Haematoporphyrin- and sodium chlorophyllin-induced phototoxicity towards bacteria and yeasts – a new approach for safe foods

Alternative methods for the decontamination of foods and surfaces in the food processing industry are under research. We introduce a new approach: the use of visible light plus photosensitizers, the photodynamic effect. First, we established an experimental model to examine the photosensitivity of immobilized micro-organisms. We tested subsequently several Gram-positive bacteria and yeasts for their photosensitivity after incubation with haematoporphyrin (HP) and sodium chlorophyllin (CHL). The survival levels of the bacteria fixed on solid media ranged from 0.0006% to 0.08% (3–5 log10 inactivations), and those of the yeasts from <0.1% to 50% (0.3–3 log10 inactivations) under the experimental conditions chosen.