Bacillus Subtilis spores have been inoculated over internal surfaces of large water bottling cups from Nestle Shanghai Source. Cups are made from soft blue PE plastic with an internal geometry, presenting a challenge to a full UV illumination: long vertical walls (ratio of its height to diameter is 1.5), groves on walls and a porous white plastic seal at the bottom, fixed by a ring at its centre.
The cups are to cup 20l glass jars each 11 seconds, in groups of ten awaiting its advance to a jar cupping mechanism on a vertical rail. Two competing UV sources (with focusing reflectors) have been used: amalgam doped high-performance U-shaped low pressure Mercury lamp (load 1.5 w/cm, 30% UVC) and our UV flashlamp. Within the production time of 11 sec the sterilisation goal of three logs was achieved only with our UV flash lamp with four pulses (750J/pulse) without heating cups. It took 40 sec to get the same sterilisation with continuous UVC (254nm) lamp. Energy consumptions were 3kJ for the flash lamp and 2.4kJ for the Mercury vapour lamp.