Enzymatic dishwashing and rinsing process

Abstract: The inclusion of lipases in machine dishwashing and rinsing compositions provides for a significant reduction of the spot and film formation on the dishware. Particularly the use of bacterial lipases, which show a positive immunological cross-reaction with the lipase, produced by Chromobacter viscosum var. lipolyticum NRRL B 3673 provides for such such significant reduction of spot and film formation.

Description: The present invention relates to enzymatic dishwashing or rinsing processes using compositions comprising lipolytic enzymes. EP-A-0 130 064 (Novo) concerns detergent additives based on Fusarium oxysporum lipase (e.g. 20,000-100,000 LU/g, used in detergent at e.g. 0.2-2% w/w. DE-A-1 930 636 (= GB 1 273 545) (Albright & Wilson) concerns cleaning compositions based on protease, lipase and/or decarboxylase (of unspecified type) and surfactant, used inter alia for dishwashing. EP-A-0 205 208 (Unilever) (not prepublished) discloses enzymatic detergent compositions comprising lipase with 1-40% anionic surfactant and builders. The lipases disclosed are those that cross-react with antibody against lipase from Pseudomonas fluorescens 1AM 1057. EP 0 206 930 (Unilever) (not prepublished) also discloses enzymatic detergent compositions comprising similar lipases together with combinations of anionic and nonionic detergent. Thus, enzymatic dishwashing compositions have been proposed in the art. As enzymes, mainly amylases and/or proteases have been proposed for inclusion in dishwashing compositions. Lipases have also been suggested, but have received far less attention that the amylases and/or proteases. Dishwashing compositions, in particular machine dishwashing compositions which are used in the main wash step of a machine dishwashing operation, have in general a satisfactory cleaning performance. However, frequently the article cleaned with such products still do not have a satisfactory visual appearance after rinsing and drying, showing film or spots. Some main wash liquor is usually carried over from the main wash step to the rinse step, causing some deposition of soil resulting in insoluble calcium salts on the articles to be rinsed, which results in visible film or spots on the articles when they are dry. In particular with glass articles, this causes an unsightly visual appearance. We have now found that the addition of lipases to a main wash dishwashing composition or to a rinse composition significantly reduced the formation of film or spots on the articles cleaned or rinsed with such a composition. Accordingly the invention provides the use of a lipolytic enzyme as a spot reducing agent a process for machine dishwashing or rinsing, comprising treating dishes with an aqueous liquid having dissolved or dispersed therein an effective amount of an enzymatic dishwashing or rinsing composition comprising from 0.5-10% by weight of a detergent surfactant and from 0-90% by weight of a builder and from 0.005-100 LU/mg of a lipolytic enzyme. The lipases, used according to the present invention, may be of any suitable origin such as yeasts, fungi and bacteria. Preferably, however, they are of bacterial origin, and particularly preferably they belong to the class of bacterial lipases which show a positive immunological cross-reaction with the antibody of the lipase, produced by the microorganism Chromobacter viscosum var lipolyticum NRRL B-3673. This lipase has been described in Dutch Patent Specification 154,269 of Toyo Jozo, and the microorganism is available to the public at the United States Department of Agriculture, Agricultural Research Service, Northern Utilisation and Development Division at Peoria, Illinois, under the number NRRL B-3673. This lipase will hereinafter be referred to as "Toyo Jozo" lipase. The preferred lipases to be used in the present invention should show a positive immunological cross-reaction with the Toyo Jozo lipase antibody, using the standard and well-known immunodiffusion procedure according to Ouchterlony (Acta. Med. Scan., 133 , pages 76-79 (1950)). The preparation of the antiserum is carried out as follows: Equal volumes of 0.1 mg/ml antigen and of Freund's adjuvant (complete or incomplete) are mixed until an emulsion is obtained. Two female rabbits are injected with 2 ml samples of the emulsion according to the following scheme: day 0 : antigen in complete Freund's adjuvant day 4 : antigen in complete Freund's adjuvant day 32 : antigen in incomplete Freund's adjuvant day 60 : booster of antigen in incomplete Freund's adjuvant. The serum containing the required antibody is prepared by centrifugation of clotted blood, taken on day 67. The titre of the anti-Toyo Jozo-lipase antiserum is determined by the inspection of precipitation of serial dilutions of antigen and antiserum according to the Ouchterlony procedure. A 2 5 dilution of antiserum was the dilution that still gave a visible precipitation with an antigen concentration of 0.1 mg/ml. All lipases showing a positive immunological cross reaction with the Toyo Jozo lipase antibody as hereabove described are preferred lipases for use in the present invention. Typical examples thereof are the lipases ex Pseudomonas fluorescens IAM 1057 (available under the trade name Amano-P), the lipase ex Pseudomonas fragi FERM P 1339 (available under the trade name Amano-B), lipase ex Pseudomonas nitroreducens var. lipolyticum FERM P 1338, the lipase ex Pseudomonas sp. available under the trade name Amano-CES, the lipase ex Pseudomonas cepacia , lipases ex Chromobacter viscosum , e.g. Chromobacter viscosum var. lipolyticum NRRLB 3673, commercially available from Toyo Jozo Co., Tagata, Japan; and further Chromobacter viscosum lipases from US Biochemical Corp., U.S.A. and Diosynth Co., The Netherlands, and lipases ex Pseudomonas gladioli . The lipases used in the present invention are included in the detergent composition in such an amount that the final detergent composition has a lipolytic enzyme activity of from 100 to 0.005 LU/mg preferably 25 to 0.05 LU/mg of the composition. A Lipase Unit (LU) is that amount of lipase which produces 1 µmol of titratable fatty acid per minute in a pH stat. under the following conditions: temperature 30°C; pH = 9.0; substrate is an emulsion of 3.3 wt.% of olive oil and 3.3% gum arabic, in the presence of 13 mmo1/1 Ca 2+ and 20 mmo1/1 NaC1 in 5 mmo1/1 Tris-buffer. Naturally, mixtures of the above lipases can be used. The lipases can be used in their non-purified form, or in a purified form, e.g. purified with the aid of well-known adsorption methods, such as a phenylsepharose-adsorption techniques. The composition used according to the invention may furthermore comprise the usual ingredients of dishwashing or rinse compositions. Thus it may contain one or more alkali salts commonly used in dishwashing compositions. Thus, it may contain organic and/or inorganic builders such as the alkali metal ortho-, pyro and tripolyphosphates and hexametaphosphates, silicates, carbonates, zeolites, borates, citrates, carboxymethyloxy-succinates, nitrilotriacetates and ethylenediamine-tetraacetates, polymeric polyelectrolytes such as polyacrylates, polymaleates, and other known organic and inorganic builder compounds. Usually, the amount of builders in the composition varies from 10-90% by weight, generally from 30-70% by weight. The composition may also contain a detergent-active compound. If a detergent-active compound is included, it usually is in an amount of from 0.5-10%, usually 1-5%. Any well-known type of detergent active compound may be used, such as soaps, synthetic anionic, non-ionic, amphoteric detergent surfactant and mixtures thereof. Preferably, a nonionic detergent surfactant is used, especially a low-foaming one. Suitable examples of such nonionic detergent surfactants can easily be found in M.Schick "Nonionic Surfactants" (1967). The composition may furthermore contain other useful additives such as bleaching agents, bleaching agent activators, hydrotropes, fillers, perfumes, colouring agents, germicides, soil-suspending agents, aminopolyphosphonic acids and alkali metal or alkaline earth metal salts thereof, clays such as hectorites, anti-corrosion agents such as fatty acids, benztriazole and so on. Other enzymes such as proteases, amylases, oxidases may also be included. As bleaching agents the peroxygen type bleaching agents, preferably with a bleach precursor such as TAED are suitable for inclusion in the machine dishwashing compositions. A typical example of a conventional machine dishwashing composition usually contains an alkali metal tripolyphosphate in an amount of from 20-60%, an alkali metal silicate in an amount of from 40-80%, or an alkali metal disilicate in an amount of 5-30% by weight a peroxy type bleaching agent in an amount of from 1-15%, a low-foaming detergent surfactant in an amount of from 0.5-5%, and minor ingredients such as perfumes, colouring agents, hydrotropes, fillers, etc. When formulated as a rinse composition, it may contain from 0.5-10% by weight of a nonionic surfactant, from 5-25% by weight of an inorganic or organic acid, from 1-5% by weight of a hydrotrope, dyes, germicides, clays, silica sols, etc., the balance being water. The products of the invention can be formulated in any desirable form, such as powders, granulates, cakes, bars, pastes, liquids etc. The invention will further be illustrated by way of example. Example 1 In a commercial dishwashing machine tests were carried out under the following conditions: detergent composition dosage 30 g lipase dosage 2.5 g (= 15 LU/ml) water hardness main wash 27° GH flood 9° GH rinse 1 9° GH rinse 2 9° GH final rinse 9° GH wash temperature and time 55°C - 60 minutes articles to be cleaned clean dishes clean glasses test soil 35 g egg-yolk, added at the beginning of the main wash. The detergent composition had the following formulation: in gr. sodium tripolyphosphate 11.61 sodium carbonate 2.7 TAED (59.7%) 1.81 sodium perborate 2.43 calcium-Dequest (47.6%) 0.397 sodium disilicate 3.3 low foaming nonionic (Plurafac RA40) 0.405 hectorite clay (Laponite XLS) 0.675 sodium sulphate 5.610 amylase (4.8 Maltose units/mg) 0.540 As lipase, the Toyo Jozo lipase was used. The test was carried out in two runs, one without and one with lipase. The glasses were appraised by an expert panel as to their visual appearance, and were given a score according to the following scale: Film Spots 1. no film 1. no spots 2. slight film 2. 1-5 spots 3. clear film 3. 5-10 spots 4. heavy film 4. 11-20 spots 5. more than 20 spots The following results were obtained: run 1 (no lipase) run 2 (with lipases) average film score 2.3 2.3 average number of spots 250 100 Example 2 The test of Example 1 was repeated, but under the following different conditions: wash temperature 65°C soil standard soil; at the end of the main wash, clean plates were put in the machine, so that no cleaning took place in the final rinse, but only a carry-over took place. run 1 no lipase added in the final rinse run 2 2.5 g Toyo Jozo lipase was added to the final rinse (15 LU/ml). The main wash composition had the following formulation: % by weight sodium tripolyphosphate 36 sodium carbonate 9 sodium disilicate 15 TAED 3.8 sodium perborate tetrahydrate 8.8 potassium metaborate 0.35 sodium metaborate 0.85 calcium-Dequest 0.63 Amylase (4.8 MU/mg) 1.8 Esperase (a protease; 675 GU/mg) 1.8 low-foaming nonionic (Plurafac RA 40) 1.35 hectorite (Laponite XLS) 2.25 benzotriazole 0.1 sodium sulphate 14.0 water 9.5 The following spot and film scores of the glasses were obtained: run 1 (no lipase) run 2 (with lipases) average film score 1 1 average spot score 5 2.7 Example 3 Replacing the Toyo Jozo lipase by the Amano-P lipase or Lipase MY (ex Candida cylindracea ) or Amano AP-6 lipase (ex Aspergillus niger ) in Example 2 gave similar results. Example 4 The following formulation is an example of a rinse aid composition to which lipases can be added: % by weight low-foaming nonionic (Plurafac RA 30) 10 citric acid 18 sodium xylene sulphonate 3.0 dye 0.003 butylated hydroxytoluene 0.1 water q.s.

Claims: Use of a lipolytic enzyme as a spot reducing agent in a process for machine dishwashing or rinsing, comprising treating dishes with an aqueous liquid having dissolved or dispersed therein an effective amount of an enzymatic dishwashing or rinsing composition comprising from 0.5-10% by weight of a detergent surfactant and from 0-90% by weight of a builder and from 0.005-100 LU/mg of a lipolytic enzyme. Use according to claim 1, characterised in that the lipase is a bacterial lipase which shows a positive immunological cross-reaction with the antibody of the lipase, produced by Chromobacter viscosum var. lipolyticum NRRL B 3673. Use according to claim 2, characterised in that the lipase is producible by the microorganism selected from the group consisting of Pseudomonas fluorescens, Pseudomonas fragi , Pseudomonas nitroreducens var. lipolyticum , Pseudomonas cepacia , Pseudomonas gladioli and Chromobacter viscosum . Use according to any of claims 1-3 in a machine dishwashing process, characterised in that there is used a composition containing from 20-60% by weight of an alkali metal silicate, from 1-15% by weight of a peroxy type bleaching agent and from 0.5-5% by weight of a low-foaming nonionic detergent. Use according to any of claims 1-3 in a machine rinsing process, characterised in that there is used a composition containing, in an aqueous medium, from 0.5-10% by weight of a nonionic surfactant, from 5-25% by weight of an organic or inorganic acid and from 1-5% by weight of a hydrotrope.

Inventors: VAN DIJK WILLEM ROBERT, VAN DIJK, WILLEM ROBERT
Applicants: UNILEVER NV, UNILEVER PLC, UNILEVER N.V.
Application year: 1987
Main classification: C11D3
IPC codes: C11D7, C11D3