JP2023004435A - Dish washing method - Google Patents

Abstract

To suppress increase in recontamination of dishes and the like by contaminants in washing liquid when washing dishes under a washing condition that contaminants are mixed in the washing liquid by using an automatic dishwasher equipped with a washing liquid tank for storing washing liquid and a washing tank where the washing liquid supplied from the washing liquid tank is caused to be brought into contact with the dishes.SOLUTION: At least a part of washing liquid used for washing dishes is recovered in a washing liquid tank, and is reused at least as a part of new washing liquid. The reused washing liquid is caused to contain (a) a protein degrading enzyme (hereinafter called component (a)), and the washing liquid is brought into contact with dishes after an enzymatic activity value of the washing liquid is caused to become 5 U/mL or more.SELECTED DRAWING: None

Description

The present invention relates to a method for washing tableware. In particular, it relates to a method of washing dishes using an automatic dishwasher.

In recent years, among automatic dishwashers, water-saving automatic dishwashers that use less than half the rinsing water of conventional automatic dishwashers have become popular.
Automatic dishwashers include a conveyor type in which tableware and the like are set on a conveyor, a door type in which a door is opened and closed to take in and out dishes and the like, and an under-counter type which is provided under the counter. In hotels, catering establishments, restaurants, pubs, convenience stores, and the like, automatic dishwashers of a preferred type are used according to the amount of dishes to be washed, installation space, and the like. From the viewpoint of reducing the amount of detergent used and running costs, efforts are being made to reduce the amount of water used in all automatic dishwashers. In an automatic dishwashing machine, for example, the cleaning liquid in the cleaning liquid tank is circulated to wash dishes, etc., and then this cleaning liquid is collected in the cleaning liquid tank for reuse in the next wash, and all or part of the rinse water is used. is made to flow into the cleaning liquid tank, and the dirt accumulated in the cleaning liquid tank is overflowed and discharged.

Patent Document 1 discloses an automatic Dishwasher cleaning compositions are disclosed.
Patent Document 2 discloses (A) a predetermined nonionic surfactant, (B) a predetermined nonionic surfactant, (C) alkanolamine, (D) an enzyme, (E) n-hexyl glycoside, (F) Disclosed is a liquid hard surface cleaner composition for use in an automatic dishwashing machine containing a calcium additive, (G) water.
U.S. Pat. No. 5,300,000 discloses an automatic dishwasher detergent composition comprising (a) a predetermined ester and (b) a bleach activator.
Patent Document 4 describes a dishwasher containing (a) a nonionic surfactant, (b) a polymer chelating agent, (c) a specific weakly acidic or weakly alkaline water-soluble electrolyte, and a detergent enzyme. Disclosed is a cleaning composition for .

WO2013/175659 JP 2018-024723 A JP 2012-214539 A JP 2005-154716 A

In water-saving automatic dishwashers, rinsing water is also conserved, so there is a tendency for the reused washing liquid to accumulate more dirt. In particular, automatic dishwashers for business use have a large number of times of washing, so this tendency is remarkable. In addition, repeated use and washing of tableware tends to accumulate stains on the tableware and the like.
When the dishes, etc., are washed repeatedly under washing conditions in which dirt is mixed in the washing liquid, if the recontamination of the dishes, etc. due to the dirt in the washing liquid increases, the dirt tends to accumulate on the dishes, etc. due to the repeated washing.
Therefore, in automatic dishwashers, it is required to suppress an increase in recontamination of tableware and the like due to dirt in the washing liquid when washing is performed under washing conditions in which dirt is mixed in the washing liquid.

SUMMARY OF THE INVENTION The present invention provides a method for washing tableware that suppresses an increase in recontamination of the tableware and the like due to dirt in the washing liquid when washing is performed under washing conditions in which dirt is mixed in the washing liquid.

The present invention relates to a method for washing dishes using an automatic dishwasher, comprising a washing liquid tank containing a washing liquid, and a washing tank for bringing the washing liquid supplied from the washing liquid tank into contact with the dishes, comprising:
At least part of the cleaning liquid used for washing dishes is collected in a cleaning liquid tank and reused as at least a part of new cleaning liquid, and (a) protease [hereinafter referred to as component (a) is added to the recycled cleaning liquid. ], the enzymatic activity value of the washing liquid is adjusted to 5 U/mL or more, and then the washing liquid is brought into contact with the dishes.

According to the present invention, there is provided a method for washing tableware that suppresses an increase in recontamination of the tableware due to dirt in the washing liquid when washing is performed under washing conditions in which dirt is mixed in the washing liquid.

The inventors analyzed the dirt accumulated in the washing liquid of the automatic dishwasher and the adhered components of the dishes recontaminated by the dirt in the washing liquid. It was found that the composition ratio of the adhering dirt was different. For example, it was found that even if the constituent ratios of stains accumulated in the washing liquid were lipid, protein, and sugar in descending order, protein stains were relatively abundant in the redeposited components adhering to the tableware. This is because when the protein is exposed to high temperatures in the washing process of tableware, especially in the rinsing process where the amount of proteolytic enzyme is extremely small, the protein becomes hydrophobic due to heat denaturation, making it easier to stick to the tableware. This is thought to be because
Based on these findings, the inventors have made intensive studies and completed the present invention. In the method of washing tableware of the present invention, the washing liquid used for washing is recovered and reused as a new washing liquid. decompose. As a result, it is possible to suppress reattachment of dirt accumulated in the cleaning liquid to the tableware, and also to suppress the accumulation of dirt on the tableware even when the tableware is washed repeatedly. That is, when washing is performed under washing conditions in which dirt is mixed in the washing liquid, it is possible to suppress the increase in recontamination of the tableware, etc. due to the dirt in the washing liquid, and it is thought that the finish of the tableware, etc. is improved. In addition, after repeated washing and use of dishes using the cleaning liquid, the parts of the dishes that did not come into direct contact with the ingredients, such as the back of the dishes and the glass cups used for drinking water, etc. The adhesion and accumulation of contaminants in the cleaning liquid are suppressed. As a result, it is considered that the degree of deterioration of the finish of the tableware is reduced, and the finish of the tableware and the like is improved.

A method for washing dishes according to the present invention is a method for washing dishes using an automatic dishwasher comprising a washing liquid tank containing a washing liquid, and a washing tank for bringing the washing liquid supplied from the washing liquid tank into contact with the dishes. ,
At least part of the cleaning liquid used for washing dishes is collected in a cleaning liquid tank and reused as at least a part of new cleaning liquid, and (a) protease [hereinafter referred to as component (a) is added to the recycled cleaning liquid. ], the enzymatic activity value of the washing liquid is adjusted to 5 U/mL or more, and then the washing liquid is brought into contact with the dishes.
The enzymatic activity value of the washing liquid may be the enzymatic activity value for protein, ie, the enzymatic activity value for protein degradation.

In the tableware washing method of the present invention, the washing liquid is reused one or more times. From the viewpoint that the effects of the present invention can be obtained more remarkably, the dishwashing method of the present invention is preferably a dishwashing method in which the cleaning liquid is reused two or more times, more preferably three times or more, and still more preferably. It is 4 times or more, and more preferably 5 times or more. As the number of times the washing liquid is reused increases, the effect of the method for washing tableware of the present invention becomes more pronounced.
From the standpoint that the effects of the present invention can be obtained more remarkably, the method for washing tableware of the present invention is preferably a method of washing tableware in which the same tableware is washed twice or more using the washing liquid, and more preferably three times. or more, more preferably 4 times or more, and even more preferably 5 times or more. The effect of the method for washing tableware of the present invention becomes more pronounced as the number of times the same tableware is washed using the washing liquid again increases. Here, washing the same tableware twice or more by using the washing liquid again includes using the tableware after washing and then subjecting the used tableware to the next washing.

First, the component (a) used in the washing method for tableware will be described.

<(a) Protease>
Component (a) is a proteolytic enzyme. As component (a), one or more proteolytic enzymes selected from proteases and peptidases can be used, and proteases are preferred. Component (a) is not particularly limited as long as it is commonly used in detergent compositions. carboxypeptidase A, carboxypeptidase B, aminopeptidase, aspergylopeptidase A, aspergylopeptidase B and the like. Crude enzymes and their granules can be used as well as their purified fractions. Commercially available enzymes (protease formulations) include, for example, alkaline proteases such as Ovozyme, Savinase, Evalase, Alcalase, Esperase, Kannase, Durazyme (registered trademark; manufactured by Novozyme), Maxatase, Maxapem, Maxacal, Properase, Plafect, Plafect OX (registered trademark; manufactured by Genencore), Brap (registered trademark; manufactured by Henkel), KAP (manufactured by Kao Corporation), API21 (manufactured by Showa Denko KK), Neutrase (registered trademark; manufactured by Novozyme) as a neutral protease ). As component (a), alkaline protease can be particularly preferably used.

Next, the detergent composition for automatic dishwashers (hereinafter referred to as the detergent composition of the invention) used in the method for washing tableware of the invention will be described.

<Cleaning agent composition>
The cleaning composition of the present invention contains component (a). The cleaning composition of the present invention can contain one or more of the components (a) as described above. The detergent composition of the present invention comprises, in addition to component (a), (b) an alkaline agent [hereinafter referred to as component (b)], (c) a surfactant [hereinafter referred to as component (c)] and (d) a chelate. It may contain one or more selected from agents [hereinafter referred to as component (d)].

Component (b) is an alkaline agent. As the alkaline agent, one or more selected from alkali metal hydroxides, alkali metal carbonates, alkali metal silicates and amine compounds can be used.
Examples of alkali metal hydroxides include sodium hydroxide and potassium hydroxide.
Alkali metal carbonates include sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate. Anhydrous salt of sodium carbonate known as soda ash may also be used as component (b).
Examples of alkali metal silicates include sodium silicate and potassium silicate. Examples of sodium silicate include sodium orthosilicate, sodium metasilicate, sodium silicate No. 1, sodium silicate No. 2, sodium silicate No. 3, sodium metasilicate pentahydrate, sodium metasilicate nonahydrate and the like. Potassium silicates include potassium orthosilicate, potassium metasilicate, A potassium silicate, B potassium silicate, and C potassium silicate. Specifically, as the component (b), crystalline layered sodium silicate (manufactured by Tokuyama Co., Ltd., "PURIFEED") and the like can be used. Also, an amorphous alkali metal silicate may be used. The alkali metal silicate is also effective as an antioxidant for tableware.
Alkanolamine can be mentioned as an amine compound. In the present invention, primary alkanolamines are particularly preferred, and specific examples include monoethanolamine. Among these alkali agents, alkali metal carbonates are preferred.
The alkaline agent can be used in the form of powder or granules. Granules can be used by appropriately adjusting the particle size and bulk specific gravity by granulation treatment or the like.

Component (c) is a surfactant. Component (c) includes one or more selected from nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants. , and anionic surfactants are preferred, and nonionic surfactants are more preferred.

Nonionic surfactants include, for example, polyoxyethylene alkyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, polyoxyalkylene dialkyl ethers, polyoxyethylene alkenyl ethers, polyoxyalkylene alkylphenyl ethers, reverse pluronic block polymers, reverse Tetronic block polymer, sucrose fatty acid ester, sorbitan fatty acid ester, polyethylene glycol fatty acid ester, glycerin fatty acid ester, polyglycerin fatty acid ester, propylene glycol fatty acid ester, polypropylene glycol fatty acid ester, coconut fatty acid diethanolamide, lauric acid diethanolamide, lauric acid myristic acid diethanolamide, myristic acid diethanolamide, oleic acid diethanolamide, palm kernel fatty acid diethanolamide, alkyl glucosides, amine oxides and the like. A reverse pluronic block polymer and a reverse tetronic block polymer are preferred. These nonionic surfactants may be used alone or in combination of two or more.

(d) Component is a chelating agent. As component (d), one or more chelating agents selected from aminocarboxylic acid-based, hydroxycarboxylic acid-based, phosphoric acid-based, ether carboxylate, and phosphonic acid-based chelating agents can be used.

Aminocarboxylic acid-based chelating agents include ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), methylglycinediacetic acid (MGDA), diethylenetriaminepentaacetic acid (DTPA), hydroxyethylethylenediaminetriacetic acid (HEDTA), triethylene Tetraminehexaacetic acid (TTHA), glutamic diacetic acid (GLDA), hydroxyethyliminodiacetic acid (HIDA), dihydroxyethylglycine (DHEG), 1,3-propanediaminetetraacetic acid (PDTA), 1,3-diamino-2- Hydroxypropanehexaacetic acid (DPTA-OH), aspartic acid diacetic acid (ASDA), ethylenediaminesuccinic acid (EDDS), salts thereof, and the like.

Examples of hydroxycarboxylic acid-based chelating agents include malic acid, succinic acid, citric acid, lactic acid, tartaric acid, gluconic acid, and salts thereof.
Examples of phosphoric acid-based chelating agents include tripolyphosphoric acid and hexametaphosphate.

Phosphonic acid-based chelating agents include hydroxyethylidene diphosphonic acid (HEDP), nitrilotrismethylene phosphonic acid (NTMP), phosphonobutanetricarboxylic acid (PBTC), ethylenediaminetetramethylene phosphonic acid (EDTMP), salts thereof, and the like. mentioned.

Salts in the chelating agent include, for example, salts of alkali metals such as potassium and sodium, and salts of alkaline earth metals such as magnesium and calcium. Among them, alkali metal salts are preferable, and sodium salts or potassium salts are more preferable.

In the detergent composition of the present invention, the concentration of component (a) at the time of use is preferably 0.000005% by mass or more, more preferably 0.000007% by mass or more, in terms of enzyme protein, from the viewpoint of proteolytic performance. , more preferably 0.000009% by mass or more, still more preferably 0.00003% by mass or more, still more preferably 0.00005% by mass or more, still more preferably 0.0001% by mass or more, still more preferably 0 .0002% by mass or more, and from the viewpoint of reducing skin irritation, preferably 0.05% by mass or less, more preferably 0.045% by mass or less, even more preferably 0.04% by mass or less, and even more preferably 0 0.035% by weight or less, more preferably 0.03% by weight or less. The enzyme protein of component (a) can be quantified using, for example, the Lowry method. For quantification of enzyme protein using the Lowry method, for example, Protein Assay Lowry Kit (manufactured by nacalai tespue) can be used.

The detergent composition of the present invention has an enzyme activity value at the time of use of 5 U/mL or more, preferably 6 U/mL or more, more preferably 8 U/mL or more, and still more preferably 10 U/mL or more, from the viewpoint of finish quality. , And, from the viewpoint of reducing skin irritation, preferably 3,000 U / mL or less, more preferably 2,700 U / mL or less, still more preferably 2,500 U / mL or less, more preferably 2,000 U / mL or less be. The enzymatic activity value of the washing liquid is the activity value of the enzyme measured at a reaction temperature of 40°C. The enzyme activity value of the wash solution can be measured using PROTASYME AK TABLETS (Megazyme). The enzymatic activity value of the cleaning liquid to be reused may be the enzymatic activity value of the cleaning liquid contained in the cleaning liquid tank. In the present invention, the enzymatic activity value of the cleaning liquid of 5 U/mL or more means that the enzymatic activity value per 1 mL of the cleaning liquid obtained by the method shown below is 5 U or more. Also, the enzymatic activity value of the washing liquid may be the enzymatic activity value for protein.
In the present invention, the enzymatic activity value of the cleaning composition (that is, cleaning liquid) at the time of use is a value calculated by measuring by the following method. First, 67 mM phosphate buffer (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) is placed in a 1.8 mL test tube and kept at 40°C. Then add one tablet of PROTASYME AK TABLETS and stir to mix. Next, 0.2 mL of washing solution is added, mixed, and reacted at 40° C. for 30 minutes. Next, 1 mL of 10% aqueous citric acid solution is added and mixed, centrifuged (2800 r/min, 15 minutes), and the supernatant is collected as a sample, and the absorbance (590 nm) of the sample is measured. From the obtained absorbance value of the sample, the absorbance change amount is calculated by subtracting the base absorbance value as shown in the following formula, and the absorbance change amount is multiplied by a coefficient (coefficient = 1000) for converting to the enzyme activity value. The obtained value is defined as the enzymatic activity value (U/mL) of the detergent composition (that is, the cleaning liquid).
Enzyme activity value (U/mL) = (sample absorbance (590 nm) - base absorbance (590 nm)) x 1000
The absorbance (590 nm) of the base is measured by the following method. First, 67 mM phosphate buffer (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) is placed in a 1.8 mL test tube and kept at 40°C. Then add one tablet of PROTASYME AK TABLETS and stir to mix. Next, 0.2 mL of ion-exchanged water is added and mixed, and reacted at 40° C. for 30 minutes. Next, 1 mL of a 10% aqueous citric acid solution is added and mixed, and the supernatant is separated as a base after centrifugation (2800 r/min, 15 minutes), and the absorbance (590 nm) of the base is measured.

When the cleaning composition of the present invention contains the component (b), the concentration of the component (b) at the time of use is preferably 0.00010% by mass or more from the viewpoint of detergency. , more preferably 0.0005% by mass or more, more preferably 0.0010% by mass or more, and from the viewpoint of reducing skin irritation, preferably 0.30% by mass or less, more preferably 0.28% by mass or less, More preferably, it is 0.26% by mass or less.

When the cleaning composition of the present invention contains component (c), the concentration of component (c) in the cleaning composition of the present invention is preferably 0.00001% by mass or more from the viewpoint of detergency at the time of use. , More preferably 0.00002% by mass or more, more preferably 0.00003% by mass or more, and from the viewpoint of blending stability, preferably 0.075% by mass or less, more preferably 0.070% by mass or less, and further Preferably, it is 0.065% by mass or less.

When the cleaning composition of the present invention contains the component (d), the cleaning composition of the present invention preferably has a concentration of the component (d) at the time of use of 0.0001 mass from the viewpoint of scale adhesion suppression performance. % or more, more preferably 0.0002% by mass or more, more preferably 0.0004% by mass or more, and from the viewpoint of blending stability, preferably 0.25% by mass or less, more preferably 0.23% by mass or less , and more preferably 0.20% by mass or less.

When the detergent composition of the present invention contains component (c), the mass ratio (a)/(c) of the content of component (a) to the content of component (c) is, from the viewpoint of proteolytic performance, Preferably 0.00015 or more, more preferably 0.00017 or more, still more preferably 0.00020 or more, and from the viewpoint of washability, preferably 4.5 or less, more preferably 4.0 or less, still more preferably 3 .0 or less. The component (a) is the amount in terms of enzyme protein.

The pH of the detergent composition of the present invention at 25°C is preferably 9 or more and 12 or less. The cleaning composition of the present invention preferably has a pH of 10 or more and 12 or less at 25° C. in a 0.1 mass % aqueous solution of the following concentrated cleaning composition. The pH of the diluted washing solution can be measured according to JIS K3362.

The detergent composition of the present invention may also contain bleaching agents, antifoaming agents, rust preventives, hydrotropic agents, surface modifiers, fragrances and the like.

The cleaning composition of the present invention can be used by diluting a concentrated cleaning composition. The cleaning composition of the present invention can be diluted and used so that the concentration of the concentrated cleaning composition is, for example, 0.01% by mass or more and 0.5% by mass or less.

In the concentrated detergent composition, component (a) is preferably 0.05% by mass or more, more preferably 0.07% by mass or more, and still more preferably 0% by mass, in terms of enzyme protein, from the viewpoint of proteolytic performance. 0.09% by mass or more, more preferably 0.10% by mass or more, still more preferably 0.15% by mass or more, and from the viewpoint of reducing skin irritation, preferably 12% by mass or less, more preferably 11% by mass % or less, more preferably 10% by mass or less, even more preferably 9% by mass or less, even more preferably 8% by mass or less, even more preferably 5% by mass or less, even more preferably 3% by mass or less, and even more preferably is 1% by mass or less. The enzyme protein of component (a) can be quantified using, for example, the Lowry method. For quantification of enzyme protein using the Lowry method, for example, Protein Assay Lowry Kit (manufactured by nacalai tespue) can be used.

When the detergent composition of the present invention contains component (b), the component (b) in the concentrated detergent composition is preferably 1% by mass or more, more preferably 3% by mass, from the viewpoint of detergency. Above, more preferably 5% by mass or more, and from the viewpoint of reducing skin irritation, preferably 70% by mass or less, more preferably 68% by mass or less, and even more preferably 66% by mass or less.

When the cleaning composition of the present invention contains component (c), the concentration of component (c) in the concentrated cleaning composition is preferably 0.1% by mass or more, more preferably 0%, from the viewpoint of detergency. .2% by mass or more, more preferably 0.3% by mass or more, still more preferably 0.5% by mass or more, and from the viewpoint of blending stability, preferably 15% by mass or less, more preferably 14% by mass or less , more preferably 13% by mass or less, still more preferably 10% by mass or less.

When the detergent composition of the present invention contains the component (d), the component (d) in the concentrated detergent composition is preferably 1% by mass or more, more preferably 3% by mass, from the viewpoint of anti-scaling performance. % by mass or more, more preferably 5% by mass or more, and from the viewpoint of blending stability, preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less.

Concentrated detergent compositions may be in either solid or liquid form. The detergent composition of the present invention is preferably in the form of a solid, that is, a solid block, granules, powder, or the like, and is more preferably powdery from the viewpoint of ensuring workability and storage stability of the detergent.

<How to wash dishes>
Next, the method for washing tableware of the present invention will be described in detail. In the explanation of the method for washing dishes, an automatic dishwasher provided with a washing liquid tank containing washing liquid and a washing tank for bringing the washing liquid supplied from the washing liquid tank into contact with the dishes will be described as an example. It should be noted that the dishwashing method of the present invention is not limited to the disclosed embodiments.

When washing dishes, the washing liquid stored in the washing liquid tank is sent to the washing tank, and the dishes are washed by bringing the washing liquid into contact with the dishes in the washing tank. The cleaning liquid stored in the cleaning liquid tank contains the component (a) in advance, and at least part of the protein contained in the cleaning liquid from the previous cleaning has been decomposed before being sent to the cleaning tank. be. When washing dishes, if necessary, the component (a) or a detergent composition containing the component (a) is added to the washing tank or the washing liquid sent to the washing tank. In washing dishes, for example, the washing liquid can be sprayed to bring the washing liquid into contact with the dishes.
Tableware to be washed includes, for example, cups, glasses, bowls, bowls, chopsticks, plates, knives, forks, spoons, etc. made of various materials such as ceramics, glass, melamine resin, polycarbonate resin, wood, metal, etc. Items that can be washed with an automatic dishwasher, such as cooking utensils, can be mentioned. Any of the dishes to be washed is a dish to which at least protein stains are adhered.

The temperature of the washing liquid during dishwashing is preferably 40° C. or higher, more preferably 42° C. or higher, and still more preferably 44° C. or higher from the viewpoint of washing performance, and preferably 70° C. or lower, more preferably 70° C. or higher from the viewpoint of protein decomposition performance. It is preferably 68° C. or lower, more preferably 66° C. or lower.

From the viewpoint of cleaning power, the supply amount of the cleaning liquid during dishwashing is preferably 0.008 L/sec or more, more preferably 0.010 L/sec or more, still more preferably 0.012 L/sec or more, and even more preferably 0. 0.03 L/sec or more, still more preferably 0.04 L/sec or more, still more preferably 0.05 L/sec or more, still more preferably 0.08 L/sec or more, still more preferably 0.10 L/sec or more, Even more preferably 0.12 L/sec or more, and from the viewpoint of workability, preferably 200 L/sec or less, more preferably 190 L/sec or less, still more preferably 180 L/sec or less, and even more preferably 160 L/sec or less. , still more preferably 8.0 L/sec or less, still more preferably 7.8 L/sec or less, still more preferably 7.6 L/sec or less, still more preferably 3.0 L/sec or less, still more preferably 2 0.8 L/sec or less, more preferably 2.6 L/sec or less.

In addition, from the viewpoint of workability, the supply time of the cleaning liquid per one washing process for tableware is preferably 5.0 seconds or longer, more preferably 5.5 seconds or longer, still more preferably 6.0 seconds or longer, and still more preferably 6.0 seconds or longer. preferably 7.0 seconds or more, more preferably 20 seconds or more, still more preferably 22 seconds or more, still more preferably 24 seconds or more, and from the viewpoint of workability, preferably 180 seconds or less, more preferably 170 seconds seconds or less, more preferably 160 seconds or less, even more preferably 125 seconds or less, even more preferably 120 seconds or less, even more preferably 115 seconds or less, even more preferably 110 seconds or less, even more preferably 100 seconds or less, Still more preferably 95 seconds or less, still more preferably 90 seconds or less, still more preferably 60 seconds or less, still more preferably 55 seconds or less, and even more preferably 50 seconds or less.

When the automatic dishwashing machine is of the undercounter type, the supply amount of the cleaning liquid during dishwashing is preferably 0.008 L/sec or more, more preferably 0.010 L/sec or more, and still more preferably 0, from the viewpoint of washing power. 012 L/sec or more, and from the viewpoint of workability, it is preferably 3.0 L/sec or less, more preferably 2.8 L/sec or less, and even more preferably 2.6 L/sec or less.
In addition, when the automatic dishwasher is an undercounter type, the supply time of the washing liquid per washing step is preferably 20 seconds or longer, more preferably 22 seconds or longer, and still more preferably 24 seconds or longer, from the viewpoint of workability. From the viewpoint of workability, it is preferably 120 seconds or less, more preferably 115 seconds or less, and even more preferably 110 seconds or less.

When the automatic dishwasher is a door type, the amount of washing liquid supplied during washing dishes is preferably 0.03 L/sec or more, more preferably 0.04 L/sec or more, and still more preferably 0.04 L/sec or more, from the viewpoint of washing power. 05 L/sec or more, and from the viewpoint of workability, it is preferably 8.0 L/sec or less, more preferably 7.8 L/sec or less, and even more preferably 7.6 L/sec or less.
In addition, when the automatic dishwasher is a door type, the supply time of the washing liquid per washing step is preferably 20 seconds or longer, more preferably 22 seconds or longer, and still more preferably 24 seconds or longer, from the viewpoint of workability. , from the viewpoint of workability, it is preferably 100 seconds or less, more preferably 95 seconds or less, and still more preferably 90 seconds or less.

When the automatic dishwashing machine is of the conveyor type, the supply amount of the cleaning liquid during dishwashing is preferably 0.08 L/sec or more, more preferably 0.10 L/sec or more, and still more preferably 0.08 L/sec or more, from the viewpoint of washing power. 12 L/sec or more, and from the viewpoint of workability, it is preferably 200 L/sec or less, more preferably 190 L/sec or less, still more preferably 180 L/sec or less.
In addition, when the automatic dishwasher is of conveyor type, the supply time of the washing liquid per washing step is preferably 5.0 seconds or more, more preferably 5.5 seconds or more, and still more preferably 6 seconds or more, from the viewpoint of workability. 0 seconds or more, and from the viewpoint of workability, it is preferably 60 seconds or less, more preferably 55 seconds or less, and even more preferably 50 seconds or less.

When washing the dishes, the washing liquid after contacting the dishes can be pumped up by a pump and brought into contact with the dishes again. In other words, the washing liquid to be brought into contact with the dishes can be circulated in the washing tank to bring the washing liquid into contact with the dishes a plurality of times.

After washing the dishes, the dishes are rinsed. For example, after washing dishes, the washing liquid in the washing tank is collected in the washing tank, and then rinsing water such as tap water is supplied to the washing tank. Then, the dishes are rinsed by contacting the dishes with rinsing water in the washing tank. When rinsing the dishes, the rinse water can be sprayed to bring the rinse water into contact with the dishes.
Some or all of the rinse water can be directed to the wash liquid tank after contacting the dishes. The amount exceeding the capacity of the washing liquid tank is discharged to the outside of the automatic dishwasher as waste water. In this way, the washing liquid collected from the washing tank into the washing tank and diluted with the rinsing water is reused as the washing liquid for washing the next tableware. When the rinsing water is sent to the washing tank, the rinsing water can also be collected in the washing tank after previously discharging part of the washing liquid in the washing tank.

The total amount of rinsing water used in one rinsing step is preferably 0.3 L or more, more preferably 0.5 L or more, and still more preferably 0.7 L per ¹ m3 of the washing tank from the viewpoint of finish. From the viewpoint of reducing the amount of water used, it is preferably 300 L or less, more preferably 250 L or less, and even more preferably 200 L or less.

When the temperature of the rinse water is high, proteins, which are slightly present in the rinse water, are more likely to be denatured, and re-staining of the stains on tableware is more likely to occur. The temperature of the rinsing water is preferably 50°C or higher, more preferably 53°C or higher, and even more preferably 55°C or higher, from the viewpoint of easily obtaining the effect of the present invention, that is, the effect of lowering the degree of increase in recontamination due to repeated washing. And, from the viewpoint of reducing redeposition of tableware due to suppression of heat denaturation of proteins, the temperature is preferably 95° C. or lower, more preferably 93° C. or lower, and still more preferably 90° C. or lower.

The ratio of the total amount of rinsing water used in one rinsing process to the total amount of cleaning liquid present in the cleaning liquid tank is preferably 0.0004 or more, more preferably 0.0005 or more, and still more preferably 0.0005 or more, from the viewpoint of finish quality. 0.0007 or more, more preferably 0.0009 or more, and from the viewpoint of saving water, it is preferably 0.40 or less, more preferably 0.38 or less, and still more preferably 0.36 or less.
In addition, the amount of rinse water supplied during rinsing is preferably 0.008 L/sec or more, more preferably 0.010 L/sec or more, and still more preferably 0.012 L/sec or more, from the viewpoint of finish quality. from the viewpoint of, it is preferably 3.5 L/sec or less, more preferably 3.3 L/sec or less, and still more preferably 3.1 L/sec or less.
In addition, the supply time of rinsing water per rinsing step is preferably 2 seconds or longer, more preferably 3 seconds or longer, and still more preferably 4 seconds or longer from the viewpoint of cleaning performance, and from the viewpoint of water saving, preferably It is 60 seconds or less, more preferably 58 seconds or less, still more preferably 56 seconds or less.

When the automatic dishwasher is an under-counter type, the ratio of the total amount of rinse water used per rinse step to the total amount of cleaning liquid present in the cleaning liquid tank is preferably 0.03 or more from the viewpoint of finish. It is more preferably 0.04 or more, still more preferably 0.05 or more, and from the viewpoint of saving water, it is preferably 0.40 or less, more preferably 0.38 or less, and still more preferably 0.36 or less.
In addition, when the automatic dishwasher is an under-counter type, the amount of rinse water supplied during rinsing is preferably 0.08 L/sec or more, more preferably 0.10 L/sec or more, and still more preferably, from the viewpoint of finish quality. is 0.12 L/sec or more, and from the viewpoint of water saving, it is preferably 1.0 L/sec or less, more preferably 0.9 L/sec or less, and still more preferably 0.8 L/sec or less.
In addition, when the automatic dishwasher is an undercounter type, the rinse water supply time per rinse step is preferably 4.0 seconds or more, more preferably 4.5 seconds or more, from the viewpoint of cleaning performance. It is preferably 5.0 seconds or longer, and from the viewpoint of saving water, is preferably 20 seconds or shorter, more preferably 18 seconds or shorter, and still more preferably 16 seconds or shorter.

When the automatic dishwasher is a door type, the ratio of the total amount of rinse water used per rinse process to the total amount of cleaning liquid present in the cleaning liquid tank is preferably 0.010 or more, more It is preferably 0.012 or more, more preferably 0.014 or more, and from the viewpoint of saving water, it is preferably 0.20 or less, more preferably 0.18 or less, and still more preferably 0.16 or less.
In addition, when the automatic dishwasher is a door type, the amount of rinse water supplied during rinsing is preferably 0.08 L/sec or more, more preferably 0.10 L/sec or more, and still more preferably It is 0.12 L/sec or more, and from the viewpoint of saving water, it is preferably 1.0 L/sec or less, more preferably 0.9 L/sec or less, and still more preferably 0.8 L/sec or less.
In addition, when the automatic dishwasher is a door type, the rinse water supply time per rinse step is preferably 4.0 seconds or longer, more preferably 4.5 seconds or longer, and still more preferably 4.5 seconds or longer, from the viewpoint of cleaning performance. is 5.0 seconds or more, and preferably 20 seconds or less, more preferably 18 seconds or less, still more preferably 16 seconds or less from the viewpoint of saving water.

When the automatic dishwasher is a conveyer type, the ratio of the total amount of rinse water used per rinse step to the total amount of cleaning liquid present in the cleaning liquid tank is preferably 0.0004 or more, from the viewpoint of finish quality. It is preferably 0.0005 or more, more preferably 0.0006 or more, and from the viewpoint of saving water, it is preferably 0.08 or less, more preferably 0.07 or less, and still more preferably 0.06 or less.
When the automatic dishwashing machine is of conveyor type, the amount of rinse water supplied during rinsing is preferably 0.008 L/sec or more, more preferably 0.010 L/sec or more, and still more preferably 0.012 L/sec or more, and from the viewpoint of saving water, it is preferably 2.5 L/sec or less, more preferably 2.4 L/sec or less, and still more preferably 2.3 L/sec or less.
In addition, when the automatic dishwasher is a conveyor type, the rinse water supply time per rinse step is preferably 2.0 seconds or longer, more preferably 2.2 seconds or longer, and still more preferably 2.2 seconds or longer, from the viewpoint of cleaning performance. is 2.4 seconds or more, and from the viewpoint of saving water, preferably 60 seconds or less, more preferably 58 seconds or less, even more preferably 56 seconds or less, even more preferably 20 seconds or less, and even more preferably 18 seconds or less, Even more preferably, it is 16 seconds or less.

The washing liquid stored in the washing liquid tank after washing the dishes contains at least proteins removed from the dishes by washing the dishes. In the method for washing tableware of the present invention, in the washing liquid collected in the washing liquid tank after washing the dishes, after the proteins in the washing liquid contained in the washing liquid due to the washing of the dishes are decomposed, the washing liquid is re-dissolved. , is sent from the washing liquid tank to the washing tank and reused as the washing liquid for washing the next tableware.
That is, in the method for washing dishes of the present invention, at least part of the washing liquid used for washing the dishes is recovered and reused as at least part of the washing liquid for the next tableware. Then, before contacting the reused cleaning liquid with the dishes again, the proteins in the cleaning liquid that are contained in the cleaning liquid due to the previous washing of the dishes are decomposed, and the protein-decomposed cleaning liquid is used as the next cleaning liquid. Used as a washing liquid for tableware.

Decomposition of proteins in the reusable cleaning fluid can be performed, for example, by adding component (a) to the cleaning fluid stored in the cleaning fluid tank. Here, the decomposition of protein refers to reducing the molecular weight of protein. Reduction of the molecular weight of a protein means, for example, decomposing the protein into those having a relative molecular mass of less than 25 kDa.

The smaller the content of proteins with a relative molecular mass of 25 kDa or more in the reused washing solution, the better the finished product. Therefore, the content of proteins with a relative molecular mass of 25 kDa or more in the reusable washing solution is preferably 3% by mass or less, more preferably 0.3% by mass or less, and even more preferably 0.3% by mass or less, from the viewpoint of finish quality. 03% by mass or less, more preferably 0.003% by mass or less, and even more preferably 0.0003% by mass or less. The content of protein in the cleaning liquid to be reused may be the content of protein in the cleaning liquid stored in the cleaning liquid tank (content of components (a) to (e) in the cleaning liquid to be reused). The same is true for quantity). The content of proteins with a relative molecular mass of 25 kDa or more in the recycled wash solution can be quantified, for example, by the following method.

(Method for quantifying protein in washing solution)
To 16 μL of washing solution, 8 μL of sample buffer (3×SDS-PAGE Loading Buffer, Biovision) is added, stirred, and heated at 90° C. for 5 minutes. 15 μL of the sample is injected into a polyacrylamide gel (Mini-PROTEAN TGX Any kD Stain-Free Gel 12well, manufactured by Bio-Rad) and subjected to electrophoresis at 200 V for 25 minutes (PowerPac™ HC Basic, manufactured by Bio-Rad). TRIS/GLYCINE/SDS x10 BUFFER (manufactured by Bio-Rad) can be used as the running buffer, and Ezstain Aqua (manufactured by ATTA) can be used as the staining solution. Then, the bands in the relative molecular mass range of 25 kDa to 250 kDa are analyzed by image analysis software ImageJ. Based on a calibration curve obtained using albumin (Fuji Film Wako Pure Chemical Industries, Ltd.), the quality of proteins with a relative molecular mass of 25 kDa or more in the recycled washing solution is quantified.

The concentration of component (a) and the concentration of the detergent composition containing component (a) in the cleaning solution are adjusted so that the content of proteins with a relative molecular mass of 25 kDa or more in the cleaning solution to be reused is within the above range. be done. These components can be added to the cleaning solution in the cleaning solution tank and/or cleaning bath or en route to the cleaning solution tank and/or cleaning bath.

The content of component (a) in the reusable washing solution is preferably 0.000005% by mass or more, more preferably 0.000007% by mass or more, more preferably 0.000007% by mass or more in terms of enzyme protein, from the viewpoint of proteolytic performance. 0.000009 mass % or more, more preferably 0.00003 mass % or more, still more preferably 0.00005 mass % or more, still more preferably 0.0001 or more, still more preferably 0.0002 or more, and From the viewpoint of reducing skin irritation, it is preferably 0.05% by mass or less, more preferably 0.045% by mass or less, even more preferably 0.04% by mass or less, even more preferably 0.035% by mass or less, and still more Preferably, it is 0.03% by mass or less. The enzyme protein content of component (a) can be quantified using, for example, the Lowry method. For quantifying the enzyme protein by the Lowry method, for example, Protein Assay Lowry Kit (manufactured by nacalai tespue) can be used.

The enzymatic activity value of the reusable cleaning solution is 5 U/mL or higher, preferably 6 U/mL or higher, more preferably 8 U/mL or higher, still more preferably 10 U/mL or higher, from the viewpoint of finish quality, and skin irritation. From the viewpoint of reduction, it is preferably 3,000 U/mL or less, more preferably 2,700 U/mL or less, still more preferably 2,500 U/mL or less, and even more preferably 2,000 U/mL or less. The enzyme activity value is the enzyme activity value measured at a reaction temperature of 40°C. The enzyme activity value of the wash solution can be measured using PROTASYME AK TABLETS (Megazyme). The enzymatic activity value of the cleaning liquid to be reused may be the enzymatic activity value of the cleaning liquid contained in the cleaning liquid tank. Also, the enzymatic activity value of the washing liquid may be the enzymatic activity value for protein.

In the present invention, the enzymatic activity value of the reusable washing solution is measured and calculated by the following method. First, 67 mM phosphate buffer (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) is placed in a 1.8 mL test tube and kept at 40°C. Then add one tablet of PROTASYME AK TABLETS and stir to mix. Next, 0.2 mL of washing solution is added, mixed, and reacted at 40° C. for 30 minutes. Next, 1 mL of 10% aqueous citric acid solution is added and mixed, centrifuged (2800 r/min, 15 minutes), and the supernatant is collected as a sample, and the absorbance (590 nm) of the sample is measured. From the obtained absorbance value of the sample, the absorbance change amount is calculated by subtracting the base absorbance value as shown in the following formula, and the absorbance change amount is multiplied by a coefficient (coefficient = 1000) for converting to the enzyme activity value. The obtained value is defined as the enzymatic activity value (U/mL) in the cleaning composition (that is, in the cleaning liquid).
Enzyme activity value (U/mL) = (sample absorbance (590 nm) - base absorbance (590 nm)) x 1000
The absorbance (590 nm) of the base is measured by the following method. First, 67 mM phosphate buffer (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) is placed in a 1.8 mL test tube and kept at 40°C. Then add one tablet of PROTASYME AK TABLETS and stir to mix. Next, 0.2 mL of ion-exchanged water is added and mixed, and reacted at 40° C. for 30 minutes. Next, 1 mL of a 10% aqueous citric acid solution is added and mixed, and the supernatant is separated as a base after centrifugation (2800 r/min, 15 minutes), and the absorbance (590 nm) of the base is measured.

In the cleaning solution to be reused, the content of component (b) is preferably 0.00010% by mass or more, more preferably 0.0005% by mass or more, and still more preferably 0.0010% by mass or more, from the viewpoint of cleaning performance. And, from the viewpoint of reducing skin irritation, it is preferably 0.30% by mass or less, more preferably 0.28% by mass or less, and still more preferably 0.26% by mass or less.

The content of component (c) in the reusable cleaning liquid is preferably 0.00001% by mass or more, more preferably 0.00002% by mass or more, and still more preferably 0.00003% by mass or more, from the viewpoint of cleaning performance. And, from the viewpoint of blending stability, it is preferably 0.075% by mass or less, more preferably 0.070% by mass or less, and still more preferably 0.065% by mass or less.

The content of component (d) in the reusable cleaning liquid is preferably 0.0001% by mass or more, more preferably 0.0002% by mass or more, and still more preferably 0.0004% by mass, from the viewpoint of scale adhesion suppression performance. % or more, and from the viewpoint of blending stability, it is preferably 0.25% by mass or less, more preferably 0.23% by mass or less, and even more preferably 0.20% by mass or less.

The pH of the reusable cleaning solution is preferably 9.0 or higher, more preferably 9.2 or higher, and still more preferably 9.4 or higher from the viewpoint of cleaning performance, and preferably 9.4 or higher from the viewpoint of reducing skin irritation. It is 12.0 or less, more preferably 11.8 or less, still more preferably 11.6 or less. The pH is the pH at the temperature of the wash solution, but the wash solution may have a pH of 25°C. The pH of the cleaning solution can be measured according to JIS K3362. The amount of component (b) to be added may be determined so that the pH of the cleaning solution falls within this range.

The temperature of the washing liquid in the washing liquid tank is preferably 40° C. or higher, more preferably 42° C. or higher, still more preferably 44° C. or higher from the viewpoint of washing performance, and preferably 70° C. or lower from the viewpoint of proteolytic performance. It is more preferably 68° C. or lower, still more preferably 66° C. or lower.

If necessary, the cleaning liquid contained in the cleaning liquid tank and the cleaning liquid or rinsing water sent to the cleaning liquid tank may be added with the components (a) and (a) so that the components (a) to (d) are within the above ranges. ) component can be provided.

From the viewpoint of sufficiently decomposing the protein in the reused cleaning liquid, the time for which the cleaning liquid is retained in the cleaning liquid tank is preferably 10 seconds or longer, more preferably 60 seconds or longer, and still more preferably 300 seconds or longer. From the viewpoint of quality, it is preferably 50,000 seconds or less, more preferably 40,000 seconds or less, and still more preferably 30,000 seconds or less.

In the dishwashing method of the present invention, the tableware washing step, the tableware rinsing step, the step of decomposing proteins in the reused cleaning liquid, and the step of subjecting the protein-decomposed cleaning liquid to the next tableware washing step, Washing of dishes is repeated several times. After the tableware rinsing process, washed tableware is taken out, and before the tableware washing process, dirty tableware is brought in. Further, after the tableware rinsing process, if the concentration of the component (a) and the detergent composition in the cleaning liquid contained in the cleaning liquid tank is sufficient, the component (a) and the detergent composition are supplied before the tableware washing process. can be omitted.

Thus, in the method for washing tableware of the present invention, the protein in the reusable washing liquid is decomposed to reduce the molecular weight of the protein, thereby suppressing the hydrophobization (heat denaturation) of the protein and allowing the protein to adhere to the tableware. It is thought that it suppresses the re-adhesion of stains or the accumulation of stains on tableware. In other words, the method for washing tableware of the present invention can suppress an increase in recontamination of the tableware due to dirt in the cleaning liquid when washing is performed under washing conditions in which dirt is mixed in the cleaning liquid, and the washing finish of the tableware is improved. . The content of component (a) in the cleaning liquid is very small compared to the content of protein derived from stains on the dishes, so the effect on the finish can be ignored, so the protein content in the cleaning liquid is ( It is the content excluding the a) component.

The method for washing tableware of the present invention can be used for automatic dishwashing machines for commercial and domestic use. is suitable for commercial automatic dishwashing machines that require a large amount of washing and are washed many times a day. At that time, the washing method of the tableware of the present invention can reattach accumulated dirt in the washing liquid to the tableware even when the amount of rinsing water used is small (for example, 2 to 3 L per 2500 cm ² horizontal tableware setting/per rinsing). Alternatively, the accumulation of dirt on tableware can be suppressed. In other words, the method for washing tableware of the present invention can suppress an increase in recontamination of the tableware due to dirt in the washing liquid when washing is performed under washing conditions in which dirt is mixed in the washing liquid, and the washing finish of the tableware is improved. .

The tableware washing method of the present invention is suitable for a water-saving automatic dishwashing machine. A water-saving automatic dishwashing machine is, for example, an automatic dishwashing machine that can perform water-saving washing by rinsing with less water than a conventional automatic dishwashing machine. Also includes automatic dishwashers with functions. For example, in a conventional automatic dishwasher, the amount of water required for one rinse is 4 to 6 L per 2500 cm ² horizontal tableware installation surface, but in a water-saving automatic dishwasher, the amount of water required for one rinse is It is 2 to 3 L per 2500 cm ² horizontal tableware installation surface, further less than 2 L, further less than 1 L. Therefore, a water-saving automatic dishwashing machine that can perform rinsing with an amount of water per rinsing of 2 to 3L per 2,500 cm ² horizontal tableware installation surface, further less than 2L, and further less than 1L may be used.

[Method for evaluating recontamination]
Put 55L of hot water (German hardness 3°dH) at 60°C into the washing liquid tank of a commercial dishwasher (manufactured by Hoshizaki Co., Ltd., JWA-680A). Name: fresh pure milk fat, manufactured by Megmilk Snow Brand Co., Ltd.) 55.6 g, curry powder (product name: curry mix, manufactured by Isbee Foods Co., Ltd.) 55.6 g, margarine (product name: Neosoft, manufactured by Megmilk Snow Brand Co., Ltd.) 55.6 g, 27.8 g of rapeseed oil (Fujifilm Wako Pure Chemical Co., Ltd.), 27.8 g of ketchup (trade name: tomato ketchup, manufactured by Kagome Co., Ltd.), and 55.6 g of raw eggs (Akita Foods Co., Ltd.) were added. , and stirred until uniform. In the case of Tables 2 and 3, put 55 L of hot water (German hardness 3° dH) at 60°C into the washing liquid tank of the above-mentioned commercial dishwasher, and albumin (Fujifilm Wako Pure Chemical Co., Ltd.) as a protein stain. 10 g (initial protein amount 182 mg/L, Table 2) or 60 g (initial protein amount 1091 mg/L, Table 3) was added and stirred to be uniform.
Next, the detergent composition shown in the table was added to this hot water, and the detergent composition shown in the table was put in and left at 60° C. for 30 minutes. value × 10 (mg/kg)], hereinafter referred to as a washing solution) was prepared. A transparent glass plate (manufactured by Kennis Co., Ltd., 10 cm wide, 10 cm long, 2 mm thick) was set on the rack of the washing tank of a commercial dishwasher. Then, the cleaning liquid was supplied from the cleaning tank to the cleaning tank, and the cleaning liquid was brought into contact with the transparent glass plate to wash for 40 seconds. The transparent glass plate was removed from the rack and dried at 25°C for 30 minutes. This washing and rinsing process was performed five times at 30 minute intervals. The recontamination evaluation of the transparent glass plate was performed on the transparent glass plate after the cumulative number of washings was 1 time, 3 times, and 5 times.

[Method for quantifying protein adhered to transparent glass plate]
Sodium dodecyl sulfate (hereinafter referred to as SDS, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was diluted with ion-exchanged water to obtain a 0.3% by mass SDS aqueous solution. The washed and dried transparent glass plate was immersed in this SDS aqueous solution, and the protein attached to the transparent glass plate was collected in the SDS aqueous solution. Then, the protein recovered in the SDS aqueous solution was quantified using the Protein Assay Lowry Kit (manufactured by nacalai tespue).

[Method for quantifying enzyme activity]
The enzymatic activity value of the washing liquid was quantified before contacting the washing liquid with the tableware.
First, 67 mM phosphate buffer (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) was placed in a 1.8 mL test tube and kept at 40°C. Next, one tablet of PROTASYME AK TABLETS was added and stirred to mix. Next, 0.2 mL of washing liquid was added and mixed, and reacted at 40° C. for 30 minutes. Next, 1 mL of 10% aqueous citric acid solution was added and mixed, centrifuged (2800 r/min, 15 minutes), and the supernatant was separated and the absorbance (590 nm) of the sample was measured. From the obtained absorbance value of the sample, the absorbance change amount is calculated by subtracting the base absorbance value as shown in the following formula, and the absorbance change amount is multiplied by a coefficient (coefficient = 1000) for converting to the enzyme activity value. The obtained value was taken as the enzymatic activity value (U/mL) of the washing solution.
Enzyme activity value (U/mL) = (sample absorbance (590 nm) - base absorbance (590 nm)) x 1000
In addition, the absorbance (590 nm) of the base was measured by the following method. First, 67 mM phosphate buffer (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) was placed in a 1.8 mL test tube and kept at 40°C. Next, one tablet of PROTASYME AK TABLETS was added and stirred to mix. Next, 0.2 mL of ion-exchanged water was added and mixed, and reacted at 40° C. for 30 minutes. Next, 1 mL of a 10% aqueous citric acid solution was added and mixed, and the supernatant was separated by centrifugation (2800 r/min, 15 minutes) and the absorbance (590 nm) of the base was measured.

The following were used as the components (a) to (d).
・(a) component, enzyme (trade name: Savinase 18T, manufactured by Novozyme)
・(b) component, anhydrous sodium carbonate (soda ash (dense), manufactured by Tokuyama Co., Ltd.)
・ (d) component, trisodium citrate dihydrate (trade name “purified sodium citrate M”, manufactured by Fuso Chemical Industry Co., Ltd.)

Table 4 shows the cleaning conditions in the cleaning method of the present invention. In washing under these washing conditions, since a predetermined amount of component (a) is contained in the reused washing liquid, it is estimated that the enzymatic activity value of the washing liquid is 5 U/mL or more. It is thought that the accumulation of dirt on the surface is suppressed, and the finish of the automatic dishwasher is improved.

Claims (16)

A method for washing dishes using an automatic dishwasher comprising a washing liquid tank containing a washing liquid and a washing tank for bringing the washing liquid supplied from the washing liquid tank into contact with the dishes, comprising:
At least part of the cleaning liquid used for washing the dishes is collected in the cleaning liquid tank and reused as at least part of the new cleaning liquid,
(a) a proteolytic enzyme [hereinafter referred to as component (a)] is contained in the reusable washing solution,
After the enzymatic activity value of the cleaning liquid is 5 U/mL or more, the cleaning liquid is brought into contact with the tableware.
How to wash dishes. Component (a) and one or more selected from the following components (b), (c) and (d) are mixed in the cleaning solution to be reused, and the enzymatic activity value of the cleaning solution is adjusted to 5 U. /mL or more, the method for washing tableware according to claim 1.
(b) alkaline agent (c) surfactant (d) chelating agent 3. The method for washing tableware according to claim 2, wherein the component (c) is a nonionic surfactant. 4. The washing of tableware according to claim 2 or 3, wherein a detergent composition containing one or more selected from components (b), (c) and (d) is mixed with the reusable cleaning liquid. Method. In the detergent composition, the content of component (a) is 0.05% by mass or more and 10% by mass or less, the content of component (b) is 1% by mass or more and 60% by mass or less, and the content of component (c) is The method for washing tableware according to claim 4, wherein the content of component (d) is 0.1% by mass or more and 15% by mass or less, and the content of component (d) is 1% by mass or more and 50% by mass or less. The mass ratio (a)/(c) of the content of component (a) to the content of component (c) is 0.00015 or more and 4.5 or less, according to any one of claims 2 to 5. dish washing method. The method for washing tableware according to any one of claims 1 to 6, wherein the reusable washing liquid has a pH of 9.0 or more and 12.0 or less. The method for washing tableware according to any one of claims 1 to 7, wherein the enzymatic activity value of the washing liquid to be reused is 5 U/mL or more and 3,000 U/mL or less. 9. The cleaning liquid according to any one of claims 1 to 8, wherein the cleaning liquid has a temperature of 40° C. or higher and 70° C. or lower, and the cleaning liquid is brought into contact with the tableware at 0.008 L/sec or more and 200 L/sec or less and 5 seconds or more and 180 seconds or less. dish washing method. 10. The method for washing dishes according to any one of claims 1 to 9, wherein the dishes are rinsed with rinse water after the dishes are brought into contact with the cleaning liquid. The tableware according to claim 10, wherein the rinse water is 50 ° C. or higher and 95 ° C. or lower, and the rinse water is brought into contact with the tableware at 0.008 L / sec or more and 3.5 L / sec or less and 4 seconds or more and 20 seconds or less. cleaning method. 12. The method for washing tableware according to claim 10 or 11, wherein the step of contacting the tableware with the washing liquid and then the step of rinsing the tableware with rinsing water are performed multiple times. The method for washing dishes according to any one of claims 10 to 12, wherein the rinse water is sprayed onto the dishes to bring the rinse water into contact with the dishes. 14. The method for washing tableware according to any one of claims 1 to 13, wherein the washing liquid is sprayed onto the tableware to bring the washing liquid into contact with the tableware. 15. The dishwashing method according to any one of claims 1 to 14, wherein the cleaning liquid collected in the cleaning liquid tank contains proteins removed by washing the dishes. The dishwashing method according to any one of claims 1 to 15, wherein the cleaning liquid collected in the cleaning liquid tank is held at a temperature of 40°C or higher and 70°C or lower for 10 seconds or longer and 50,000 seconds or shorter.