Preparation of Antimicrobial Membranes: Coextrusion of Poly(lactic acid) and Nisaplin in the Presence of Plasticizers

• Published in: Journal of agricultural and food chemistry Vol. 57; no. 18; pp. 8392 - 8398
• Main Authors: Liu, Linshu, Jin, Tony Z, Coffin, David R, Hicks, Kevin B
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 23-09-2009
• Subjects: animal pathogenic bacteria; Anti-Infective Agents; antimicrobial properties; Biological and medical sciences; Chemical Aspects of Food Safety; extrusion; Food industries; Food microbiology; food packaging; Food Packaging - instrumentation; Food Packaging - methods; food technology; Fundamental and applied biological sciences. Psychology; General aspects; Handling, storage, packaging, transport; Hot Temperature; lactic acid; Lactic Acid - chemistry; Listeria monocytogenes; Listeria monocytogenes - drug effects; Listeria monocytogenes - growth & development; Mechanics; Microscopy, Electron, Scanning; nisaplin; nisin; Nisin - chemistry; plasticizers; Plasticizers - chemistry; Polyesters; Polymers - chemistry; polypeptides; Rheology; Thermodynamics; membranes; antimicrobial; packaging; Poly(lactic acid) (PLA); extrusion; nisin (Nisaplin); Nisin; Microorganism interrelationships; Bacteriocin; Antimicrobial agent; Plasticizer; Preparation; Packaging; Extrusion; Membrane; Conditioning; Lactic acid
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf902213w

Nisin is a naturally occurring antimicrobial polypeptide and is popularly used in the food and food-packaging industries. Nisin is deactivated at temperatures higher than 120 °C and, therefore, cannot be directly incorporated into poly(l-lactic acid) (PLA), a biomass-derived biodegradable polymer, by coextrusion because PLA melts at temperatures around 160 °C or above. However, PLA can remain in a melt state at temperatures below the T m in the presence of lactic acid or other plasticizers. In the present study, PLA was coextruded with lactic acid, or lactide, or glycerol triacetate at 160 °C. After the PLA was melted, the temperature of the barrels was reduced to 120 °C, and then Nisaplin, the commercial formulation of nisin, was added and the extrusion was continued. The resultant extrudates possess the capability to suppress the growth of the pathogenic bacterial Listeria monocytogenes, demonstrating a significant antimicrobial activity. The present study provides a simple method to produce PLA-based antimicrobial membranes. The method can also be used for the coextrusion of other heat-sensitive substances and thermoplastics with high melting temperature.