| Recently, oxo-biodegradable polymers have attracted much attention due to taking less time to break down after
disposal in comparison to ordinary polymers. Polyvinyl alcohol/gelatin (PVA/G) nanocomposite films, containing
ZnO, TiO2 or ZnO/TiO2 nanoparticles supported on 4A zeolite (4A z), are novel active packaging that can
control the release of antimicrobial compounds. The present study assessed the efficacy of PVA/G nanocomposite
films with 1.5% (w/w) ZnO/4A z (treatment 1), 1.5% (w/w) TiO2/4A z (treatment 2), or 1% (w/w)
ZnO, TiO2/4A z (treatment 3) in controlling the microbial load and maintaining the sensory qualities of white
shrimp during storage at 4 ± 1 °C. Firstly, the optimum concentration of each material for addition to the film
was determined by micro-dilution and disc diffusion. Secondly, the specimens were checked for total viable
count (TVC), as well as the counts of each of Pseudomonas spp., Enterobacteriaceae, Shewanella putrefaciens,
inoculated Staphylococcus aureus, Listeria monocytogenes, and Escherichia coli O157:H7. According to the results,
the PVA/G nanocomposite films containing treatments 1–3 significantly decreased the number of bacteria in the
treatment group in comparison to the control group (P < .05). The results of the antimicrobial activity of the
three treatments by using the disc diffusion method revealed that the inhibition zone varied from 8.11 ± 0.02
to 12.63 ± 0.04 mm. Also it should be noted that, the finding of micro-dilution test varied from 1 ± 0.01 to
3 ± 0.01. The ZnO, TiO2/4A z nanocomposite had a significantly greater antimicrobial impact against Gramnegative
bacteria compared to Gram-positive bacteria (P < .05). Finally, the microbiological and sensory investigation
of the efficacy of the PVA/G nanocomposite films as active packaging materials revealed a considerable
improvement in shrimp shelf life (12 days) in comparison to the control (6 days). Therefore, these
nanocomposite films can be used as novel active packaging in the maintenance of the microbial load and sensory
qualities of shrimp. |