Modeling the growth of H2S-producing bacteria in tropical brackish water shrimp under fluctuating temperature regimes

Abstract H2S-producing bacteria are known to be an important group of spoilage organisms associated with tropical brackish water shrimp (Penaeus notialis). This study aimed at developing a mathematical model predicting the growth of H2S-producing bacteria in P. notialis as a function of temperature for a better shrimp quality management. Shrimp samples were stored at various temperatures from 0 to 28 °C. At appropriate time intervals, samples were taken out for the enumeration of H2S-producing bacteria. Two primary models (the Baranyi model and the reparameterized Gompertz model) and two secondary models (the Ratkowsky equation and the Arrhenius equation) were used for comparison purpose. The developed model was validated under fluctuating storage temperatures simulating temperature fluctuation in the shrimp supply chain. The results showed that the initial concentration of H2S-producing bacteria was 3.6 ± 0.1 log (CFU/g). The maximum concentration reached at the end of storage was temperature dependent. As expected, storage temperature had a significant effect (P < 0.05) on growth rates of H2S-producing bacteria during shrimp storage. The reparameterized Gompertz model and the Arrhenius equation performed better (lower root mean square error of the residuals) and were selected as primary and secondary models, respectively in this study. The validation of the developed model showed that it can be used to predict satisfactorily the growth of H2S-producing bacteria, thus to predict the shelf-life of tropical brackish water shrimp.