Characterization of zinc oxide nanoparticles and their applications in food safety
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In this study, ZnO NPs suspension was studied for their antibacterial activities against Escherichia coli O157:H7. Beef cuts inoculated with E. coli O157:H7 were wrapped with 5% (wt %) yam starch films incorporated with ZnO NPs suspension of 0, 6 and 12 mM and refrigerated at 4oC. An average of 0.5‐log reduction of the bacteria growth of the cocktail mixture of three E. coli O157:H7 strains was observed with yam starch films containing 6 or 12 mM ZnO NPs in three replications after 8 days. Various concentrations of ZnO NPs powder from 0.05 to 1% w/w were added to corn starch. The presence and characterization of ZnO NPs in corn starch was investigated by scanning electron microscopy (SEM), and transmission electron microscopy (TEM), and energydispersive X‐ray spectroscopy (EDS). Quantification of ZnO NPs was determined by inductively coupled plasma optical emission spectrometry (ICP‐OES). To the best of our knowledge, this is the first systematic methodologies presented for detection, characterization, and quantification of ENPs in a food sample by a combination of methods. It could potentially be applied to other common NPs such as TiO2 NPs and MgO NPs in other food products.