Introduction: Microwave heating is a form of dielectric heating by which it is possible the generation of heat in materials of low electrical conductivity by an applied high-frequency electric field.
Materials and methods: To apply microwave pretreatment, the oranges w
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Introduction: Microwave heating is a form of dielectric heating by which it is possible the generation of heat in materials of low electrical conductivity by an applied high-frequency electric field.
Materials and methods: To apply microwave pretreatment, the oranges were placed in the microwave for 0, 1, 2, and 3 min, and after the treatment, slices with a thickness of 0.5 cm were prepared from the oranges and, then the slices were dried using an infrared lamp with a power of 250 W.
Results: By increasing the microwave treatment time from 0 to 3 minutes, the effective moisture diffusivity coefficient increased. Kinetic modeling results of the experimental data of drying orange slices showed that the best model for this process is Midilli's model. The application of microwave had a significant effect on the change of surface shrinkage of dried and rehydrated orange slices (p0.05). By increasing the microwave treatment time from 0 to 3 min, the average rehydration of dried orange slices in the infrared dryer increased from 154.25% to 212.85%.
Conclusion: In general, the use of microwave pretreatment before drying orange slices due to increasing mass transfer rate, reducing surface shrinkage, and increasing rehydration, is recommended.
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