پديد آورندگان :
Sabbaghi ، Hassan Gorgan University of Agricultural Sciences Natural Resources - Department of Food Materials Processing Design Engineering , Ziaiifar ، Aman Mohammad Gorgan University of Agricultural Sciences Natural Resources - Department of Food Materials Processing Design Engineering , Kashaninejad ، Mahdi Gorgan University of Agricultural Sciences Natural Resources - Department of Food Materials Processing Design Engineering
كليدواژه :
Infrared , Apple , Intermittent heating , Fuzzy controller , Simulation.
چكيده فارسي :
In this study, fuzzy temperature controller was designed using stepwise heating 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 inactivity of polyphenol oxidase enzyme (PPO) as blanching speed index and vitamin C preservation as maintaining quality index. The samples were removed from the infrared dryer in 2 minute intervals to separate the time required for the dry blanching process and dehydration of apple slices. For all temperatures, the heating process was continued until no sign of color change stemming from catechol reagent (adequacy of blanching). Finally, 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 timeweighted absolute error (ITAE) and steady state error (ess). These parameters must be close to zero. The results revealed that the temperature of 80°C and time of 15 minutes were appropriate for blanching operation and the temperature of 70°C was appropriate for dehydration. The simulation results confirmed that the higher order of the transfer function led to a faster response, but an increase in oscillations and reduction in the stability were not appropriate. For the firstorder 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 the secondorder 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 high sensitivity to maintain steady state error (ess) close to zero.
