Antimicrobial Coatings for Controlling Listeria monocytogenes

The anti-listerial properties of biodegradable polylactide coatings modified with titanium dioxide have been studied. Free standing films were prepared by casting solutions prepared from titanium dioxide and previously extruded polylactide. It was demonstrated that polylactide alone could support 2.84 ± 0.10 log CFU reduction of Listeria monocytogenes when incubated at 23 °C for 2 h. However, the log reduction for Listeriacould be increased to >4 log CFU with titanium dioxide:polylactide composites illuminated with UV-A. The inactivation kinetics of L. monocytogenes followed a diphasic die-off with an initial 30 min lag period then a progressive decline in bacterial levels over a further 90 min period. The anti-listeria effect of polylactide:titanium dioxide films was dependent on illumination with UV-A but independent on the concentration of TiO2incorporated in the film within the range of 1–5% w/w. The mode of L. monocytogenesinactivation was via direct contact of the pathogen with the polylactide, in addition to the generation of oxygen radicals produced by excitation of the titanium dioxide. The composite film illuminated with UV-A was equally effective against SalmonellaTyphimurium and Shiga toxin producing Escherichia coli. The coating was stable to 5 repeated sanitation cycles consisting of detergent and sodium hypochlorite rinses. The polylactide-titanium dioxide coating shows potential as an antimicrobial coating although further work is required to assess if the protective film can function under commercial conditions. 

 

Contact Us

Bionanotechnology Laboratory
Suresh Neethirajan

School of Engineering
University of Guelph
Guelph, Ontario
Canada N1G 2W1

Office:
Room 3513 - Richards Building
50 Stone Road East

Lab: THRN 2133 BioNano Lab

Phone: (519) 824-4120 Ext 53922
Fax: (519) 836-0227

E-mail: sneethir@uoguelph.ca

 
© 2016 Bionano Lab - University of Guelph. All Rights Reserved.