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

Several nonlinear models (Gompertz, Logistic-1, Logistic-2, Richards, Stann ard and Schnute models) were compared to describe Yersinia enterocolitica a nd 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 o f both Y. enterocolitica and aerobic bacteria. The biological parameters we re calculated from the modified Gompertz model. The effect of starter cultu re (Streptococcus cremoris), salt (150 or 200 g/l) and initial inoculum lev el of Y. enterocolitica on the phase of disappearance (lambda) and the rate of reduction (mu) Of Y. enterocolitica and aerobic bacteria were determine d. Addition of starter culture had a significant (P < 0.05) inhibitory effe ct on both Y. enterocolitica and aerobic bacteria in Turkish Feta cheese. H owever, salt and inoculation rate of Y. enterocolitica had no significant ( P > 0.10) effect on both lambda, and mu of microorganisms. (C) 2000 Elsevie r Science Ltd. All rights reserved.