Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Proceedings
Publication Acceptance Date: 5/20/2005
Publication Date: 7/16/2005
Citation: Pan, Z., Olson, D.A., Ameratanga, K., Olsen, C.W., Zhu, Y., Mc Hugh, T.H. 2005. Feasibility of using infrared heating for blanching and dehydration of fruits and vegetables. American Society of Agricultural Engineers Meetings Papers. ASAE Paper No. 056086. p. 1-13. St. Joseph. MI.
Interpretive Summary: Blanching and dehydration are two essential processes with high energy consumption for fruits and vegetables. Blanching is normally achieved using hot water and steam that can cause losses of nutrients. It is desirable to develop alternative blanching and dehydration technology with high process and energy efficiencies to produce high quality fruit and vegetable products. The results showed that all tested fruits and vegetables could be effectively blanched in relatively short times and the products had good appearances. The required blanching times were related to physical and chemical properties. Especially when the products needed to be further dehydrated, using infrared heating could perform simultaneous blanching and dehydrations.
Technical Abstract: The objective of this study was to evaluate the feasibility of using medium and far infrared heating for blanching and dehydration of various fruits and vegetables. The infrared blanching was referred as infrared dry-blanching (IDB) in this study since no water or steam was used. A catalytic infrared blancher/dryer was used to perform the blanching and dehydration functions. For the blanching study, fruits and vegetables, including pears, baby carrots, sweet corn and french fries, were blanched with a radiation energy intensity of 5.7 kW/m2. The pears were cut into 12.7 mm cubes and french fries had cross sections of 12.7 x 12.7 mm. The sweet corn kernels were removed from the cobs before blanching. The whole baby carrots had a diameter of 15 mm. It took 2, 4, 1, and 3.5 min to inactivate the peroxidase in the pear cubes, whole baby carrots, cut corn and french fries, respectively. The IDB also showed a high heating rate. It was concluded that all tested fruits and vegetables were effectively blanched in relatively short times and the products had good appearances. When the pear cubes were further dehydrated to 50% weight reduction with a radiation energy intensity of 2.7 kW/m2 after the blanching, the total time saving of IDB was 43.9% compared to steam blanching followed by heated air drying. The texture and appearance of IDB processed pears appeared to be superior compared to the control samples produced with steam blanching and heated air drying. Therefore, the IDB can be used for performing simultaneous blanching and dehydrations.