Microwave power control scheme for potatoes based on dielectric loss factor feedback
2021
Ma, Xiaotong | Luo, Guiyi | Li, Zhenfeng | Raghavan, G.S.V. | Chen, Haiying | Song, ChunFang
The dielectric properties of potatoes in the moisture content range of 8.3%–75.4% (w.b.) and the temperature range of 25 °C–85 °C were measured with a coaxial probe network analyzer. The regression equation of loss factor of potatoes with its moisture content and temperature was developed first and then introduced into an established LabVIEW control program to make dielectric loss factor as feedback signal for guiding the power output of the microwave drying system. Results show that the dielectric loss factor of potato chips increased with the increase in moisture content. When the moisture content of potato chips was 35%–75.4%, the loss factor decreased with the increase in temperature. The opposite trend was observed when the moisture content was lower than 35%. The proposed microwave power control scheme based on dielectric loss factor feedback and selected probable procedure on/off ratio can prevent the temperature rise of the material in the middle and last drying stages. This condition ensures the quality of the product.
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