Abstract:

A nano-structural ZnO/LDPE antimicrobial food packaging material was developed through the following steps: in the first step, activated nano-structural ZnO was dispersed into low density polyethylene (LDPE), a matrix material, by dissolving-melting-blending technique; in the second step, the resulted particulate polymer composite was blown into film by sequential treatment with a single screw extruder followed by a plastic film blowing machine; and finally the target product was obtained. Six species of common food-contaminating bacteria including Escherichia coliform, Bacillus subtilis, Staphylococcus aureus, Salmonella aertrycke, Listeria monocytogenes and Pseudomonas aeruginosa were used for testing the antimicrobial capability of the material under different illumination conditions: energy-saving lamp light (5 W, (37 ± 1) ℃), darkness (37 ± 1) ℃ and sunlight (20 ± 1) ℃. Results showed that the material had a significant antimicrobial activity against four of the 6 species of food-contaminating bacteria, which was stronger under sunlight than under other illumination conditions. Of all the tested bacterial species, the strongest inhibitory effect against Bacillus subtilis was observed, with a maximum inhibitory rate as high as 99.99% under sunlight illumination and a minimum value of 95.01% in darkness.

Key words: nano-structural ZnO, antimicrobial activitylfood packaginglLDPE