Title: Biodegradable polylactic acid polymer with nisin for use in antimicrobial food packaging Authors
Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 8, 2008
Publication Date: April 1, 2008
Citation: Jin, Z.T., Zhang, H.Q. 2008. Biodegradable polylactic acid polymer with nisin for use in antimicrobial food packaging. Journal of Food Science. 73(3):M127-M134. Interpretive Summary: Demand for safe, minimally processed, ‘fresh’ food products presents major challenges to the food-packaging industry to develop packaging concepts for maintaining the safety and quality of packaged foods. Biodegradable polylactic acid (PLA) derived from renewable resources, e.g. corn, wood residues or other biomass, are of current interest not only because of the need to ultimately replace many petroleum-based polymers but also because of their many potentially useful physical and mechanical characteristics. The special characteristics of PLA, such as generally recognized as safe (GRAS) status, biodegradability and being a bio-resource put PLA in a unique position for food applications. An antimicrobial packaging system based on PLA would be superior to other antimicrobial system due to its low cost, effective antimicrobial activity, few regulatory concerns, and environmental friendliness. In this study, PLA films were incorporated with nisin (natural bacteriocin) to provide slow release of the encapsulated antimicrobial for control of foodborne pathogens. PLA films with nisin significantly inhibit growth of three foodborne pathogens: Listeria monocytogenes, Escherichia coli O157:H7 and Salmonella Enteritidis in culture media or liquid foods (orange juice and liquid egg). The combination of a biopolymer and natural bacteriocin has potential for use in antimicrobial food packaging.
Technical Abstract: Biodegradable polylactic acid (PLA) polymer was evaluated for its application as a material for antimicrobial food packaging. PLA films were incorporated with nisin to provide slow release of the encapsulated antimicrobial for control of foodborne pathogens. Antimicrobial activity of PLA/nisin films (150 IU nisin ml-1) against Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella Enteritidis were evaluated in culture media and liquid foods (orange juice and liquid egg). Scanned electron micrograph and confocal laser microscopy revealed that nisin particles were evenly distributed in PLA polymer matrix on the surface and inside of the PLA/nisin films that provide the release of nisin into media. PLA/nisin significantly inhibits growth of these three pathogens in culture media or liquid foods; among them, L.monocytogenes was more sensitive to PLA/nisin treatments. Results of this research demonstrate the retention of nisin activity when incorporated into the PLA polymer and its antimicrobial effectiveness against foodborne pathogens. The combination of a biopolymer and natural bacteriocin has potential for use in antimicrobial food packaging. The PLA/nisin polymer can be applied in the form of a film, sheet, or bottle for solid and liquid foods.