Feasibility of using infrared heating for blanching and dehydration of fruits and vegetables

Abstract

The objective of this study was to evaluate the feasibility of using medium and far infraredheating for blanching and dehydration of various fruits and vegetables. The infrared blanching wasreferred as infrared dry-blanching (IDB) in this study since no water or steam was used. A catalyticinfrared blancher/dryer was used to perform the blanching and dehydration functions. For blanchingstudy, the fruits and vegetables, including pears, baby carrots, sweet corn and french fries, wereblanched with radiation energy intensity of 5.7 kW/m2. The pears were cut into 12.7 mm cubes andfrench fries had cross section of 12.7 x 12.7 mm. The sweet corn kernels were removed from thecobs before the blanching. The whole baby carrots had diameter of 15 mm. It took 2, 4, 1, and 3.5min to inactivate the peroxidase in the pear cubes, whole baby carrots, cut corn and french fries,respectively. The IDB also showed high heating rate. It was concluded that all tested fruits andvegetables were effectively blanched in relatively short times and products had good appearances.When the pear cubes were further dehydrated to 50% weight reduction with radiation energyintensity of 2.7 kW/m2 after the blanching, total time saving of IDB was 43.9% compared to steamblanching followed by heated air drying. The texture and appearance of IDB processed pearsappeared to be superior compared to the control samples produced with steam blanching andheated air drying. Therefore, the IDB can be used for performing simultaneous blanching anddehydrations.