29D-9 |
Mathematical model coupled with a search technique to optimize retort pouch thermal processing |
R. J. SIMPSON, Procesos Quimicos, Biotecnologicos y Ambientales, Univ. Tecnica Federico Santa Maria, Avenida España 1680, Valparaíso, 5632, Chile, S. F. Almonacid, Procesos Químicos, Biotecnológicos, y Ambientales, Universidad Técnica Federico Santa María, Avenida España 1680, Valparaíso, Chile, and M. Mitchell, Departamento de Procesos Químicos, Biotecnológicos, y Ambientales, Universidad Técnica Federico Santa María, Valparaíso, 5632, Chile. Flexible retortable pouches are a unique alternative packaging method for sterile shelf-stable products. Recently, important US companies have commercially succeeded with several products. The aim of this research was to develop a mathematical model coupled with an optimization technique for thermal processing of conduction heated foods in retortable pouches in order: a) to search for variable retort temperature profiles to minimize process time, and b) to search for variable retort temperature profiles to minimize quality gradient (thiamine) within the product. A transient isotropic heat transfer model for different product shapes was developed. The model was structured using a finite difference technique (explicit procedure) and specifically designed for a frustum of a cone and slab shapes. The model was validated utilizing Jack Mackerel (Trachurus Murphyi) packed in retortable pouches and processed in a horizontal autoclave with forced circulation with an air/steam mixture. The complex method was utilized as a search technique to find the best variable retort temperature profile. The experimental results confirmed the proposed mathematical model and its numerical solution. The simulation results were in good agreement with the observed temperatures. The prediction errors obtained in the validation study were under 5% and were not statistically significantly different (P<0.05) between the experimental and predicted values were found. Simulations showed that significant reduction in process time (40-50%) could be attained utilizing variable retort temperature profiles while maintaining product quality. The pronounced quality gradient found in thermally processed canned foods was significantly reduced. Retort pouch is already a commercial success and with the contribution of mathematical models and optimization techniques, it is possible to find better operation conditions and better products in terms of quality.
Session 29D, Food Engineering: Thermal processes
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