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ARS Home » Southeast Area » New Orleans, Louisiana » Southern Regional Research Center » Commodity Utilization Research » Research » Publications at this Location » Publication #223057
Title: Mannitol as a Sensitive Indicator of Sugarcane Deterioration and Bacterial Contamination in Fuel Alcohol Production

Author
item Eggleston, Gillian
item BASSO, L - UNIVERSADADE DESAO PAULO
item AMORIM, H - FERMETEE LTDA
item PAULILLO, S - FERMETEE LTDA
item BASSO, T - FERMETEE LTDA

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 9/17/2006
Publication Date: 9/20/2006
Citation: Eggleston, G., Basso, L.C., Amorim, H., Paulillo, S.C., Basso, T.O. Mannitol as a sensitive indicator of sugarcane deterioration and bacterial contamination in fuel alcohol production. In: Proceedings of the 2006 SPRI Conference, September 17-20, 2006, in Aqua de Sao Pedro, Brazil. p. 199-213.

Interpretive Summary: Mannitol is a chemical formed by bacteria when sugarcane deteriorates, and is a very sensitive indicator of sugarcane deterioration that can predict processing problems. A rapid, easy and inexpensive enzymatic (enzymes are chemicals that speed up reactions) method has been developed to measure mannitol in juice pressed from consignments of sugarcane delivered to the factory. This screening tool will allow factory staff to know rapidly which consignments of cane will affect processing negatively or reject consignments that will cause unacceptable processing problems. Mannitol has also been proved to be an advantageous indicator of bacterial contamination in the production of fuel alcohol from sugarcane juice or molasses. Its presence can account for unexpected yield drops, and it can be measured easily.

Technical Abstract: Mannitol, formed mainly by Leuconostoc mesenteroides bacteria, is a very sensitive indicator of sugarcane deterioration that can predict processing problems. A rapid (4 to 7 min) enzymatic method has been developed to measure mannitol in juice pressed from consignments of sugarcane delivered to the factory. This screening tool will allow factory staff to know rapidly which consignments of cane will affect processing negatively or reject consignments that will cause unacceptable processing problems. This method can be easily performed using existing equipment in sugarcane factories, with mannitol being measured spectrophotometrically using mannitol dehydrogenase (MDH) as the enzyme catalyst. The stability of the reagents, limited cane juice preparation, linearity, accuracy, and precision are described. The method is highly specific for mannitol and was not affected by the presence of sucrose, glucose, fructose, or dextran. The current cost is only ~60 U.S. cents per analysis. Mannitol has also been proved to be an advantageous indicator of bacterial contamination - one of the main factors causing drops in fuel alcohol fermentation yields as well as yeast (Saccharomyces) flocculation and foaming problems. Compared to other indicators, mannitol is not produced by yeast cells but only by some contaminating bacteria (mostly Lactobacillus strains) during fermentation. Its presence can account for unexpected yield drops, and it can be measured easily. A strong correlation existed between mannitol formation and bacteria counts in sugarcane juice and molasses fermentations with induced mannitol producing bacterial contaminations.