The Effect of Hot Fill and Hold Processing on the Performance of Multilayer Packaging Film

Heat transfer in thermal processing is crucial to ensure all parts of a product are sufficiently treated to achieve commercial sterility without unacceptable loss of quality. Optimizing pasteurization methods is recommended to preserve quality attributes such as color, texture, and flavor while maintaining food safety integrity. This research evaluated the temperature variability in pouches during a hot fill and hold process and the effect of those identified differences on color quality of a tomato based food simulant. The performance of multilayer films for pasteurized products in accelerated storage conditions were also studied.;The research project was separated into two phases. The objective of the first phase was to understand the profiles of heating and cooling in pouches processed in a simulated hot fill and hold process. The corners of the pouch were found to be the fastest cooling spot within the pouch (p<0.05). The center of the pouch was found to have the highest mean temperature during the hold step of the process and had the slowest cooling rate in the pouch (p<0.05). The trends of heating and cooling were also evaluated using a low viscosity food simulant. This study compared the time and temperature profiles for a static hot fill process versus a process that incorporated rotating the pouch 180° every 10 seconds. For the static hot fill and hold process, mean temperatures of the center and corners of a pouch showed non-uniform heat transfer during the holding period and cooling process. More uniform heating and cooling within pouches was achieved by implementing 180° rotation during processing.;In the second phase, the time and temperature combinations representative of the hold step in a hot fill process were determined from the results obtained from the first phase of the research project. Processing treatments were selected for the corners, the fastest cooling location and the center, the slowest cooling location for both static and process conditions. Three different types of multilayer films were evaluated using a tomato based food simulant. Color was measured as a quality parameter to predict the effects of time-temperature combinations and the performance of the barrier properties in different films. Results showed that barrier properties had a significant effect (p<0.05) on color retention. In the case of low barrier films, the process with the highest temperature and longest retention time had the greatest loss of color (p<0.05).;This research evaluated the heating trends within a pouch during hot filling and lack of uniformity during processing. Food manufacturers producing acidic or acidified products could use this information to improve quality and safety in hot filled products. These findings also highlight the importance of selecting suitable packaging films for pasteurization processes.