KINETIC MODELING OF ESCHERICHIA COLI O157:H7 GROWTH IN RAINBOW TROUT FILLETS AS AFFECTED BY OREGANO AND THYME ESSENTIAL OILS AND DIFFERENT PACKING TREATMENTS

Abstract

The effect of different essential oils (oregano and thyme) and packing (aerobic packing, modified atmosphere packing, and vacuum packing) treatments on the growth of Escherichia coli O157:H7 was studied using nonlinear regression of modified-Gompertz and logistic equations to generate the best fit. Parameters of nonlinear modified-Gompertz and logistic models of E. coli O157:H7 in trout samples treated with the different essential oils and packing treatments were matched satisfactorily. Both the modified-Gompertz and logistic models showed a good fit to all the growth curves as evaluated by using mean percentage error, mean bias error, root mean square error, modeling efficiency, and (2) as well as the correlation coefficients (R) between the experimental and predicted values. Generally, higher values of R-2 and modeling efficiency values were obtained with the modified Gompertz model. However, both models resulted in similar absolute values of mean bias error, root mean square error, mean percentage error, and (2). The growth of E. coli O157:H7 was remarkably delayed by the essential oils and packing treatments. These treatments can be used in the protection of fish and fishery products from microbial risks and the fish can also be aromatized with the essential oils. Based on the obtained results in this study, it can be concluded that the modified Gompertz and logistic models can be used effectively to predict the effect of plant essential oils on growth potential of E. coli O157:H7 in fish products to be stored under aerobic, modified atmosphere packing, and vacuum packing conditions.