Effects of Packaging Geometry on Heat Penetration Time in Retortable Semi-Rigid Plastic Trays

Abstract

Semi-rigid, retortable trays were filled with a food simulate and thermally processed in a water immersion automated batch retort system at rotational speeds of 6 RPM and 11 RPM. Triangle, rectangle, oval, and round trays were evaluated, each having approximately the same overflow capacity. During processing, trays were fixed in place with racks containing one shape per rack. Various rack location combinations were tested to provide processing data for each shape in each rack location. Heat penetration data was gathered using thermocouples located in the geometric center of each tray shape and this data was modeled to determine the slowest heating container. No differences were observed in rack location among tray geometries at either RPM level (P>0.05). The data generated during heat penetration runs was also used to model different retort temperatures and lethality values. A retort temperature of 215°F and a lethality value of 10 showed the highest average sterilization time (P 0.05) than any other shape tray. At a rotational speed of 11 RPM, differences in average process time to reach lethality between tray geometries were insignificant (P>0.05).