Green synthesis of zinc oxide nanoparticles using Citrus sinensis peel extract and application to strawberry preservation: A comparison study

ZnO nanoparticles synthesized by Citrus sinensis peel extract (SNP) were characterized and compared with commercial ZnO nanoparticles (CNP), and were then applied as nanocoatings on fresh strawberries to evaluate the preservation effect. The results revealed that SNP had a similar crystal structure to CNP, but a higher crystallinity and a larger particle size. The cytotoxicity of SNP towards human umbilical vein endothelial cells (HUVECs) was close to CNP when the concentration was below 25 mg/L. Furthermore, SNP and CNP had a similar minimum inhibitory concentration (MIC) against E. coli. and S. aureus, but SNP showed a significantly lower minimum bactericidal concentration (MBC) against E. coli compared with CNP. Higher antifungal activities of CNP against Botrytis cinereal purified from mildewed strawberries compared with SNP were found when the concentration was lower than 400 mg/L. When SNP and CNP were incorporated into carboxymethylcellulose sodium (CMC) and coated on fresh strawberries, both coatings significantly decreased the weight loss and the rate of rotting, and also improved the storage quality. Therefore, SNP prepared by the green method has great potential in food packaging application.