Document Type : Original Paper

Authors

• Z. Jaderi ¹
• A. Maskooki ²
• S. A. Mortazavi ³

¹ MSc. Graduated Student, Department of Food Science and Technology, Islamic Azad University, Sabzevar Branch

² Assistant Professor, Department of Food Processing, Research Institute of Food Science and Technology

³ Professor, Department of Food Science and Technology, College of Agriculture, Ferdowsi University of Mashhad

Abstract

Titanium Oxide nanoparticles with semi conductive and photo catalytic properties exhibits bactericidal activity when irradiated under UV ray in aqueous solutions. This is a phenomenon caused from formation of oxygenated hydroxyl groups. The oxygenated hydroxyl groups could disintegrate the cell wall of some microorganisms. We investigated the lethal effects of TiO2 nanoparticles on four harmful microorganisms in food. Pathogenic strains of E. coli and St. aureus, toxicogenic strain of A. parasiticus and putrefactive strain of  S. cerevisiae cultured on their selective media including 1% and 2% TiO₂ concentrations activated by UV irradiation using two UV lamps 14W for 30, 60 and 120 minutes before inoculation. Viable cells in cell suspensions were counted after incubation at desired conditions for each microorganism. The results statistically analyzed and showed that the total count of pathogenic E. coli significantly reduced in both concentrations of activated TiO₂ up 60 min UV irradiation whereas none of the treatments were unaffected on St. aureus. The viable count reduction were 56.8% and 70% for S. cerevisiae and A. parasiticus respectively on their culture media including 2% TiO₂ concentration with 60min irradiated by UV irradiation. This study showed the lethal or growth inhibitory effects of photocatalytic TiO₂ on pathogenic and toxicogenic of various microorganisms types and could be applied for further investigations.