Modeling the γ-irradiation inactivation kinetics of foodborne pathogens <i>Escherichia coli</i> O157:H7<i>, Salmonella, Staphylococcus aureus and Bacillus cereus</i> in instant soup

The objective of the present study was to assess the inactivation kinetics of gamma-irradiation of selected foodborne pathogens in instant soup. Escherichia coli O157:H7 (ATCC 25922), Salmonella enterica subsp. enterica serovar Enteritidis (ATCC 13076), Staphylococcus aureus (ATCC 2592), and Bacillus cereus (ATCC 11778) were inoculated into instant soup and irradiated at various doses of 0 (control), 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0, and 10.0 kGy using Co-60 source. The radiation response of these four major foodborne disease pathogens in instant soup was tested. As expected, the pathogen population decreased with increasing irradiation dose. By comparing bacterial resistance in instant soups according to D-10 values, E coli O157: H7 was the most radio-resistant bacteria (D-10 of 1.580 kGy), followed by Salmonella (D-10 of 1.160 kGy), S aureus (D-10 of 0.775 kGy), B cereus (D-10 of 0.462 kGy). For modeling of inactivation kinetics, both, the conventional first-order linear model and Weibull model were compared and the goodness of fit of these models was investigated. Weibull model produced a better fit to the data. This research has shown that gamma-irradiation was effective to eliminate pathogens in instant soup and it can be a great way to assure the microbiological safety of the instant soup.