Unveiling the synergistic effect of combining low and high frequency electric fields for microbiological safety in liquid food processing

Rezaeimotlagh, Adel; Resch, Marlies; Kuchel, Rhiannon P.; Biazik, Joanna; Ziuzina, Dana; Bourke, Paula; Cullen, Patrick J.; Trujillo, Francisco J.

doi:10.1016/j.jfoodeng.2021.110588

Cited by 10 publications

(6 citation statements)

References 11 publications

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“…In E. coli , peptidoglycan, as the major structural component of bacterial cell walls, provides an organizational role and also governs the osmotic pressure inside the cell 41 . This is important because RFEF inactivates E. coli by creating numerous enlarged pores inside the microbial cell wall, which damage the ultrastructure of these cells to an extent that the cells are unable to function 9 . The over‐expression in set B (long‐term effect) indicates that E. coli increased the activities to repair the call wall due to the damage caused by the electric field.…”

Section: Discussionmentioning

confidence: 99%

“…At electric fields above approximately 7.5 kV cm −1 , the number and size of pores electrically formed within the microbial cell membrane disrupt the ultrastructure of these cells and, subsequently, the cells are unable to sustain their functionality and they die. 8,9 A difference between RFEF and PEF is that RFEF can achieve microbial inactivation at lower electric fields. 10 As RFEF is a novel technology, the studies in the literature mostly cover the effect of processing parameters, such as temperature, treatment time and electric field strength, on microbial inactivation.…”

Section: Introductionmentioning

confidence: 99%

“…The mechanism of inactivation by RFEF, which is similar to pulsed electric fields (PEF), is due to irreversible electroporation. At electric fields above approximately 7.5 kV cm −1 , the number and size of pores electrically formed within the microbial cell membrane disrupt the ultrastructure of these cells and, subsequently, the cells are unable to sustain their functionality and they die 8,9 . A difference between RFEF and PEF is that RFEF can achieve microbial inactivation at lower electric fields 10 …”

Section: Introductionmentioning

confidence: 99%

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An investigation into the electro‐tolerance of Escherichia coli treated by radio frequency electric fields

Rezaeimotlagh

Serasinghe

Manefield

et al. 2022

J of Chemical Tech & Biotech

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BACKGROUND Radio frequency electric field (RFEF) is a novel technology for the microbial disinfection of liquids such as water and fruit juices. Here we investigated the development of microbial tolerance against RFEF to assess the long‐term suitability of this technology. We applied a constant electric field, outlet temperature and treatment time of 14 kV cm−1, 40 °C and 1.275 ms, respectively, to Escherichia coli inoculated in saline water to observe whether the descendants of the surviving bacteria could develop tolerance against RFEF. Escherichia coli that survived the RFEF treatment were recultivated and treated under similar processing conditions for 15 generations. RESULTS The results showed that although inactivation levels due to RFEF treatments fluctuated during consecutive generations, no significant difference between inactivation at cycles 1 and 15 was observed. Furthermore, inactivation levels during consecutive generations hovered around an average value of 2.18 log10 CFU mL−1. For short‐term effect, which compared untreated cells to treated ones at cycle 1, proteomics showed mixed trends of up‐ and down‐regulated differentially expressed proteins (DEPs). However, in the long term, which compared treated cells at cycles 1 and 15, DEPs involved in stress response, cell wall structure and antioxidant activities were all up‐regulated. CONCLUSION The results indicate that although cell wall is the main target for the effect of electric field, they suggest that, in the long term, oxidative stress may also be induced. © 2022 Society of Chemical Industry (SCI).

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

An investigation into the electro‐tolerance of Escherichia coli treated by radio frequency electric fields

Rezaeimotlagh

Serasinghe

Manefield

et al. 2022

J of Chemical Tech & Biotech

Self Cite

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“…However, increasing the number of pulses to 10,000 inactivated 67 ± 8% spores. Rezaeimotlagh et al [ 137 ] showed that processing with low frequency at 12.5 kV/cm and 40 °C, followed by a high-frequency electric field at 2.1 kV/cm and 65 °C, had a synergistic effect on Escherichia coli by 5 logs in saline water and cranberry juice. In such studies, the conductivity of the medium can influence the aforementioned factors, which means that if there is low conductivity of the medium, the lethal dose would not be obtained by increasing the intensity of PEF [ 134 ].…”

Section: Emerging Non-thermal Technologies and Their Potential Applic...mentioning

confidence: 99%

Physical Treatments to Control Clostridium botulinum Hazards in Food

Munir

Mtimet

Guillier³

et al. 2023

Foods

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Clostridium botulinum produces Botulinum neurotoxins (BoNTs), causing a rare but potentially deadly type of food poisoning called foodborne botulism. This review aims to provide information on the bacterium, spores, toxins, and botulisms, and describe the use of physical treatments (e.g., heating, pressure, irradiation, and other emerging technologies) to control this biological hazard in food. As the spores of this bacterium can resist various harsh environmental conditions, such as high temperatures, the thermal inactivation of 12-log of C. botulinum type A spores remains the standard for the commercial sterilization of food products. However, recent advancements in non-thermal physical treatments present an alternative to thermal sterilization with some limitations. Low- (<2 kGy) and medium (3–5 kGy)-dose ionizing irradiations are effective for a log reduction of vegetative cells and spores, respectively; however, very high doses (>10 kGy) are required to inactivate BoNTs. High-pressure processing (HPP), even at 1.5 GPa, does not inactivate the spores and requires heat combination to achieve its goal. Other emerging technologies have also shown some promise against vegetative cells and spores; however, their application to C. botulinum is very limited. Various factors related to bacteria (e.g., vegetative stage, growth conditions, injury status, type of bacteria, etc.) food matrix (e.g., compositions, state, pH, temperature, aw, etc.), and the method (e.g., power, energy, frequency, distance from the source to target, etc.) influence the efficacy of these treatments against C. botulinum. Moreover, the mode of action of different physical technologies is different, which provides an opportunity to combine different physical treatment methods in order to achieve additive and/or synergistic effects. This review is intended to guide the decision-makers, researchers, and educators in using physical treatments to control C. botulinum hazards.

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“…RF processing is an alternative to conventional heating of liquid foods that ensures microbial safety (Rezaeimotlagh et al ., 2021). There are different studies in which liquid foods have been treated with RF heating using batch or continuous systems.…”

Section: Radiofrequency Pasteurisation Of Liquid Foodmentioning

confidence: 99%

Advances in radio frequency pasteurisation equipment for liquid foods: a review

Soto‐Reyes

Sosa‐Morales

Rojas-Laguna

et al. 2022

Int J of Food Sci Tech

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Radiofrequency (RF) heating is an alternative emerging technology to conventional thermal methods; it has been employed for food pasteurisation, providing fast and volumetric heating. However, nonuniformity in the heating pattern has been reported. RF pasteurisation has been studied in different liquid foods. This review provides information about the RF heating mechanism and equipment used to pasteurise liquid food to control deteriorative or pathogen micro-organisms and the effect of the RF treatment on the quality of liquid foods. Developing an effective RF pasteurisation for liquid foods requires knowing the food dielectric properties, which determine the heating uniformity, temperature distribution and heating rate. The efficiency of continuous RF heating systems could depend on the fluid rate, resident time and absorbed power. RF heating can pasteurise liquid food, decrease microbial population and preserve the product's nutritional and physicochemical quality.

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Unveiling the synergistic effect of combining low and high frequency electric fields for microbiological safety in liquid food processing

Cited by 10 publications

References 11 publications

An investigation into the electro‐tolerance of Escherichia coli treated by radio frequency electric fields

An investigation into the electro‐tolerance of Escherichia coli treated by radio frequency electric fields

Physical Treatments to Control Clostridium botulinum Hazards in Food

Advances in radio frequency pasteurisation equipment for liquid foods: a review

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