Re-examining the Applications of Amylase in the Sugar Industry: Conquering the Control of Insoluble and Soluble Starch

摘要

The new knowledge that there is markedly more insoluble starch than previously considered in products across both the sugarcane factory and refinery has processing implications. Processing parameters such as viscosity and filtration are implicated, as well as the application of a-amylases in the factory to control not only soluble but insoluble starch. A two-year study was conducted at the laboratory and factory scales to optimize the application of amylase for control of both starch forms. Most, but not all, insoluble starch becomes swollen and/or solubilized during clarification. High-temperature (HT) and intermediate-temperature (IT) stable amylases can hydrolyze starch in clarified juice at 96 °C for the first 10 min before substantial denaturation, but HT amylases cause carry-over amylase activity. Novel combinations and doses (0 to 10 ppm) of an IT stable amylase were added to a clarifier tank, next-to-the-last evaporator, and/or last evaporator at a factory. Using the new USDA research starch method to measure total, insoluble, and soluble starch, a full picture of how starch is transformed and removed by the application of an IT amylase was achieved. As expected, soluble starch was easier to control than insoluble starch. Small but meaningful reductions in viscosity of syrup occurred inside the evaporator where the amylase was directly applied. The simultaneous addition of IT amylase to the next-to-the-last evaporator and last evaporator gave the highest hydrolysis of both soluble (99.8%) and insoluble (73.1%) starches and this is recommended during normal processing. The additional application of IT amylase to the clarifier tank as well as both evaporators is recommended in times of very high starch concentrations and high levels of insoluble starch in the factory. Another possible solution to controlling both insoluble starch and carry-over amylase at the factory and refinery is also briefly discussed.