Synergistic blends of antimicrobials useful for controlling microorganisms in industrial processes

Abstract

The present invention provides a method of controlling bacterial contamination using synergistic interactions of antimicrobials. The invention consists of combinations of chlorine dioxide and organic acid whose combined antimicrobial effect is greater than the sum of their individual activities, i.e., synergistic.

1 . A aqueous composition comprising:
 a) chlorine dioxide,   b) hops acids, and   c) at least one organic acid or their salts,   wherein the concentration of chloride dioxide is at least 1 ppm; wherein the concentration of hops acid is at least 0.5 ppm; and wherein the concentration of the at least one organic acid is at least 50 ppm.   
     
     
         2 . An aqueous composition comprising:
 (a) chlorine dioxide, and   (b) at least one first organic acid or its salt, and   (c) at least one second organic acids or its salt,   wherein the concentration of chloride dioxide is at least 1 ppm; and wherein the sum concentration of the first organic acid and the second organic acid is at least 50 ppm.   
     
     
         3 . A composition of  claim 1  wherein the at least one hops acid is selected from the group consisting of beta acid compounds, alpha acids, isomerized alpha acids, rho isomerized alpha acids, tetra isomerized alpha acids, hexa isomerized alpha acids and hop leaf or combination thereof. 
     
     
         4 . The composition of  claim 1  wherein the at least one organic acid is selected from the group consisting of citric acid, propionic acid, benzoic acid, or their salts and combinations thereof. 
     
     
         5 . The composition of  claim 1  wherein the at least one organic acid comprises citric acid or its salt. 
     
     
         6 . The composition of  claim 1  wherein the ratio of chlorine dioxide to organic acid is from 1:1 to 1:15,000. 
     
     
         7 . The composition of  claim 2  wherein the ratio in ppm of chlorine dioxide to the sum of the first organic acid and the second organic acid is from 1:1 to 1:15,000. 
     
     
         8 . The composition of  claim 1  wherein the concentration of chloride dioxide is at least 1 ppm to 50 ppm, and wherein concentration of the hops acid is at least 0.5 ppm to 20 ppm, and wherein the concentration of the at least one organic acid is at least 50 ppm to 5000 ppm. 
     
     
         9 . The composition of  claim 2 , wherein the at least one first organic acid is citric acid and the at least second organic acid is selected from the group consisting of propionic acid, benzoic acid, or their salts and combinations thereof. 
     
     
         10 . A method of controlling undesirable microorganism concentration in an aqueous system, the method comprising the steps of:
 (a) introducing chlorine dioxide into an aqueous system,   (b) introducing an organic acid into the aqueous system,   (c) introducing an hops acids into the aqueous system,   wherein the organic acid is selected from the group consisting of citric acid, propionic acid, benzoic acid, and their salts and wherein the concentration of chlorine dioxide is at least 1 ppm in the aqueous system being treated.   
     
     
         11 . The method of  claim 10  wherein the aqueous system is a fermentation process, and the method further comprising the steps of:
 (x) introducing a fermentable carbohydrate to an aqueous solution; 
 (y) introducing at least one yeast to said solution. 
 
     
     
         12 . The method of  claim 10  wherein the concentration of chloride dioxide is at least 10 ppm in the aqueous system being treated. 
     
     
         13 . The method of  claim 10  wherein the concentration of chloride dioxide is from 1 ppm to 50 ppm in the aqueous system being treated. 
     
     
         14 . The method of  claim 10  wherein the at least one organic acid comprises citric acid or its salt, and the ratio of chlorine dioxide to at least one organic acid is from 1:1 to 1:1000. 
     
     
         15 . The method of  claim 10  wherein said at least one organic is propionic acid or its salt, and a ratio of chlorine dioxide to at least one organic acid is from 1:1 to 1:1000. 
     
     
         16 . The method of  claim 10  wherein at least one organic acid comprises citric acid or its salt. 
     
     
         17 . The method of  claim 10  wherein the at least one organic acid is benzoic acid or its salt, and the ratio of chlorine dioxide to benzoic acid is from 1:1 to 1:32,000, and the concentration of chlorine dioxide is from 1-50 ppm in the aqueous system being treated. 
     
     
         18 . The method of  claim 16  wherein the ratio of chlorine dioxide to at least one organic acid is from 1:4 to 1:1000.