Predictive Modeling of the Effect of e-Polylysine Hydrochloride on Growth and Thermal Inactivation of Listeria monocytogenes in Fish Balls

• Autores: Zhen Jia, Changcheng Li, Ting Fang, Jinquan Chen
• Localización: Journal of food science, ISSN 0022-1147, Vol. 84, Nº 1, 2019, págs. 127-132
• Idioma: inglés
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• Resumen

  • This study aimed to evaluate the effect of e-polylysine hydrochloride (e-PLH) on the growth and thermal inactivation kinetics of Listeria monocytogenes in fish balls. Samples, supplemented with e-PLH (0, 150, or 300 ppm, w/w), were inoculated with a three-strain cocktail of L. monocytogenes and incubated at constant temperatures of 3.4, 8, 12, or 16 °C for growth studies, or heated at 60, 62.5, 65, or 67.5 °C for thermal inactivation tests. The growth curves were fitted to the Huang primary model, and the Huang and Ratkowsky square-root models (SRM) were used as the secondary models to evaluate the effect of temperature on bacterial growth. The survival during heating was analyzed with a log-linear model. The results showed that, while the lag time of L. monocytogenes was affected by both e-PLH concentration and temperature, the specific growth rate was unaffected by e-PLH. Under the same temperature, a 10-time in increase of the lag time would be expected for every 565 ppm in the increase of e-PLH concentration. Using the Ratkowsky SRM, the estimated nominal minimum growth temperature was ?2.04 °C, while the minimum growth temperature was 0.29 °C when estimated with the Huang SRM. Validation at 10 °C showed that the Huang primary model, in combination with either the Huang or Ratkowsky SRM, could accurately predict the growth of L. monocytogenes. On the other hand, the thermal resistance of the pathogen was significantly reduced by increase in temperature or e-PLH. The thermal z value of L. monocytogenes was 5.78 °C, and the e-PLH z value was 1642 ppm. The results of this study showed that the combined application of e-PLH and temperature can be used to control L. monocytogenes in fish balls and to improve food safety and reduce risks to public health.