Improvement of Gelatin-Based Coating in Order to Enhance the Oxygen Barrier and Mechanical Properties of Biobased PLA (Polylactic Acid) and Cellulose Films

This study presents a gelatin-based coating designed to improve the barrier and mechanical properties of biobased films such as polylactic acid (PLA) and cellulose. A formulation consisting of 8 wt % gelatin, 2 wt % glycerol, and 0.1 wt % Tween 80 was found to exhibit favorable barrier and mechanical properties based on parametric studies. Coated compostable films were evaluated under controlled conditions (80% RH, 23 °C). Oxygen permeability (OTR) was significantly reduced, from >200 to 16.19 cm³/m²/day for PLA and from 2.20 to 0.64 cm³/m²/day for cellulose, indicating an over 90% improvement. Tensile tests confirmed increased durability and load-carrying capacity, while the coating enhanced surface scratch resistance without compromising optical clarity. Spectral and color analyses showed that the Δ<i>E</i> values ranged from 2.66 to 2.73, remaining below the Δ<i>E</i> < 5 threshold, thereby confirming their suitability for printing applications. These findings demonstrate that gelatin-coated biobased films offer remarkable oxygen barrier properties, enhanced mechanical strength, and consistent optical characteristics, making them viable for sustainable packaging. By improving biodegradable film performance without sacrificing printability, this study contributes to reducing the environmental footprint of flexible packaging and advancing a circular economy.