Poly (lactic acid) and whey protein/pullulan composite bilayer film containing phage A511 as an anti-Listerial packaging for chicken breast at refrigerated temperatures

Listeria phage A511 were stabilized in whey protein concentrate/pullulan (WP) composite and poly (lactic acid) (PLA) bilayer films with different thickness ratios (100%, 70/30%, 50/50%, 30/70%). As the thickness of WP layer decreased, so did the phage recovery from the film. The highest phage recovery belonged to 30PLA/70WP, which was statistically similar to 100WP. Investigation of storage of phage-containing 100WP and 30PLA/70WP films for 60 days at 25 °C and 53% relative humidity revealed that films could maintain phage titers for up to 20 days. Phage-containing bilayer film was selected for studying chicken breast due to its better barrier, mechanical, and visual properties than 100WP and stability of these properties during storage. The maximum release of phages from 30PLA/70WP to the chicken breast fillet at 4 °C and 10 °C occurred after 24 h. The phage-containing films had inhibition effects on Listeria in chicken fillets similar to free phage treatment.