Abstract

A mid-log phase broth culture of Escherichia (E.) coli O157:H7 381 (final concentration 104 cfu/mL) was monitored by conventional liquid- and solid-based enumeration techniques combined with PCR while it was subjected to thermal stress in gradually more complex systems (i.e., Tryptone Soya Broth, pasteurized milk and during lab-scale productions of a pasta filata fior di latte cheese obtained from raw or pasteurized milk). Our results highlighted: i) the incapability of the selective medium, ii) the effectiveness of the thin agar layer-PCR method, and iii) the effectiveness of the most probable number (MPN)-PCR method (in comparison with both plating-based methods) in recovering and selectively counting viable and stressed or injured E. coli O157:H7. Moreover, MPN-PCR was superior to both plating-based methods in terms of speed and easiness to get results. The thermal stresses herein applied (heating at 55 °C for 5 and 8 min) were less effective on the pasteurized milk than on the Tryptone Soya Broth and the pathogen was more protected in the raw milk-based matrices than in the pasteurized ones. Moreover, given the contamination level (104 cfu/mL of milk) of the strain, the temperature/time of stretching and the hardening and brining conditions herein used, the complete inactivation of the pathogen is not achievable.

Autore Pugliese

• Fusco Vincenzina

Tutti gli autori

• Fusco V.; Riccardi M.; Quero G.M.

Titolo volume/Rivista

International journal of food microbiology

Anno di pubblicazione

2012

ISSN

0168-1605

ISBN

Non Disponibile

Numero di citazioni Wos

Nessuna citazione

Ultimo Aggiornamento Citazioni

Non Disponibile

Numero di citazioni Scopus

Non Disponibile

Ultimo Aggiornamento Citazioni

Non Disponibile

Settori ERC

Non Disponibile

Codici ASJC

Non Disponibile