• thermal processing;
  • canning;
  • internal temperatures;
  • modeling;
  • inverse superposition


A procedure was developed for theoretical calculation of internal product temperatures during in-container sterilization of foods. Experimental product temperatures were determined through traditional heat penetration tests (processing in a retort with come-up time of increasing temperature and holding time at constant temperature). These were used to produce, through a proposed inverse superposition solution, a “standardized,” normalized, dimensionless product temperature curve corresponding to the response of product temperature to a constant retort temperature profile. This “standardized” curve was then used, through Duhamel's superposition theorem, to calculate product temperatures for time-varying retort temperature profiles. Limitations associated with the application of Duhamel's theorem were also transferred to the proposed methodology. Theoretical, for perfect mixing, and experimental, for conduction heating, data were used in example calculations.