Abstract: As one of the main grain reserves in China, maize is subject to mildew due to its high moisture content, rich nutrients and high microbial load, resulting in the production of mycotoxins exceeding the safe limit. In this research, antimicrobial zinc oxide nanoparticles (ZnO-NPs) were prepared by a hydrothermal method under the optimized conditions as follows: using water as the solvent, n(Zn2+):n(OH-) of 1:8, water temperature of 120 ℃, and holding time of 6 h. The nanoparticles were spherical with an average diameter of 93 nm, and polydispersity index (PDI) of 0.024 as determined by dynamic light scattering. Characterization by energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) showed that the nanoparticles only contained Zn and O elements and had the unique crystal structure and chemical bond characteristics of ZnO. The ZnO-NPs had a significant inhibitory effect on the growth of bacteria and fungi. After 30 days of storage, the total viable count on maize with the ZnO-NPs was significantly lower than that on the control group, and the deterioration of maize quality was slowed down in the ZnO-NPs treatment group. Therefore, the ZnO-NPs could help to inhibit the growth of microorganisms during the storage of maize, which will provide data support for the development of new grain preservatives.

Key words: hydrothermal method; ZnO nanoparticles; antibacterial activity; maize storage