Abstract:
Nanomaterials have been used recently in food packaging as antibacterial coatings because
of their desirable antibacterial and antifungal properties. The use of antimicrobial packaging
is to deter the growth of microorganisms responsible for spoilage or diseases in packaged
foods, therefore prolonging their shelf life. In this study, potato peel starch and ZnO-starch
nanocomposite paper (ZnO-starch NC paper) were developed and evaluated for
antibacterial activity against Escherichia coli, Bacillus subtilis, Staphylococcus aureus,
Pseudomonas aeruginosa, and antifungal activity against the Botrytis cinerea fungi. The
ZnO nanoparticles (ZnO NPs) were synthesized using the hydrothermal method whilst the
ZnO-starch NCs were synthesized by adding the potato starch to the ZnO NPs. The
synthesized ZnO nanomaterials and potato starch were characterized using X-ray
diffractometry (XRD) and UV-Vis spectrophotometry (UV-Vis). The analysis showed that
the nanomaterials were purely synthesized without the presence of impurities. The ZnO starch NC paper was made by coating Whatman filter paper (size 3) with the ZnO-starch
NC. The antibacterial/antifungal activity of the ZnO-starch NC paper showed that the
nanomaterials were effective against the Gram-positive bacteria S. aureus and B.
subtilis but not against the Gram-negative E. coli and P. aeruginosa. The ZnO-starch NC
paper was used to package inoculated strawberries in plastic containers for 10 days at 4°C
and 27°C, respectively. Quality assays on the incubated strawberries showed that the
percentage weight loss and bacterial counts of the fruits packaged with the ZnO-starch NC
paper at 4°C were lower than those packaged without the ZnO-starch NC paper. The fruits
incubated with the NPs were seen to be more acceptable in appearance and sensory value
than their respective controls. In conclusion, the ZnO-starch NC paper was able to prolong
the shelf life of strawberries for longer at lower temperatures. Hence, this nanomaterial
could be used to explore nano-packaging for prolonging the shelf life of fruits.
