Antibacterial efficacy of chemically and plant-synthesized zinc oxide nanocomposite against Staphylococcus aureus and Escherichia coli inoculated in Tilapia fillet

ABSTRACT

Aims@#Edible coatings developed from biodegradable materials such as starch and zinc oxide nanoparticles (ZnO-NPS) are efficient antimicrobials that could be used as a food additive to reduce the bacterial load on the food surface. Therefore, this study was aimed to examine the effect of chemical and green synthesized ZnO-NPS with different concentrations on the survival of Escherichia coli and Staphylococcus aureus in fish fillets during chilling storage at 4 ± 1°C.@*Methodology and results@#ZnO-NPS were chemically prepared by mixing zinc acetate dihydrate with sodium hydroxide. Lavandula officinalis was used for the green synthesis of ZnO-NPS. The sterile biodegradable coating containing 2 and 5% of both chemically and green synthesized ZnO-NPS were made using starch, gelatin, xanthan gum and glycerol. Different bacterial cocktail strains of both E. coli and S. aureus were inoculated onto Tilapia fillet samples. The coating solution with different antimicrobials was aseptically spread in Tilapia fillets and examined periodically within two days intervals for the survival of S. aureus and E. coli during chilling at 4 ± 1 °C. Both chemically and plantsynthesized ZnO-NPS reduced the growth of both S. aureus and E. coli by about 3.7 log10 CFU/cm2 of Tilapia fillet. The incorporation of L. officinalis increased the antibacterial activity of ZnO-NPS. Staphylococcus aureus was more sensitive than E. coli for both chemically and plant-synthesized ZnO-NPS. Moreover, zinc oxide biodegradable coating extended the shelf-life of chilled Tilapia fillets by about 4 days.@*Conclusion, significance and impact of study@#The results of the current study demonstrated the incorporation of L. officinalis into ZnO-NPS biodegradable coating which may be promising in reducing microbial growth on food surfaces.