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Dielectric Properties and Microwave Drying of Tomato Slice

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation:   No Citation available.
Authors:   P.Rajkumar, G.S.V.Raghavan, Y.Gariepy M., V.Orsat

Dielectric properties of tomato slices are highly useful for predicting the heating rates and behaviour of the materials when subjected to high frequency electromagnetic waves. Dielectric properties of tomato slice (6 mm) at different moisture contents such 10, 30, 50 and 70% (w.b) were determined by using microwave spectroscopy. The corresponding dielectric properties like dielectric constant (e') and dielectric loss (e.) were observed. The result showed that both dielectric constant (77 to 7.2) and dielectric loss (48 to 3.4) decreased with increase in frequency from 200 MHz to 200 GHz. Drying of tomato slices were carried out at 50, 60, 70oC by using two methods namely microwave assisted vacuum dryer and microwave assisted hot air dryer at the selected temperatures. From the study, it was found that the time taken for drying of tomato slice in microwave assisted vacuum was lower (150, 100 and 70 min) when compared to microwave assisted hot air drying at 50, 60 and 70oC, respectively.

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