Sugar processing in Louisiana

Linda Benedict  |  7/2/2008 9:32:27 PM

The Cora Texas Manufacturing Co. sugar factory at White Castle, La., is near the Mississippi River. (Photo by Ron Olivier)

Benjamin L. Legendre and Harold S. Birkett  

Of all the U.S. sugar-producing areas, Louisiana is the oldest and most historic. Sugarcane arrived in Louisiana in 1751 with the Jesuit priests who planted it near where their church now stands on Baronne Street in New Orleans. Several plantations were planted within the city limits of New Orleans, and in 1795, Etienne DeBoré first granulated sugar on a commercial scale in Audubon Park. Except for disastrous production years during the Civil War, during the disease epidemics of the 1920s and from a severe freeze that reached 10 degrees during December 1989 affecting the 1990 crop, the Louisiana sugarcane industry has continued to prosper, mainly due to improved varieties, cultural practices, pest control and sugar processing innovations. The Louisiana sugarcane industry is currently in its third century of uninterrupted sugar production.

Currently, sugarcane ranks first economically in the state for plant commodities and produces about 16 percent of the total sugar grown in the United States. In 2007, sugar, including molasses, had an economic impact to the state of approximately $645 million. Considering the total economic impact, that figure jumps to $2 billion. Louisiana has 609 sugarcane producers in 23 parishes and 12 factories. Eleven of these factories, or mills, produce raw sugar and molasses; one produces only molasses. Approximately 25,000 employees are involved in sugar production and processing in Louisiana.

In 2007, farmers grew sugarcane on 418,933 total acres with an estimated 391,702 acres available for harvest for sugar – 6.5 percent of the total acres were assumed to be used for seedcane production. The 12 factories processed 13,372,571 tons of cane and produced 1.456 million tons of sugar with an average recovery of 218 pounds of sugar per ton of cane processed. Louisiana has produced more than one million tons of sugar per year since 1994. The greatest production was in 1999 when 1.698 million tons of sugar were produced.

Although seven factories have closed in the past eight years, the remaining factories have increased their capacity to absorb the cane supply that had been processed at the factories that closed. At the same time, the remaining factories have become more efficient. This is due, in part, to the Audubon Sugar Institute staff, who have made a concerted effort to visit each of the factories during the off season and again during the milling season. These visits are well-received, and slow-but-steady improvements in processing efficiency are evident. Further, many research projects conceived by ASI faculty are funded by the industry through recurring appropriations and the dedicated research funding of the American Sugar Cane League along with the Louisiana Farm Bureau and conducted onsite at the factories.

A 1998 study of the Louisiana sugar industry by Landell Mills Limited, an international consulting company based in the United Kingdom, showed the field sector was more competitive than the processing sector when considering efficiencies of the two segments; therefore, it is imperative for the survival of the Louisiana sugar industry that improvements in the competitiveness of the factories be initiated as soon as possible. A significant factor in increased efficiency has been the consolidation of factories so those that remain have an ample cane supply that allows them to make the upgrades necessary to improve efficiency. Since the Landell study, notable advances in factory efficiency include improved sucrose extraction, reduced sucrose in bagasse and in filter cake, reduced molasses purities and improved sugar recovered as a percent of sugar in cane. Another factor in improved efficiency has been the total automation of various processes at many of the factories. Factories also have made great strides in factory steam use and some improvements in boiler efficiency that have reduced natural gas usage to a minimum and greatly lowered the cost of operation.

Over the past 20 years the remaining factories have gradually improved sucrose extraction; however, much improvement can still be made. Research by ASI faculty has shown that in most factories, one or more of the six or seven mills in what is called the tandem perform poorly as indicated by increasing moisture percentage in bagasse and/or low extraction from an individual mill. At the same time, many factories have curtailed washing cane altogether or infrequently, especially under favorable weather conditions. Although this change generally has led to increased ash in bagasse, washing cane, especially cane cut into short pieces (billets), could cause sugar losses exceeding 10 pounds per ton of cane processed.

Research on cane losses in storage yards is continuing at a number of factories. Previous studies have shown deterioration is a problem within 12 hours of delivery and storage, especially in billeted cane. New studies will investigate storage methods and try to determine the losses not only due to deterioration of juice and cane but also due to the loss of cane weight. Several factories have modified their cane transportation and unloading systems to improve efficiency and reduce handling costs; however, little data have been collected regarding recoverable sugar losses resulting from these new systems.

Although the Louisiana sugar industry is entrenched in tradition, one of its factories installed a diffuser in 1999 to complement its conventional tandem. A diffuser is an alternative to heavy-duty milling as a method of extracting juice from prepared sugarcane. The diffusion process adds water to aid juice extraction. The new syrup factory at Lacassine also installed a diffuser in 2005; however, it processed a limited amount of cane in both 2006 and 2007. In comparative studies in 2004 and 2005 at the Enterprise Factory at Patoutville, juice analyses between the two extraction units indicated that juice purity and monosaccharide/ ash ratio in both raw juices were very similar despite the higher extraction in the diffuser, indicating that no difference in recovery of sugar from the juice was expected.

Under Louisiana conditions, the color of the juice from a diffuser was about 10 percent higher than from a conventional milling tandem, but this was less than the seasonal variation of up to 30 percent in raw juice color from both mills and diffusers. In recent years, several factories have been evaluating the cost of transporting cane long distances for processing. This has led to the consideration of constructing a factory in the Bunkie area of central Louisiana; however, the cost of a new factory, even one for syrup only, has been the deterring factor. In recent years, several factories have agreed to swap cane supplies, resulting in reduced cane transportation costs to all participants.

Color of raw sugar is an important parameter defining major operation expenses of a sugar refinery. Under current economic conditions in Louisiana, limited incentives are offered to raw sugar factories to produce sugar with very high sucrose content (VHP) and/or very low color (VLC). The situation may change, however, because several factories are negotiating to build a new, state-of-theart refinery in Louisiana. This should allow these factories to become vertically integrated from field to raw factory to refinery to consumer, allowing them to take advantage of all segments of the market.

Changes in sugar quality during storage may reduce the quality of raw sugar. This could yield a product that is less desirable to the refinery, resulting in additional processing costs and possible penalties in the price paid to the producer of the raw sugar. Research under way at ASI is examining how raw sugar changes in storage, which is of critical importance for the future competitiveness of the Louisiana sugar industry.

Other research under way at ASI and Louisiana factories includes the use of biocides (antibacterial agents), the enzymes amylase to control starch and dextranase to control dextran in process streams, clarification, adding sugar crystals to induce crystallization (the transition from syrup to sugar crystals), and processes that remove sugar from molasses. The outcome of these studies should result in further improvements in efficiency as well as lower costs of production, thus allowing the Louisiana sugar industry to remain competitive in a global economy.

Benjamin L. Legendre, Denver T. Loupe/American Society of Sugarcane Technologists Sugar Heritage Professor and Interim Head, and Harold S. Birkett, Associate Professor, Audubon Sugar Institute, LSU AgCenter, St. Gabriel, La.

(This article was published in the spring 2008 issue of Louisiana Agriculture.)
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