Physicochemical and Mechanical Characterization of HDPE and LDPE Films Used in the Postharvest Packaging of Banana (Musa paradisiaca)

The postharvest preservation of banana (<i>Musa paradisiaca</i>) is essential to maintain fruit quality and minimize losses during storage and export. Packaging films play a critical role in protecting fruit from mechanical damage and environmental stress. This study compared the physicochemical and mechanical properties of two commercial polyethylene films-high-density polyethylene (HDPE) and low-density polyethylene (LDPE)-under controlled postharvest conditions (13 °C, 95% RH). Films were characterized using Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), and Flame Atomic Absorption Spectroscopy (AAS), while tensile testing evaluated mechanical performance. HDPE exhibited greater melting stability (+8%), relative crystallinity (+12%), and tensile strength (+15%) compared with LDPE, which presented higher flexibility. HDPE contained trace zinc (0.82-0.94 mg/100 g), whereas LDPE was zinc-free. Both polymers retained their polyethylene fingerprint without oxidative degradation, confirming structural integrity under cold storage. The TGA data verified the absence of thermally unstable additives rather than operational degradation, supporting material homogeneity. Overall, HDPE demonstrated superior stability and durability for banana packaging applications, highlighting the relevance of integrated polymer diagnostics for safe and sustainable postharvest systems.