MINIMIZING ASCORBIC ACID LOSS DURING AIR DRYING WITH A CONSTRAINT ON ENZYME INACTIVATION FOR A HYPOTHETICAL FOODSTUFF

The utility of a simulation-optimization approach based on the complex method was demonstrated for a multi-stage drying process. Optimal stage-duration and temperature control were found for minimizing ascorbic acid loss using a literature-derived kinetic model. In addition, enzyme (catalase) inactivation was considered in the staged process. It was desired to control the process so that catalase activity was reduced below a specified level while minimizing ascorbic acid loss. Inequality constraints were also placed on the final retention of moisture and the temperature control range. Due to the large difference in temperature sensitivity at high moisture levels, the optimal configuration maintained the dry- and wet-bulb temperatures very high in a brief first stage to inactivate catalase, followed by milder drying conditions in the final stages to reduce ascorbic acid degradation.