Prior freezing impact on the growth kinetics of Listeria monocytogenes in hot dog sausages

Abstract

Listeria monocytogenes adapts to low-temperature environments and grows rapidly at room temperature. This bacterium is associated with several foodborne outbreaks due to cold chain breaks, particularly ready-to-eat foods such as sausages. The present study evaluated how frozen storage (-10 °C) for 30 and 90 days of hot dog sausages influences the bacterial growth kinetics between 7 and 30 °C under isothermal conditions. L. monocytogenes growth measurements were based on the ISO 11290-2 standard, and the mathematical model of Baranyi and Roberts was used to describe the bacterial growth. The sausages were incubated with around 2 log CFU/cm2, remaining constant for up to 90 days. However, prior freezing periods influenced bacterial growth behavior, mainly at chilled conditions (7 and 10 °C), increasing the maximum specific growth rate by 60%, lag phase time by 72%, and physiological state of the cells by 166%. The maximum population was not influenced by prior freezing. The proposed model fits the isothermal conditions studied. L. monocytogenes, after food thawing, grows at the same or higher rate than before freezing, which could represent a risk if the manufacturer's recommendations are not followed.