Efficiency of pulsed UV light for microbial decontamination of food powders

The aim of this study was to evaluate the efficiency of pulsed light on the destruction of dried microorganisms on fluidized glass beads and to determine treatment parameters (energy level, water activity, final product quality) for process optimization. The applied drying method allowed microorganisms to remain viable on glass beads or dried powdered products with viability yields approaching 100%. The pulsed UV light system enabled an efficient fluidization of food powders, even for granular products (up to 5 mm diameter) and avoided shadowed areas. For Saccharomyces cerevisiae decontamination, the dose effect of UV rays was preponderant with glass beads and quartz plate, and in this case, 58 J/cm(2) were required to decrease the microbial population by 7 log. For colored food powders (black pepper and wheat flour), the thermal effect of pulsed light dominated the UV effect.