Heat resistance of Staphylococcus aureus, Salmonella sp., and Escherichia coli isolated from frequently consumed foods in the Lebanese market

Abstract

The purpose of this study was to determine the heat resistance of isolated Staphylococcus aureus, Salmonella sp., and Escherichia coli bacterial strains obtained from frequently consumed foods (chicken sandwiches, cheese, raw chicken, tahini, and raw meat) in Lebanon. The isolated bacterial strains were heat-treated at 55, 60, 65, 70, and 75°C. The colony-forming unit per gram (CFU.g−1) was recorded for each temperature every minute for 10 min. Survival curves were plotted, and D- and z-values were calculated and compared using a two-sample T-test. All bacterial strains exhibited total resistance to heat at 55°C. Their D60 ranged from 3.00 to 28.80 min, D65 from 0.47 to 1.78 min, D70 from 0.19 to 1.91 min, and D75 from 0.11 to 0.46 min. Their z-values ranged from 4.74 to 19.65°C. When comparing these results to previous years, the need for combined interventions, such as active packaging solution, seems necessary as S. aureus, Salmonella sp., and E. coli are continually developing resistance to thermal processing. This study highlights emerging concerns regarding the safety of certain food products in the market. These results suggest further revising of the associated processing conditions to ensure compliance with food safety standards and avoid foodborne disease outbreaks.

Keywords

• Heat resistance
• Staphylococcus aureus
• Salmonella
• bacteria
• meat
• chicken