or more selected from polyacrylic acid, citric acid, and salts thereof. Examples of salts include alkali metal salts such as sodium and potassium, ammonium salts, or alkanolamine salts such as monoethanolamine and triethanolamine, and from the viewpoint of availability, potassium salts or sodium salts are preferred.

[0020] (b) The polyacrylic acid or salt thereof of component (b) may be a copolymer containing monomers other than acrylic acid that are copolymerizable with acrylic acid (except maleic acid). From the viewpoint of protein washing properties, the molar ratio of monomers copolymerizable with acrylic acid (except maleic acid) in the total constituent monomers is 0 mol% or more, and 5 mol% or less, preferably 3 mol% or less, and more preferably 0 mol%. Furthermore, from the viewpoint of protein washing properties and workability, the weight-average molecular weight of the polyacrylic acid or salt thereof of component (b) is 1,000 or more, preferably 2,000 or more, and 20,000 or less, and preferably 17,000 or less. This weight-average molecular weight was determined by gel permitting chromatography using a mixed solvent of acetonitrile and water (phosphate buffer solution) as the developing solvent, with polyacrylic acid (e.g., Sigma-Aldrich molecular weight standard reagent), which is a commonly available polymer standard reagent with a known molecular weight, as the standard substance.

[0021] (b) The acrylic acid-maleic acid copolymer or salt thereof of component (b) has an acrylic acid / maleic acid molar ratio of 0.25 or more, preferably 0.4 or more, and 4 or less, preferably 2.5 or less, from the viewpoint of protein washing properties. The acrylic acid-maleic acid copolymer or salt thereof of component (b) may also be a copolymer containing monomers other than acrylic acid and maleic acid that are copolymerizable with acrylic acid and / or maleic acid. From the viewpoint of protein washing properties, the molar ratio of monomers other than acrylic acid and maleic acid that are copolymerizable with acrylic acid and / or maleic acid in the total constituent monomers is 0 mol% or more, and 5 mol% or less, preferably 3 mol% or less, more preferably 0 mol%. Furthermore, from the viewpoint of protein washing properties and workability, the weight-average molecular weight of the acrylic acid-maleic acid copolymer or salt thereof of component (b) is 1,000 or more, preferably 2,000 or more, preferably 100,000 or less, more preferably 90,000 or less. This weight-average molecular weight was determined by gel permitting chromatography using a mixed solvent of acetonitrile and water (phosphate buffer solution) as the developing solvent, with polyacrylic acid (e.g., Sigma-Aldrich molecular weight standard reagent), a commonly available polymer standard reagent with a known molecular weight, as the standard substance.

[0022] The washing solution of the present invention may contain component (b) in an amount of preferably 0.0001% by mass or more, more preferably 0.0005% by mass or more, even more preferably 0.001% by mass or more, even more preferably 0.002% by mass or more, even more preferably 0.005% by mass or more, even more preferably 0.01% by mass or more, and preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 3% by mass or less, even more preferably 1% by mass or less, even more preferably 0.5% by mass or less, even more preferably 0.1% by mass or less, and even more preferably 0.05% by mass or less, from the viewpoint of protein washing ability.

[0023] In the washing solution of the present invention, the mass ratio (a) / (b) of the content of component (a) to the content of component (b) is preferably 0.05 or more, more preferably 0.1 or more, even more preferably 0.15 or more, even more preferably 0.2 or more, even more preferably 0.3 or more, and preferably 3.0 or less, more preferably 2.5 or less, even more preferably 2 or less, even more preferably 1.5 or less, and even more preferably 1 or less.

[0024] The cleaning solution of the present invention may contain the following component (c) from the viewpoint of protein cleaning ability. (c) Ingredients: Anionic surfactant

[0025] (c) The component may be one or more selected from alkyl or alkenylbenzenesulfonic acid, polyoxyalkylene alkyl or alkenyl ether sulfate ester, alkyl or alkenyl sulfate ester, alkanesulfonic acid, olefin sulfonic acid, fatty acid, and salts thereof. From the viewpoint of protein cleaning ability, the number of carbon atoms in the alkyl or alkenyl group of these anionic surfactants is preferably 6 or more, more preferably 8 or more, preferably 22 or less, and more preferably 18 or less. The salts of these anionic surfactants may be, for example, alkali metal salts such as sodium salts and potassium salts, ammonium salts, etc.

[0026] (c) As for component (c), alkyl or alkenyl sulfate esters or salts thereof, having 6 to 16 carbon atoms, are preferred from the viewpoint of protein washing properties and foam suppression properties. The aforementioned carbon number refers to the carbon number of the alkyl or alkenyl group. From the viewpoint of protein washing properties, the alkyl or alkenyl group has 6 or more carbon atoms, preferably 8 or more, more preferably 10 or more, and from the viewpoint of foam suppression properties, it has 16 or less carbon atoms, preferably 14 or less, more preferably 12 or less, and is linear or branched, preferably linear. Furthermore, from the viewpoint of protein washing properties, the carbon atoms of the alkyl or alkenyl group bonded to the sulfate ester group are preferably primary carbon atoms. Examples of salts of alkyl or alkenyl sulfate esters with 6 to 16 carbon atoms include alkali metal salts such as sodium salts and potassium salts, and ammonium salts. Component (c) is preferably, from the viewpoint of protein washing properties, an alkyl sulfate ester with 10 carbon atoms or a salt thereof.

[0027] The cleaning solution of the present invention may contain component (c) in an amount of 0.0001% by mass or more, more preferably 0.0005% by mass or more, even more preferably 0.001% by mass or more, even more preferably 0.002% by mass or more, even more preferably 0.005% by mass or more, and preferably 20% by mass or less, even more preferably 10% by mass or less, even more preferably 5% by mass or less, even more preferably 1% by mass or less, even more preferably 0.5% by mass or less, even more preferably 0.1% by mass or less, and even more preferably 0.05% by mass or less, from the viewpoint of protein cleaning ability.

[0028] In the washing solution of the present invention, the mass ratio (a) / (c) of the content of component (a) to the content of component (c) is preferably 0.01 or more, more preferably 0.05 or more, even more preferably 0.08 or more, even more preferably 0.1 or more, even more preferably 0.5 or more, and preferably 10 or less, more preferably 6 or less, even more preferably 4 or less, and even more preferably 2 or less.

[0029] The cleaning solution of the present invention may contain the following component (d) from the viewpoint of protein cleaning ability, oil cleaning ability and finish of the cleaned product. (d) Ingredients: Nonionic surfactant

[0030] (d) Examples of nonionic surfactants for component (d) include polyoxyalkylene alkyl ethers, polyoxyalkylene alkenyl ethers, polyoxyalkylene sorbitan fatty acid esters, alkyl glycosides, alkyl polyglycosides, sucrose fatty acid esters, alkyl polyglyceryl ethers, etc., and one or more of these can be used. From the viewpoint of protein washing properties, the number of carbon atoms in the alkyl or alkenyl group of these nonionic surfactants is preferably 6 or more, more preferably 8 or more, and preferably 22 or less, and more preferably 18 or less. From the viewpoint of protein washing properties, the alkylene oxide of polyoxyalkylene alkyl ethers, polyoxyalkylene alkenyl ethers, and polyoxyalkylene sorbitan fatty acid esters preferably contains an alkylene oxide selected from ethylene oxide and propylene oxide, and from the viewpoint of protein washing properties, the average number of added moles of alkylene oxide is preferably 2 or more, and preferably 25 or less.

[0031] As the nonionic surfactant, polyoxyalkylene alkyl ether (hereinafter referred to as component (d1)) is preferred. From the viewpoint of protein washing properties, the number of carbon atoms in the alkyl group of component (d1) is preferably 10 or more, more preferably 12 or more, preferably 20 or less, more preferably 18 or less, and even more preferably 16 or less. From the viewpoint of protein washing properties, the alkylene oxide in component (d1) is preferably an alkylene oxide selected from ethylene oxide and propylene oxide. Furthermore, from the viewpoint of protein washing properties, the average number of moles of alkylene oxide added to component (d1) is preferably 2 or more, more preferably 4 or more, preferably 20 or less, and more preferably 18 or less.

[0032] (d1) Component may be a secondary alcohol alkylene oxide adduct having 10 to 24 carbon atoms. From the viewpoint of protein washing properties, the carbon number of the secondary alcohol is preferably 10 or more, more preferably 12 or more, preferably 20 or less, more preferably 18 or less, and even more preferably 16 or less. From the viewpoint of protein washing properties, an alkylene oxide having 2 to 4 carbon atoms is preferred. From the viewpoint of protein washing properties, the alkylene oxide is preferably an alkylene oxide selected from ethylene oxide and propylene oxide. From the viewpoint of protein washing properties, the average number of added moles of alkylene oxide is preferably 2 or more, more preferably 4 or more, preferably 20 or less, and more preferably 18 or less.

[0033] The cleaning solution of the present invention may contain component (d) in an amount of preferably 0.00001% by mass or more, more preferably 0.0001% by mass or more, even more preferably 0.0005% by mass or more, even more preferably 0.001% by mass or more, even more preferably 0.005% by mass or more, preferably 10% by mass or less, more preferably 8% by mass or less, even more preferably 5% by mass or less, even more preferably 1% by mass or less, even more preferably 0.5% by mass or less, even more preferably 0.1% by mass or less, even more preferably 0.05% by mass or less, and even more preferably 0.01% by mass or less, from the viewpoint of protein cleaning ability, oil cleaning ability and the finish of the cleaned product.

[0034] In the cleaning solution of the present invention, the mass ratio (a) / (d) of the content of component (a) to the content of component (d) is preferably 0.1 or more, more preferably 0.2 or more, even more preferably 0.3 or more, even more preferably 0.4 or more, even more preferably 0.8 or more, even more preferably 1.2 or more, and preferably 5 or less, more preferably 4 or less, even more preferably 3 or less, and even more preferably 2 or less.

[0035] In the cleaning solution of the present invention, the content ranges of component (a), component (b), component (c), and component (d) can be set by arbitrarily selecting and combining the aforementioned numerical values.

[0036] From the viewpoint of reducing the risk of chemical burns, the cleaning solution of the present invention has a pH of 6 or higher, preferably 6.2 or higher, more preferably 6.5 or higher, and 11 or lower, preferably 10 or lower, more preferably 9 or lower at 25°C. This pH is determined by the following measurement method. (1) Method for measuring pH Connect a pH measuring composite electrode (e.g., glass ground-joint sleeve type, manufactured by Horiba, Ltd.) with saturated potassium chloride aqueous solution (3.33 mol / L) as the internal solution of the pH electrode to a pH meter (e.g., pH / ion meter F-23, manufactured by Horiba, Ltd.). Next, fill 100 mL beakers with pH 4.01 standard solution (phthalate standard solution), pH 6.86 (neutral phosphate standard solution), and pH 9.18 standard solution (borate standard solution), and immerse them in a 25°C constant temperature bath for 30 minutes. Immerse the pH measuring electrode in the standard solutions adjusted to constant temperature for 3 minutes and perform calibration in the order of pH 6.86 → pH 9.18 → pH 4.01. Adjust the automatic dishwasher detergent composition to be measured to 25°C, immerse the electrode of the pH meter in the sample, and measure the pH after 1 minute.

[0037] The cleaning solution of the present invention contains water. The water is not particularly limited, but examples include tap water, well water, deionized water, and distilled water. Preferably, the amount of water used is the amount of the remainder of the cleaning solution (totaling 100% by mass). The water content can be, for example, 20% by mass or more, further 30% by mass or more, further 50% by mass or more, further 55% by mass or more, further 60% by mass or more, further 65% by mass or more, further 70% by mass or more, further 80% by mass or more, further 90% by mass or more, further 95% by mass or more, and further 99% by mass or more in the cleaning solution.

[0038] The cleaning solution of the present invention may contain ingredients such as surfactants, enzymes (protein-degrading enzymes, lipid-degrading enzymes, carbohydrate-degrading enzymes, etc.), solvents, hydrotropes, dispersants, pH adjusters, thickeners, viscosity modifiers, fragrances, colorants, antioxidants, preservatives, antifoaming agents, bleaching agents, and bleaching activators (excluding those falling under ingredients (a) to (d)), as long as they do not impair the purpose of the present invention.

[0039] The present invention provides a method for cleaning hard surfaces, preferably for cleaning tableware and / or hard articles around the kitchen, preferably for cleaning tableware. Hard materials used around the kitchen are items used in the vicinity of the kitchen, and specifically, (1) Refrigerators, cupboards, and other storage places for food, dishes, and cooking utensils, (2) Drains, countertops, range hoods, sinks, gas ranges, microwave ovens and other food preparation areas, (3) Floors, walls, etc. surrounding the storage area and the cooking area. In this invention, these are referred to as "hard articles for kitchen use" for convenience. Also, as for tableware, specifically, (i) Dishes such as plates and bowls, (ii) Storage containers such as Tupperware and glass jars, (iii) Cooking utensils such as knives, cutting boards, pots, frying pans, and fish grills, (iv) Cooking appliances such as food processors and blenders, etc. These include components and utensils that come into contact with the food ingredients. For convenience, in this invention, these will be referred to as "tableware." Furthermore, the cleaning method for hard surfaces of the present invention is preferably applied to items selected from tableware, storage containers, cooking utensils, and kitchen appliances, and more preferably to items selected from plates, bowls, Tupperware, bottles, knives, cutting boards, pots, frying pans, fish grills, food processors, and mixers.

[0040] The hard surface cleaning method of the present invention targets hard articles made of materials such as plastic (including silicone resin), metal, ceramic, wood, and combinations thereof. The hard surface cleaning method of the present invention can effectively clean these hard articles, preferably dishes and / or kitchen items, of protein-containing stains, particularly those containing protein derived from egg yolks.

[0041] In the cleaning method for hard surfaces of the present invention, it is preferable that the contact between the hard surface and the cleaning solution of the present invention is performed using an automatic dishwasher.

[0042] In the cleaning method for hard surfaces of the present invention, the cleaning solution of the present invention is brought into contact with the hard surface for a period of time, preferably 20 seconds or more, more preferably 30 seconds or more, even more preferably 40 seconds or more, and even more preferably 60 seconds or more, from the viewpoint of protein cleaning performance, and preferably 600 seconds or less, more preferably 300 seconds or less, even more preferably 180 seconds or less, and even more preferably 100 seconds or less, from the viewpoint of cleaning efficiency.

[0043] In the hard surface cleaning method of the present invention, the temperature of the cleaning solution of the present invention is preferably 30°C or higher, more preferably 35°C or higher, even more preferably 40°C or higher, even more preferably 50°C or higher, and preferably 80°C or lower, more preferably 70°C or lower, and even more preferably 65°C or lower, from the viewpoint of protein cleaning performance.

[0044] In the hard surface cleaning method of the present invention, the flow rate when the cleaning solution is brought into contact with the tableware is preferably 5 m / min or more, more preferably 10 m / min or more, even more preferably 50 m / min or more, and preferably 2000 m / min or less, more preferably 1000 m / min or less, even more preferably 500 m / min or less, even more preferably 250 m / min or less, and even more preferably 150 m / min or less, from the viewpoint of protein cleaning performance.

[0045] After bringing the cleaning solution of the present invention into contact with the hard surface, the hard surface is rinsed with water. The temperature of the water used to rinse the hard surface is 50°C or higher, preferably 55°C or higher, more preferably 60°C or higher, and 80°C or lower. The rinsing time for hard surfaces is 4 seconds or more, preferably 5 seconds or more, and 10 seconds or less, preferably 9 seconds or less. The flow velocity of the rinse water is preferably 5 m / min or more, more preferably 10 m / min or more, even more preferably 100 m / min or more, and preferably 2500 m / min or less, more preferably 2000 m / min or less, and even more preferably 1500 m / min or less.

[0046] In the present invention, the automatic dishwasher can be any dishwasher that is generally available on the market, and a household automatic dishwasher can also be used, but a commercial automatic dishwasher is preferred. When washing with a commercial dishwasher, the cleaning solution of the present invention is generally prepared by mixing a concentrated composition of the cleaning solution of the present invention with water. At that time, the concentrated composition is arbitrarily transferred in a fixed amount into the commercial dishwasher by a supply device, and an appropriate concentration of the cleaning solution is maintained. The concentrated composition is supplied, for example, by inserting a tube specifically for the commercial dishwasher directly into a container such as a plastic container filled with the composition and drawing it up. The cleaning solution is then supplied into the commercial dishwasher. [Examples]

[0047] The ingredients used in the examples and comparative examples are summarized below.

[0048] <(a) Components> Sodium sulfite: Oxidation-reduction potential 50mV, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Sodium disulfate: Oxidation-reduction potential 17mV, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. • Potassium iodide: Oxidation-reduction potential 28mV, manufactured by Fujifilm Wako Pure Chemical Corporation.

[0049] <(a') component (comparative component of (a) component)> • Sodium dithionite: Oxidation-reduction potential 76mV, manufactured by Fujifilm Wako Pure Chemical Corporation. • Thiourea dioxide: Oxidation-reduction potential 147mV, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

[0050] The oxidation-reduction potentials of components (a) and (a') were measured by the following method. Distilled water was added to component (a) or (a') to a concentration of 0.016 mol / L, and 1 mol / L hydrochloric acid and / or sodium hydroxide was added to adjust the pH to 7.5 to prepare a solution. The solution was heated to 60°C, and the oxidation-reduction potential was measured using an ORP meter (ORP5 pen ORP meter) manufactured by Sem Corporation.

[0051] <(b) Component> • Citric acid: pK'Ca3.4, manufactured by Showa Chemical Co., Ltd.

[0052] (b) The conditional calcium stability constant pK'Ca of component at pH 7.5 and 60°C was measured by the following method. Using a calcium ion selective electrode manufactured by HORIBA, 0.2 mL of a 2 g / L calcium chloride solution at 25°C was added dropwise to 100 mL of distilled water at 60°C, and the potential was measured. A first-order approximation formula was calculated by plotting the logarithm of the calcium ion concentration at each dropwise volume on the x-axis and the potential on the y-axis. Subsequently, distilled water was added to component (b) to prepare a concentration of 1 g / L, and the pH was adjusted to 7.5 with 1N sodium hydroxide and / or 1N hydrochloric acid to prepare a chelating agent solution. 100 mL of the chelating agent solution was taken out, heated to 60°C, and 3 mL of a 2 g / L calcium chloride solution at 25°C was added dropwise. The potential was measured using a calcium ion selective electrode manufactured by HORIBA. The potential at this time was substituted into the approximation formula to calculate the uncaptured calcium concentration A (mol / L) in the chelating agent solution. This was substituted into the following formula along with the chelating agent concentration B (mol / L) to calculate K'Ca, and the logarithm was taken to calculate pK'Ca. K'Ca = (5.4 × 10 -5 -A) / (A×(B-(5.4×10 -5 -A)

[0053] <(c) component> • C10AS: Sodium decyl sulfate, manufactured by Kao Corporation in "Emal 3F"

[0054] <(d) component> • secC12-14EO7PO8.5: Softanol EP7085, manufactured by Nippon Shokubai Co., Ltd., is a nonionic surfactant obtained by adding an average of 7 moles of ethylene oxide and an average of 8.5 moles of propylene oxide in that order to a secondary alcohol with 12 to 14 carbon atoms.

[0055] [Measurement of disulfide bond cleavage rate] The disulfide bond cleavage rate of disulfide bond-breaking agents on egg yolk stains was measured using the following procedure. A 100 μM ABD-F solution (hereinafter referred to as solution (A)) was prepared by adding 4-(Aminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole (ABD-F) manufactured by Tokyo Chemical Industry Co., Ltd. to a pH 8 0.1 M borate buffer. A 1 mM EDTA2Na solution was prepared by adding disodium ethylenediaminetetraacetate (EDTA2Na) to a pH 8 0.1 M borate buffer. To this solution, 1000 ppm of egg yolk, a stain containing proteins with disulfide bonds, and component (a) or (a') as a disulfide bond-clearing agent were added in an amount twice the concentration in the cleaning solution of the present invention used in the cleaning power evaluation below, to prepare solution (B). 500 μL each of solution (A) and solution (B) were placed in an Eppendorf tube and mixed. The mixture was heated at 50°C for 5 minutes using an ATTO Corporation block heater (WSC-2620), and then cooled in ice water for 10 minutes. After cooling, 300 μL of 0.1 M hydrochloric acid was added to the mixture. 200 μL of the mixture was placed in a 96-well plate, and fluorescence measurements were performed using a Corona Electric Co., Ltd. SH-9000 (excitation wavelength / measurement wavelength = 389 / 513 nm, measurement sensitivity × 100). Next, 1000 ppm of egg yolk, which is a contaminant containing proteins with disulfide bonds, was added to an aqueous NaOH solution adjusted to pH 11 to prepare solution (B). This solution was then mixed with solution (A) to prepare a mixture using NaOH as a disulfide bond-clearing agent, and fluorescence measurements were performed in the same manner as described above. Next, in preparing solution (B), glutathione (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), a simple compound containing disulfide bonds, was added in varying concentrations instead of egg yolk, and 1000 ppm of sodium sulfite was added as a disulfide bond-cleaving agent. Otherwise, solution (B) was prepared in the same manner as above, and these were mixed with solution (A) to prepare various mixtures with varying glutathione concentrations. Fluorescence measurements were performed in the same manner as above to create calibration curves for glutathione concentration and fluorescence intensity. Based on this calibration curve and the fluorescence measurement results of stains containing proteins with disulfide bonds for each disulfide bond-cleaving agent, the amount of disulfide bond cleavage by each disulfide bond-cleaving agent was estimated. The fluorescence measurement results when NaOH was used as the disulfide bond-cleaving agent were set as 100% disulfide bond cleavage rate, and the disulfide bond cleavage rate of each disulfide bond-cleaving agent was calculated.

[0056] The cleaning power against egg yolk stains was evaluated using the concentrated compositions shown in Tables 1 and 2, following the procedure below. The results are shown in Tables 1 and 2. The pH of the compositions in Tables 1 and 2 was adjusted with sodium hydroxide and / or sulfuric acid as needed.

[0057] [Cleaning power evaluation] (1) The mass (mass A) of a SUS stainless steel tray (external dimensions: width 258 mm x depth 177 mm x height 18 mm, internal bottom dimensions: 235 mm x 155 mm) was measured. (2) 3g of egg yolk was spread onto the stainless steel tray and dried at room temperature for at least 3 hours. (3) The mass (mass B) of the stainless steel tray after drying was measured. (4) A JWE-400TA dishwasher manufactured by Hoshizaki Electric Co., Ltd. was used. The concentrated compositions in Tables 1 and 2 were diluted with water to a concentration of 0.2% by mass to prepare the washing solution. The dried stainless steel trays were washed at the washing time and washing solution temperature described in Tables 1 and 2, with a washing solution flow rate of 100 m / min. A few seconds later, they were rinsed with 80°C rinse water for 7 seconds with a rinse water flow rate of 1000 m / min. A portion of the washing solution was taken out and its pH was measured at 25°C. (5) The mass (mass C) of the stainless steel tray after washing was measured, and the rate of change in mass was evaluated as the rate of removal of egg yolk stains. Specifically, the rate of change in mass can be calculated using the following formula. Mass change rate (%) = [BC / BA] × 100

[0058] [Table 1]

[0059] [Table 2]

Claims

1. A method for cleaning a hard surface using an automatic dishwasher, comprising: contacting a hard surface to which a protein-containing stain is attached with a cleaning solution containing the following components (a), (b), (c), and (d), wherein the content of component (a) is 0.001% by mass or more and 0.1% by mass or less, and the cleaning solution has a pH of 6 or more and 9 or less at 25°C, at a temperature of 40°C or more and 80°C or less, for 20 seconds or more and 100 seconds or less, such that the rate of disulfide bond cleavage in or between protein molecules is 30% or more and 100% or less. (a) Ingredients: Reducing agent with an oxidation-reduction potential of +71 mV or less (b) Ingredients: Chelating agent (c) Ingredients: Anionic surfactant (d) Ingredients: Nonionic surfactant

2. (a) The method for cleaning a hard surface according to claim 1, wherein the component is a reducing agent having an oxidation-reduction potential of 0 mV or more and +71 mV or less.

3. (a) The method for cleaning a hard surface according to claim 1 or 2, wherein the component is one or more selected from sulfites, disulfates, thiosulfates, and iodides.

4. (a) A method for cleaning a hard surface according to any one of claims 1 to 3, wherein the component is one or more selected from sodium sulfite, potassium sulfite, sodium disulfate, potassium disulfate, sodium thiosulfate, potassium thiosulfate, sodium iodide, and potassium iodide.

5. (b) A method for cleaning a hard surface according to any one of claims 1 to 4, wherein the component is a chelating agent having a conditional calcium stability constant pK'Ca of 2.6 or higher at pH 7.5 and 60°C.

6. (b) A method for cleaning a hard surface according to any one of claims 1 to 5, wherein component (b) is one or more selected from ethylenediaminetetraacetic acid, hexametaphosphate, polyacrylic acid, acrylic acid-maleic acid copolymer, citric acid, tripolyphosphate, nitrilotriacetic acid, glutamine diacetate, and salts thereof.

7. A method for cleaning a hard surface according to any one of claims 1 to 6, wherein the mass ratio (a) / (b) of the content of component (a) to the content of component (b) in the cleaning solution is 0.1 or more and 3.0 or less.

8. (c) A method for cleaning a hard surface according to any one of claims 1 to 7, wherein the component is one or more selected from alkyl or alkenylbenzenesulfonic acid, polyoxyalkylene alkyl or alkenyl ether sulfate, alkyl or alkenyl sulfate, alkanesulfonic acid, olefin sulfonic acid, fatty acid, and salts thereof.

9. (c) The method for cleaning a hard surface according to any one of claims 1 to 8, wherein the component is an alkyl or alkenyl sulfate ester having 6 to 16 carbon atoms or a salt thereof.

10. The method for cleaning a hard surface according to any one of claims 1 to 9, wherein the mass ratio (a) / (c) of the content of component (a) to the content of component (c) in the cleaning solution is 0.1 or more and 10 or less.

11. The method for cleaning a hard surface according to any one of claims 1 to 10, wherein the mass ratio (a) / (d) of the content of component (a) to the content of component (d) in the cleaning solution is 0.1 or more and 5 or less.

12. A method for cleaning a hard surface according to any one of claims 1 to 11, wherein the contact between the hard surface and the cleaning solution is performed using a commercial automatic dishwasher.

13. A method for cleaning a hard surface according to any one of claims 1 to 12, wherein after bringing the cleaning solution into contact with the hard surface, the hard surface is rinsed with water at a temperature of 50°C or 80°C for 4 seconds or more or 10 seconds or less.

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