Freezing characteristics and relative permittivity of rice flour gel in pulsed electric field assisted freezing
2022
Zhang, Roujia | Ding, Fuyuan | Zhang, Yang | Zhou, Chenguang | Zhang, Wen | Shi, Jiyong | Xiaobo, Zou | Xiao, Jianbo
This study investigated the effect of pulsed electric field assisted freezing treatment on the freezing characteristics of rice flour gel under output voltages varying from 0 to 25 kV. The results indicated that by applying a pulsed electric field, the phase change time decreased. Scanning electron microscopy images indicated that pulsed electric field treatment led to the formation of rounder and smaller ice crystals. For further understanding and quantifying the interaction between rice flour gel and a pulsed electric field, the relative permittivity of rice flour gel with and without the addition of salt was measured between 100 and 3100 kHz and −20 and 20 °C. Relative permittivity increased with decreasing frequency or increasing temperature, and sharp variation was observed during the phase transition period. In addition, salt was proved to be an effective additive for increasing relative permittivity.
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