Protective performance of a composite packaging for kiwifruit under simulated express transport and variable environmental conditions

This study aims to assess the efficacy of the CT-NU packaging system, which combines corrugated cardboard boxes and expandable polyethylene (EPE) foam packaging nets, in preventing mechanical damage to kiwifruit during transport within express delivery. The protective performance of the composite packaging under top and side-load compression was thoroughly analyzed, considering varying temperature conditions (1, 21, and 40℃) and relative humidity (RH) levels (40%, 60%, and 80%). Experiments were conducted to determine the mechanical properties of both the packaging materials and kiwifruit under different environmental conditions, leading to the development and validation of a three-dimensional finite element model (FEM). The results indicated at a compression depth of 15 mm, the peak local stress in the kiwifruit exceeded 0.35 MPa during the top-load compression simulation and surpassed 0.4 MPa during the side-load compression simulation, both of which under the simulated compression conditions exceeded the fruit’s damage threshold. The compression depth and the modulus of elasticity of the corrugated board are critical factors influencing the maximum compressive force and stress in corrugated boxes. The developed regression models for top-load compression (R 2 > 0.85) and side-load compression (R 2 > 0.79) demonstrate a high level of accuracy in predicting the system’s mechanical response. Damage to kiwifruit arises from the combined effects of multiple factors, including the maximum stress, maximum compressive force, compression depth, and the elastic modulus of both the corrugated cardboard box and the EPE foam packing nets. This study lays the foundation for optimizing packaging design and minimizing mechanical damage during transportation, integrating experimental validation with finite element simulation.