Czech J. Food Sci., 2023, 41(5):358-366 | DOI: 10.17221/83/2023-CJFS

Refined approach to the evaluation of heat resistance applied to Enterobacteriaceae in cheese stretchingOriginal Paper

Irena Němečková^* ORCID..., Šárka Trešlová, Eliška Lešková

Dairy Research Institute, Prague, Czech Republic

Heat resistance of bacteria is a factor potentially limiting the production of safety foods. We focused on five Enterobacteriaceae strains related to cheese stretching and sub-pasteurisation experimental temperatures of 50–59 °C. Heat resistance was screened and obtained data were fitted to a classical log-linear model with D-values indicating highly heat-resistant strains used. For example in Klebsiella oxytoca S525, D(50)-value was 96.1 min and D(59)-value 5.1 min. In subsequent detailed measurements, the shape of inactivation curves was sigmoid with defined lag, log-linear and stationary phase. We suggest calculating refined D-values (D^r-values) using only data obtained in log-linear phases, namely D^r(temperature; lag phase). In K. oxytoca S525, the obtained results were: D^r(50; 80.9) = 61.7 min, D^r(53; 12.4) = 36.8 min, D^r(56; < 10) = 10.6 min, and D^r(59; < 3) = 4.3 min. The research of particular inactivation phases can provide interesting findings both in science and industrial practice, especially concerning the passage or persistence of hazardous strains in food processing plants.

Keywords: D-value; Klebsiella; non-linear model; Pantoea; sub-pasteurisation heating

Received: May 31, 2023; Revised: October 10, 2023; Accepted: October 12, 2023; Prepublished online: October 25, 2023; Published: October 30, 2023  Show citation