Inactivation of Escherichia coli, Salmonella enterica serovar Typhimurium, and Bacillus cereus in roasted grain powder by radio frequency heating.

AIMS: The objective of this study was to evaluate the antimicrobial effects of radio frequency (RF) heating and the combination treatment of RF heating with ultraviolet (UV) radiation against foodborne pathogens in roasted grain powder (RGP). METHODS AND RESULTS: Foodborne pathogens inoculated on RGP were subjected to RF heating or RF-UV combination treatments. After 120 s of RF heating, 4·68, 3·89 and 4·54 log reductions were observed for Escherichia coli, Salmonella Typhimurium and Bacillus cereus vegetative cells respectively. The combined RF-UV treatment showed synergistic effects of over 1 log unit compared to the sum of individual treatment for E. coli and S. Typhimurium, but not for B. cereus vegetative cells because of their high UV resistance. Germinated B. cereus cells were not significantly inactivated by RF heating (<1 log CFU per gram), and increased heat resistance compared to the vegetative cells was verified with mild heat treatment. The colour of RGP was not significantly affected by the RF or RF-UV treatments. CONCLUSIONS: Applying RF heating to grain-based food products has advantages for the inactivation of E. coli and S. Typhimurium in RGP. SIGNIFICANCE AND IMPACT OF THE STUDY: The results of the present study could be used as a basis for determining the treatment conditions for inactivating E. coli and other foodborne pathogens such as S. Typhimurium and B. cereus in RGP.

Self-assembled growth of nanocomposites consisting of TiO(2) nanopillars and Pb(Zr(0.52)Ti(0.48))O(3) thin films.

We report for the first time the self-assembled growth of nanocomposites of 'TiO(2) nanopillars on Pb(Zr(0.52)Ti(0.48))O(3) (PZT) thin films' using a modified sol-gel processing. Both TiO(2) nanopillars and PZT thin films are simultaneously formed during the post-annealing process. The growth behaviours of TiO(2) nanopillars are controlled by adjusting the Ti excess amounts of PZT solutions and the post-annealing conditions. The self-assembled growth can be explained on the basis of the combined effects of five factors which can have influence during the annealing process: a Ti ion diffusion to the film surface, a phase separation of PZT and TiO(2), a void formation on the film surface, a Ti oxidation at the film surface under oxygen atmosphere, and a nanopillar growth on the film surface.