Effect of Imbibition Water Temperature on Tandem Mill Extraction

Incauca sugar mill and the Colombian Sugar Cane Research Center (Cenicaña) determined the effect of imbibition temperature in milling extraction, analyzing Brix, sucrose, colorants, and microbial metabolites associated with the production of acids in the Farrell tandem mill. The experiments consisted of laboratory-scale tests and factory trials. In the laboratory tests, six bagasse samples from the fifth mill were macerated with 40–90 °C condensates, heated with an electrical resistance, and automatically regulated with a controller. Using a hydraulic press, juice from the bagasse samples was extracted at a controlled pressure for a fixed time, then organics acids and sucrose contents (using high-performance liquid chromatography (HPLC)) and colorants content were analyzed. Additionally, bagasse composition was determined before maceration to obtain an extraction analysis. Given the obtained laboratory results, a direct and indirect heating system was implemented for the imbibition condensates and maceration juice tanks, respectively. Samples were analyzed with and without use of the heating system, with different juice flux being used across the mill (first and final extraction and diluted). Extraction performance results in terms of Brix and sucrose were greater as the imbibition temperature increased, with maximum values between 60 and 70 °C. Additionally, the generation of microbial metabolites (lactic acid and volatile acidity) decreased after imbibition at the laboratory and industrial scales.