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Behavior of the surviving population of Lactobacillus plantarum 564 upon the application of pulsed electric fields

Seratlic, Sanja; Bugarski, Branko; Nedovic, Viktor; Radulovic, Zorica; Wadsö, Lars LU ; Dejmek, Petr LU and Gomez, Federico LU (2013) In Innovative Food Science & Emerging Technologies 17. p.93-98
Abstract
The behavior of the surviving population of Lactobacillus plantarum 564 growing in MRS broth after pulsed electric field (PEF) treatments of different intensities was monitored by isothermal calorimetry, optical density and plate counts. Bacterial cells were treated with monopolar square pulses at varying nominal electric field strengths and number of pulses, corresponding to applied energies of 34.6, 65.8 and 658.1 J/cm(3). After the PEF treatment, samples were inoculated into the MRS broth and incubated at 37 degrees C. The presented results show that surviving bacterial cells resume growth after a treatment-dependent delay. Both the untreated and treated cultures had similar growth rates, but the latter showed a higher growth rate... (More)
The behavior of the surviving population of Lactobacillus plantarum 564 growing in MRS broth after pulsed electric field (PEF) treatments of different intensities was monitored by isothermal calorimetry, optical density and plate counts. Bacterial cells were treated with monopolar square pulses at varying nominal electric field strengths and number of pulses, corresponding to applied energies of 34.6, 65.8 and 658.1 J/cm(3). After the PEF treatment, samples were inoculated into the MRS broth and incubated at 37 degrees C. The presented results show that surviving bacterial cells resume growth after a treatment-dependent delay. Both the untreated and treated cultures had similar growth rates, but the latter showed a higher growth rate during the late-growth phase, and the growth rate increased with the intensity of applied electric field. After the PEF treatment, the surviving population of bacteria was less susceptible to killing by further PEF application, showing that this subpopulation was less sensitive to the PEF treatment and could grow again. Industrial relevance: The application of pulsed electric field (PEF) technology as a non-thermal alternative to traditional pasteurization of liquid foods has received considerable attention during the last years. Effective inactivation for most of the spoilage and pathogenic microorganisms has been shown in fruit and vegetable juices and milk with little or no impact on nutritional and sensorial properties of the food. However, very little is known about the growth abilities of the surviving population. Ensuring food safety requires a better understanding of the behavior of the surviving populations of microorganisms which may be recovering from sub lethal injury, such as PEF-induced stress. This paper reveals that the surviving population of the bacteria subjected to the PEF treatment could grow again, showing higher growth rates as the intensity of the PEF treatment increased. Also, the new bacterial population showed higher resistance to further PEF treatment. Therefore, for industrial application of the PEF technology, an in-depth characterization of surviving microorganisms in the treated product is required. Moreover, the evidence of bacterial persistence indicates that the PEF technology, as a non-thermal alternative to traditional pasteurization, could not completely replace thermal treatment, but can be applied as a supplement treatment. (C) 2012 Elsevier Ltd. All rights reserved. (Less)
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author
organization
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type
Contribution to journal
publication status
published
subject
keywords
Lactobacillus plantarum, Pulsed electric fields, Isothermal calorimetry, Stress recovery
in
Innovative Food Science & Emerging Technologies
volume
17
pages
93 - 98
publisher
Elsevier
external identifiers
  • wos:000316094600012
  • scopus:84873060158
ISSN
1466-8564
DOI
10.1016/j.ifset.2012.11.011
language
English
LU publication?
yes
id
1506ea0c-f598-4a33-8206-1b803eba2c6f (old id 3651178)
date added to LUP
2013-04-24 15:37:43
date last changed
2019-02-20 07:13:31
@article{1506ea0c-f598-4a33-8206-1b803eba2c6f,
  abstract     = {The behavior of the surviving population of Lactobacillus plantarum 564 growing in MRS broth after pulsed electric field (PEF) treatments of different intensities was monitored by isothermal calorimetry, optical density and plate counts. Bacterial cells were treated with monopolar square pulses at varying nominal electric field strengths and number of pulses, corresponding to applied energies of 34.6, 65.8 and 658.1 J/cm(3). After the PEF treatment, samples were inoculated into the MRS broth and incubated at 37 degrees C. The presented results show that surviving bacterial cells resume growth after a treatment-dependent delay. Both the untreated and treated cultures had similar growth rates, but the latter showed a higher growth rate during the late-growth phase, and the growth rate increased with the intensity of applied electric field. After the PEF treatment, the surviving population of bacteria was less susceptible to killing by further PEF application, showing that this subpopulation was less sensitive to the PEF treatment and could grow again. Industrial relevance: The application of pulsed electric field (PEF) technology as a non-thermal alternative to traditional pasteurization of liquid foods has received considerable attention during the last years. Effective inactivation for most of the spoilage and pathogenic microorganisms has been shown in fruit and vegetable juices and milk with little or no impact on nutritional and sensorial properties of the food. However, very little is known about the growth abilities of the surviving population. Ensuring food safety requires a better understanding of the behavior of the surviving populations of microorganisms which may be recovering from sub lethal injury, such as PEF-induced stress. This paper reveals that the surviving population of the bacteria subjected to the PEF treatment could grow again, showing higher growth rates as the intensity of the PEF treatment increased. Also, the new bacterial population showed higher resistance to further PEF treatment. Therefore, for industrial application of the PEF technology, an in-depth characterization of surviving microorganisms in the treated product is required. Moreover, the evidence of bacterial persistence indicates that the PEF technology, as a non-thermal alternative to traditional pasteurization, could not completely replace thermal treatment, but can be applied as a supplement treatment. (C) 2012 Elsevier Ltd. All rights reserved.},
  author       = {Seratlic, Sanja and Bugarski, Branko and Nedovic, Viktor and Radulovic, Zorica and Wadsö, Lars and Dejmek, Petr and Gomez, Federico},
  issn         = {1466-8564},
  keyword      = {Lactobacillus plantarum,Pulsed electric fields,Isothermal calorimetry,Stress recovery},
  language     = {eng},
  pages        = {93--98},
  publisher    = {Elsevier},
  series       = {Innovative Food Science & Emerging Technologies},
  title        = {Behavior of the surviving population of Lactobacillus plantarum 564 upon the application of pulsed electric fields},
  url          = {http://dx.doi.org/10.1016/j.ifset.2012.11.011},
  volume       = {17},
  year         = {2013},
}