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

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 (lambda) and the rate of reduction (mu) 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 lambda, and mu of microorganisms. (C) 2000 Elsevier Science Ltd. All rights reserved.