Effect of salt and sucrose content on dielectric properties and microwave freeze drying behavior of re-structured potato slices

Potato puree was used to prepare re-structured potato slices. The effect of salt and sucrose content on microwave freeze drying (MFD) and the variation of the dielectric properties of the potato slices were studied. Results showed that the dielectric constant (epsilon') and loss factor (epsilon '') of the potato purees decreased significantly after freezing. Both salt and sucrose addition increased epsilon' and epsilon '' of the samples at low temperatures (-25 to -5 degrees C). The salt content had greater influence relative to sucrose content on dielectric properties of the samples. Sucrose addition shows insignificant influence on dielectric properties of the thawing samples; while for the salted samples, epsilon' decreased gradually with increasing salt content and epsilon '' increased significantly with increasing salt content and temperature. MFD drying rate was significant higher after adding salt and sugar. (C) 2011 Elsevier Ltd. All rights reserved.