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Title: Factory trials to determine how sugarcane trash impacts downstream processing including affinated sugar production

Author
item MUIR, BARBARA - Sugar Milling Research Institute
item Eggleston, Gillian

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 5/1/2009
Publication Date: 5/11/2009
Citation: Muir, B., Eggleston, G. 2009. Factory trials to determine how sugarcane trash impacts downstream processing including affinated sugar production. Proceedings of the 38th Annual Sugar Industry Technologists Meeting, Clewiston, FL. Paper 960, pp.24-48.

Interpretive Summary: The effect of the world-wide change from burnt to unburnt (trashy or leafy) sugarcane harvesting on processing has not been fully characterized, particularly the effect of sugarcane trash (leaves and tops) on downstream processing at the factory. This paper reports on the effects of processing green billeted and/or whole-stalk sugarcane compared to burnt billeted and/or whole-stalk sugarcane. Trials were conducted at two factories situated in South Africa. Juice from the factories was processed across a pilot plant. The increased trash levels, especially the green leaves and growing part region trash tissues caused an increase in the colors of raw and refined sugar. Trash reduced sucrose yields with serious economic consequences.

Technical Abstract: In many countries including the United States and South Africa, certain areas are changing to green from burnt cane harvesting, due to public and environmental pressures against burning and the current interest in using sugarcane trash as biomass. Since the 1940s there have been world-wide factory trials on green cane processing but none have managed to shed light on the effect on downstream processing beyond clarification. This paper reports on the effects of processing green billeted and/or whole-stalk sugarcane compared to burnt billeted and/or whole-stalk sugarcane. Trials were conducted at two factories situated in the Midlands area of South Africa, which operate either a tandem mill or a diffuser. Sufficient cane of each treatment was harvested and processed at each mill to purge the extraction plant of other cane. Trash tissues, direct analysis of cane (DAC), and bagasse samples in the front end were collected and analyzed. A bulk sample of mixed juice was transported to the Sugar Milling Research Institute (SMRI) pilot plant to produce clarified juice, syrup, A-massecuites, A-molasses, A-sugar, and affinated sugar. Stalks contribute more to the load of colour delivered to the factory than the trash tissues because of their higher mass and volume. The increased trash levels caused an increase in the colours of affinated sugar of 25 IU (relating to 50 IU in VHP sugar) per 1% trash. The green leaves and growing part region trash tissues markedly affected the affinated sugar colour. Increased trash levels resulted in decreased DAC and mixed juice (MJ) purities in the factories with serious economic consequences. For every 1% increase in trash there was an approximate 0.41% decrease in MJ purity. An increase in trash, generally, increased the clarification settling rate but also increased mud volumes. The effect of trash on processing of the mixed juice in the pilot plant was a reduction in purity all the way through to A-massecuite.