Effect of pulse electric field applied to carrot prior to its heating

Publication date: Available online 24 January 2020Source: Journal of Food EngineeringAuthor(s): Jiří Blahovec, Pavel KouřímAbstractThe tissue of carrot (variety Jereda) was tested using dynamic mechanical analysis (DMA) combined with dielectric thermal analysis (DETA), in air of 90% humidity in temperature scans between 30 and 90 °C. Temperature plots of loss tangent were determined. In DETA, based on alternated current of frequency 20 kHz, both components of impedance were continually determined. Pulsed electric field (PEF) was applied prior to the DMA and DETA tests. Four sets of experiments were performed, without PEF (b), with a single 10 ms long pulse given an alternated field of 500 V/cm (c), with two similar pulses at 0.1 s interval (d) and with two similar pulse at 1 s interval (e). The impedance was recalculated giving parameters of a single model represented by parallel connection of a resistor Re and a capacitor with capacitance ωC. Three stages of the range of temperature, namely subcritical (30–70 °C), critical (70–80 °C), and supercritical (80–90 °C) were considered. For set b, in subcritical stage, the parameter, Re decreased whereas capacitance was nearly constant. Both of these parameters decreased slightly in the supercritical stage but whereas Re is in supercritical stage much lower than in the subcritical stage, the capacitance is in supercritical stage rather higher than it is in subcritical stage. In critical stage, Re sh...
Source: Journal of Food Engineering - Category: Food Science Source Type: research