FOOD. Science. Technology. Quality

Food. SCIENCE. Technology. Quality

Food. Science. TECHNOLOGY. Quality

Food. Science. Technology. QUALITY

Authors

ARTUR WIKTOR, MATTHIAS SCHULZ, ERIK VOIGT, DIETRICH KNORR, DOROTA WITROWARAJCHERT

Title

Impact of pulsed electric field on kinetics of immersion freezing, thawing, and on mechanical properties of carrot

Abstract

The objective of the research study was to determine the impact of pulsed electric field (PEF) on the processes of immersion freezing, thawing, and on the selected parameters of thawed carrot tissue. The carrot tissue was treated by a pulsed electric field (E = 1.85-5 kV/cm; n = 0 – 100 impulses, Ws = 0 – 80 kJ/kg) and, next, it was immersion-frozen in ethanol at a temp. of -20 °C. The freezing and thawing curves were determined and, on their basis, the duration time of individual process stages of those processes was computed. The thawed tissue was assessed based on the mass loss during thawing and on the mechanical properties: maximal compressive force, and on the compressive work. It was found that the impact of the pulsed electric field application applied prior to freezing caused the total freezing time to decrease 31.7 % maximally compared to the PEF-untreated tissue. Moreover, the thawing time was also reduced (31.1 % maximally). Compared to the PEF-untreated tissue, the PEF-treated samples were also characterized by different mechanical properties, i.e. by lower values of both the compressive work (21.5 – 83.6 %) and the maximal compressive force (16.4 – 87.3 %). The mass loss after thawing of PEFuntreated tissue was 9.21 % and of the PEF-treated samples the mass loss ranged between 7.15 and 11.35 %. A statistically significant correlation (r = 0.84; p-value = 0.002) was also reported between the total freezing time and the cell disintegration index (CDI) (r = 0.84).

Keywords

pulsed electric field, carrot, immersion freezing, thawing, mechanical properties

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