<![CDATA[Traditional salted egg production commonly relies on static immersion methods, which often result in long processing times, non-uniform salt diffusion, and inconsistent product quality due to the absence of controlled pressure regulation. Moreover, previous pressure-assisted approaches frequently emphasize hardware feasibility without providing a comprehensive quantitative evaluation of control stability and repeatability. To address these limitations, this study proposes a PLC-based air pressure control system employing a hysteresis-based ON–OFF strategy to ensure safe, stable, and repeatable curing conditions. The system integrates an Omron CP1E Programmable Logic Controller (PLC), Human Machine Interface (HMI), high-resolution pressure sensing, and a pneumatic solenoid valve to regulate the curing environment within a 1.5–2.0 bar hysteresis band around a 2.0 bar reference pressure. The novelty of this work lies in integrating industrial PLC automation with a multi-metric control performance evaluation framework (IAE, ISE, ITAE, MAE, RMSE, and Maximum Error) specifically applied to salted egg processing. Multi-cycle experimental validation demonstrates consistent rise times of 30–35 seconds, zero overshoot, and low variability across all performance indices, confirming stable closed-loop behavior and bounded pressure deviation. Furthermore, the controlled-pressure environment contributes to more uniform salt penetration and consistent physicochemical characteristics within a 14-day curing cycle, with optimal equilibrium observed around day eleven. Overall, the proposed system provides a practical and scalable automation solution that enhances process stability, repeatability, and product quality compared to conventional curing methods.]]>
