Assessment of pH control strategies to minimise sucrose losses during juice evaporation in raw sugar manufacture

During juice evaporation sucrose loss can occur as a result of degradation reactions that are catalysed by heat, pH and other juice components. The impacts of heat and juice quality can be controlled through process and equipment design. Potential pH control strategies for juice were assessed to minimise sucrose degradation and the subsequent impacts on downstream processing during the sugar manufacturing process. These strategies were: (1) the use of reagents to improve the buffering capacity of the juice; (2) the use of neutralising alkanolamines; and (3) on-line pH adjustment during juice evaporation to minimise pH drop. All these strategies achieved significant reductions in sucrose loss of 20-50% in both the small-scale and laboratory rig trials but some come at the expense of chemical costs and other processing implications such as scaling of the evaporators. The use of ammonia was the preferred pH control strategy, although it led to an increase in juice colour.