Clarification of sugarcane juice by ultrafiltration membrane: Toward the direct production of refined cane sugar

The conventional process for producing white sugar is energy intensive and inefficient. This paper discusses an intensified sugar refining process that utilizes ultrafiltration (UF) membrane technology as an alternative to a chemical purification process to remove color and simplify further refining. The inclusion of sodium bicarbonate combined with UF filtration improved the occlusion index of the cane juice, by removing excess calcium ions and polysaccharides, which led to improvements in crystal growth rate, crystal size, and sugar color. The UF permeate could be directly boiled and crystallized to produce United States Food Grade white sugar. Pilot studies of the UF process achieved a refined sugar of 83 ICUMSA from a clarified syrup of 11,425 ICUMSA and 85% purity. Application of a UF membrane system in sugar mills can eliminate various refining processes such as affination, phosphatation, and/or granular carbon/bone char/ion exchange for decolorization. Therefore, the UF-assisted process would produce high-quality food-grade sugar products meeting commercial specifications with considerable savings in both capital and operating costs.