Kinetic model of sugar diffusion from sugar beet tissue treated by pulsed electric field

Abstract

Extraction of sugar from sugar beet slices was studied following various pulsed electric field (PEF) treatments (intensities from 300 to 800 V cm −1 and number of pulses varying between 50 and 1000). Slices treated by PEF were immersed in water at ambient temperature at a liquid/solid ratio of 3. A significant increase in extraction yield was observed. This enhancement was due to permeabilisation of the cellular membrane and to the additional quantity of juice appearing on the surface of slices after PEF treatment being extracted rapidly by convection. The optimal conditions of PEF treatment were an intensity of 670 V cm −1 and 250 pulses. The extraction kinetics was studied on the basis of two approaches: Fick's diffusion equation and a two-exponential kinetic model. The coefficient of diffusion was only slightly influenced by the conditions of PEF treatment. The two-exponential model successfully described both the rapid and prolonged stages of extraction. By heating the solution at mild temperatures of 30-50 • C, the coefficient of diffusion was increased and the kinetics of extraction was enhanced. The quality of cellular juice obtained after PEF treatment was higher than that of juice obtained after thermal pretreatment at 75 • C.

Enhanced Extraction from Solid Foods and Biosuspensions by Pulsed Electrical Energy

“…It can be noted that effective electroporation of the red beet tissue at ambient temperature can be attained even at lower electric fields of 400-600 V/cm [89]. The PEF-assisted expression [15,49,77], aqueous extraction [23,24] and their combination [36] were studied for carrots. The material enhancement of the juice yield could be attained even at rather low voltage gradient of 360 V/cm [15].…”

“…The PEF application has a large potential as an alternative to conventional thermal technology. Recently, the PEF-assisted pressing and aqueous extraction from sugar beets were intensively studied [14,16,21,23,24,28,45,46,62,93].…”

Observations on the water distribution and extractable sugar content in carrot slices after pulsed electric field treatment

“…Previous studies have found that plant tissue disruption under PEF treatments can be achieved within 0.1 to 10 ms at electric field strengths between 0.5 to 5.0 kV/cm (Lebovka, Bazhal, & Vorobiev, 2001;Angersbach, Heinz, & Knorr, 2000). Significant membrane breakdown in potato and apple tissues has been observed when electric field strengths applied increased from 0.4 to 0.8 kV/cm (El-Belghiti, Rabhi, & Vorobiev, 2005). Under the conditions applied in the present study, it is suggested that membranes may be considered to exist in either of the two states, i.e.…”

Mass Transfer Enhancement by Means of Electroporation

“…Fig. 9b shows the Arrhenius plots of the effective sugar diffusion coefficient D eff of PEF treated sugar beets from two independent experiments (Lebovka et al, 2007a;El-Belghiti et al, 2005). For example, PEF treatment conducted at E=0.1 kV/cm and t PEF = 1 s caused the reduction of the activation energy from ≈ 75 kJ/mol (untreated sample) to ≈ 21 kJ/mol, with the D eff values being always larger for PEF treated samples (Lebovka et al, 2007a).…”