Pulsed electric fields cause sublethal injury in Escherichia coli.
OBJECTIVE
The objective was to investigate the occurrence of sublethal injury in Escherichia coli by pulsed electric fields (PEF) at different pH values.


RESULTS
The occurrence of sublethal injury in PEF-treated E. coli cells depended on the pH of the treatment medium. Whereas a slight sublethal injury was detected at pH 7, 99.95% of survivors were injured when cells were treated at pH 4 for 400 micros at 19 kV. The PEF-injured cells were progressively inactivated by a subsequent holding at pH 4.


CONCLUSIONS
PEF cause sublethal injury in E. coli. The measurement of sublethal injury using a selective medium plating technique allowed prediction of the number of cells that would be inactivated by subsequent storage in acidic conditions.


CONCLUSIONS
This work could be useful for improving food preservation by PEF technology and contributes to the knowledge of the mechanism of microbial inactivation by PEF.
García
D
D
Tecnología de los Alimentos, Facultad de Veterinaria C/Miguel Servet, 177, 50013, Zaragoza, Spain.
Gómez
N
N
Condón
S
S
Raso
J
J
Pagán
R
R
D015169:Colony Count, Microbial; D003470:Culture Media; D004553:Electric Conductivity; D004558:Electric Stimulation; D004926:Escherichia coli / Q000254:growth & development / Q000302:isolation & purification; D005519:Food Preservation; D006863:Hydrogen-Ion Concentration
D003470:Culture Media