Starch-polyester bilayer films with phenolic acids for pork meat preservation

Starch (S) films containing gellan gum (90:10) and polyester (P) blend films (PLA:PHBV, 75:25) with and without ferulic, p-coumaric or protocatechuic acid at 2% (w/w) were obtained by melt-blending and compression moulding for the purposes of obtaining SP bilayers by thermo-compressing both monolayers together. These were characterised as to their mechanical and barrier properties and as to their performance as packaging materials for pork meat slices. The incorporation of phenolic acids promoted the water vapour and oxygen barrier capacity of bilayers while reducing their stiffness and resistance to break, mainly in the case of protocatechuic acid. Phenolic acids significantly improved the antioxidant capacity of the bilayer films, reducing the lipid oxidation of packaged meat during storage. Phenolic acid loaded bilayers also reduced the microbial counts of meat, mainly for lactic acid bacteria. These effects positively affected the development of the sample pH and colour parameters throughout storage. Active starch-polyester bilayer films exhibited great potential as a means of extending the shelf-life and improving the quality preservation of pork meat.