3D modeling and optimization of batch sterilization for irregularly shaped spicy chicken retort pouches

Sterilization is essential for achieving the safety, shelf life, and quality of spicy chicken retort pouches (SCRPs). However, the irregular and geometrically complex shapes of chicken pieces lead to variable cold spot locations, complicating optimization of batch sterilization. To address this challenge, a 3D simulation-based approach was adopted to develop a transient heat transfer model for irregularly shaped SCRPs, and a novel geometry-control method was introduced to standardize product shape, enabling the construction of a corresponding model for regularly shaped SCRPs. Both models were validated, showing high accuracy with coefficients of determination (R² > 0.981) and low mean relative errors (σ < 2.997 %) between experimental and simulated temperature profiles. The regularly shaped SCRP model was then applied to process optimization, identifying an optimal thickness of 20 mm and a variable retort temperature (VRT) profile of 95℃ for 25 min followed by 121℃ for 15 min. This schedule achieved an F value of 6.58, reduced the surface cook value (C_s) and the volume-average cook value (C_avg) by 42.95 % and 42.05 %, respectively, and shortened sterilization time by 26.07 %. Furthermore, the optimized process improved product quality by lowering shear force, moisture loss, and oil viscosity, while enhancing color retention and sensory acceptance. These findings confirm the reliability of the developed models and their potential to guide industrial batch sterilization design.