Purpose: Since inadequate cooking time and temperature are significant factors that may result in foodborne illness, this study was conducted to quantify the interactive effects of olive and pomegranate extracts (each at 0.4 – 2% w/w) on the heat resistance of a mixture of eight-strain Salmonella serotypes in ground chicken.
Methods: The inoculated meat samples were heated in a water bath at 55, 56.5, 58.7, 61 and 62.5°C for various times that were predetermined based on the heating temperature. After heating, the surviving microbial population was recovered on tryptic soy agar supplemented with 0.6% yeast extract and 1% sodium pyruvate solution. A survival model was then fitted to the data using a curve fitting program and decimal reduction times (D-values) were calculated. The D-values were transformed to the natural logarithms and mathematically analyzed by second order response surface regression to develop a regression model for temperature, olive and pomegranate extract, each of which may contribute to the inactivation of the pathogen.
Results: The D-values at 56.5ºC in unsupplemented ground chicken of 24.3 min was reduced to 11.3 min in ground chicken with added 1% olive and 1% pomegranate extract. While supplementing chicken with either extract increased sensitivity of the pathogen to heat, the simultaneous addition of both extracts exhibited a synergistic effect, as evidenced by a 53.5% reduction of the heat resistance. These results suggest that the described thermal death time predictive model can be used to estimate D-values in ground chicken for any combinations of temperature and food-compatible olive and pomegranate powders.
Significance: The facilitated heat reduction has the potential to enhance the microbial safety of cooked chicken products.