AUTHOR=De Silvestri Andrea , Ferrari Enrico , Gozzi Simone , Marchi Francesca , Foschino Roberto 

TITLE=Determination of Temperature Dependent Growth Parameters in Psychrotrophic Pathogen Bacteria and Tentative Use of Mean Kinetic Temperature for the Microbiological Control of Food

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.03023

DOI=10.3389/fmicb.2018.03023

ISSN=1664-302X

ABSTRACT=<p>Temperature is the main factor to control the microbial growth in perishable foods. The psychrotrophic pathogen bacteria are microorganisms of concern for food products with extended shelf life in chilling conditions. The aims of this work were two. Firstly, to evaluate growth behavior of <italic>Aeromonas hydrophila</italic> DSM-30187, <italic>Listeria monocytogenes</italic> DSM-20600, and <italic>Yersinia enterocolitica</italic> DSM-27689 strains, at different temperatures (4, 7, 10, 15, 25, and 30°C) and starting cell concentrations (10 and 10<sup>6</sup> CFU/mL), in order to determine the activation energies (<italic>E</italic><sub>a</sub>) of the relevant lag phases and growth rates. Secondly, to investigate if Mean Kinetic Temperature (MKT) might be applied in recording temperature devices to alert a thermal abuse in a management control system for food safety. As expected, lag phase and growth rate proved to be heavily affected by temperature whereas the inoculum size did not. The <italic>E</italic><sub>a</sub> values involved in the duration of latent periods, calculated on the basis of the Arrhenius model, were comparable for <italic>A. hydrophila</italic> and <italic>L. monocytogenes</italic> strains (from 21.3 to 24.4 kcal/mol), while significantly differed for <italic>Y. enterocolitica</italic> (16.6 kcal/mol). The <italic>E</italic><sub>a</sub> values of growth rates were similar for <italic>A. hydrophila</italic> and <italic>L. monocytogenes</italic> strains (from 20.9 to 21.1 kcal/mol), while were considerably lower for <italic>Y. enterocolitica</italic> (from 14.2 to 16.7 kcal/mol). The use of MKT is widespread and well-accepted in pharmaceutical field as convenient method for estimating drugs degradation in relation to storage temperature. The <italic>E</italic><sub>a</sub> value of the lag phase found for <italic>L. monocytogenes</italic> (23.9 ± 1.2 kcal/mol) was included in the MKT formula. In this work, the air temperature of two chilling rooms was monitored during the normal operating activity in a catering company for a period of 8 months. The MKT profiles were then compared with those of mean temperatures in different conditions (short or prolonged events of thermal abuse) with the purpose to evaluate if it may be applicable to reduce false alarms without lowering the safety level of stored food.</p>