Development and Characterization of Bilayer Films Based on Pea Starch/polylactic Acid and Use in the Cherry Tomatoes Packaging

Renewable and biodegradable packaging materials are desired for numerous applications. Pea starch (PS) and polylactic acid (PLA) are promising alternatives to petrochemical-based polymers except that their phase separation causes poor mechanical properties. To surmount this problem, PS/PLA films with a double-layer structure were designed. The bilayer films displayed better toughness, thermal stability and barrier capacity over those of PLA films. The incorporation of PLA on a PS layer increased water resistance and tensile strength over those of a monolayer PS film. Weak interfacial adhesion between the PS and PLA layers was revealed by Fourier transform infrared spectroscopy and scanning electron microscopy. The bilayer films reduced weight loss ratio of cherry tomatoes and extended the retention of organic acids and vitamin C. A bilayer architecture represents a promising route to develop packaging materials that display the advantageous properties of each material layer.