Antagonistic effects of Lactobacillus reuteri against Escherichia coli O157:H7 in white-brined cheese under different storage conditions

Anas A. Al-Nabulsi, Tareq M. Osaili, Saba B. Oqdeh, Amin N. Olaimat, Ziad W. Jaradat, Mutamed Ayyash, Richard A. Holley

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

This study aimed to investigate the survival of the foodborne pathogen Escherichia coli O157:H7 in white-brined cheeses as influenced by the presence of Lactobacillus reuteri. The white cheeses were made from pasteurized bovine milk inoculated with E. coli O157:H7 (cocktail of 3 strains) to achieve ∼5 log10 cfu/g with absence or presence of Lb. reuteri (∼6 log10 cfu/g). Cheese samples were brined in 10% or 15% NaCl solution and stored at 10°C and 25°C for 28 d. The white-brined cheeses were assessed for salt content, pH, water activity (Aw), and numbers of E. coli O157:H7, Lb. reuteri, nonstarter lactic acid bacteria (NSLAB), yeasts, and molds. Results showed that E. coli O157:H7 survived in cheese stored in both brine solutions at 10°C and 25°C regardless of the presence of Lb. reuteri. A substantial reduction was observed in cheese stored in 10% NaCl brine at 25°C, followed by cheese stored in 15% NaCl brine at 10°C by 2.64 and 2.16 log10 cfu/g, respectively, in the presence of Lb. reuteri and by 1.02 and 1.87 log10 cfu/g, respectively, in the absence of Lb. reuteri under the same conditions. The pathogen in brine solutions survived but at a lower rate. Furthermore, the growth of Lb. reuteri and NSLAB were enhanced or slightly decreased in cheese and brine by 28 d, respectively. The salt concentrations of cheese ranged from 4 to 6% and 5 to 7% (wt/wt), during 28-d ripening in 10 and 15% brine, respectively. Values of pH and Aw slightly increased at d 1 after exposure to brine and reached 4.69 to 6.08 and 0.91 to 0.95, respectively, in all treatments. Therefore, the addition of Lb. reuteri can be used as a biopreservation method to inhibit the survival of E. coli O157:H7 in white-brined cheese when combined with the appropriate temperature, NaCl level, and storage time.

Original languageEnglish
Pages (from-to)2719-2734
Number of pages16
JournalJournal of Dairy Science
Volume104
Issue number3
DOIs
Publication statusPublished - Mar 2021

Keywords

  • Escherichia coli O157:H7
  • Lactobacillus reuteri
  • biopreservation
  • white-brined cheese

ASJC Scopus subject areas

  • Food Science
  • Animal Science and Zoology
  • Genetics

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