PLLA-ZIF-8 metal organic framework composites for potential use in food applications: Production, characterization and migration studies

Abstract

PLLA-15% ZIF-8 MOF composites were fabricated by melt compounding followed by injection molding for active packaging applications. The injection-molded discs were then converted into films by compression molding. The samples were morphological and thermally characterized. Migration studies using Atomic Absorption Spectrometry were conducted on the successful produced PLLA and PLLA-15% MOF films incubated at 40°C for 240 h with two simulants, Simulant A: aqueous and acidic foods with 10% ethanol, and Simulant B: low and high alcoholic foods with 50% ethanol as per the U.S. Food and Drug Administration guidelines for packaging application testing. After 240 h Zn2+ ion concentrations in Simulants A and B were 354 and 166 mg L−1, respectively. Higher Zn2+ ion migration observed in Simulant A can be ascribed to the decomposition of the ZIF-8 MOF under acidic environment. Thermo-gravimetric studies indicated that the thermal stability of PLLA dropped from 338°C to 207°C with the addition of ZIF-8 MOF, which may be credited to the catalytic depolymerization effect of the MOF. Due to high migration, the studied composite films are not suitable for direct food contact applications in their present form. Future work must be directed to explore how to engineer these composites for food contact applications. © 2021 John Wiley & Sons, Ltd.