Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: February 8, 2009
Publication Date: N/A
Technical Abstract: Zinc oxide quantum dots (ZnO QDs) are nanoparticles of purified powdered ZnO. The ZnO QDs were directly added into liquid foods or coated on the surface of glass jars using polylactic acid (PLA) as a carrier. The antimicrobial activities of ZnO QDs against Listeria monocytogenes, Salmonella Enteritidis and Escherichia coli O157:H7 in liquid egg white (LWE), orange juice (OJ) and apple cider (AC) were evaluated at 22, 10 or 4 degree C by means of direct addition or slow release from PLA coating. Nisin alone or in combination with ZnO was also used in coating/release tests. The ZnO QDs showed significant antimicrobial activities against all three pathogens and the inhibitory efficacies of ZnO QDs were concentration dependent. The treatments of PLA+ZnO, PLA+nisin and PLA+ZnO+nisin coatings significantly reduced L. monocytogenes, S. Enteritidis and E. coli O157:H7 in LEW, AC and OJ. Among them, PLA+ZnO+nisin coating was the most effective in the reduction of all three pathogens at tested temperatures. This study demonstrates that ZnO QDs in combination with nisin has potential for use in antimicrobial food packaging to enhance microbiological safety of liquid foods.