Quality optimization of conduction heating foods sterilized in different packages

Heat transfer during the sterilization of conduction heating foods packaged in cylindrical, retort pouch and rectangular containers, was modelled using a finite difference numerical method. Finite surface heat transfer coefficients were considered. Optimal temperatures, defined as the processing conditions that maximize surface or volume average quality retention with the constraint of a target sterility value at the coldest point, were calculated for several types of container. Optimal conditions for several case studies were compared with temperatures estimated by generalized formulae available in literature for the prediction of optimal temperatures as a function of all relevant variables. For all case studies, optimal temperatures predicted in both ways were very similar, with deviations often below ± 1°C. For most packages, the simple-to-use generalized equations, developed for one-dimensional geometries, can therefore be used instead of lengthy numerical calculations involving two- and three-dimensional geometries.