Modelling the inactivation of Escherichia coli ATCC 25922 using pulsed electric field

Effect of electric and flow parameters on PEF treatment efficiency

“…In particular, a parallel plate electrodes configuration was widely used, with it not only being the simplest in design but also producing the most uniform distribution of the electric field in the treatment region. Nevertheless, in several cases, heterogeneities of the treatment were reported as a result of field fringing effects at the electrode periphery related, for example, to the existence of a triple point (i.e., the interface between the electrodes, insulator, and liquid food) (Alkhafaji and Farid, 2008;Donsì et al, 2007). In addition, owing to their static nature, batch chambers cannot support any movement of the microbial cells in relation to the electrodes apart from those related to either the influence of gravity or to very slight convective currents in the samples due to mild heating effects under PEF.…”

Reactor modelling of treatment chamber for the inactivation of Escherichia coli by radio frequency electric field – mechanistic versus empirical approaches

“…23 A semi-logarithmic sigmoidal model was proposed by Geeraerd et al, 24 correlating the logarithmic survival fraction with treatment time, having shoulder, log-linear and tail regions. Assuming exponential decay behaviour of survival fraction with treatment time, Bazhal et al 25 and Alkhafaji and Farid 26 modelled the survival rate of E. coli with first-order kinetics, but found deviations at high orders of inactivation, possibly due to the existence of variable resistances within the microbial population. 27 In other studies, a log-logistic model proposed by Cole et al 28 accurately fitted the experimental data of Raso et al 29 for Salmonella senftenberg, whereas a Weibull distribution model showed a good fit for E. coli 16 and Listeria monocytogenes.…”

“…30 In spite of frequent literature on the traditional curve-fitting approach, mechanistic PEF models are not mathematically explained in connection with the reaction engineering principles applied to the treatment chamber. In the present work, following the work of Alkhafaji and Farid, 26 the treatment chamber is modelled as a PFR by utilizing mechanistic kinetic models.…”

“…Next, a multi-stage flow configuration, which involves flowing the liquid through consecutive chambers, was employed to elucidate the effect of treatment time. A recirculation approach suggested by Alkhafaji and Farid, 26 with a common feeding and collection point of liquid, was examined as a convenient and low-cost alternative to multi-stage configuration for kinetics studies. Chemical reactor balances were employed, in combination with mechanistic kinetic models, to represent the observed changes in microbial inactivation.…”

Effects of electrode materials on the degradation, spectral characteristics, visual colour, and antioxidant capacity of cyanidin-3-glucoside and cyanidin-3-sophoroside during pulsed electric field (PEF) treatment

“…The reaction products that are formed can react with other compounds in the liquid. Recently, the inactivation of microorganisms (Alkhafaji & Farid, 2008;Álvarez, Raso, Sala, & Condón, 2003;Amiali, Ngadi, Raghavan, & Smith, 2004) and enzymes (Marsellés-Fontanet & Martín-Belloso, 2007;Ohshima, Tamura, & Sato, 2007;Zhong et al, 2007) by PEF have been widely investigated. The effects of PEF on the compounds in treated foods have also been reported in the literature (Sampedro, Geveke, Fan, & Zhang, 2009;Schilling et al, 2008), showing that PEF can preserve these compounds.…”