Thermoplastic starch and green tea blends with LLDPE films for active packaging of meat and oil-based products

Thermoplastic starch (TPS) is an alternative biomaterial that can be used to produce bioplastics to replace petroleum-based food packaging. Active films were developed from acetylated cassava TPS and green tea using the blown extrusion process. Green tea (GT) and TPS from native starch (NS) and acetylated starch (AS) with different degrees of substitution (DS) were extruded with linear low-density polyethylene (LLDPE) at LLDPE/TPS-GT ratios of 70/30 and 60/40 prior to blown-film extrusion. Results indicated that a higher DS of AS enhanced melt flow index which altered processability and subsequently impacted film microstructures and physical and barrier properties. NS showed highest dispersed particles in film matrices with a lower reduction of mechanical and barrier properties. AS showed reduced surface hydrophobicity with increased water vapor permeability and film solubility due to pore formation. Increased DS of AS films showed enhanced radical scavenging activity (DPPH center dot and FRAP) with improved phenolic release. GT release from the starch matrix effectively limited microbial growth, reduced metmyoglobin forming brown pigment, and stabilized the red color of bacon. Lipid oxidation of packaged soybean oil was effectively reduced by up to 38% depending on the TPS ratio which was attributed to hydrophobicity of the film matrices. Developed TPS-GT films showed high efficacy as active eco-friendlier food packaging, with enhanced stability of meat and oil-based food products.