Forward osmosis for the concentration of sugarcane juice

During evaporation, loss of sucrose can occur due to acid-catalysed hydrolysis to glucose and fructose, a reaction that is exponential with temperature. This paper reviews non-thermal methods for concentrating juices, particularly focusing on the developments of forward osmosis (FO) membranes for juice processing, detailing the benefits and limitations of this technology. A laboratory FO membrane was used in this preliminary study to concentrate pure sucrose solutions and clarified juice from ~10 to 45 Bx using a calcium chloride draw solution. A small amount of reverse salt flux was observed. There was little impact of the impurities in factory juices on flux performance, with the flux reducing inversely with the volumetric concentration factor. By concentrating to a limit of 45 Bx, concentration polarisation factors that can have a detrimental impact on the flux were not realised. Possible strategies were also explored for the integration into the sugar-manufacturing process.