Experiments with edible films made from pullulan and incorporating essential oils from oregano and rosemary and zinc oxide and silver nanoparticles showed that the films were able to inhibit the growth of four pathogens – Staphylococcus aureus, Salmonella Typhimurium, Listeria monocytogenes and E. coli O157:H7 – to varying degrees. Rosemary oil at 2% and 110nm zinc oxide nanoparticles were found to be particularly effective.
The researchers then prepared films containing a combination of the most inhibitory antimicrobials and used them to carry out challenge tests against pathogens inoculated onto meat and poultry products stored for up to three weeks at chill temperature. The films were found to inhibit the four pathogens as compared to control films.
The study’s authors conclude that the films could be the basis of a useful packaging tool to improve the safety of meat products. However the usefulness of pullulan films is compromised by their lack of oxygen barrier properties. Professor of food science Catherine Cutter is keen to investigate co-extrusion of antimicrobial films with polyethylene vacuum packaging materials. “The chemistry of binding the two together is a challenge, but we need to find a way to do it because marrying the two materials together in packaging would make foods – especially meat and poultry – safer to eat.”
The study is published in the Journal of Food Science and an abstract can be found here.