Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/11/2003
Publication Date: 3/11/2004
Citation: Eggleston, G., Damms, M., Monge, A., Endres, T. 2004. New insights on sucrose losses across factory juice and syrup clarifiers and evaporators(abstract). Zuckerindustrie. 129(3):192
Technical Abstract: Major aims of an Agricultural Research Service project of the United States Department of Agriculture have been to improve the measurement of industrial sucrose losses, and to reduce sucrose losses. This paper discusses new insights gained from this project on sucrose losses in sugarcane juices and syrups at high temperatures (55-115 degrees C) during different clarification and evaporation processes. The accurate method of gas chromatography was used to determine glucose, fructose, and sucrose concentrations on a Brix or chloride basis. Sucrose losses to acid inversion across one factory's juice and syrup clarification processes were investigated. In the juice clarifier, chloride trended with Brix and, therefore, either could be used as a sucrose loss reference. In comparison, in the syrup clarifier Brix was more preferentially destroyed than chloride. Kestoses were shown not to be viable markers of sucrose losses across both clarifiers. High operational pHs for juice hot (~200 degrees F) lime clarification (pH range=8.38-9.55 measured at room temperature) minimized sucrose losses to ~0.00-0.58% even with an estimated Rt of 3h, but excessive lime addition can accelerate scaling and color formation. Higher acidic conditions (pH range=6.28-7.35) across syrup clarification (phosphatation) caused considerable sucrose losses of ~0.57-1.26% even at a lower Rt and temperature of ~1h and 165 degrees F, respectively. Comprehensive studies were also conducted at two other U.S. factories to determine the effects of time between cleanings of Robert's-type calandria and plate evaporators on sucrose losses and overall evaporator performance. In general for both factories, most sucrose inversion losses occurred in the pre-evaporators, and only occurred in later evaporator bodies when scale had built up after a clean-out and, usually, became worse until the next clean. Less inversion occurred across the low retention time plate evaporator; the plate was also susceptible to scaling although to a lesser extent than the Robert's type evaporators. Increasing the factory target pH of the clarified juice (CJ) or final evaporator syrup (FES) systematically reduced losses of sucrose and a target FES pH of ~6.3-6.5 (equivalent to a target CJ pH of ~ 7.0-7.3) is recommended; however, scaling effects can override pH effects. There was a consistent increase in pH in the last evaporator bodies because of the evaporation of volatile acids into the condensates. Economic implications of sucrose losses are also described.