US3634267A - Enzyme additives - Google Patents

Abstract

METHOD FOR PREPARING STABLE PARTICULATE ADDITIVES, USEFUL IN DETERGENTS, WHICH COMPRISES A CORE OF ENZYMATICALLY INACTIVE MATERIAL COMPRISING AN ETHYLENE-MALEIC ANHYDRIDE COPOLYMER OR THE ALKALI METAL, AMMONIUM AND AMINE SALTS THEREOF AND A SURFACE COATING OF ENZYME MATERIAL.

Description

United States Patent 3,634,267 ENZYME ADDITIVES Richard T. Haynes, Kirkwood, Robert P. Langguth, St. Louis, and Raymond L. Liss, Warson Woods, Mo., assignors to Monsanto Company, St. Louis, M0. N0 Drawing. Filed Apr. 25, 1968, Ser. No. 724,270 Int. Cl. Clld 3/066 US. Cl. 252-527 3 Claims ABSTRACT OF THE DISCLOSURE Method for preparing stable particulate additives, useful in detergents, which comprises a core of enzymatically inactive material comprising an ethylene-'maleic anhydride copolymer or the alkali metal, ammonium and amine salts thereof and a surface coating of enzyme material.

This invention relates to new compositions of matter, processes for preparing the novel compositions of matter, and to detergent formulations including the same. More specifically, the invention relates to particulate materials useful as a detergent additive having a surface layer of an enzyme material and an inner core of material that is enzymatically inactive.

The detergent industry has long recognized the beneficial effects of enzymes in aiding in the removal of soils of a protein, carbohydrate or a fatty nature. Enzymes are powerful cleaning substances and, consequently, only a small amount is included in a detergent formulation. Previous attempts to include enzymes in detergent formulations have achieved only limited success, either because most of the activity of the enzyme is lost within a short period of time and/or because of the tendency of the enzyme to segregate. It will be seen, therefore, that an enzyme material in a form such that it can be added to a detergent composition without excessive loss of activity and such that it does not tend to segregate from the detergent mixture would constitute an important advance in the art.

In accordance with this invention, an enzymatically active product is prepared in the form of a particulate material in which the particles comprise a core of enzymatically inactive material and a surface coating of enzyme material. The particles can be added to a conventional detergent product with surprisingly little loss of activity, and since a wide variety of core materials has been found to be suitable, a core material can be selected such that the resulting particles have a density approximating that of the detergent product to which they are to be added, thus greatly reducing or eliminating the problem of segregation.

The reason or reasons for the greatly increased stability of enzyme products of the present invention as compared to previously available products are not known with certainty, but the increased stability is believed to be due to the neutral nature of the core material. Even though it might be assumed that there would at most be surface inactivation in a dry mixture, it now appears that the instability of conventional enzyme products in detergent compositions is most often due to the alkaline nature of some conventional detergent materials, and in the products of the present invention, the enzyme is protected perhaps by limited contact with the alkaline detergent materials and/or by the lack of action of the neutral core material on the enzyme. However, applicant does not wish to be bound by any particular theory or theories.

Generally, the enzyme material obtained by the fermentation of microorganisms is in an impure state, a finely divided solid material containing an enzyme or a mixture of enzymes and substances used in their preparation. The term enzyme material as used herein refers to a material composed of about 1% to about of the active enzyme or a mixture of enzymes and about 5% to about 99% of materials used in its or their preparation. The active enzyme or enzyme activity as used herein refers to the enzymes ability to change or degradate the undesirable soils and the stability refers to its property of remaining active, to perform these functions.

Enzymes are generally classified in terms of their functions, which represent different chemical reactions, as in this instance, where the chemical reaction results in either the degradation or change of soil. However, as with most classification systems, there are some enzymes whose functions will fit into two or more classes. Following is a list of five subclasses of enzymes based on their functions.

(1) Hydrolases are enzymes that catalyze the splitting of soil, especially that of a proteinaceous nature by the addition of water.

(2) Oxidoreductases are enzymes that catalyze the oxidation or reduction of soil.

(3) Transferases are enzymes which transfer one radical from one molecule to another and change soil from an insoluble form, for example, to a soluble form.

(4) Demolases are enzymes which split or form linkages without transferring groups and degradate soil of the hydrocarbon type, for example, making it easier to remove.

(5) Isomerases are enzymes which isomerize molecules and chemically change soil particles of the fat type, for example, making it easier to remove.

Generally speaking, hydrolases, oxidoreductases and demolases degradate soil such as that of the proteinaceous nature until it is removed or rendered easier to remove and transferases and isomerases change or modify soil such as that of the fat type, making it easier to remove. Of these types, hydrolases are particularly preferred.

Hydrolases catalyze the addition of water to the soil and thus cause a splitting of the soil, for example, hydrolases split body proteins making them easier to remove. The hydrolases which are particularly preferred include proteases, esterases and neucleases. The protease enzyme is particularly effective in its ability to degradate soil. Proteases catalyze the hydrolysis of peptide linkages, poly peptides and compounds related to the carboxyl and free amino groups and thus degrade the protein substances in hard-to-remove soils such as blood, gravy, egg, skin protein containing perspiration and the like.

Specific examples of proteases suitable for use in this invention include neutral protease. pepsin, rennin, trypsin, chymotrypsin, subtilisn and the like.

Esterases catalyze the hydrolysis of ester links in fats, alcohol esters, phosphoric esters, sulfuric esters, thioesters and phenolic esters. Examples of these esterases include lipase, chloinesterase, phytase and phosphatase.

Carbohydrases catalyze the splitting of glycosidic linkages and are particularly effective in decomposing carbo- 3 hydrates. Specific examples include maltase, sucrase, cellulase and amylase.

Nucleases catalyze the splitting of nucleic acids and related compounds such as skin cells. Two specific examples of this group are ribonuclease and deoxyribonuclease.

The above enzymes can be produced from the following microorganisms which include bacteria, yeasts, fungi and the like by well-known methods such as that of fermentation described in Kirk and Othman, Encyclopedia of Chemical Technology, volume 8, pages 173, 204. Examples of actinomycetes include Strcptomyces griseus, Streptomyces albus. Illustrative yeasts include Saccharomyces cerevisiac, T orula utilis, and Candida lipolylica. Examples of fungi include Aspergillus oryzae and Aspergillus aureus.

The following microorganisms produce either a protease, lypase, amylase or mixtures thereof. Illustrative of the proteolytic enzymes are Bacillus subtilis and Aspargillus oiyzac. Examples of lypolitic enzymes include Aspergillus aureus and Candida lypolytica. Examples of amolytic enzymes include Bacillus subtilis and Bacillus mcscrztericus.

The activity of the above enzymes depends on the method of preparation and is not critical to the present invention, providing, however, that the enzyme material has the desired enzyme activity. Various analytical methods are available to determine the activity of the different enzymes, for example, the protease activity of a proteolytic enzyme is determined by the well known Casein Method. According to this test a protease catalyzes the hydrolysis of the casein for a certain period of time and temperature. The reaction is then stopped by the addition of trichloroacetic acid then the solution is filtered. The color of the filtrate is developed by a Folin reagent and the level of enzyme activity is measured spectrophotometrically. This method is more thoroughly described in the Journal of General Physiology 30, 291, 1947 and in Methods of Enzymology, Academic Press, New York, 1955, volume 2, page 33.

The enzyme materials which are produced from the aforementioned bacteria generally will pass through the Standard U.S. 12 mesh screen. Some enzyme materials are sufiiciently fine to pass through the Standard U.S. 100 mesh screen. Generally, the greater part of the particles will be retained on a U.S. 400 mesh screen. Thus the enzyme materials used herein have a particle size within the range of from about 1 micron up to a thousand microns and more commonly from about microns to about 100 microns.

An enzyme material suitable for use in accordance with this invention is one that is active at a pH from about 4 to about 12 preferably from about 7 to about 11 and at a temperature of about 10 C. to about 85 C. preferably from about C. to about 76 C. A particularly effective enzyme material that can be used in accordance with the present invention is one produced by a mutated Bacillus subtilis organism. The process for producing this organism is described in U.S. Patent No. 3,031,380. A culture of the Bacillus subtilis organism has been deposited with the United States Department of Agriculture, Agricultural Research Service, Northern Utilization and Development Division, 1815 North University Street, Peoria, Ill. 61604, and has been assigned No. NRRL B3411. An enzyme material produced from this organism consists of two proteases approximately 65% to 75% neutral protease (active at a pH of 7 to 7.5) and about 35% alkaline protease (active at pH of 10 to 11). A significant amount of amylase is present. There are generally about 700 thousand to 1.2 million units of neutral protease activity per gram and about 250 thousand to about 400 thousand units of alkaline protease activity per gram as determined by the Casein Method. There are generally about 300 thou sand to 350 thousand units of amylase activity per gram.

Its particles size is predominantly in the range from about 5 microns to about 35 microns. This enzyme material used in accordance with the invention gives excellent results in washing solutions at a temperature in the range from approximately 10 C. to approximately C. and at a pH from about 6 to about 11.

Another enzyme material that can be used in the present invention is one produced from a Streptomyces griseus culture broth used for the manufacture of streptomycin. It is isolated by the treatment of sucecssive columns of resin. The principal component is a neutral protease called Streptomyccs griseus protease. This enzyme material stabilized with calcium salt, is active at a pH of from about 4 to about 10 and at a temperature from about 10 C to about 65 C.

Other effective enzyme materials are produced by S rreptomyase rectus and Prolisin.

The amount of active enzyme used in the detergent additives can be any amount from about 1% to about by weight of the additive preferably any amount from about 2% to about 50% by weight.

The enzymatically inactive inert core materials that can be used in accordance with this invention are watersoluble materials that dissolve in water to produce a solution having a pH at 25 C. of from about 5.5 to about 8.5 at a concentration of 1% by weight or at saturation if the solubility of the material in water at 25 C. is less than 1% by weight and water-insoluble materials where less than 0.01 gram of a material is soluble in 100 cc. of water at 25 C. These materials include the inorganic salts, organic salts, carbohydrates, mineral fibers and resins and the like.

Illustrative inorganic salts include sodium bicarbonate, sodium sulfate, magnesium sulfate, borax, calcium sulfate, aluminum oxide, aluminum silicate and calcium oxide. Examples of organic salts include aluminum-tristearate, calcium laureate, lithium laureate. Illustrative carbohydrates include starch, carboxy methyl cellulose and sucrose. Illustrative mineral fibers include asbestos. Illustrative resins include the salts of an olefin maleic anhydride and a substituted olefin maleic anhydride including the alkali metal, ammonium and amine salts of ethylene maleic anhydride. Other core materials include silica. It is preferred that the inner core material be watersoluble.

The amount of inner core material used in accordance with this invention depends on the ratio of enzyme material to inner core material. This ratio is from about 0.1 :9.9 to about :25 and preferably from about 1:9 to about 1:1. The ratio of enzyme material to a carbohydrate, for example, would be about 1:9 to about 1:1 and when the enzyme material is obtained from a Bacillus subtilis organism, and the carbohydrate is starch, the ratio is about 1:9. The ratio of the enzyme material to an inorganic salt is from about 1:9 to about 1:1, for example, when the enzyme material is obtained from a Bacillus subtilis organism and the salt is sodium bicarbonate, the ratio is about 1:4.

Although any bulk density from about .2 to about 1.5 grams per cc. can be prepared according to this invention, it is preferred to prepare a product having a bulk density of from about .4 to about .8 gram per cc. Likewise, any particle size can be produced in accordance with the invention; however, it is preferred to produce a product which has particles which will pass through a U.S. Standard 12 mesh screen and be retained on a U.S. Standard 200 mesh screen. In most instances it will be desired to produce a detergent additive having a bulk density and particle distribution which is similar to that of the commercially available detergents to minimize segregation of the particles after mixing.

Generally the particles produced in accordance with this invention will have a core material which is enzymatically inactive and a surface layer of material which is enzymatically active; however, these particles may adhere to each other forming aggregates. These aggregates will have enzymatically active materials on the surface as well as at the interfaces of the particles making up the aggregates. It is within the scope of this invention to produce these aggregates.

The novel process in accordance with this invention involves the intermixing of a particulate core material, hereinbefore mentioned and a slurry of enzyme material in an inert liquid diluent, the ratio of liquid diluent in which the enzyme material is slurried to core material being such that the core material remains predominantly undissolved. The weight ratio of enzyme material to the core material is from about 0.1 :9.9 to about 7.5 ;2.5, preferably from about 1:9 to about 1:1. The liquid diluent is removed by evaporation from the mixture to thereby result in a particulate material in which the particles have a core of material which is enzymatically inactive and a surface layer of enzymatically active material.

Any inert liquid diluent can be used in slurring the enzyme. Illustrative liquids include the alkyl and alkenyl alcohols having 1 to 5 carbons in the alkyl group such as methyl, ethyl, and isopropyl; the polyhydric alcohols such as ethylene glycol and 1,3-butane diols, and the cyclic alcohols having 1 to 15 carbon atoms such as cyclohexanol. Examples of ethers include dialkyl ethers having 1 to carbon atoms including ethyl ether and ethyl normal butyl ether. Examples of ketones include dialkylketones having 1 to 10 carbon atoms such as acetone, methyl ethyl and diethyl. Illustrative esters having 1 to 5 carbon atoms include methyl acetate and methyl formate. Examples of hydrocarbons include the hydrocarbons having 1 to carbons such as benzene, toluene and ethyl benzene. Although any of the above inert liquids can be used in accordance with this invention, it is preferred to use water because it is readily available and economical. Water can be used in the form of ice, or liquid water. In most instances liquid water would be preferred because it is easier to disperse than ice.

Any concentration of the enzyme material in the slurry can be used so long as the ratio of liquid diluent to core material remains such that the core material remains predominantly undissolved in said liquid diluent. Generally speaking, a to about 80% concentration of the enzyme material in the slurry can be used and it is preferable to use a concentration of about to about 50% of the enzyme material in the slurry.

As mentioned hereinbefore the ratio of liquid diluent to core material must be such that the core material remains predominantly undissolved in said liquid diluent. It is preferred that no more than about 20% by weight of the core material and more preferably no more than about 10% by weight of the core material dissolve in the liquid diluent.

Although the proper ratio of liquid diluent to core material can be maintained by adding the slurry to the core material over a short period of time, it is preferred to add it at a rate which will generally result in even distribution of the enzyme material on the core material. The rate used will be dependent upon the equipment design and can be easily determined by those skilled in the art of blending. Generally, the slurry of enzyme material can be intermixed with the core material while this material is being mixed or tumbled in a suitable mixing vessel such as a ribbon blender. However, a slurry of the enzyme could be first added to a suitable mixing vessel such as a ribbon blender and then the core material could be added either over a short period of time or preferably over a longer period of time. A preferred way of intermixing the enzyme material is to spray a slurry of the enzyme material onto the core material while it is being mixed in a ribbon blender.

Any convenient method of evaporation can be used in accordance with this invention such as air drying, vacuum drying and the like. Generally when heat is used to dry the coated material, the temperature should be kept below about 60 C. as temperatures above 60 C. generally result in some loss of activity of the enzyme material.

In accordance with this invention a detergent formulation comprising a particulate material having a surface layer of enzyme and an inner core of a material which is inactive, an organic surfactant and a builder can be prepared. As noted hereinbefore, that by using an ordinary detergent, that is, one that is commercially available, it is very difficult to remove soil of the protein, carbohydrate or a fat nature such as blood, perspiration, gravy and the like. However, by using a detergent formulation containing one of the enzymes hereinbefore mentioned these soils can readily be removed. The detergent additive contains from about 1% to about 95% of the active enzyme and from about 5% to about 99% of the inert ingredients. Preferably the range of the active enzyme is from about 3% to about 50%. The amount of active enzyme that must be incorporated into a detergent to remove the above mentioned soil generally is in the range of from about .001% to about 2% by weight and generally from about .005% to about 0.5% by weight of the detergent composition. The detergent ingredients that can be used in accordance with this invention include the surface active agents. The surface active agents which are generally employed are various soaps, such as those produced from the saponification of a fatty acid such as palmitic, oleic and the synthetic organic surfactants including the anionic, nonionic, and ampholytic types and mixtures thereof. Anionic synthetic surface active agents are generally described as those compounds which contain hydrophilic and lyophilic groups in their molecular structure and ionized in an aqueous medium to give anions containing both the lyophilic group and the hydrophilic group. The alkyl aryl sulfonates such as sodium dodecylbenzene sulfonate; the alkane sulfates, such as sodium dodecyl sulfate; and the sulfated oxyethylated phenols, such as sodium tetradecyl phenoxy triethyleneoxy sulfate, are illustrate of the well-known class of anionic type of surface active compounds.

Nonionic surface active compounds can be broadly described as compounds which do not ionize but acquire hydrophilic characteristics from an oxygenated side chain such as polyoxyethylene and the lyophilic part of the molecule may come from fatty acids, phenol, alcohols, amides, or amines. The compounds are usually made by reacting an alkylene oxide such as ethylene oxide, butylene oxide, propylene oxide and the like with fatty acids, the straight or branched chain alcohols, phenols, thiophenols, amides, and amines to form polyoxyalkylene glycol ethers and esters, polyoxyalkylene alkyl phenol and polyoxyalkylene thiophenols, and polyoxyalkylene amides and the like. It is generally preferred to react from about 3 to about 30 moles of alkylene oxide per mole of the fatty acids, alcohols, phenols, thiophenols, amides or amines. Illustrative of the surface active agents include the product obtained from condensing ethylene oxide with the following: propylene glycol, ethylene diamine, diethylene glycol, dodecyl phenol, nonyl phenol and the like.

Amphoteric surface active compounds can be broadly described as compounds which have both an anionic and cationic group in their structure. Illustrative of the amphoteric surface active agents are the amido alkane sulfonates, such as sodium C-tridecyl, N-methyl, amido ethyl sulfonate.

Other individual compounds which are illustrative of the foregoing classes of surface active agents are well known in the art and can be found in standard detergent reference materials such as Surface Active Agents, Schwartz and Perry, Interscience Publishers, Inc., New York, N.Y. (1940).

Builders which can be employed in detergent composition formulations in accordance with the process of this invention include various organic and inorganic salts and mixtures thereof. Generally, these additives constitute from about 10 to about by weight of the detergent composition and add to the detergency efficiency of the surface active agent.

The organic compounds which are used included aminopolycarboxylic acids, their water soluble salts, such as nitrilo triacetic acid and its alkali metal salts; the amino tri (lower alkylidenephosphonic acids) and their water-soluble salts such as amino tri (methylenephosphonic acid) and its alkali metal salts and the alkylene diphosphonic acids and their water-soluble salts such as methylene diphosphonic acid and its alkali metal salts and mixtures of the foregoing compounds.

The inorganic salts which are normally used in detergent compositions include the alkali metal polyphosphates and in particular the sodium and potassium tripolyphosphates and pyrophosphates. The detergent materials will contain an alkali metal polyphosphate and particularly it is preferred that some sodium tripolyphosphate be present, generally in amounts of from at least about to about 80% by weight with amounts from 20% to 60% by weight being especially preferred.

Additionally in many of the detergent compositions other additives are present such as anti-redeposition agents, brightening agents, corrosion inhibitors, perfumes, inert fillers, dyes, bluing agents and the like. Typical examples of such additives are sodium carboxymethyl cellulose, polyvinyl alcohol, sodium sulfate, sodium silicate, methyl cellulose and sodium carbonates.

The following non-limiting detailed examples are presented to further illustrate the invention. All parts, portions and percentages are by weight unless otherwise stated.

EXAMPLE I About 1,000 parts of starch having about retained on a U.S. Standard mesh screen and essentially 90% retained on a U.S. Standard 140 mesh screen are charged into a ribbon mixer. A aqueous slurry of an enzyme material produced by a mutated Bacillus subtilis organism NRRL No. B-34l1, is sprayed onto the starch in the ribbon blender using an aerosol atomizer. The product is allowed to air dry overnight. Analysis of this product indicated that the ratio of enzyme material to starch is about 1:9. The particle size is such that 5% is retained on a U.S. Standard 20 mesh screen and essentially 95% retained on a U.S. Standard 200 mesh screen. Five parts of this product is then admixed with a detergent having the following formula:

Percent Sodium alkyl benzene sulfonate 15 Sodium tripolyphosphate 41 Sodium silicate 6 Sodium sulfate 20.5 Sodium carboxymethylcellulose 0.5 Water 8 The detergent containing the product of Example I is placed in a carton, sealed and then stored at a tempera ture of 90 F. and 85% relative humidity to test stability. Five parts of the same enzyme having the same activity are sprayed directly onto the detergent having the same formula as in Example I, and tested for stability at 90 F. and 85% relative humidity. Results of these tests are given in Table I.

The functional performance of the detergent containing Example I, and the detergent, in which the enzyme is added by spraying, along with a detergent containing no enzyme is determined immediately after incorporation of the enzyme and after about 4 weeks of storage at 90 F. and 85% relative humidity.

In this test four 3" x 4 /2 standard blood-milk-ink soiled swatches are washed in one liter of 0.15% detergent solution at 120 F. and 150 parts per million water hardness for 10 minutes. The swatches are dried on a fiat bed press and readings taken on a Gardner Color Difference Meter. Appearance numbers are then calculated. Results are given in Table I for this test and for the same test using four standard cocoa-milk-sugar soiled swatches.

TABLE I 0 days storage 28 days storage A.N. A.N. bloodblood- Aetivity, milk-ink Activity, milk-ink percent soil percent soil Formulation without enzyme 30 30 Formulation with enzyme sprayed on 100 33 32 Formulation with product of Example I 100 55 77 45 AN. AN.

eoeoacocoamilkn1ilk- Activity, sugar Activity, su ar percent soil percent soil Formulation without enzyme 18 18 Formulation with enzyme sprayed on 100 33 33 19 Formulation with product of Example I 100 33 77 28 As can be seen from the above test there is a significant improvement in the stability of the enzyme material which has been deposited on the core material and then admixed into a detergent formulation, over the enzyme material that has been sprayed directly onto the detergent formulation. This test is conducted under accelerated conditions, to get an indication of the stability of the product for its entire shelf life. Therefore, some activity loss is expected. It will readily be appreciated that a product produced in accordance with this invention will lose only a minor amount of activity after incorporation into a detergent.

The soil removing ability is indicated by the magnitude of the appearance number. As can be seen from the above table, the soil removing ability of the detergent containing the enzyme is better than the detergent that does not contain the enzyme. However, the detergent with the enzyme sprayed on is barely better than the control after 28 days of storage, whereas the formulation containing the product of Example I is far superior to the control after 4 weeks storage. It will readily be appreciated that enzyme products produced in accordance with this invention and included in a detergent are superior in stability and performance to those detergents that have the enzyme sprayed directly onto the detergent particles.

EXAMPLE II About 900 parts of asbestos having about 1% retained on a U.S. Standard 20 mesh screen and essentially retained on a U.S. Standard 140 mesh screen are charged into a ribbon mixer. A 25 aqueous slurry of enzyme material, the same as used in Example I containing 100 parts of enzyme in the slurry, are sprayed onto the core material in the mixer using an aerosol atomizer. The product is allowed to air dry overnight. An analysis showed the ratio of enzyme material to asbestos of about 1:9. The particle size is such that 15% is retained on a U.S. Standard 20 mesh screen and are retained on a U.S. Standard 140 mesh screen. The product of Example II is included in a detergent formulation and tested in the same manner as Example I, yielding similar results.

EXAMPLE III About 900 parts of calcium sulfate having about 5% retained on a U.S. Standard 20 mesh screen and essentially retained on a U.S. Standard 200 mesh screen are charged into a ribbon mixer. A 25 aqueous slurry of enzyme material, the same enzyme as used in Example I containing parts of enzyme material are sprayed onto the calcium sulfate using an aerosol atomizer. Analysis of this product that the ratio of the enzyme material to calcium sulfate is about 1:9. The

product is tested in the same manner as Example I, giving substantially similar results.

EXAMPLE IV Substantially similar results are achieved as in Examples I through III when substantially equal amounts of carboxymethylcellulose, sodium bicarbonate, borax and silica are used.

EXAMPLE V Substantially similar results are achieved as in Examples I through III when substantially equal amounts of methyl alcohol, ethyl alcohol, 50% aqueous solution of methyl alcohol and propyl alcohol are used to slurry the enzyme material.

What is claimed is:

1. A method for producing a particulate enzyme composition useful as a detergent additive, which method comprises (1) intermixing a particulate core material and a slurry of enzyme material in an inert liquid diluent selected from the group consisting of alkyl and alkenyl alcohols having 1 to 5 carbon atoms, ethylene glycol, 1,3-butane diol, ketones selected from the group consisting of acetone and methyl ethyl and diethyl ketones, benzene, toluene and ethyl benzene and water, the ratio of liquid diluent, in which said enzyme is slurried, to said core material being such that said core material remains predominantly undissolved in said liquid diluent, said core material being selected from the group consisting of ethylene-maleic anhydride copolymers and the alkali metal, ammonium and amine salts thereof, said core material being dissolvable in water to produce a solution having a pH at 25 C. of from about 5.5 to about 8.5 at a concentration of 1%, said enzyme material being selected from the group consisting of proteases and carbohydrases active at a pH of 4 to 11, and (2) removing said liquid diluent from the resulting mixture by evaporation to thereby result in a particulate material in which the 10 particles have a core material which is enzymatically inactive and a surface layer of enzymatically active material, the ratio of enzyme material to core material in said particles being from about 0.1:99 to about :25.

2. The product formed by the process of claim 1.

3. A particulate detergent composition consisting essentially of about .2% to about 30% based on the weight of the detergent composition of the detergent additive produced by the process of claim 1 and from about 70% to about 99.8%, based on the weight of the detergent composition, of a detergent mixture consisting essentially of an organic detergent active selected from the group consisting of anionic and non-ionic actives and a builder selected from the group consisting of the alkali metal salts of nitrilotriacetic acid, alkali metal polyphosphates and mixtures thereof, the ratio of active to builder being from about 1:10 to about 10:1.

References Cited UNITED STATES PATEN f S 2,922,749 1/ 1960 Snyder et a1. 19566 3,031,380 4/1962 Minagawa et a1. 19566 3,451,935 6/1969 Roald et a1. 252

FOREIGN PATENTS 916,931 1/1963 Great Britain -63 OTHER REFERENCES J. Biochem., Hornsby et al., vol 107, 1968, pp. 669 670.

LEON D. ROSDOL, Primary Examiner P. E. WILLIS, Assistant Examiner US. Cl. X.R.

195-63; 252 DIG 12, 110, 117, 121, 539