Purpose: The objective of this study was to develop a predictive model for the inactivation of Salmonella spp. in ground beef jerky, as a function of T, pH, potassium sorbate (PS), and final aw.
Methods: Following a central composite design, ground beef was combined with PS (0 to 0.3%, w/w), adjusted from pH 5 - 7 and inoculated with a cocktail of 6 serotypes of Salmonella spp. Then, each combination was processed in an oven between 65 to 85°C until a final aw ranging from 0.65 to 0.85 was achieved. Surviving Salmonella cells were enumerated on tryptic soy agar overlaid with xylose lysine deoxycholate agar (pre-tempered to 47°C) after petri dishes were incubated for 48 h at 30°C. Bacterial inactivation was quantified in terms of logarithmic reductions of Salmonella counts (log CFU/g) and inactivation rate (log (CFU/g)/h).
Results: The results indicated that pH, PS and T interacted to inactivate Salmonella in beef jerky. Decreasing pH of the meat significantly increased (P < 0.05) the efficacy of PS and T in reducing levels of Salmonella spp. Processing jerky at pH 5.5 with 0.25% PS, heated at 82°C achieved final aw of 0.7 which resulted in a maximum Salmonella logarithmic reduction of 5.0 CFU/g and an inactivation rate of 1.3 log (CFU/g)/h.
Significance: The predictive model developed will be useful in designing effective drying processes for beef jerky under low humidity conditions and thereby, ensuring adequate degree of protection against risks associated with Salmonella.