The effectiveness of biocides in limiting microbial growth in Louisiana raw sugar mills

In Louisiana, the majority of sucrose destruction occurs during storage in mill yards and truck sleeper loads. Raw sugarcane factories in Louisiana apply biocides to reduce sucrose loss caused by bacterial contamination. Few onsite factory studies have evaluated biocide usage, and no known studies have included cane grinding rates. During cane juice processing at two Louisiana raw sugar factories this study assessed three biocides, sodium hypochlorite (bleach), carbamate and humulone (hops) using cane grinding or juice flow rates by integrating factory tank and pipe retention times as sampling intervals. Processed juice exposure to biocide was calculated at less than 10 minutes. Results showed that bleach reduced microorganism growth by two logs. Carbamate and humulone application had no effect on growth. Generally, biocide efficacy varied with juice temperature and initial titer of raw cane juice. Currently, discontinuing usage of carbamate, humulone and bleach is not recommended. More research is needed in the area to determine if biocide application is practical and effective during factory operation. Study findings emphasize the increased need for consistent, rigorous factory and mill yard sanitation.