The increase of dielectric loss factor with increasing moisture content in materials at RF frequencies may lead to the potentially advantageous phenomenon “moisture levelling” (Feng, Tang, & Cavalieri, 2002; Mexatas & Meredity, 1983). During the dielectric heating process, the portion with higher moisture content has larger dielectric loss factor, thus may be heated preferentially and absorb more electromagnetic energy than that with lower moisture content. It contributes to the uniformity of product heating in dielectric drying. Moreover, the portion with lower moisture content has low temperature, which would be beneficial to the quality of food materials after heating. However, the increase of dielectric loss factor with increasing temperature may lead to “thermal run away” (Zhao, Flugstad, Kolbe, Park, & Wells, 2000). The portion with higher temperature has larger dielectric loss factor, resulting in more dielectric heating. But this phenomenon
may be reduced by the moisture levelling effect
The increase of dielectric loss factor with increasing moisture content in materials at RF frequencies may lead to the potentially advantageous phenomenon “moisture levelling” (Feng, Tang, & Cavalieri, 2002; Mexatas & Meredity, 1983). During the dielectric heating process, the portion with higher moisture content has larger dielectric loss factor, thus may be heated preferentially and absorb more electromagnetic energy than that with lower moisture content. It contributes to the uniformity of product heating in dielectric drying. Moreover, the portion with lower moisture content has low temperature, which would be beneficial to the quality of food materials after heating. However, the increase of dielectric loss factor with increasing temperature may lead to “thermal run away” (Zhao, Flugstad, Kolbe, Park, & Wells, 2000). The portion with higher temperature has larger dielectric loss factor, resulting in more dielectric heating. But this phenomenonmay be reduced by the moisture levelling effect
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