Relationship between inactivation kinetics of a Listeria monocytogenes suspension by chlorine and its chlorine demand.
OBJECTIVE
Chlorine demand by Listeria monocytogenes cells and inactivation of L. monocytogenes by chlorine (0.6-1.0 mg l(-1)) at different temperatures (4, 20 and 30 degrees C) have been investigated in a batch reactor.


RESULTS
Chlorine demand depended on the microbial concentration and was independent on the initial chlorine concentration and temperature. Chlorine decay was modelled by the addition of two first-order decay equations. Inactivation of L. monocytogenes by chlorine depended on the initial microbial concentration, initial chlorine concentration and temperature. A mathematical model based on a biphasic inactivation properly described survival curves of L. monocytogenes and a tertiary model was developed that satisfactorily predicted the inactivation of L. monocytogenes by different concentrations of initial chlorine at different temperatures.


CONCLUSIONS
Both available chlorine decay and inactivation of L. monocytogenes by chlorine were biphasic and can be modelled by a two-term exponential model.


CONCLUSIONS
The biphasic nature of survival curves of L. monocytogenes did not reflect the effect of a change of available chlorine concentration during the treatment. The microbial inactivation was caused by successive reactions that occur after the consumption of the chlorine by the bacterial cell components.
Virto
R
R
Tecnología de los Alimentos, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain.
Sanz
D
D
Alvarez
I
I
Condon
S
S
Raso
J
J
D002713:Chlorine / Q000378:metabolism* / Q000493:pharmacokinetics; D015169:Colony Count, Microbial / Q000379:methods; D004202:Disinfectants / Q000494:pharmacology; D008089:Listeria monocytogenes / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D008954:Models, Biological; D012973:Sodium Hypochlorite / Q000494:pharmacology; D013696:Temperature; D014871:Water Microbiology
D004202:Disinfectants; D002713:Chlorine; D012973:Sodium Hypochlorite