Purpose: Investigation of the effect of undissociated acetic acid (ACV) concentration and temperature on the inactivation of Salmonella spp. in vinegar marinated chicken fillets stored under aerobic conditions.
Methods: Chicken breast fillets, inoculated with 5 strains of Salmonella spp., were immersed in 4 concentrations of ACV ranging from 0.5 to 2% in acetic acid, for 1 hour at 4oC. The molar concentration of the undissociated acid (UAC) was 24-204 mmol/L. After marination, samples were stored aerobically at 4, 8, 12, and 16oC for 9 days. Changes in pH, Total Viable Counts, and Salmonella spp. were determined, while data were fitted to a second order logistic regression model. For model validation, several vinegar marinades containing oil and various herbs were tested. Pulsed Field Gel Electrophoresis (PFGE) was conducted to monitor Salmonella strains after marination and at the end of storage.
Results: No inactivation was observed in samples with 24 mmol/L UAC at any temperature, whereas at 16oC, inactivation was observed in samples with 204 mmol/L UAC (2% acetic acid) only, and after 5 days of storage. The degree of agreement between predictions and observations was 93.7 % concordant whereas 4.8 and 9% of the misclassified predictions were false positive and false negative, respectively. Validation on various vinegar marinades data was not effective in 31 (27 fail-safe and 4 fail-dangerous) out of 170 cases. PFGE results revealed that at the end of the storage the strain S. enteritidis P167807 phage type 4 was detected at a proportion greater than 80% after treatments with ACV.
Significance: The developed model could be used to control Salmonella spp. in vinegar marinated poultry products.