Sulfite incorporated thermoplastic cassava starch blended PBAT blown films as antimicrobial and antibrowning packaging

Abstract

Microbial growth and browning cause quality loss in intermediate moisture foods. This research developed and characterized novel active films to prevent microbial growth and brown discoloration in dried meat and fruits. Biodegradable films based on thermoplastic starch (TPS) and poly(butylene adipate-co-terephthalate) (PBAT) blends incorporating sodium metabisulfite (SM) (up to 7% w/w) were developed using blown film extrusion. SM interacted with the TPS phase, involving O-H stretching vibration and hydrogen bonding which modified the thermal degradation behavior of the TPS phase and improved the smoothness of the film microstructures. Excessive SM formed crystal particles at ≥ 3% that were detected by X-ray diffraction. Addition of SM decreased the mechanical properties but film clarity and hydrophobicity improved, with enhanced water vapor barrier properties. The SM blend film showed significant antibacterial activity against E. coli, B. cereus, and S. aureus. TPS/PBAT/SM active films effectively prevented mold growth and darkening in packaged salami for at least 16 days, while the non-SM blend film was only effective for 6 days at room conditions. Active films with SM loading, particularly at > 3% prevented browning reaction and darkening in dried bananas and longans at both ambient (60% RH) and 85% RH stored at room temperature. SM addition improved packaging characteristics and functional efficiency, resulting in higher dried fruit and meat product quality. TPS/PBAT/SM composite films showed promise as sustainable active packaging and an alternative technique to sulfite treatment for dried fruit and meat.