MXPA97003633A - Granulos de enzima revesti - Google Patents

Abstract

The present invention relates to coated enzyme granules and a method for preparing coated enzyme granules including the steps of (i) contacting the enzyme granules with a coating material which is either (a) a non-liquid aqueous or aqueous emulsion thereof, or (b) an oily mixture comprising at least one liquid as in (a) having dissolved therein a second component having a melting point in the range of 30 to 90 ° C, the contact is carried out to provide a substantially uniform coating on the granules of the coating material at less than 25% by weight, and (ii) to contact the granules depicted in step (i) with an anti-caking agent to obtain the granules which flow free that have a dust figure of less than 2 ug as determined by the Heuba rubbing wear test

Description

ENZYME GRANULES COATED The present invention relates to coated enzyme granules, and in particular to coated enzyme granules, suitable for use in detergent compositions, such laundry detergents and dishwashing compositions; bleaching compositions; and foods such as bakery or pastry products. In addition, the invention is directed to a method of producing such coated enzyme granules. In the field to which the present invention refers, the figuration of powder is a well-recognized problem. The granules are prone to wear by rubbing between the particles, which can lead to a partial or even total disintegration of the granules leading to reduced storage capacity and increase powder figuration. The enzyme powder can cause discomfort (eg skin irritation) to both the granule manufacturer and the consumer, especially when the enzyme granules are contained in the washing compositions. In addition, prolonged exposure to the enzyme powder REF: 24715 can lead to supersensitive and allergic reactions. Enzyme formulations and processes for preparing them have been developed to overcome or alleviate the dust problem. For example, in US Patent No. 4,106,991 and Japanese Patent No. 293167/85, processes for coated enzyme agglomerates are described. Enzyme granules are heated and carried in a high speed mixer. The melted PEG 1500 or PEG 4000 and Ti02 are added, so that the granules are coated by the PEG / TIO2 mixture. By this technique, the figure of dust by elutriation is considerably reduced compared to the uncoated granules and the enzyme powder figures of about 90 AU / 60 g are obtained from the elutriation test. U.S. Patent No. 4,973,417 describes a method wherein an aqueous dispersion of coating material comprising an ester copolymer of (meth) acrylic acid and having a temperature of about 60 ° C, is sprayed onto the enzyme granules in a fluidized bed drying apparatus in order to increase the stability of the enzyme in the detergent composition. The process described in WO-92/11347 also makes use of a fluidized bed coater wherein an aqueous solution of PEG 2000 and Ti02 is sprayed onto the hot granules in order to improve the color and powder figures of these granules. European Patent Application No. 0 139 829 describes a process comprising the steps of providing a soluble or dispersible enzyme, aqueous to the surface of core particles in a fluidized bed dryer; and spraying a solution or dispersion of a macromolecular film containing a coating agent into the coated core material, enzyme, dried in a fluidized bed dryer. International patent application No. 93/07263 discloses a granular enzyme composition comprising a core, an enzyme layer and one or more coating layers. The outer coating layers are applied in a fluidized bed. The product obtained showed, as compared to the products described in the documents cited above, figures of the enzyme powder, relatively low in the order of 4-7 μg as determined in the Heubach rubbing wear test. In US Patent No. 4,242,219 a coating is described to be applied to the enzyme particles. The applied coating should prevent moisture loss from the coated particle. This coating can be applied in an amount of less than 5% by weight and consists of a water-impelling agent selected from paraffin oil, linseed oil, petroleum, cocoa wax, candelilla wax, carnauba wax, paraffin wax , beeswax, ceresin wax and lanolin as well as mixtures thereof. The powder figures of these granules are high: up to 50 DE as measured in the elutriation test, and this document does not explicitly describe any method for applying the moisture retention coating. Belgian patent application No. BE-A-838125 discloses a coating process by which a liquid is added at the same time as a powder product to be coated on the granules which are rapidly rotated in a whisper. The granules obtained are loose particles. It is the object of the present invention to provide enhanced, coated enzyme granules having reduced enzyme powder figures, compared to enzyme granules known in the art, and without the need for extensive use of a bed coating apparatus. fluidified. In addition to this reduction of enzyme powder, the coating used in accordance with the present invention provides the possibility of incorporating additives that change the functional characteristics of the granules such as color, stability, solubility, and antistatic properties. In particular, an object of the present invention is the provision of a process wherein the amount of material of the outer coating layer, necessary to provide lower, powder figures, is low, less than 25% by weight. Also, according to the invention, the time to produce the coating layer in a fluidized bed apparatus is reduced by 50% or more compared to previously known methods.

This is achieved by the use of a liquid or oily coating material that does not need to be applied in a fluidized bed apparatus. Accordingly, the invention provides a method for preparing the coated enzyme granules which includes the steps of (i) contacting the enzyme granules with a coating material which is either (a) a non-aqueous liquid or aqueous emulsion thereof, or (b) an oily mixture comprising at least one liquid as in (a) having dissolved therein a second component having a melting point in the range of 30 to 90 ° C. contacting is carried out to provide a substantially uniform coating on the granules of the coating material at less than 25% by weight, and (ii) contacting the granules depicted in step (i) with an anti-caking agent for obtain free flowing granules having a powder figure of less than 2 μg as determined by the Heubach rubbing wear test. The invention further provides coated enzyme granules, prepared by such a process, and detergent compositions comprising them. The coated enzyme granules of the invention can be obtained by preparing enzyme granules in a method known per se and subsequently coating these enzyme granules as described above. In a preferred embodiment, the coating material is applied by spreading the liquid or oily coating material on the granules to be coated. An advantage of this process of the invention is the fact that no coating material or the granule to be coated need to be heated. This means that the activity of the enzyme is not adversely affected. The coating material is of a liquid or oily character and can simply be applied and diffused at room temperature. The coating is diffused over the granules containing enzymes when using a low speed or low shear mixing unit such as a screw or tapered screw mixer or planetary mixer, a high speed mixer or any kind of mixer or mixing unit that is able to distribute the coating material uniformly on the granules. In addition, coated enzyme particles known in the art typically require the presence of at least about 25% by weight but in general more than 30% by weight (of the weight of the complete granule) of the outer coating material to obtain a figure of acceptable powder. This amount is less than 25%, for example from 1 to 25% by weight, in preferred figure from 5 to 20% by weight using the coating method of the present invention. A further advantage is that the coating material used in the process of the present invention does not need to be applied in a fluidized bed dryer. The coating time per batch of enzyme granules in the fluidized bed apparatus is preferably expensive, therefore it can be shortened to at least 50%, which is, as the skilled artisan will appreciate, an economic and technical advantage of the process, huge.

In general, according to the invention, the liquid or oily coating material and the granules are attracted together in a mixing unit. For example, it is possible to bring the coating material and the granules to be coated into contact with one another by spraying the coating material in the liquid state on the enzyme-containing material. Subsequently, the materials are subjected to a mixing operation that provides a substance that gives the impression of wet sand. After mixing, the mass to such a degree that the fluid coating material is uniformly and homogeneously distributed over the enzyme granules, any known anticaking agent, for example fumed silica, talcum powder or starch material, can be added in order to effect that the coated particles become free flowing. The granules to be coated with the liquid or oily coating of the present invention can be of any type known in the art, especially those useful for use with detergents. Examples are small metal granules (for example, described in NL-C-148807); F-granules (US patent application No. 4,242,219); Marums (NL-A-7110323); T-granules (U.S. Patent Application No. 4,106,991); Perls (WO 91/02340) as well as coated granules thus produced in a fluidized bed dryer such as those described in WO-91/06638 and Japanese patent application No. 58/79492. In general, all kinds of granules which they have a size of approximately 150-3000, in more specific figure 300-2000 μm they can be coated according to the present invention The granules to be coated comprise a core material to which an enzyme-containing layer is applied. Core material should be dissolved or dispersed rapidly in water, it can be comprised of sugar crystals, for example, sucrose, or salts, such as NaCl, Na2S04, (NH4) 2S04, and Na2C03; small metal granules of a melting component, such as non-ionic liquids, and PEG 6000; sugar in small pellets of various colors consisting of, for example, clays and agglutinators; and powders of, for example, starch. The core of the granules normally has a size of 200 to 1500 μm and can be pre-coated in order to make the core material more resistant to rubbing. This precoating may, for example, be a cellulose derivative, a starch or derivative thereof, or a polymer such as polyvinyl pyrrolidone (PVP) or polyvinyl alcohol (PVA). The enzyme is typically applied to the granule in a fluidized bed coater. The enzymes used according to the invention are usually in the figure of a liquid. This liquid can be a microfiltrate or an ultrafiltrate, a dissolved powder or any other type of liquid that is derived from a fermentation process. The right types of enzymes are proteases, amylases, lipases, celluloses, oxidases, etc. In addition, the known agglutinators such as polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA), polyvinyl acetate (PVAc), carboxy methyl cellulose (CMC), hydroxy propyl cellulose (HPC), hydroxy ethyl cellulose (HEC), hydroxy propyl methyl cellulose (HPMC), methyl cellulose (MC) and ethyl cellulose (EC ) can be added to the enzyme-containing liquid; as well as plasticizers similar to PEG 400, propylene glycol, glycerin: coloring agents; agents that regulate pH; enzyme stabilizers; and antioxidants. All these mentioned adjuvants are well known to the person skilled in the art. If desired, the core materials containing enzymes can be precoated in a fluidized bed apparatus with a coating material known in the prior art. The advantages of the present invention, of course, will also be obtained for precoated particles even if these particles are previously coated several times. Such fluidized bed precoats can be applied to optimize the color, to improve the stability or to influence the dissolution rate of the granules. This coating of the fluidized bed slightly improves the powder figures of the granules of the invention, as compared to a situation in which the coating material of the present invention is applied in the absence of a precoating. The granules of the present invention show Heubach wear powder figures, reduced as compared to the enzyme granules (coated) known in the art, and in particular as compared to the granules described in Wj-93/07263. In this regard, reference is made to WO-93/07263, which describes the rubbing wear test of Heubach. As discussed above, the coating process of the invention, which employs a liquid or oily coating material, has various advantages over the processes wherein the outer coating is applied in a fluidized bed. Fluidized bed coated granules such as those described in WO-93/07263 are subsequently produced by spraying an enzyme layer, a salt layer and finally a coating layer to a core material in a fluidized bed coater. In order to obtain acceptable powder shapes, these granules comprise at least about 25% by weight of coating material, much more than is present in granules of the invention. The process of the present invention makes it possible to use considerably lower amounts of coating material while maintaining characteristics that are at least comparable, but in general improved, compared to the fluidized bed coated granules known in the art. In fact, it is possible to obtain granules having the advantages of the present invention which are based on the granules which do not possess any fluidized bed coating throughout. In accordance with the present invention, it is preferred that an enzyme layer (in a fluidized bed) be applied to a core material and that subsequently the enzyme layer be converted directly by the liquid or oily coating material of the invention. The granules prepared by this technique have very low powder figures. The granules of the present invention, which are coated in a mixing unit and not in a fluidized bed, only require a total amount of coating material of about 1-25% by weight, in preferred figure 5-20% by weight , to obtain extremely low dust figures of less than 2 μg, in preferred figure less than 1.5 μg; fluidized bed coated granules require at least 25% by weight of coating material to obtain powder figures that are at least 2 to 4 times higher.

The coating layer applied in accordance with the present invention is usually about 4-5 μm thick. A further advantage of the process of the invention is that the step of spraying the time consuming coating in a fluidized bed coater is no longer necessary. The coating application can be carried out in a suitable mixing unit. This greatly increases the capacity of the fluidized bed equipment as the total coating time for which the fluidized bed apparatus is required to obtain finished granules is reduced by more than 50%, and in general by more than 75%, compared to known methods. In addition, it is not necessary to heat the granules or dissolve the coating material in a solvent that has to be evaporated in a next step. The liquid or oily coating is brought into contact - for example, by spraying - with the granules to be coated, granules that are at room temperature. The oily or liquid coating material of the invention has the ability to be uniformly distributed, typically diffused, over the enzyme granules, typically in a mixing unit. This means that the liquid or oily coating material must not be too viscous. A too viscous liquid or oily mass will lead to the figuration of pieces of coating material with granules that stick to them. Similarly, the coating (which must be diffused) can not be too volatile. Preferably the compositions in which the granules of the invention are used, maintain their characteristics for at least six weeks and in a more preferred figure three months or more. This means that the fluid coating material in the preferred embodiment must remain stable during this period of time. In general, the fluid coating material must adhere to, or be adsorbed to, the surface to be coated. Also, the coating material of the invention in preferred embodiment should not adversely affect the characteristics of the enzymes or vice versa. For example, a granule comprising lipase in a preferred embodiment should not be coated with a coating material comprising glycerol monostearate, because the lipase decomposes the stearate.

The liquids used in the process of the present invention are generally non-aqueous. However, if an oily coating material or a material in the form of a liquid or oily emulsion is used, water may be present. For example, a water emulsion in a non-polar continuous phase can be used. Suitable non-aqueous liquids are oils, polyalcohols, fatty alcohols and non-ionic liquids. Examples of suitable oils are paraffin oil and flax oil; suitable polyalcohols comprise polyethylene glycol (PEG) 200-800 (ie PEG having an average molecular weight of 200-800); examples of fatty alcohols are mixtures of straight chain alcohols (lorols) of 6 to 12 carbon atoms; and liquid non-ionic liquids, suitable are Dobanol 45-11® and Triton X-114®. The oily coating materials of the invention comprise at least one solid in addition to the non-aqueous liquid described above. This solid should have a melting point in the range of 30-90 ° C, in a preferred figure of 40-80 ° C, in a more preferred figure of 50-70 ° C. In addition, the solid must be dissolved in the liquid in the melt. The advantages of introducing a solid into the liquid are, for example, an increase in the moisture barrier effect of the coating and / or a decrease in the amount of the anti-caking agent necessary to obtain a flow-free material. Suitable solids include PEG > 900 (PEG having an average molecular mass of greater than 900), in preferred figure > 1500, stearic acid, glycerol monostearate, paraffin, non-ionic surfactants, sodium laurate, and waxes such as beeswax. The solid in the molten state must be dissolved in the liquid. In cooling to room temperature, a homogeneous oily mass is typically shown, having a hardness and viscosity such that it can diffuse or otherwise be uniformly applied to the granules in a mixing unit. In general, a liquid to solid ratio of between about 5: 1 and about 1: 2 for example 5: 3 or 1: 1 may be adequate. For example, a mixture of PEG 4000: 400 (1: 1) provides an oily, relatively hard coating formulation, while the PEG 4000: 400 (1: 3) is almost very soft. It is within the ability of the person skilled in the art to find other suitable mixtures having these characteristics. The liquid or oily coating material can provide a water impermeable layer that covers the enzyme layer. In addition, this makes it easy to add the agents that stabilize the enzyme to improve the stability of the enzymes in a laundry detergent compositions. Any suitable additive can be added to the liquid or oily coating material. First, colorants such as Ti02, CaC03, Na-Al-silicates, Patent Blue V80, Tartrazine XX90, etc. can be added. In addition, known antioxidants (for example, tert-butyl hydroxy toluene (BHT), tert-butyl hydroxy anisole (BHA), octyl gallate); known antistats, for example, Prápagen WK (Hoechst A.G.), Ciastat SN (NVCP Chemicals), Zelec NK (Inernatio Alchemy Handelsmij B.V.); agents that regulate moisture permeation such as cellulose derivatives (ethylcellulose, hydroxypropyl cellulose), cellulose esters ((meth) acrylic acid esters such as Eudragit) and other polymers can be used. The only requirements of these additives that must be met are compatibility with the enzymes in the granules and the liquid or oily coating, and solubility or dispersibility in the oily or liquid coating material. In addition, the application of the coating layer of the present invention can play a role in the controlled release of various types of enzyme. By adapting the composition or thickness of the coating layer, it is possible to effect a time-dependent enzyme release. The anti-caking agent which is used to make the coated granules of the invention free flowing, can be any anti-caking agent, known such as fumed silica (Aerosil, for example, Aerosil R 972, R 200; Cab-o-sil®, example TS 610), calcium phosphate (Cafos), Ti02, talcum powder, starch materials from corn and other cereals, etc. The following examples illustrate the invention.

EXAMPLE 1 1000 g of small uncoated Maxacal metal granules (Gist-brocides) prepared as described in NL-C-148807, were introduced into a planetary mixer (HOBART® model N-50). To these small metal granules, 30 g of an oily mixture of PEG 4000: PEG 400 (3: 5) were added at 55 ° C. After 30 minutes of mixing, 15 g of Cab-o-sil TS-610 was added, followed by mixing for 5 minutes. The free flowing, obtained coated granules were subjected to an elutriation test, as well as the small untreated Maxacal metal granules. In this elutriation test, 60 g of the granules were fluidized during 40 minutes in a fluidized bed, maintaining a surface velocity of 0.8 m / s. The figured powder was collected on a Whatman® GF / C filter, the mass of the powder was determined and tested on the activity of the enzyme. In this regard, reference is made to Belgian patent application No. 838125 which describes the elutriation test. The figure of enzyme powder obtained by the small uncoated Maxacal metal granules was 125 DE / 60 g, while the powder figure of the granules of the invention was only 12 DE / 60 g. The enzyme powder figure was expressed in DE (Delft Eenheden; Delft Units) as described in British patent application No. 1,353,317.

Example 2 500 g of uncoated Maxacal® F, prepared as described in the US patent application No. 4,242,219, was introduced into a planetary mixer (HOBART model N-50). To these granules, 5 g of an oily mixture of paraffin oil were added: glycerol monostearate (1: 1). After 30 minutes of mixing, 5 g of Aerosil® R-972 (Degussa AG) were added, followed by mixing for 5 minutes. The powder figures measured as described in Example 1 were 80 DE / 60 g (uncoated Maxaca'l F) and 10 DE / 60 g (granules of the invention).

Example 3 1000 g of uncoated Maxacal fluidized bed granules, prepared as described in WO-93/07263, was introduced into a planetary mixer (HOBART model N-50). To these granules, 30 g of oily mixture of paraffin oil were added: glycerol monostearate (3: 1).

After 45 minutes of mixing, 24 g of Aerosil R 972 were added, followed by mixing for 10 minutes. The elutriation of the powder figures of the uncoated and coated granules was measured, but both were lower than the detection limit. However, the wear value per rub of Heubach was reduced from 580 μg to 1.1 μg of enzyme powder / 16.25 ml of granules. The wear value by rubbing Heubach is obtained from a fluidized bed test in which the balls having a mass of approximately 32 g on a bed having a volume of 16.25 ml of granules, through which an air current of 20 1 / min is housed it flows for a period of 20 minutes. The air passes through a filter. The mass of the filter is determined before and after the test and the collected dust is analyzed to determine the content of the enzyme in μg.

Example 4 To 1000 g of small uncoated Lipomax® metal granules prepared as described in NL-C-148807, 25 g of Triton X114 (Union Carbide) was added. After mixing for 30 minutes, 10 g of Aerosil R972 was added as an anti-caking agent. The entire mixture was mixed for another 10 minutes. The Heubach powder figures of the small coated and uncoated metal granules were found to be less than 0.8 μg and were 30 μg, respectively.

Example 5 In 6 kg of Na2SO4 crystals of 400-600 μm, 3.5 kg of Maxacal® UF of 2,800 ADE / mg, having a dry solid content, were sprayed into a fluidized bed apparatus (MP-1 of Niro-Aeromatic). of 26% and containing 1% by weight of borax as an enzyme stabilizer. Immediately after this step, 10 kg of a 12% Sepifilm® 046 (SEPPIC) coating containing 5% by weight of Ti02 based on the weight of the dry substance was sprayed onto the enzyme layer. This process had a mass yield of 98.5% and an enzyme activity yield of 95%. The obtained products were sieved using 1000 μm and 315 μm sieves. The friction wear test value was determined to be 1 μg of enzyme powder. In an additional test, the fluidized bed coating was replaced by a mixture of hydroxy propyl methyl cellulose (HPMC), hydroxy ethyl cellulose (HEC), cellulose, Ti02, talc and PEG-400 in water. Before and during the fluidized bed coating by spraying, samples were taken in fixed time periods. In a number of cases, the samples were coated using the coating described in Example 3. The characteristics of the samples that were expressed in Enzyme Powder (PE) were determined in the elutriation test and in the Heubach test, respectively. The results are mentioned in table 1.

Table 1 Enzyme Powder Figures Amount of Heubach (PE) μg Elutriation (PE) coating (bed ADE / 60 g fluidized + ointment) FB * 0% + U # al 1.2 28 5.4% FB at 5% + U al < 1.0 23 5.4% 10% FB 186 134 20% FB 3.5 52 * FB: Fluidized Bed Coating #U: Oily coating Coated granules according to the present invention have powder figures that are reduced in powder figures than granules which only comprise a fluidized bed coating.

Example 6 Example 5 was repeated, except that borax was not used in this example. No fluidized bed coating was applied. Due to the absence of the fluidized bed coating step, the process of this example only took 25% of the necessary process time in Example 5. The product obtained was sieved on a 1000 μm screen. This sieved product was placed in a planetary mixer and coated with paraffin oil: glycerol monostearate (3: 1). The Heubach powder value of the uncoated product was found to be above 1000 μg of enzyme powder per 16.25 ml of granules, whereas this value was only less than 0.2 μg of enzyme powder per 16.25 ml of granules per product. coated according to the invention.

Example 7 In a Nauta mixing unit (conical screw or screw) having a content of 7 cubic meters, 4000 kg of small Maxacal metal granules were introduced by means of a diaphragm. 120 kg of oily coating material, described in Example 3 having a temperature of 70 ° C, were sprayed onto the incoming stream of small metal granules at room temperature.

After the introduction of all the small metal granules and the coating material, the entire mixture was mixed for 15 minutes. 96 kg of Aerosil R972 was added as an anti-caking agent. The mixing procedure was continued for 15 minutes. The elutriation value decreased from 72 (uncoated) to less than 5 DE / 60 g (coated according to the invention).

Example 8 In order to measure the influence of electrostaticity, Example 1 was repeated using the same oily coating as well as coatings to which were added % by weight of Zelec NK and to which 5% by weight of Prápagen WK were added. After the coating, the small metal granules were passed through a plastic container, flat, open. The three different types of small metal granules were each shaken by hand in the containers for 1 minute, in order to load them.

Subsequently, the charged particles were carried in a 30x30 cm wooden vessel. The resistance of the electric field was determined using a magnetic field strength meter or Electronic inductor of STAT-ARC Digital, Model 255 M-l (Monroe Electronics). The distance between the magnetic field strength meter and the surface of the small metal granules was about 1 cm. Results: the small metal granules that did not contain any antistatic had a low initial charge that disappeared slowly within 10 minutes; the small metal granules containing Zelec NK did not obtain any initial charge; the small metal pellets containing Prápagen WK lost 50% of their initial charge within 10 seconds.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, the content of the following claims is claimed as property.

Claims (14)

1. A method for preparing coated enzyme granules including the steps of (i) contacting the enzyme granules with a coating material which is either (a) a non-aqueous liquid or aqueous emulsion thereof, or (b) an oily mixture comprising at least one liquid as in (a) having dissolved therein a second component having a melting point in the range of 30 to 90 ° C. contacting is carried out to provide a substantially uniform coating on the granules of the coating material at less than 25% by weight, and (ii) contacting the granules depicted in step (i) with an anti-caking agent for obtain free flowing granules having a powder figure of less than 2 μg as determined by the Heubach rubbing wear test.

2. A method according to claim 1, characterized in that the liquid is selected from oils, polyalcohols, fatty alcohols and nonionic liquids.

3. A method according to claim 1, characterized in that the enzyme granules to be coated are precoated in a fluidized bed with a precoat comprising not more than 5% by weight of the granules to be coated.

4. A method according to claim 1, characterized in that the coating material (a) or (b) is applied directly to the enzyme layer of the granules.

5. A method according to any of claims 1 to 4, characterized in that the coating material (a) or (b) and optionally the anti-caking agent are applied to the granules in a mixing unit or a mixing unit.

6. A method according to claim 5, characterized in that the mixing unit is a mixing unit with low shear stress.

7. A method according to any of the preceding claims, characterized in that the coating material (a) or (b) is applied to produce a coating of 5 to 20% by weight.

8. A method according to any of the preceding claims, characterized in that the anti-caking agent is smoked silica, calcium phosphate, Ti02, talcum powder or starch.

9. A method according to any of the preceding claims, characterized in that the core of the granules to be coated have a size of 200 to 1500 μm.

10. A method according to any of the preceding claims, characterized in that the coating material (a) or (b) is applied to include a layer having a thickness of 4 to 5 μm.

11. A method according to any of the preceding claims, characterized in that in component (b), the ratio of liquid (a) to solid is from 5: 1 to 1: 2.

12. A coated enzyme granule characterized in that it has a powder figure of less than 2 μg, in preferred figure less than 1.5 μg as determined in the Heubach rubbing wear test.

13. A coated enzyme granule according to claim 12, characterized in that it can be obtained by a process according to any of claims 1 to 11.

14. A detergent composition, characterized in that it comprises one or more enzyme granules, coated as defined in claim 12.