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 fo od 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 i mmobilized micro-organisms. We tested subsequently several Gram-positive ba cteria and yeasts for their photosensitivity after incubation with haematop orphyrin (HP) and sodium chlorophyllin (CHL). The survival levels of the ba cteria fixed on solid media ranged from 0.0006% to 0.08% (3-5 log10 inactiv ations), and those of the yeasts from <0.1% to 50% (0.3-3 log10 inactivatio ns) under the experimental conditions chosen. (C) 2001 Elsevier Science Ltd . All rights reserved.