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United States Department of Agriculture

Agricultural Research Service

Title: Changes in Chemistry Across Sugarbeet Factory Evaporators

Author
item Eggleston, Gillian

Submitted to: Sugar Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 1, 1998
Publication Date: N/A

Interpretive Summary: Millions of dollars are lost each year in the sugar industry due to chemical losses of sucrose in sugar manufacture and refining. Such losses are difficult to measure and a more accurate measurement is needed. Ion chromatography with integrated pulsed amperometry (IC-IPAD) is an accurate carbohydrate analysis technique, which can directly measure sucrose, glucose, fructose and mannose levels. IC-IPAD was used to measure the loss of sucrose and formation of degradation products, across a beet factory's five stage evaporator. Conventional sugar factory methods used to monitor sugar losses, were compared to IC-IPAD values and were shown not to be accurate enough for determining losses across the evaporators. Losses and color formed across the evaporators are due to a complex of reactions: Maillard reactions are more dominant at the early stages of evaporation and alkaline degradation reactions of fructose and glucose (invert) sugars at the later stages. Detection of mannose in the evaporator samples, confirmed that alkaline degradation of invert had occurred. Mannose can be used by sugar industry technicians as a marker compound for invert losses. Principal users beneficiaries of this research will be the sugar industry technicians.

Technical Abstract: Chemical loss of sucrose, and formation of degradation products including color compounds, across a beet factory's five-effect evaporator were investigated. Kinetic samples of thin juice and evaporation syrups were obtained hourly, over a six hour sampling period. This sampling period occurred once in the 1995/96 and 1996/97 campaigns. Ion chromatography with integrated pulsed amperometric detection (IC-IPAD), an accurate carbohydrate analysis technique was used to measure directly sucrose, glucose, fructose and mannose levels. Conventional sugar factory analyses for monitoring sugar losses, i.e., changes in pol, purity, pH and color, were compared to IC-IPAD analyses; purity was shown not to be viable for determining sucrose losses across the evaporator process. Color formed across the evaporators in both campaigns, with a concomitant decrease in pH. Color formation is due to a complex of reactions: Maillard reactions are more dominant at the early stages of evaporation and alkaline degradation reactions of invert sugars and sucrose at the latter stages, as indicated by color Indicator Values, invert levels and the detection of mannose. Detection of mannose in the evaporator samples, confirmed that alkaline degradation of invert had occurred. Mannose can be used as a marker compound for invert losses. A complete mechanism of color forming reactions across the evaporators is described. glucose%sucrose ratios (as measured by IC), were shown not to be viable to determine sucrose losses in these samples, and are underestimates. Excellent correlations existed between polarizations measured at 589 and 880nm for the 1995/96 (r squared=.997) and 1996/97 (r squared=1.000) campaigns.

Last Modified: 12/19/2014
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