Heat inactivation of Listeria innocua in broth and food products under non-isothermal conditions

Abstract

a b s t r a c tThe objective of this work was to study the effect of three linear temperature profiles (heating rates of 1.5, 1.8 and 2.6 C/min, from 20 to 65 C) on Listeria innocua inactivation in liquid medium. The inactivation was also analyzed in artificially contaminated parsley (heating rate of 1.8 C/min) and throughout a frying process, using a pre-cooked frozen food as case study. Inactivation showed a sigmoidal behaviour and all data was fitted with a Gompertz-inspired model. Results demonstrated that, in liquid media, Listeria inactivation is influenced by the temperature profile used. As heating rate increases, the shoulder decreases and the tail effect disappears. If Listeria was in parsley, its heat resistance increased (for identical experimental conditions in broth). Besides model adequacy was proven in all studied situations, the heating rate affected parameters' precision.

Predicting Bacillus coagulans Spores Inactivation in Tomato Pulp under Nonisothermal Heat Treatments

“…The square root (secondary) model (Eq. ) proposed by Ratkowsky and others () can be used to describe the dependence of a primary model to changes in 1 or more of the environmental conditions as a linear relation between the square root of the parameter of interest and the temperature, and this model has subsequently been used as a secondary model by many authors (Van Impe and others ; Miller and others ; Psomas and others ). where ε [1/min] is a parameter of the isothermal primary model ( k max or 1/ L ), T is the temperature [°C], T min is the theoretical minimal temperature of inactivation [°C], and b is an empirical parameter ([1/°C min 0.5 ]).…”

Dynamic Approach to Assessing Food Quality and Safety Characteristics: The Case of Processed Foods

“…Bacteria submitted to a non-isothermal heating process (i.e. in which temperature rises throughout the process time till a target value) are more heat resistant than bacteria treated at constant target temperatures [2].…”