AU713330B2 - A method and composition for warewashing without bleach - Google Patents

Description

WO 96/15710 PCT/EP95/04606 1 A METHOD AND COMPOSITION FOR WAREWASHING WITHOUT BLEACH Field of the Invention The present invention relates to a warewashing detergent composition and its use for cleaning dishware, especially in industrial or institutional systems, as opposed to domestic automatic dishwashing machines.

Background of the Invention A typical conventional industrial warewashing system consists of a conveyor system separated into prewash, wash, rinse and drying stations. Wash water is typically introduced into the rinse zone of this system and is passed cascade fashion toward a prewash zone, while dishware is transported in a countercurrent direction.

Dishwashing compositions used in such systems generally contain a chlorine bleaching agent combined with a cleaning ingredient such as an aqueous solution of a caustic agent and a sequestering agent or builder such as sodium tripolyphosphate.

While these systems provide excellent levels of tea stain removal, incomplete removal of starchy soils is a problem.

Starchy soils are especially difficult to remove when dishware is subject to high temperatures during food preparation and such foods are left for a long time on heated substrates during distribution.

A proposed solution to this problem is described in EP-A- 282,214 (Diversey). This document discloses a process for cleaning dirty dishware with a non-directional mist-like spray of a strongly alkaline solution. However, a highly alkaline spray is potentially hazardous for an operator.

WO 96/15710 PCT/EP95/04606 2 An industrial dishwashing process using a low alkaline detergent and an enzyme dosed into either a rinsing or a washing bath of the system is described in WO 94/27488 (Henkel-EcoLab). The publication describes a means of compensating for the degradation of the enzyme, particularly an amylase, during standstill'phases of the system by adding intermittent doses of the enzyme to the washing zone.

German patent specification DE-A-4 219 620 describes a domestic dishwasher in which bleach- and enzyme- containing components are dosed in different stages of the wash process.

The enzyme is added during the prerinse or at the very beginning of the wash cycle. The bleach is added only during the cleaning cycle after a predetermined time after which the wash liquor reaches a desired temperature. Thus the negative interaction between the bleach and the enzyme is avoided.

This approach is not feasible in an industrial dishwasher where a cascade flow of water occurs from one tank to another and wherein the cleaning operation is a continuous process.

An approach which is feasible to minimize negative interactions between active .ingredients while maximizing cleaning performance in institutional industrial warewashing is the introduction of the active ingredients sequentially into the system. In sequential dosing, components of the cleaning composition are separately introduced into different compartments of the machine. Thus sequential dosing separates active ingredients to minimize negative interactions and thereby maximize cleaning performance of each individual component.

Bleach agents have been removed from warewashing detergent compositions to minimize the deactivation of enzyme ingredients. It is known in the absence of a bleach that good stain removal tea stain removal) may be effected across a range of water hardness by utilizing a strong WO 96/15710 PCT/EP95/04606 3 builder or sequestrant at a relatively high wash pH. Thus, the negative interaction between bleach and enzyme may be avoided while maintaining a good cleaning performance.

However, it is also known in the art that many enzymes, particularly amylase enzymes useful for starch removal, are unsuitable for use in cleaning systems where the pH value of the composition is above 10. Such high pH values diminish enzyme activity and stability. See GB 1 296 839 (Novo).

Therefore, there exists a need for a cleaning system that provides effective cleaning performance for both starch and tannin removal and which at the same time minimizes those negative interactions responsible for deactivation of the active ingredients within the system.

Summary of the Invention One object of the invention is to provide a chemical cleaning system for an industrial or institutional warewashing process which contains at least two separate components. Each component is dissolved or diluted in an aqueous solution to a concentration useful for cleaning. The cleaning system comprises an enzyme containing component which must be sequentially introduced into the warewashing process so that a 1% aqueous solution of the enzyme dosed into the wash has a solution pH of less than about 9.

The second component comprises a cleaning agent which is sequentially dosed into thewarewashing system in a separate tank or zone from the area in which the enzyme component is dosed and a 1% aqueous solution of the cleaning agent must be more alkaline than the enzymatic solution by at least about 1 pH value, preferably the cleaning component solution has a pH of from 9.5 to 13. The chemical cleaning system has substantially no bleaching agents among its components.

Accordingly, the present invention provides a chemical cleaning system for a multi-tank mechanical warewashing WO 96/15710 PCT/EP95/04606 4 machine comprising at least two separate components for aqueous dissolution or dilution to respective use concentration, a first component comprising a cleaning agent and a second component comprising an enzyme, the system being substantially free of an added bleaching agent and a 1% aqueous solution of the first component being at least about 1 pH unit more alkaline than a 1% aqueous solution of the second component, wherein said components are sequentially dosed into the warewashing machine in different tanks or zones thereof.

A method of warewashing in a multi-tank industrial or institutional machine is also described said method comprising the steps of: a) selecting at least two separate components for aqueous dissolution or dilution to respective use concentration in two separate zones of a warewashing machine, the first component comprising a cleaning agent and the second component comprising an enzyme, the system being substantially free of an added bleaching agent and a 1% aqueous solution of the first component being at least about 1 pH unit more alkaline than a 1% aqueous solution of the second component; b) introducing the first component into a washing zone to clean dirty dishware; c) subsequently introducing the second component into a second washing zone to further clean the dishware; and d) rinsing the dishware with an aqueous solution to substantially rinse away the chemical cleaning system.

Detailed Description of Preferred Embodiments Typical industrial warewashing processes are either continuous or non-continuous and are conducted in either a WO 96/15710 PCTIEP95/04606 single tank or a multi-tank/ conveyor type machine. In the conveyor system a prewash, wash, rinse and drying zone are generally established using partitions. Wash water is introduced into the rinsing zone and is passed cascade fashion back toward the prewash zone while the dirty dishware is transported in a countercurrent direction.

The inventive chemical cleaning system may be utilized in any of the conventional warewashing processes, but is especially effective in the multi-tank/ conveyor type systems. In these types of systems, contact time between the cleaning composition and the articles to be washed is relatively short. Means of maximizing these contact times are constantly sought while at the same time any negative interaction time of the actives of- the cleaning composition needs to be minimized to provide the best cleaning performance.

Adequate cleaning performance has been achieved in the present invention in spite of the elimination of a bleaching agent. Reason is that bleaches generally create a negative interaction with other cleaning components such as enzymes.

Enzymatic Component Amylolytic enzymes are used to remove starch stains. The amylolytic enzymes usable can be derived from bacteria or fungi. Preferred amylolytic enzymes are those prepared and described in GB 1 296 839 which are cultivated from the strains of Bacillus licheniformis NIB 8061 NIB 8059, ATCC 6334. ATCC 6598, ATCC 19945, ATCC 8480 and ACTT 9945 A.

Examples of such amylolytic enzymes are those produced and supplied under the trademark Termamyl® by Novo Industri A/S, Copenhagen, Denmark.

Also useful in the invention are a-amylase enzymes which have been mutated by modifying one or more amino acid sequences as described in WO 94/14951 and WO 94/02597 and supplied by Novo WO 96/15710 PCTIEP95/04606 6 Industri under the tradename Durmamyl. Other a-amylase enzymes useful in the invention are described in EP-A-208,491 (Genencor Int'l).

The amylolytic enzymes may be used in either granular or liquid form and have enzymatic activities of from about 2 to about 25 Maltose units/milligram. They may be incorporated in the cleaning system of the invention in amount such that the final composition has an amylolytic activity of from 103 to 108 Maltose units/kilograms, preferably from 105 to 108 Maltose units per kilogram(s), and more preferably 106 to 10 8 Maltose units per kilogram.

The amylolytic activity referred to herein can be determined by the method described by in P. Bernfeld in "Method of Enzymology", Vol 1 (1955), pg. 149.

Proteolytic enzymes may also be incorporated in the cleaning system to remove protein stains. Usable proteolytic enzymes include the subtilisin obtained from strains of Bacillus Subtilis licheniformis, such as the commercially available subtilisins Maxatase supplied by Gist-Brocades Delft, Holland and Alcalase. supplied by Novo Industri A/S, Copenhagen, Denmark. Particularly suitable proteases are those obtained from a strain of Bacillus having maximum activity throughout a pH range of 8 to 12 and are commercially available from Novo Industri A/S under the -tradenames of Esperase and Savinase. Also useful is a protease supplied under the tradename of OxP by Genencor Int'l. The preparation of these analogue enzymes is described in GB 1 243 784. Proteolytic enzymes are generally presented as granules, such as marumes, prills, p-granulates, etc. or in liquid form. The proteolytic enzyme activities of these samples are from 500 to 6000 glycine units per milligram. Proteolytic enzyme activity can be determined by the method described M.L. Anson in "Journal of General WO 96/15710 PCT/EP9504606 7 Physiology", Vol 22 (1938), pg. 79 (1 Anson unit/gram=733 glycine units per milligram).

In the cleaning composition of the invention, proteolytic enzymes may be present in amounts such that the final composition has a proteolytic-enzyme activity of from about 103 to 1010 glycine units per kilogram, preferably from 105 to 1010, more preferably 106 to 109.

Other enzymes which may be incorporated in the cleaning system are lipolytic enzymes useful to improve fat removal.

Commercially available lipolytic enzymes include Lipase YL, Amano CE, Wallerstein AW, Lipase MY and Lipolase supplied by Novo Industri.

The enzyme containing component, especially amylolytic enzyme containing component, is dosed into the warewashing system so that upon aqueous dissolution or dilution to its use concentration, the pH value of a 1% aqueous solution is less than about 9, preferably 7 to 9, most preferably 8 to 9.

The enzyme containing component should be introduced into the system separately from the other active components of the cleaning system. Generally, the component will be applied in a washing zone of the system using any conventional means such as suitable spray nozzles or jets which are directed upwards or downwards toward the dishware. In a preferred embodiment, the enzyme containing component is sprayed directly onto the dishware as it moves in a countercurrent direction from the dosed component. A thorough rinsing of the enzyme from the dishware once the contact time is completed should follow.

To avoid undue exposure to the cleaning agents of the second component, the enzyme containing component should be sequentially dosed into the warewashing process after the cleaning agent containing component and preferably in a WO 96/15710 PCT/EP95/04606 8 separate tank from the tank in which the cleaning agent containing component is introduced.

CleaninQ Agent Containing Component An aqueous solution of the component which contains the cleaning agent must have a higher alkalinity than that of the enzyme component by at least about one unit, preferably more than one pH unit. Thus a 1% aqueous solution of the cleaning component which results from its dissolution or dilution to its use concentration should have a pH of at least about 1 pH unit more alkaline than a pH value of a 1% aqueous solution of the enzymatic component. Preferably, the cleaning agent component solution has a pH of 9.5 or greater, preferably to 13.

It is understood that more than one component may contain a cleaning agent so that the component which contains the greatest total amount (that is by weight) of the cleaning agent is referred to by the phrase "that component which contains the cleaning agent or the cleaning agent containing component". It will also be appreciated that the total cleaning agent in any given component may comprise two or more different and individual cleaning agents as described below.

The concentration of the cleaning agent following its dissolution or dilution is such that the weight of the component per volume unit of water should be in the range of 1 to 5 grams per liter, preferably from 1 to 4 grams per liter, more preferably from 1 to 3 grams per liter.

The cleaning agent may be selected from a caustic or strongly alkaline material, a detergency builder, a surfactant or a mixture thereof.

I_~liiiil -I~~_IYIIYI~IYi---;~Li~iiiill~Lii--Xi-LL .0-Y__-~X*I__IY~Ylii~rr----iil-4-ili WO 96/15710 PCT/EP95/04606 9 Suitable caustic agents include alkaline metal hydroxides such as sodium or potassium hydroxides, alkaline metal silicates such as metasilicates, preferably sodium metasilicate, and other alkaline caustic materials such as borax. Especially effective is sodium silicate having a mole ratio of SiO 2 :Na2O of from about 1 to about 3.3, preferably from about 1.8 to about 2.2 generally referred to as sodium disilicate.

Suitable builder materials are well known in the art and many types of organic and inorganic compounds have been extensively described in the literature. Builder materials include both the phosphate and non-phosphate compounds. They are generally used in cleaning compositions to provide alkalinity and buffering capacity, prevent flocculation, maintain ionic strength, extract metals from soils, remove alkaline earth metal ions from washing solutions.

The builder material usable herein can be any one or mixtures of the various phosphate and non-phosphate builder materials. However, non-phosphate builder materials can also be used, such as, for example, the alkali metal citrates carbonates and bicarbonates; and the salts of nitrilotriacetic acid (NTA); dipicolinic acid (DPA), oxydisuccinic acid (ODS), alkyl and alkenyl succinates (AKS); ethylenediamine tetracetates, oxidized heteropolymeric polysaccharides, polycarboxylates such as polymaleates, polyacetates, polyhydroxyacrylates, polyacrylate/polymaleate and polyacrylate;polymethacrylate copolymers and the terpolymer of polyacrylate/polymaleate and vinylacetate (ex Huls), as well as zeolites; layered silicas and mixtures thereof. They may be present in more than one component of the system but in the only component which contains builder, or in that component which contains the most total builder material (in by in the range of from 1 to preferably from 5 to 40, more preferably from 10 to WO 96/15710 PCTIEP95/04606 Particularly preferred builders are citrates, DPA, ODS, alkenyl succinates, carbonates, bicarbonates, the higher molecular weight block copolymers ITA/VA having Mw greater than 60,000, maleic anhydride/(meth)acrylic acid copolymers, e.g. Sokalan CP5 ex. BASF; NTA and the terpolymer of polyacrylate/polymaleate and vinylacetate (ex. Huls).

Scale formation on dishes and machine parts is an important problem that needs to be resolved or at least mitigated in formulating a machine warewashing product, especially in the case of low-phosphate less than theequivalent of by weight, particularly 10% by weight of sodium triphosphate) and phosphate-free machine warewashing compositions, particularly zero-P machine warewashing compositions.

In order to reduce this problem, co-builders, such as polyacrylic acids or polyacrylates (PAA), and the various organic polyphosphonates, e.g. of the Dequest range, may be incorporated in one or more system components. For improved biodegradability, (as such co-builders), the block copolymers of formula as defined in published PCT patent specification WO 94/17170 may also be used. In any component, the amount of co-builder may be in the range of from 0.5 to 10, preferably from 0.5 to 5, and more preferably from 1 to 5% by weight.

Further, the cleaning agent may comprise one or more surfactants. Surfactant may also be present in one or more of components of the system. However, in the component(s) which contain the most surfactant, they may be present in the range of from 0.5 to 20, preferably from 1 to 15, and moie preferably from 3 to 15% by weight. Such surfactant (if present) is of course separate from any surfactant used as rinse aid in the rinse phase, after use of a system according to the present invention.

Normally, in a properly built or highly built composition as is conventional, only small amounts of low- to non-foaming nonionic surfactant, to aid detergency and particularly to suppress excessive foaming caused by some protein soil.

Higher amounts of highly detersive surfactants, such as the high HLB nonionic surfactants, the anionic sulphate or sulphonate surfactants and the alkyl polyglycoside class of surfactants, may be used in lower builder-containing active/enzyme-based compositions.

0* 12J **ID These compositions may further include a defoamer. Suitable defoamers include mono- and distearyl acid phosphate, silicone oil and mineral oil. Preferred antifoam systems are described in US patent 5, 705, 465.

1 The compositions may include 0.02 to 2% by weight of defoamer, or preferably 0.05 to In the method of the invention, it will be normal to follow application of all system components by a final rinse using water, preferably containing a rinse aid.

Any known silver anti-tarnish agents may also be included such as benzotriazole or 1,3-N azole compounds described in U.S. 5, 468, 410 (Angevaare et al.) and U.S. 5, 480, 576 (Gary et al.).

S Minor amounts of various other components may be present in the chemical cleaning composition. These components include solvents, and hydrotropes such as ethanol, isopropanol and xylene sulfonates, flow control agents; enzyme stabilizing agents; soil suspending agents; anti-redeposition agents; anti-tarnish agents; anti-corrosion agents; colorants, bleach scavengers sulfite) and other functional additives.

SN. The use of bleach scavengers in the method and system of the 3' 3invention could be advantageous, since even in a non-bleach -j system traces of bleach could unexpectedly be present as a WO 96/15710 PCT/EP95/04606 12 residue from previous runs.

Components of the present invention may independently be formulated in the form of solids, (optionally to be dissolved before use), aqueous liquids or non-aqueous liquids, also to be diluted before use.

The present invention will now be described in more detail by way of the following non-limiting examples, in which parts and percentages are by weight unless otherwise indicated.

Example 1 In a non-bleach system it was observed that tea stain removal was significantly improved when formulations contained a builder formulated at a high alkalinity wash pH, that is greater than about 10. The following warewashing compositions were prepared: Ingredient Sample 1 Sample 2 Nitrilotriacetate(NTA) 20% Huls polymer' Nonionic surfactant 2% 2% Potassium hydroxide 75% Water to balance Neither of the sample formulations contained a bleaching agent or an enzyme. The pH value of a 1% aqueous solution of 'A terpolymer of acrylate/maleate and vinyl acetate supplied by Huls.

I II WO 96/15710 PCT/EP95/04606 13 each of the samples was adjusted by the addition of either NaOH or H 2

SO

4 to a pH value of between 7 and 11.

The cleaning performance of the two compositions were compared using a residual tea stain test.

Porcelain cups were stained with tea three times prior to washing. Cleaning experiments were conducted in a dishwashing machine. The temperature of the water in the main wash was 55°C and the wash time was 1 min.

The cleaned dishware was then observed by a panel which rated tea stain removal on a scale from 0 to 5 with 0 indicating no visible tea stain and 5 indicating heavy staining. The panel results are as follows: Residual Tea Stain Solution pH Sample 1 Sample 2 3.0 2.2 2.5 1.8 1.8 1.3 1.5 0.8 0.8 0.8 10.0 0.5 0 11.0 0 0 It was thus observed that as the pH of the aqueous solutions of the detergent compositions increased tea stain removal improved for both compositions containing NTA or Huls polymer builder materials, without the presence of either ii~ii WO 96/15710 PCT/EP95/04606 14 bleach or an enzyme. Thus, at high alkalinity tea stain removal is very effective in the presence of only a builder.

Example 2 High alkalinity and the presence of a builder material can, however, have a negative impact on amylase enzyme stability and on starch removal, as demonstrated below.

Sample 1 described in Example 1 was prepared with the addition of an amylase enzyme (supplied as Termamyl 300L by Novo) to provide an enzymatic activity of 2x10 7 Maltose units per kilogram. A second sample was prepared with the Termamyl enzyme, but no builder was present. Each sample was adjusted to pH values of 8.5 and 10 and the four samples were observed for enzyme stability and starch removal as follows.

Porcelain plates were soiled with potato starch. A single tank Industrial dishwashing machine was run over a period of about 30-40 minutes during which time 11 wash cycles were completed. At the end of each wash cycle, fresh product was dosed to compensate for the dilution of the wash solution by the rinse water.

The enzyme stability of the amylase was measured by conventional means.

Residual starch on the cleaned dishware was rated by a panel on a percentage scale with 100% indicating residual soil over the entire area of the plate and 0 indicating complete removal of the soil. The observed amylase stability and cleaning effectiveness in the four samples were as follows: WO 96/15710 PCT/EP95/04606 Elapsed Samples Loss of Amylase Activity) time (minutes) NTA and NTA and Amylase Amylase Amylase Amylase pH 10 pH 8.5 pH 10 pH 0 0 0 0 0 30 15 5 30 15 0 0 40 10 0 0 40 10 0 0 25 50 10 0 0 50 5 0 0 Sample Residual Starch Area) NTA and Amylase pH 10 NTA and Amylase pH 8.5 Amylase pH 10 Amylase pH 8.5 This data shows that starch removal benefits are generally greater at pH 8.5 compared to pH 10 and that at both wash pHs the NTA builder has a detrimental effect on starch removal. The presence of NTA leads to a significant reduction in the stability of the enzyme at a wash pH of A less detrimental effect of the builder on the enzyme stability was observed at a pH of Example 3 The significant effect of the presence of a strong builder on the amylase enzyme stability at a high alkalinity was again observed in wash solutions of 65 0 C. High temperature washes are conventionally used in industrial and institutional WO 96/15710 PCTEP95/04606 16 warewashing and in a multi-chamber machine are most likely to be encountered in the final wash tank. The four compositions of Example 2 were prepared and the amylase stability was measured at a temperature of 65 0 C with the following results (expressed as residual Amylase Activity): Elapsed Time NTA NTA Amylase Amylase Amylase Amylase pH 10 pH pH 10 pH 0 100 100 100 100 30 82 92 98 20 20 70 87 100 18 60 80 98 18 55 76 100 19 45 72 98 17 43 63 100 Thus, at pH 10 and 65c the effect of the presence of a strong builder on the amylase stability is devastating and would have a significant negative impact on starch removal by the enzyme.

Furthermore, while amylase stability is improved significantly at pH 8.5 compared to pH 10, even at pH there are clear benefits for not having a strong sequestrant present in the wash tank wherein the amylase enzyme is dosed.

Example 4 The cleaning efficiency of a composition according to the invention was compared to the cleaning of a commercial composition used in warewashing. The evaluation was carried out in a multi-chamber machine (ex. Hobart) to assess the WO 96/15710 PCT/EP95/04606 17 real benefits to be gained from a sequential dosing of ingredients and a pH differential between the washing zones into which the cleaning and enzyme components are dosed.

The inventive composition having two (2) no bleaching agent was prepared as follows: components and A. Cleaning Agent Component Ingredients Active potassium hydroxide 2.8 antiscalant (Dequest-2000) nitrilotriacetate (NTA) 28.0 potassium silicate water to balance The pH of a 1% aqueous solution of the cleaning component was adjusted to pH 9.8. The cleaning agent component was dosed into a wash zone in an amount of 2 grams per liter followed by a sequential dosing of an enzymatic component.

B. Enzymatic Component 100 ppm of an amylase (Termamyl 300L supplied by Novo) was dosed into the last washing zone following the dosing of the cleaning component. The pH of a 1% aqueous solution of the enzymatic component was The cleaning efficiency of the inventive composition was compared to a commercial composition of the prior art having the following cleaning and bleach components:

I

WO 96/15710 PCTIEP95/04606 18 A. Cleaning Component Ingredients Active sodium hydroxide phosphono 1,2,4, 6 butanetricarboxylic acid polyacrylic acid, sodium salt 8 water to 100 B. Bleach Component Ingredients Active Potassium hydroxide Potassium triphosphate Neutral sodium silicate sodium hypochlorite (as active Chlorine) water to 100 The pH of a 1% aqueous solution of the cleaning component was about 11. The bleach containing component was first dosed into a prewash or wash zone in an amount of 0.5 g/liter, followed by a sequential dosing of the cleaning component into a wash zone in an amount of 2 grams per liter.

Porcelain cups were stained with tea three times prior to washing. Porcelain plates were soiled with potato starch.

To mimic the gradual buildup of starch soil due to incomplete WO 96/15710 PCT/EP95/04606 19 starch removal in one wash, the starch plates were resoiled after the first wash and then subjected to further consecutive wash/starch soiling procedures.

The cleaning performance of the two compositions was evaluated by a panel. The following results were observed: Cleaning after 10 soil/wash cycles Soil Inventive Commercial Composition Composition tea 100 100 starch 97 Thus the inventive formula which does not contain a bleaching agent but does have an enzymatic component which has a pH of at least one unit less than the pH value of the cleaning component shows significantly improved cleaning performance over the performance of the commercial product with bleach.

Example The cleaning efficiency of a composition according to the invention, wherein the cleaning agent and enzymatic component were sequentially dosed into separate wash tanks, was compared to a system wherein the same cleaning agent and enzyme components were used, but instead were dosed into the same (final) wash tank. The composition of the cleaning agent and enzyme component and the test protocol are as described in Example 4. Both systems are free of bleach.

The following results were observed: X0 Cleaning after 10 soil/wash cycles soil Inventive Same tank F composition dosing (sequential dosing) tea 100 i0o starch 97 7 Sequential dosing of the cleaning agent and enzyme components into separate wash tanks gives significantly improved starch removal compared to the situation where cleaning agent and enzyme are separate I y 'dosed into thesame wash tank.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" or'bomprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Claims (15)

1. A chemical cleaning system for a multi-tank mechanical warewashing machine comprising at least two separate components for aqueous dissolution or dilution to respective use concentration, a first component comprising a cleaning agent and a second component comprising an enzyme, the system being substantially free of an added bleaching agent and a 1% aqueous solution of the first component being at least 1 pH unit more alkaline than a 1% .0 aqueous solution of the second component, wherein said components are sequentially dosed into the warewashing machine in different tanks or zones thereof. .5

2. A system according to claim 1, wherein the aqueous solution of the first component has a pH 9.5 or greater.

3. A system according to claim 1 or 2, wherein the aqueous solution of the second component has a pH value of less than 9. 0

4. A system according to any one of claims 1-3, wherein the first component is selected from the group consisting of a caustic or strongly alkaline material, a detergency builder, a surfactant and a mixture thereof.

5. A system according to claim 4, wherein the detergency builder is a phosphate or non-phosphate material. OS S 005 0 0.

6. A system according to claim 5, wherein the non-phosphate builder is selected from the group consisting of the salts of nitrilotriacetic acid, dipicolinic acid, oxydisuccinic acid, alkyl succinate,. alkenyl succinate, ethylenediamine S- tetracetate, oxidized heteropolymeric polysaccharides, (i polycarboxylates, zeolites, layered silicas and mixtures thereof. i\'7 t"^

7. A system according to any one of claims 1-6, wherein the enzyme is selected from the group consisting of an amylase, a protease, a lipase, and mixtures thereof

8. A system according to any one of claims1-7, further comprising a third omponent selected from the group consisting of an anti-tarnishing agent, an enzyme stabilizing agent, an anti-corrosion agent, a flow control agent, a bleach scavenger and mixtures thereofenger and mixtures S.0.

9- A method of warewashing in a tak ndustria or Sa minstitutional i 1 o r institutional machine comprising the steps of: S a) selecting at least two separate components for aqueous dissolution or dilution to respective use concentration i respective use concentration in Stwo separate ones of a warewashing machine, the first component comprising a cleaning agent and the second component comprising an enzyme, the system being substantially free of an added bleaching agent and a 1 *"aqueous solution of the first c en eing at leas H unit omponent b e i n g a t l e a s t pH unit more alkaline than a 1% aqueous solution of the second component; b) introducing the first component into a washing one to clean dirty dishware; a washing zone to subsequently introducing the second component into a second washing zone to further clean the dishware; and d) rinsing the dishware with an aqueous solution to substantially rinse away the chemical cleaning system.

A method according to claim 9, wherein the aqueous solution f the first component has a p w value of 9.5 or greate a lue of 9.5 or i//i

11. A method according to claim 9 or 10, wherein the aqueous solution of the second component has a pH value of less than

12. A method according to any one of claims 9-11, wherein the first component is selected from the group consisting of a caustic or strongly alkaline material, a detergency builder, a surfactant and a mixture thereof.

13. A method according to claim 12, wherein the detergency builder is a phosphate or non-phosphate material. *0

14. A method according to claim 13, wherein the non- phosphate builder is selected from the group consisting of the salts of nitrilotriacetic acid, dipicolinic acid, oxydisuccinic acid, alkyl succinate,. alkenyl. succinate, ethylenediamine tetracetate, oxidized heteropolymeric polysaccharides, polycarboxylates, zeolites, layered silicas and mixtures thereof. :'a0

15. A method according to any one of claims 9-14, wherein the enzyme is selected from the group consisting of an amylase, a protease, a lipase, and mixtures thereof. 25 DATED this 22nd day of September, 1999 UNILEVER PLC 0 0 0. By Its Patent Attorneys DAVIES COLLISON CAVE