Antibacterial and antioxidant triple-side filler composed of fumed silica, iron, and tea polyphenols for active food packaging

The development of novel and alternative fillers to improve food packaging properties is an ongoing trend. In this work, a triple-side filler composed of fumed silica (FS), iron (Fe), and tea polyphenols (TP) was synthesized and properly characterized, to be used for release-based active coating packaging. Polylactic acid (PLA) was used to create PLA/Fe-TP@FS films as biodegradable coating layers. The physicochemical and thermal effects of the filler in the PLA matrix, and its effectiveness as an antibacterial and antioxidant filler were studied. The films displayed ∼4-log reduction against the Gram-positive Staphylococcus aureus and the Gram-negative Pseudomonas aeruginosa and Salmonella enterica bacteria. Furthermore, the antioxidant activity was positively confirmed with increasing loading content reaching a maximum of ∼67%. Migration of Fe(II) and of tea polyphenols was associated to the observed active properties, being the specific migration limit for iron below that applied in the current legislation on food contact materials. This triple-side filler is a novel and alternative option to provide active properties to a polymer matrix for food packaging.