Low-Temperature Carrot Cooking Supported by Pulsed Electric Field—DMA and DETA Thermal Analysis

Abstract

The paper deals with carrot processing that com- bines the effect of the electric pulse loading with the low- temperature heating. The pulse procedure was formed by one 10-ms long electric pulse (amplitude, 600 V/cm; basic frequency, 20 kHz) on the 160-ms long electric background less than 30 V/cm. The procedure was followed by the com- bined dynamic mechanical analysis (DMA) and dielectric thermal analysis (DETA) tests with the initial temperature of 30 °C and final temperature of 90 °C. Humidity in the test chamber was kept at 90 % during the whole heating test, with the heating rate of 1 °C/min. During the whole test, both components of the complex modulus of elasticity (DMA) of the specimen as well as both components of the specimen's permittivity (DETA) were registered. A similar test was also performed with other specimens with- out the initial pulse procedure. Ratios of corresponding data (storage modulus, loss modulus, dielectric constant, and dielectric loss) are approximately constant up to the temperature of approximately 70 °C where it starts to reduce substantially. The obtained results denote that can be processed using electric pulses reaching the similar state as during the tissue heating.