US 3761420 A
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3,761,420 STABILIZED LIQUID ENZYME STAIN REMOVER Rodger E. Bogardus, Winchester, Mass, assignor to A. E. Staley Manufacturing Company, Decatur, II]. No Drawing. Filed June 8, 1970, Ser. No. 44,630
Int. Cl. (309d 9/04 US. Cl. 252-171 3 ClalmS ABSTRACT OF THE DISCLOSURE A stabilized enzyme composition dispersed in an aqueous solution which is particularly suitable for removing stains from fabrics, especially from washable items such as cottons, permanent press synthetic-cotton blends and similar washable fabrics.
BACKGROUND OF THE INVENTION Enzymes are naturally occurring proteins with certain catalytic properties due to their power to activate specific substrates or substances to cause breakdown of more complex molecules into smaller fragments. Enzymes are normally produced by living cells, and can be easily obtained from natural sources by solvent extraction or other well known methods with full retention of their catalytic prop erties. The crude enzyme solutions are clarified as necessary by filtration or centrifugation, or concentrated by vacuum evaporation at low temperatures.
Solid enzyme products may then be provided by spray drying the enzyme concentrate or the enzyme may be precipitated from solution by means of an aliphatic ketone or alcohol. Precipitated enzyme products are recovered by filtration or centrifugation and dried in vacuum dryers.
Dried or powdered enzyme products have been used in laundry detergent products for their stain removing properties, but until now, there has been no liquid enzyme laundry product known to applicant. The detergent products incorporating dried enzyme products are packaged while dry and are desirably stored dry, being protected from absorption of moisture until placed in use. Dry storage for these products was thought necessary, because moisture tends to destabilize the enzymes and it is generally believed that enzymes stored in the presence of water tend to lose activity after a short period of time. The typical dry enzyme detergent products are added to water at the time of use to provide a relatively dilute enzyme solution. Articles of clothing having stains must then be soaked for extended long periods of time for the relatively weak enzyme solution to catalyze the breakdown and removal of the stain.
ADVANTAGES OF THE INVENTION This invention eliminates the extended soak time necessary when using the dry powder products and provides a relatively concentrated liquid enzyme product that is applied directly onto a stain from a storage container without first adding water. The liquid storage problem has been solved by applicant by providing an enzyme stabilizer which makes possible a stabilized aqueous enzyme produce with excellent shelf storage life. Applicants stabilized aqueous enzyme product overcomes the need for dispersing enzyme in water just prior to use, and applicants aqueous enzyme products eliminates the dust exposure hazard inherent with dry powder detergent products. The relatively concentrated aqueous enzyme preparations can also be poured directly onto stains on clothing to further accelerate the stain removal process with even higher concentrations of enzyme thus being applied to the stain substrate in the presence of less diluting water. If desired, the liquid enzyme composition of the invention can be included as part of a liquid laundry detergent while retaining the advantages listed above.
flfilhim Patented Sept. 25, 1973 SUMMARY OF THE INVENTION This invention is directed to a stain-hydrolyzing aqueous enzyme composition which is particularly useful for dissolving stains on washable fabrics which has an excellent shelf storage life in an aqueous media because of the addition of certain enzyme stabilizing agents. In the presently preferred embodiment, a proteolytic enzyme is employed which is stabilized by a polyhydric alcohol such as glycerin. When used as a liquid stain remover, a chelating agent such as sodium hexametaphosphate is normally included in the product to increase its effectiveness and to maintain the pH of the aqueous solution in a controlled range.
DETAILED DESCRIPTION OF THE INVENTION In accordance with the present invention, a stabilized enzyme composition is produced which contains an enzyme, water and a polyhydric organic stabilizing agent. The organic stabilizing agent is present at a level suflicient to stabilize the enzyme and to prevent inactivation of the enzyme when stored for long periods of time. The polyhydric organic stabilizing agent is present at particular levels with respect to the water so as to provide a stabilized aqueous enzyme system which is effective in treating and removing stains from clothing.
The stabilizing agent of the invention is preferably selected from polyhydric organic compounds having a carbon chain length of from 2 to 6. By polyhydric is meant that the organic compound has at least two hydroxyl groups and may contain up to 6 hydroxyl groups per molecule. More specifically, those polyhydric organic compounds having a hydroxyl group on the initial and terminal carbon atom of the molecule are preferred. Such compounds include ethylene glycol, propylene glycol, glycerol, sorbitol and mannitol. Glycerol is the presently preferred stabilizing agent, but certain other less expensive polyols may also be used. Monosaccharide aldose and ketose sugars may also be used as the polyhydric organic stabihzmg agent, but their use depends on the particular use intended for the stabilized enzyme product and whether a particular chelating agent is to be used. Suitable sugars include dextrose, fructose, galactose, mannose and sorbitose.
The polyhydric organic stabilizing agent should be present at particular ratios with respect to the water in the composition in order to obtain a stable liquid enzyme WhlCh also retains the catalytic ability of the enzyme to treat stains on clothing. In this connection, a mole ratio of the stabilizing agent to water of from about 10:1 to about 1:37 is preferred. When a chelating agent is used, water should be present in the composition at levels of from about 25 percent to about 60' percent by weight of the composltion, and the stabilizing agent would then comprise about 15 percent to about 40 percent by weight of the composition. The mole ratio of the polyhydric organic stabilizing agent to Water in the range set forth above is more important when a chelating agent such as a glassy phosphate is used, because when an excess of the stabilizmg agent over this range is used, some of the glassy phosphate tends to fiocculate and precipitate from the liquid composltion. It is not necessary in all instances to include chelating agents, for example, where the product will be used in pre-softened water. In such situations, the concentration of stabilizing agent can be considerably higher, that is, up to by weight of the total liquid composition, the remainder being water and enzyme.
The enzyme to be employed is usually selected based on the intended use for the stabilized liquid enzyme composition. In some applications, a protease enzyme is preferred, because the usual stains on clothing are proteinaceous in character. Proteases and similar enzymes employed for stain removal normally lose their potency after a very short time in water, so the presence of the stabilizing agent is most important to maintain the effectiveness of these enzymes.
Other enzymes which are normally unstable in water may also be used, and a mixture of enzymes may also be used to treat complex stains, specific enzymes in the mixture being used for particular stain removing action. In this connection, the enzyme may be selected from protease, esterase, lipase or mixtures thereof, or mixtures with other stain-selective enzymes. The enzyme component of the composition is present in the composition at a level of up to about one percent by weight of the composition. At such levels, the enzyme concentration is significantly greater as compared to the enzyme concentration in the dry powder enzyme active detergent products described above. The dry powder enzyme products normally have less than about one percent enzyme on a dry basis and, when added to water under the usual directions, the concentration of enzymes in these dry powder based systems is usually less than about .003 percent of the liquid solution.
The composition of the present invention is particularly useful for treating stains on clothing by applying the composition directly to the stain until the enzyme has catalyzed breakdown of the stain. The composition of the invention may also be used as an active component of a liquid detergent product, or as a supplement to standard washing procedures, being combined with detergent products at the time of preparing the wash water. The recommended concentration of the enzyme when used in a liquid detergent product is in the range of .5 percent to 2.0 percent by weight of the total product, and the enzyme containing liquid detergent is normally applied directly to the stains as set forth above.
The water used in preparing the aqueous enzyme composition of the enzyme is preferably softened to remove polyvalent cations prior to use. However, as mentioned above, a chelating agent may be combined with the composition in the event that softened water is not available, and particularly when used in hard water. The chelating agent is selected so as to provide a pH in the aqueous enzyme system of 9.0, and should normally not be above this to prevent loss of activity of the enzyme, which is sensitive to excessive alkalinity. When used, the chelating agent is preferably present in a range from about 20 percent to about 40 percent by Weight of the composition.
Glassy phosphates, such as sodium hexametaphosphate, which provide a pH of not more than about 9.0 in solution are among the preferred chelating agents because they provide good chelating action and also maintain the desired pH range. The enzymes tend to break down if the solution becomes more alkaline than a pH of about 9. The presently preferred glassy phosphates include those compounds having the structure (NaPO in which n=2-l3, average 11:5-6. Such chelating agents also have good liquid solubility and, because of their excellent chelating action, improve the effectiveness of the enzyme.
In the preferred method of making the aqueous enzyme composition of the invention, the enzyme is first mixed with the polyhydric organic stabilizing agent prior to combining the enzyme with water. While the step of combining the enzyme with the polyhydric organic stabilizing agent prior to addition to water is not necessary, it has been found that activity of the enzyme tends to remain higher when this is done.
Although the exact interaction of the stabilizing agent and the enzyme has not yet been demonstrated, one plausible explanation of the phenomena is that the polyhydric organic stabilizing agent becomes intertwined with the protein molecule of the enzyme and acts to prevent water degradation of the enzyme during storage. Thus, combining the polyhydric organic stabilizing agent with the enzyme prior to adding the water appears to enable the intertwining reaction to become completed prior to the time that the enzyme is contacted with water. However, suitable levels of activity can also be attained when the enzyme is first added to water and the polyhydric organic stabilizing agent is added shortly thereafter.
The following example illustrates various features of the present invention, but is intended to in no way limit the scope of the invention which is defined in the appended claims.
EXAMPLE An aqueous enzyme composition is prepared in accordance with the present invention. The composltion contains the following ingredients at the indicated levels.
Ingredients: Weight percent Water 40.9 Glassy phosphate (Sodaphos-manufactured by FMC Corp.) 28.5 Blue dye 0.0003 Fragrance No. 3634 (International Flavors and Fragrances, Inc.) 0.10 Proteolytic enzyme (Alcalase-Enzyme Development Corp.) 0.50 Glyercol 30.0
The above composition had a shelf life stability of more than seven months when stored at an ambient temperature of about 77 F.
In preparing the above composition, the enzyme is first combined with the glycerol with mild agitation. The fragrance, dye and glassy phosphate in an aqueous solution are then combined with mild agitation to provide the composition.
The composition is then used to treat a blood stain on a cotton fabric. The composition is applied directly to the blood stain and is permitted to remain in contact with the blood stain for a period of about three minutes before washing actually commences. At the end of this time, the blood stain has been broken down by the catalytic activity of the enzyme and the blood stain is easily removed from the fabric during normal wash cycles. When a blood stain is treated by preparing a pre-soak from a commercially available dry powder enzyme-containing detergent in accordance with instructions supplied therewith, treatment for a period of one-half to two hours is needed to effect any appreciable breakdown of the blood stain.
The various features of the invention which are believed to be new are set forth in the following claims.
1. The process of removing stains from fabrics with a stabilized aqueous enzyme preparation which consists essentially of the following ingredients in the amount specified:
Percent by weight said enzyme preparation remaining substantially effective for stain removing even after more than seven months storage at a temperature of 77 F., said enzymes comprising a mixture of enzyme selected from the group consisting of lipase, protease, esterase, and combinations thereof, which are normally unstable in aqueous solutions.
2. A stabilized aqueous enzyme preparation for dissolving stains on fabrics consisting essentially of by weight of the preparation:
(1) from 25 to 60% water;
(2) about .5% of an enzyme selected from the group consisting of lipase, protease, esterase, and combinations thereof, which are normally unstable in aqueous solutions;
6 (3) from to 40% of water soluble polyhydric or- References Cited ganic stabilizing agents selected from the group con- UNITED STATES PATENTS sisting of ethylene glycol, propylene glycol, and 3,557,002 1/1971 McCarty H 12 glycerol; 3,627,688 12/1971 McCarty et a1. 252Dig. 12 said aqueous enzyme preparation having a pH in the 5 3,553,139 1/ 1971 McCarty 252-439 range of about 5.5 to 9.0, and capable of effective stain 2,164,914 7/1939 Gore et 5- removing for more than seven months at a temperature ggg iffi l of about 77 F.
3. The enzyme preparation of claim 2, including 10 OTHER REFERENCES to by Weight of a chelating agent consisting of a Nature, VOL July 1967 -L P glassy phosphate having the structure (NaPO in which WILLIAM SCHULZ Primary Examiner n=2-13, and average n=5-6, whereby the effectiveness of said aqueous enzyme preparation is enhanced when 15 mixed with hard mineral containing water. -63; 252Dig. 12; 424-94