GB2228945A - Detergent composition - Google Patents

Abstract

A detergent composition particularly suited for use in a machine dishwasher comprises an enzyme capable of breaking alpha-1, 6-glucosidic linkages. The presence of this enzyme assists in the breakdown of complex soils, notably starch and glycogen. The enzyme may be pullulanase or isoamylase. The composition may contain a surfactant, builder and alkaline material.

Description

ENZYMATIC DISHWASHING COMPOSITIONS The present invention relates to an enzymatic dishwashing composition containing enzymes capable of catalysing the hydrolysis of alpha-l,6 glucosidic linkages.

The use of enzymes in dishwashing compositions has been described in a number of prior patent publications.

Thus, EP 135 227 (Unilever) proposes detergent cleaning compositions containing up to 5 wt% amylolytic enzyme at a low pH. US 4 162 987 (Maguire et al) proposes detergent compositions containing amylolytic enzyme, the composition being free from active chlorine. Lipases have also been suggested for inclusion in dishwashing compositions (e.g. EP 271 155, Unilever). The use of proteases in dishwashing compositions has also been proposed. Amylases, lipases and proteases may be used alone or in combination to assist in soil removal.

Dishwashing compositions, in particular machine dishwashing compositions which are used in the main washing step of a machine dishwashing operation, have in general a satisfactory cleaning performance. However, frequently the articles cleaned with such products still do not have a satisfactory cleanliness. This has been found to be at least in part caused by starch and/or glycogen based soils remaining on the articles.

An analysis of starch shows that it is comprised of amylose, which is a linear chain having 1,4-glucosidic bonds and amylopectin, a highly branched chain having 1,4- and 1,6-glucosidic bonds. Glycogen is also a very highly branched structure. Soils based on such polymers (which may be of plant or animal origin), e.g. from potatoes or sponge puddings may be more easily removed by increasing the pH of the composition. However, such high pH's are not safe to the user. Amylases have been found to help to break down the polymers, but decreasing the pH leads to worse performance overall.

We have now found that the addition of debranching enzymes which catalyse the hydrolysis of alpha-l,6-glucosidic linkages to a detergent composition assists in the breakdown of the complex soils. The affinity for a specific linkage distinguishes these enzymes from other amylases which are primarily effective in breaking down alpha-l,4-glucosidic bonds. The debranching enzymes have generally been used in the production of glucose and for maltose-type syrups.

However, as far as we are aware, their use has not been proposed for machine dishwashing compositions, or for use in a machine dishwashing process.

The enzymes 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. All of the debranching enzymes may be classified as pullulanases or isoamylases according to substrate specificities. Pullulanases degrade pullalan (poly alpha-1,6-maltotriose) whereas isoamylases do not.

Pullulanases are particularly preferred for use in compositions according to the present invention.

Microbial sources include Aerobacter Aerogenes, Pseudomonas, stutzeri, Bacillus polymyxa B.maceranas, Klebsiella pneumonia and Streptomyces sp. Particularly preferred is the Pullulanase Promozyme (Trade Mark of Novo), isolated from Bacillus sp.Pullulanase. The activity of this enzyme is standardised at 200 PUN/g (Pullulanase Unit Novo). lPUN is defined as the amount of enzyme which under standard conditions hydrolyses pullulan liberating reduced carbohydrate, with a reducing power equivalent to 1A-mole glucose per minute. The enzyme is stable at below 600. Also preferred is pullulanase isolated from a strain of Bacillus No. 202-1 as described in Biochimica et Biophysica Acta, 397 (1985) 188-193.This pullulanase has an optimum pH of about 8.55-9.0, and is therefore of particular interest in more alkaline detergent compositions.

Isoamylases have the ability to debranch glycogen.

The enzymes have been detected in a variety of microorganisms including B.amyloliquefacines, Cytophaga sp., P.amyloderamosa and Streptomyces sp.

No.28. The activity of the enzyme is given in MU (maltose units). lMU is defined as the amount of enzyme which under standard conditions hydrolyses isoamylose liberating reduced carbohydrate, with a reducing power equivalent to ly-mole maltose per minute.

The types of debranching enzymes described above may be used singly or in combination. The pullulanases or isoamylases can be used in their non-purified form or in a purified form, irrespective of methods of purification.

The debranching enzymes of the present invention are included in the detergent composition in such an amount that the final detergent composition has an activity of 0.1 to 500, preferably 10 to 80 PUN/g of the composition.

The composition of 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, zeolites, silicates, carbonates, borates, citrates, carboxymethyloxy-succinates, nitrilotriacetates and ethylenediamine-tetraacetates, polymeric polyelectrolytes such as polyacrylates, polymaleates, and other known organic and inorganic builder compounds, together with combinations thereof.

Usually, the amount of builders in the composition varies from 10-90% by weight, generally from 20-70% 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, drainage-promoting agents, threshold agents, aminopoly-phosphonic acids and alkali metal or alkaline earth metal salts thereof, clays such as hectorites, anti-corrosion agents such as fatty acids and benztriazole. Other enzymes such as amylases, proteases and lipases may also be included.

It is particularly preferred to use the isoamylases in conjunction with amylases so as to achieve degradation of alpha-1,6 and alpha-l,4 bonds.

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.

The composition of the present invention may be formulated as a powder, as a pourable liquid or gel, as a tablet or cake, or in any other conventional form.

A typical example of a conventional powder machine dishwashing composition usually contains an alkali metal tripolyphosphate in an amount of from 10-60 wt , an alkali metal silicate or disilicate in an amount of from 20-85 wt %, a peroxy type bleaching agent in an amount of from 1-15 wt %, a low-foaming detergent surfactant in an amount of from 0.5-5 wt %, and minor ingredients such as perfumes, colouring agents, hydrotropes, fillers, etc.

A typical example of a conventional liquid machine dishwashing composition usually contains alkali metal tripolyphosphate in an amount of from 10-30wt, an alkali metal disilicate in an amount of from 5 to 30wt%, a bleach in an amount equivalent to from 0.5 to Swtt available chlorine and a thixotropic thickener in an amount of from 0.5 to 5wt% the balance being water.

Minor ingredients as above may also be present.

The invention will further be illustrated by way of examples.

Example 1 Scaled-down experiments were carried out to demonstrate potato removal from glass using the enzymes Termamyl and Promozyme.

A glass slide was coated in potato soil, 19-25 mg per slide. The slide was soaked in a sodium acetate buffer, pH5 at 45 cm, 90 hardness (GH) in the presence of enzymes. The % weight of residual potato was measured as a function of soaking time.

Time Enzyme (Mins) Blank Termamvl1 Promozyme2 Termamvl3 + Promozyme2 0 100 100 100 100 8 95 85 92 85 16 95 75 90 74 24 95 70 87 68 32 94 64 84 60 40 94 58 80 55 48 92 53 79 50 56 90 48 77 45 64 90 42 75 42 1 Termamyl 120 MU/L 2 Promozyme 200 PUN/L 3 Termamyl 240 MU/L The experiment shows the beneficial effect of the enzymes on the starch soil, more potato being removed for a given period of time in comparison with tests where no enzyme is present.

Example 2 Dishwashing compositions are prepared according to the following formulations in which the ingredients are expressed as percentages by weight: A B C D E F G H Sodium tripolyphosphate 30 30 30 30 30 30 30 30 Sodium metasilicate. 0aq - - - - 20 20 20 20 Sodium Disilicate.2aq 20 20 20 20 10 10 10 10 Sodium carbonate. 0aq 10 10 10 10 - - - Sodium perborate. 1aq 4 4 4 4 7 7 7 7 Ethylenediamine-tetraacetate 2 2 2 2 - - - Pullulanase/isoamylase - - 0.5 0.5 - - 1 1 Alpha-amylase - 0.5 - 0.5 - 1 - 1 Nonionic (Lutensol LF403) 1 1 1 1 1 1 1 1 Sodium sulphate 33 32.5 32.5 32 32 31 31 30 ---- ---- ---- ---- ---- ---- ---- ---100 100 100 100 100 100 100 100 Pullulanase or isoamylase having an activity of abut 4PUN/mg or 4MU/mg respectively.

Termamyl 60T (available from NOVO INDUSTRI, Denmark) with an activity of about 5MU/mg is used as an alpha-amylase.

Using these compositions for cleaning plates soiled with starch-containing foods (e.g. custard, pudding) the results with the compositions containing pullulanase and/or isoamylase (C, D, G and H) are always better in terms of starch soil removal than the formulations without enzymes (A and E) or with alpha-amylase only (B and F).

Claims (6)

1. A detergent composition comprising a builder salt, an alkaline agent and, optionally, a detergent active, characterised in that it further comprises an enzyme capable of breaking alpha-1,6-glucoside linkages.

2. A composition as claimed in claim 1, wherein said enzyme is a pullulanase.

3. A composition as claimed in claim 1, wherein said enzyme is an isoamylase.

4. A composition as claimed in any one of claims 1 to 3, wherein the enzyme is present in such an amount as to give an activity of 10 to 80 PUN/g of composition.

5. A composition as claimed in any one of claims 1 to 4 in liquid or powder form.

6. A detergent composition comprising: (a) 20-60 wt % of an alkali metal phosphate builder; (b) 20-60 wt % of an alkali metal silicate or disilicate; (c) 1-15 wt % of a peroxy bleaching agent; (d) 0.5-5 wt % of a low-foaming detergent surfactant; (e) Pullulanase in a sufficient amount so as to provide an enzyme activity of 10-80 PUN/g of composition.