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United States Department of Agriculture

Agricultural Research Service

Title: Clarification of Mixed Juice from Fresh and Stale Sugarcane: Investigationof Sugar Losses

Authors
item Eggleston, Gillian
item Clarke, Margaret - SPRI
item Pepperman Jr, Armand

Submitted to: Sugar Processing Research Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: July 20, 1998
Publication Date: N/A

Interpretive Summary: Millions of dollars a year are lost in the sugar industry because of the degradation of sugars in process. This investigation shows the changes in levels of sucrose, glucose and fructose in samples collected across a sugarcane factory's "cold lime" clarification process. Sampling was repeated seven times across the grinding season; in the last two sampling periods the crushed cane was stale because the field cane had been subjected to freezing, then warm weather conditions. For the fresh cane, color, clarity and pH of the mixed juice improved across the season because of increasing cane maturity. Generally, color formed in the lime tank. Minimum sucrose loss across the clarification process was 3.39%. Very high levels of glucose and fructose occurred in the mixed juice from the stale cane, as well as high levels of dextran. The stale cane was shown to be very acidic and pH control in the lime tanks was erratic across the grinding season.

Technical Abstract: Changes in levels of sucrose, glucose and fructose, across a sugarcane factory's clarification process were investigated. The cooperating factory uses a "cold liming" process, where lime is added to the mixed juice before heating, prior to clarification. Samples of mixed, limed, heated limed and clarified juice were obtained hourly over a seven hour sampling period. Th hsampling period was repeated seven times across the grinding season; in th last two sampling periods the crushed cane was stale because the field cane been subjected to freezing, followed by warm weather conditions. Ion chromatography with integrated pulsed amperometric detection (IC-IPAD), an accurate sugar analysis technique, was used to measure directly sucrose, glucose and fructose levels. For the fresh cane, color, turbidity and pH o the mixed juice improved across the season because of increasing cane matur Generally, color formed in the lime tank because of the alkaline degradatio oglucose and fructose (invert). Minimum sucrose loss across the clarificat process was 3.39%. Very high levels of glucose and fructose (both often >7 a deg Brix basis) occurred in the mixed juice from the stale cane, as well high levels of dextran. Glucose/fructose ratios were also higher in stale cane, because of more associated trash, which gave falsely high pols and purities, especially in the clarified juice. Turbidity removal in the clarification tanks was worse with stale cane. The stale cane was very aci and pH control of its mixed juice in the lime tanks was exceptionally difficult, causing acid degradation of sucrose (inversion) to occur in the tanks. pH control in the lime tanks was erratic across the grinding season it is, therefore, recommended that lime should be added as lime saccharate the future. A full statistical analysis of the data is presented and discus

Last Modified: 10/26/2014
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