Limiting microbial degradation in Louisiana sugarcane mills: Are biocides effective?

Authors: Boone, Stephanie; St Cyr, Eldwin; Eggleston, Gillian; Klasson, K Thomas; MONTES, BELISARIO - Alma Plantation, Llc; PONTIF, KEVIN - Lafourche Sugar, Llc - Us; Wright, Maureen

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 1/30/2017
Publication Date: 6/22/2017
Citation: Boone, S., St Cyr, E., Eggleston, G., Klasson, K.T., Montes, B., Pontif, K., Wright, M. 2016. Limiting Microbial Degradation in Louisiana Sugarcane Mills: Are Biocides Effective? p. 343-355. In: Eggleston, G., Lima, I. (eds.). Proceedings for the Advances in Sugar Crop Processing and Conversion Conference 2016, Vol. 1. 412 pp.

Interpretive Summary: Sucrose loss takes place post-harvest in sugarcane, and still represents a significant problem for the global sugar industry. Biocides are often used in Louisiana’s raw sugarcane factories to reduce microbial contamination. However, few studies have investigated biocide usage during factory operations using cane juice retention times in pipes and tanks, or cane processing rates. This factory study evaluated three different biocides, sodium hypochlorite (bleach), carbamate and Humulone (Hops), at two different Louisiana raw sugar factories during processing. Retention times in factories indicated that juice was exposed to biocides for less than 10 min. After the factory study was completed the mill purchased a Thermo ScientificTM DionexTM ICS-5000+ HPIC system in its analytical laboratory in August, 2015. Results showed that microorganism growth in factory cane juice varied with juice temperature, and the greatest reduction in microbe growth was during juice clarification. Only bleach reduced microorganism growth by two logs, and carbamate and humulone compounds had no effect on microbial growth as compared with controls. Discontinuing short-term usage of the biocides tested (carbamate, hops and bleach) is not recommended. More research is still needed in the area to find practical and effective alternatives to biocides and/ or biocides that are effective during raw sugar factory operation. Study findings also emphasize the need for consistent, rigorous factory cleaning, and thorough factory storage yard sanitation.

Technical Abstract: Sucrose loss takes place post-harvest in sugarcane, and still represents a significant problem for the global sugar industry. In Louisiana, microorganisms cause the majority of sucrose loss during sugarcane transport to the factory, in cane piles at factory stock yards, and during overnight truck loads (sleeper loads). Biocides are often used in Louisiana’s raw sugarcane factories to reduce microbial contamination. However, few studies have investigated biocide usage during factory operations using cane juice retention times in pipes and tanks, or cane processing rates. This factory study evaluated three different biocides, sodium hypochlorite (bleach), carbamate and Humulone (Hops), at two different Louisiana raw sugar factories during processing. Retention times in factories indicated that juice was exposed to biocides for less than 10 min. Results showed that microorganism growth in factory cane juice varied with juice temperature, and the greatest reduction in microbe growth was during juice clarification. Only bleach reduced microorganism growth by two logs, and carbamate and humulone compounds had no effect on microbial growth as compared with controls. Discontinuing short-term usage of the biocides tested (carbamate, hops and bleach) is not recommended. More research is still needed in the area to find practical and effective alternatives to biocides and/ or biocides that are effective during raw sugar factory operation. Study findings also emphasize the need for consistent, rigorous factory cleaning, and thorough factory storage yard sanitation.