Modeling the effects of Bunium persicum [Black Zira] essential oil, pH, inoculums size and temperature on the growth of Listeria monocytogenes

ABSTRACT

Listeriosis is acknowledged as a major foodborne disease throughout the world caused by Listeria monocytogenes. Different factors can affect the growth of food borne microbial pathogens. The aim of this study was to investigate the combined effects of different concentrations of Bunium persicum essential oil [EO] [0%, 0.08%, 0.16%, 0.24%], three incubation temperatures [35ºC, 25ºC, 4ºC], three levels of pH [5, 6, 7] and two inoculum sizes [103 and 105 cfu ml-1] on the growth of Listeria monocytogenes in brain heart infusion [BHI] broth. To evaluate effects of explanatory variable on time to detection [TTD] of bacterial growth, parametric survival models based on the log normal distribution were used. All explanatory variables had significant association with TTD [P<0.05]. The final model accurately predicted the growth initiation and inhibition of L. monocytogenes. Key words Listeria monocytogenes, Black Zira essential oil, Time to detection, Modeling