Calculation of the total lethality of conductive heat in cylindrical cans sterilization using linear and non linear survival kinetic models

Abstract

There is growing evidence suggesting that inactivation of bacterial spores may follow the Weibullian model, of which the log linear relationship between survival ratio and time is just a special case. Where true, the time and not only the temperature dependence of the rate must be taken into account. Also, it is of interest to estimate spores survival not only at the coldest point but also throughout the whole container's volume. Numerical calculation on changing survival ratios was performed by combining the conductive heat transfer model with that of the nonlinear inactivation kinetics. Results are based on published linear and non linear inactivation parameters of Clostridium botulinum spores, typical thermal properties of solid foods and realistic thermal processing conditions. Results could be used to quantify the efficacy of thermal processes of solid products in terms of spores' residual survival ratio at the coldest point and in the container as a whole.