Efficiency of Treatments Involving Ultraviolet Irradiation for Decontaminating Packaging Board of Different Surface Compositions

Reflectivity, smoothness and geometry of several types of food packaging board were studied in relation to the effectiveness of decontamination treatments involving ultraviolet (UV-C, 254 nm) irradiation. Surfaces containing aluminum in the laminate reflected more light in the 325 to 550 nm range and showed a lower lethal effect when Bacillus subtilis spores were irradiated. Visible light of wavelengths between 325 and 550 nm is known to cause photoreactivation of UV damage in vegetative cells. It was suggested that a similar phenomenon might occur in spores on reflective surfaces. Smoothness of the board surface was not an important factor in the extent or the variability of the lethal effect. The geometry of the irradiated surface was shown to be important for aluminum/polyethylene laminatelined surfaces only, as more spores were killed on board normal to incident UV-C irradiation than in cartons with reflective angles. Spores on the inner sides of this type of carton may have received more reflected li...