1. Microbiological Control of a Milling Tandem Milling Seminar - May 11, 2005

2. Microbes are Everywhere Microbes Protect Themselves in nature by: 1. growing as biofilms Resistant to penetration by antimicrobials, important in sugar mills Modifying or excluding antibacterial agent 2. Forming spores Most resistant form of bacteria. Generally found in sugar

3. Microbial Biofilm (Heat Exchanger)

4. Commonly Found Genera in Sugar Process Streams Gum ProducersGum Producers L. mesenteroides, L. dextranicumL. mesenteroides, L. dextranicum YeastYeast Saccharomyces, Torula, PichiaSaccharomyces, Torula, Pichia Common BacteriaCommon Bacteria includes Pseudomonas and Bacillusincludes Pseudomonas and Bacillus Filamentous FungiFilamentous Fungi Aspergillus, Penicillium, StreptomycesAspergillus, Penicillium, Streptomyces

5. Microorganisms in the Raw House (processing problems) acid pH and high sugar concentrations in juice favor growth of Streptococci and Leuconostocacid pH and high sugar concentrations in juice favor growth of Streptococci and Leuconostoc Microbial loading of sugar juices reflects the bacteria flora of the source materialsMicrobial loading of sugar juices reflects the bacteria flora of the source materials These gum forming microorganisms form biofilms on the equipment and secrete dextran in the process streamThese gum forming microorganisms form biofilms on the equipment and secrete dextran in the process stream

6. Biofilms pBacteria have the ability to colonize process surfaces p this leads to build up of slime materials or biofilms. pThe biofilm can become an ecosystem with a wide variety of pathogenic and spoilage microorganisms and a penetration barrier for biocides. Rod-shaped bacterium

7. Bacterial Biofilms SEM image of six day old Pseudomonas aeruginosa biofilm.

8. Processing Problems due to Polysaccharide Producers Direct loss of sucroseDirect loss of sucrose Viscosity increaseViscosity increase crystal deformationcrystal deformation sugar loss to molassessugar loss to molasses penaltiespenalties analytical interferenceanalytical interference

9. Economic Implications of Dextran 0 100 200 300 400 500 600 700 800 900 123456789 week ppm Dextran 36 37 38 39 40 41 42 43 44 45 46 47 TP Dextran

10. Sugar Losses In Louisiana, molasses purity rise is 2.2 - 2.5 points/ 1000 ppm dextran in juiceIn Louisiana, molasses purity rise is 2.2 - 2.5 points/ 1000 ppm dextran in juice a rise in final molasses purity of one point is equivalent to losing one pound of sugar to molasses for every ton of cane processeda rise in final molasses purity of one point is equivalent to losing one pound of sugar to molasses for every ton of cane processed

11. Role of a Biocide Control Dextran FormationControl Dextran Formation Microbiocidal activityMicrobiocidal activity Minimize Biofilm FormationMinimize Biofilm Formation Residual ActivityResidual Activity Protect Juice from Deterioration in Stagnant RegionsProtect Juice from Deterioration in Stagnant Regions Residual ActivityResidual Activity

12. Organic Biocides Two classes of compounds approved by FDA for use in sugar processingTwo classes of compounds approved by FDA for use in sugar processing CarbamatesCarbamates Quaternary Ammonium compoundsQuaternary Ammonium compounds “Quats” may not be present in molasses sold for animal feed“Quats” may not be present in molasses sold for animal feed

13. Some Results: No Biocide HgCl 2 200ppm NaN 3 500ppm 5,10,15,20ppm mDTC NaN 3 100ppm mDTC 15 ppm Initial Trial: 92.17 hours at 30oC

14. Results: Antibody Dextran on Brix

15. Results: HPLC Sucrose on Brix The Good The Bad The Ugly

16. Biocide Use (Louisiana 2001) MillsBiocideLocationDose (ppm) A,B,C,G, Q BleachKnives Last mill ? D,I,PBusan 881Knives Last Mill 0 -18 E,J,O,S K Midland 6001 Magnicide Last Mill0.6- 15 10 HBleach + Midland Knives Last Mil 21 and 10

17. Control Measures in the Factory Strict Sanitation proceduresStrict Sanitation procedures Biocide application at earliest points where juice can contact surfaces.Biocide application at earliest points where juice can contact surfaces. The maintenance of residual biocide until the juice heatersThe maintenance of residual biocide until the juice heaters

18. Effective Dose Rate

19. Summary Microorganisms are ubiquitousMicroorganisms are ubiquitous The “environmental” conditions of the sugar mill dictate which organisms will be foundThe “environmental” conditions of the sugar mill dictate which organisms will be found Microorganisms will consume sugarMicroorganisms will consume sugar Some microorganisms produce products which have processing effects far exceeding what would be expected based on their bulk compositionSome microorganisms produce products which have processing effects far exceeding what would be expected based on their bulk composition

20. Summary Microbial growth can be controlled at the mill (but not eliminated) through judicious cleaning (steam, hot water) on a routine basis and by use of a biocide in hard to clean areasMicrobial growth can be controlled at the mill (but not eliminated) through judicious cleaning (steam, hot water) on a routine basis and by use of a biocide in hard to clean areas All areas touched by juice can grow biofilms and shed dextran into the process.All areas touched by juice can grow biofilms and shed dextran into the process.