NO174896B - Detergent and its use - Google Patents

Description

The present invention relates to an enzymatic dishwashing liquid, in which special lipolytic enzymes are used. The washing-up liquid is characterized in that it comprises 0.5-10% by weight of a surfactant and a lipase in an amount of 0.005-100 LU/mg of the washing-up liquid. The lipase has been chosen from among lipases which have been produced by rDNA technology and which originally originate from the lipase gene from Humicola lanuginosa (syn. Thermomyces lanuginosus). The washing-up liquid is free of layered clay.

The invention also relates to the use of the products for mechanical dishwashing.

Enzymatic detergents have been proposed in the prior art. As enzymes, mainly amylases and/or proteases are proposed for incorporation in dishwashing detergents. Lipases have also been proposed, but have received far less attention than the amylases and/or the proteases. Dishwashing detergents, especially for machine use, which are used in the main washing step in a machine dishwashing operation, generally have a satisfactory cleaning effect. However, the articles cleaned with such products often still do not have a satisfactory visual appearance after rinsing and drying, showing coatings or stains. Some of the main wash liquid is usually carried over from the main wash stage to the rinse stage, causing some deposition of soil resulting in insoluble calcium salts on the articles to be rinsed, resulting in visible film coating or staining on the articles when dry. Especially for glass objects, this causes an unattractive visual appearance.

We have now found that the addition of special lipases to a main wash detergent mixture significantly reduced the formation of film coating or stains on the articles cleaned with such an agent. The special lipases, used according to the present invention, are lipases produced by cloning, by rDNA technologies, of the gene that codes for the lipase produced by the fungus Humicola lanuginosa and expression of the gene in Aspergillus oryzae as host. One such lipase is produced and sold by Novo Industri A/S, Denmark, under the trade name Lipolase (Biotechnology Newswatch, March 7, 1988, page 6). Further such lipases are mentioned in EP patent applications, publ. Nos. 258,068 and 305,216 (herein incorporated by reference).

The lipases used in connection with the present invention are included in the final mixture in such an amount that the final mixture has a lipolytic enzyme activity of from 100 to 0.005 LU/mg, preferably 25 to 0.05 LU/mg calculated on the mixture.

A lipase unit (LU) is the amount of lipase that produces

1 micromol of titratable fatty acid per minute in a pH state, under the following conditions: Temperature 30°C; pH = 9.0; the substrate is an emulsion of 3.3 wt% olive oil and 3.3% gum arabic, in the presence of 13 mmol/1 Ca<2+> and 20 mmol/1 NaCl in 5 mmol/1 Tris buffer.

Naturally, mixtures of the above-mentioned lipases with other lipases can be used. The lipases can be used in their unpurified form, or in purified form, e.g. purified using well-known adsorption methods, e.g. phenylsepharose adsorption techniques.

The mixture according to the invention can further include the usual ingredients in dishwashing detergents. Thus, it may contain one or more alkali salts that are commonly used in washing-up liquid mixtures. Furthermore, it may contain organic and/or inorganic builders, e.g. the alkali metal ortho-, -pyro- and -tripolyphosphates and -hexametaphosphates, silicates, carbonates, zeolites, borates, citrates, carboxymethyloxysuccinates, nitrile triacetates and ethylenediaminetetraacetates, polymeric polyelectrolytes, e.g. polyacrylates, polymaleates, and other known organic and inorganic building compounds.

Caustic alkali (e.g. NaOH) may also be present, and the mixtures often generate a pH >10 upon dissolution/dispersion at a surfactant level in the range 0.4-0.8 g/l.

Usually the amount of builders in the mixture varies from 10 to 90% by weight, generally 30-70% by weight.

The mixture must also contain a detergent-active compound. If a detergent active compound is included, it is usually in an amount of 0.5-10%, usually 1-5%. Any well-known type of detergent-active compound can be used, e.g. soaps, synthetic anionic, nonionic, amphoteric detergent surfactants and mixtures thereof. Preferably, a non-ionic surface-active detergent is used, especially one that is low-foaming. Suitable examples of such nonionic surfactant detergents can readily be found in M. Schick "Nonionic Surfactants" (1967).

The mixture may also contain other useful additives, e.g. bleaches, bleach activators, hydrotropes, fillers, perfumes, dyes, germicides, stain removers, aminopolyphosphonic acids and alkali metal or alkaline earth metal salts thereof, anti-corrosion agents such as e.g. fatty acids, benztriazole, etc. Other enzymes, e.g. proteases, e.g. Savinase<®> from Novo, amylases e.g. Termamyl<®> from Novo and oxidases can also be used.

As bleaching agents, those of the peroxygen type, preferably together with a bleaching precursor such as TAED, are suitable for inclusion in machine dishwashing agents.

A typical example of a conventional machine detergent composition usually contains an alkali metal tripolyphosphate in an amount of 20-60%, an alkali metal silicate in an amount of 40-80%, or an alkali metal disilicate in an amount of 5-30% by weight, a bleaching agent of peroxy type in an amount of 1-15%, a low-foaming surfactant detergent in an amount of 0.5-5% and small ingredients such as e.g. perfume, colorants, hydrotropes, fillers, etc.

The invention shall further be illustrated by means of an example.

EXAMPLE

Glass was cleaned in a Kenmore Sears dishwasher, using the normal wash program at 50°C followed by hot drying. The water hardness was 14° FH. The detergent mixture was dosed in an amount of 3 g/l and had the following composition:

The charge was a blank charge without dirt, and the contamination was 35 g/trial fresh egg yolk.

The glasses were washed once, and the number of spots on the glasses was then determined. These experiments were performed with and without lipolase (dosed at 15 LU/ml) with or without Savinase<®> (dosed at 47 GU/ml) or with Termamyl<®> (dosed at 80 MU/1) (see note).

The following results were obtained:

Note: One GU is a glycine unit, which is the amount of proteolytic enzyme which, under standard incubation conditions, produces an amount of terminal NH2 groups equivalent to 1 microgram/ml glycine.

A MU is a maltose unit, determined by the method described by P. Bernfeld in "Methods in Enzymology", Vol. I, (1955), p. 149.

Claims (5)

1. Dishwashing liquid, characterized in that it comprises 0.5-10% by weight of a surface-active agent and a lipase in an amount of 0.005-100 LU/mg of the washing-up agent, the lipase being selected from among lipases which are produced by rDNA technology and which originally originate from the lipase gene from Humicola lanuginosa (syn. Thermomyces lanuginosus), as the washing-up liquid is free of layered clay. 2. Dishwashing liquid as set forth in claim 1, characterized in that the dishwashing liquid further comprises a subtilisin protease enzyme in an amount in the range 0.1-50 GU/mg. 3. Detergent as specified in claim 1, characterized in that the detergent, when dissolved or dispersed at a surfactant level in the range of 0.4-0.8 g/l, generates a pH value of over 10, and comprises sodium silicate or other alkali salt, possibly with added caustic alkali. 4. Detergent as stated in claim 1, characterized in that the lipase enzyme is produced in Aspergillus oryzae as host. 5. Use of washing-up liquid as stated in claims 1-4, for mechanical use.