Simulation of temperature fuzzy controller during infrared dry blanching and dehydration of apple slices by intermittent heating method

In this research, stepwise cooking and temperature fuzzy controller were designed during the infrared irradiation of apple with intermittent heating method. For this purpose, the dry blanching process and dehydration of apple slices were examined at three temperatures of 70, 75 and 80 °C based on the blanching speed and vitamin C preservation. The fuzzy controller of the temperature with the feedback loop was designed, simulated, and implemented by comparing two first and second order transfer functions in MATLAB software. Simulation efficiency was examined using the indices of integral squared error (ISE), integral absolute error (IAE), integral time-weighted absolute error (ITAE) and steady state error (ess). The results revealed that the temperature of 80 °C and time of 15 minutes were appropriate for blanching operation and temperature of 70 °C was appropriate for dehydration. The simulation results confirmed that the higher order of the transfer function led into a faster response, but increase in oscillations and reduction in the stability were not appropriate.  For the first-order transfer function, the values of efficiency indices, including (ISE), (IAE) and (ITAE) were calculated to be 0.760, 0.821 and 0.589, respectively, of second-order transfer function. The simulation indicated the reliability of the fuzzy control model and showed an acceptable computational efficiency, since the fuzzy rule test during simulation showed a high sensitivity to maintain steady state error (ess) close to zero.