Sugar syrup used for soft drinks mainly is cane sugar with 60° - 68° brix and at a filtration temperature of 70° - 85°C. The quality of sugar syrup differs widely depending on its origin and refining process. In the beverage industry the purity of the sugar solution is measured in ICUMSA or RBU units. A high ICUMSA or RBU reading (150 - 450) indicates a poor quality sugar and means it is difficult to process. The international accepted standard for sugar syrup with 65° brix is less than 50 ICUMSA.
To reduce the ICUMSA / RBU value the syrup often is treated with activated carbon (AC). The AC dosages range from 0.2 - 0.5 - 0.8 % (w/w). Because of the high dosage of AC, filters with a large sludge volume should be used. In cases where a continuous filtration process is required, it is advisable to use two filters so that while one filter is filtering, the second filter can be in preparation or CIP.