Predictive modeling of Yersinia enterocolitica inactivation in Turkish Feta cheese during storage

Abstract

Several nonlinear models (Gompertz, Logistic-1, Logistic-2, Richards, Stannard and Schnute models) were compared to describe Yersinia enterocolitica and aerobic bacteria inactivation in Turkish Feta cheese during the storage period. They were compared statistically by using the F-test. The Gompertz model was decided as a sufficient model, which describes the inactivation of both Y. enterocolitica and aerobic bacteria. The biological parameters were calculated from the modified Gompertz model. The effect of starter culture ( Streptococcus cremoris), salt (150 or 200 g/l) and initial inoculum level of Y. enterocolitica on the phase of disappearance ( λ) and the rate of reduction ( μ) of Y. enterocolitica and aerobic bacteria were determined. Addition of starter culture had a significant ( P<0.05) inhibitory effect on both Y. enterocolitica and aerobic bacteria in Turkish Feta cheese. However, salt and inoculation rate of Y. enterocolitica had no significant ( P>0.10) effect on both λ and μ of microorganisms.