Inactivation of Bacillus subtilis spores by pulsed electric fields (PEF) in combination with thermal energy – I. Influence of process- and product parameters

Siemer, Claudia; Toepfl, Stefan; Heinz, Volker

doi:10.1016/j.foodcont.2013.10.025

Cited by 62 publications

(25 citation statements)

References 55 publications

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“…Although the majority of pathogenic and spoilage micro‐organisms can be inactivated in an electric field intensity range of 20–50 kV cm −1 at ambient or sublethal temperatures, no spores inactivation is possible at electric field strengths below 25 kV cm −1 (Siemer et al . ). However, spores inactivation can be achieved using temperatures above 50°C and electric field strengths above 50 kV cm −1 .…”

Section: Nonthermal Processingmentioning

confidence: 97%

“…Compared to other PEF variables, for example, number and type of pulses, the electric field strength and the treatment time are the key processing variable influencing microbial inactivation. Although the majority of pathogenic and spoilage micro-organisms can be inactivated in an electric field intensity range of 20-50 kV cm À1 at ambient or sublethal temperatures, no spores inactivation is possible at electric field strengths below 25 kV cm À1 (Siemer et al 2014). However, spores inactivation can be achieved using temperatures above 50°C and electric field strengths above 50 kV cm À1 .…”

Section: Nonthermal Processingmentioning

confidence: 99%

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State of the art of nonthermal and thermal processing for inactivation of micro-organisms

et al. 2018

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Despite the constant development of novel thermal and nonthermal technologies, knowledge on the mechanisms of microbial inactivation is still very limited. Technologies such as high pressure, ultraviolet light, pulsed light, ozone, power ultrasound and cold plasma (advanced oxidation processes) have shown promising results for inactivation of micro-organisms. The efficacy of inactivation is greatly enhanced by combination of conventional (thermal) with nonthermal, or nonthermal with another nonthermal technique. The key advantages offered by nonthermal processes in combination with sublethal mild temperature (<60°C) can inactivate micro-organisms synergistically. Microbial cells, when subjected to environmental stress, can be either injured or killed. In some cases, cells are believed to be inactivated, but may only be sublethally injured leading to their recovery or, if the injury is lethal, to cell death. It is of major concern when micro-organisms adapt to stress during processing. If the cells adapt to a certain stress, it is associated with enhanced protection against other subsequent stresses. One of the most striking problems during inactivation of micro-organisms is spores. They are the most resistant form of microbial cells and relatively difficult to inactivate by common inactivation techniques, including heat sterilization, radiation, oxidizing agents and various chemicals. Various novel nonthermal processing technologies, alone or in combination, have shown potential for vegetative cells and spores inactivation. Predictive microbiology can be used to focus on the quantitative description of the microbial behaviour in food products, for a given set of environmental conditions.

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Section: Nonthermal Processingmentioning

confidence: 97%

Section: Nonthermal Processingmentioning

confidence: 99%

State of the art of nonthermal and thermal processing for inactivation of micro-organisms

et al. 2018

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“…In the same way, the effect of some phenolic acids were found to negatively influence the growth and survival of wine LAB (Campos, Couto, & Hogg, 2003) and wine yeast (Stead, 1995). The electrical conductivity and the complexity buffer could have influence on the treatment conditions (Siemer, Toepfl, & Heinz, 2014a). In this way, the higher the electrical conductivity, the lower resistance of the liquid flowing into the treatment chamber and consequently a high energy is necessary to reach the same inactivation rates (Pataro, Falcone, Donsì, & Ferrari, 2014).…”

Section: Resultsmentioning

confidence: 93%

“…The chemical composition of wine was as follows: pH 3.68; alcohol content 14.6% v/v; total acidity 6.92 g/L (as tartaric acid); electrical conductivity 0.23 S/m. As far as it was described, the wine acidity was a favourable feature since it has been demonstrated that microbial inactivation with low pH requires less energy than in neutral pH value (Siemer, Toepfl, & Heinz, 2014a;Timmermans et al, 2014). The effect of ethanol content and the phenolic compounds of wines have been also studied by several authors as Puértolas et al…”

Section: Resultsmentioning

confidence: 99%

Inactivation of wine-associated microbiota by continuous pulsed electric field treatments

González‐Arenzana

Portu

López

et al. 2015

Innovative Food Science & Emerging Technologies

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“…As the residence time in the treatment chambers is fixed and no holding time is used, inactivation kinetics of a PEF treatment can be characterised as series with different maximum temperatures and a fixed 'holding' time. Often the intensity of the PEF treatment is expressed in electrical energy applied to the system, but this can be converted to maximum temperatures using the specific heat capacity of the matrix (Siemer et al, 2014;Timmermans et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the Gauss-Eyring model to predict thermal inactivation of micro-organisms at short holding times

Timmermans

Mastwijk

Groot

et al. 2017

International Journal of Food Microbiology

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Application of mild (non)-thermal processing technologies have received considerable interest as alternative to thermal pasteurisation, because of its shorter holding time and lower temperature aiming for an improved product quality. To understand and develop these alternative technologies, like pulsed electric fields, a proper comparison between the conventional thermal and alternative process is necessary. Up to recent, no suitable models were available to predict the inactivation of micro-organisms by a thermal process at a chosen short holding time, due to non-linearity. The recently developed Gauss-Eyring model with two variables temperature and time has the properties to be a suitable model to apply for short holding times, and was tested for this purpose. Therefore, this study aims to validate if the Gauss-Eyring model can be used to describe non-linear isothermal (a fixed temperature with varying holding time) and isotime (a fixed holding time with varying temperature) thermal inactivation data, and if it is a suitable model to predict the thermal inactivation as a function of temperature for short holding times. Inactivation data of Escherichia coli, Listeria monocytogenes, Lactobacillus plantarum, Salmonella Senftenberg and Saccharomyces cerevisiae in orange juice were collected via isothermal and isotime inactivation kinetics. Survival of the tested micro-organisms was modelled with the Gauss-Eyring model, which contains three parameters σ, Tr and Z. The transition of 'no inactivation' to 'inactivation' (i.e. the 'shoulder' in inactivation curves) can be characterised as the temperature-time (T,t) combination where T=Tr-Z·log(t), with Tr as the reference temperature defined for 1s treatment, Z as the temperature needed for a 10-fold increase of decrease of the holding time t, and σ as the temperature width of the distribution. The Gauss-Eyring model fitted well to the experimental data, and revealed different sensitivity for the tested micro-organisms. Based on the parameter estimations, survival curves for the desired short holding times were predicted.

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Inactivation of Bacillus subtilis spores by pulsed electric fields (PEF) in combination with thermal energy – I. Influence of process- and product parameters

Cited by 62 publications

References 55 publications

State of the art of nonthermal and thermal processing for inactivation of micro-organisms

State of the art of nonthermal and thermal processing for inactivation of micro-organisms

Inactivation of wine-associated microbiota by continuous pulsed electric field treatments

Evaluation of the Gauss-Eyring model to predict thermal inactivation of micro-organisms at short holding times

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