Effect of moderate pulsed electric field treatment on viscoelastic properties of sugar beet

Abstract

Pulsed Electric Field processing is a non-thermal alternative to sucrose extraction from sugar beet. The aim of the study was to investigate the impact of pulsed electric field (PEF) treatment on the viscoelastic properties of sugar beet tissue. The electrical conductivity disintegration index was used for characterization of the PEF-induced damage of sugar beet tissue. Cell membrane disintegration increased with increasing field strength and pulse number. Stress–relaxation tests were also performed. The changes in viscoelastic properties were quantified as a result of applied field strength and pulse number and were correlated with cell disintegration index. The generalized Maxwell model was used to fit the measured stress-relaxation data. The rheological constants, elastic module (MPa), equilibrium elastic module (MPa) and relaxation time (s) were decreased significantly with increase of cell disintegration index. Scanning electron microscope images of the intact and PEF- treated samples showed increased deformation of cells and larger intercellular spaces for the PEF-treated samples.