Andrews and Godshall: Comparing the Effects of Sulphur Dioxide on Model Sucrose and Cane Juice Systems 90 COMPARING THE EFFECTS OF SULPHUR DIOXIDE ON MODEL SUCROSE AND CANE JUICE SYSTEMS

Sulphur dioxide (SO2) has been used for centuries to minimize color in food processing and fruit and vegetable storage. In the sugar industry, it is used routinely by sugar beet processors to reduce and prevent color formation in white refined sugar. Sugarcane processors throughout the world use SO2 to produce plantation white sugars. This study was undertaken to determine the effect of SO2 on pure sucrose solutions in comparison to real factory sugarcane juice streams. Sugar systems included 15 brix pure sucrose, clarified juice and mixed juice from a Louisiana sugarcane mill. A pH of 8.0 was obtained by adding milk of lime then lowered to approximately pH 5.0 with either SO2 or HCl (control). Several samples ranging from pH 5 to 8 were processed at 0-120 min at 850 C. Analyses included pH, SO2, color, calcium, and invert (as a measure of sucrose loss). Results indicated that the model system was much more sensitive to low levels of SO2 than real juice samples which demonstrated a greater buffering capacity. The pH levels of the model sucrose solution dropped rapidly, and invert levels increased with time. There was 1.6 % loss of sucrose in the SO2 trial as compared with no sucrose loss with HCl. Clarified juice resisted changes in pH with both SO2 and HCl. Sucrose loss at 120 min of processing and a pH of 5.0 was only 0.88 %. There was a maximum color reduction of 10-15 % in the SO2 trial, whereas no color reduction or sucrose loss was observed in the HCl trial. The mixed juice was very resistant to pH changes, and a minimum pH of 6.0 was achieved with 4800 ppm SO2. No sucrose loss was observed in either trial with mixed juice, and color reduction was the same in both the SO2 and HCl trials. In real juice streams, SO2 reduced color by 10-15 % more than clarification alone but also induced some sucrose loss (0.88%) after a lengthy time.