Autor(es):
Rodrigues, Diana 
; Teixeira, P. ; Tavares, C. J. ; Azeredo, Joana
Data: 2013
Identificador Persistente: http://hdl.handle.net/1822/24330
Origem: RepositóriUM - Universidade do Minho
Assunto(s): Food-contact surfaces; N-TiO2 coating; Photocatalytic disinfection; Listeria monocytogenes
Descrição
Improvement of food safety is a very important issue, and is on the basis of production and application
of new/modified food contact surfaces. Titanium dioxide (TiO2) and, more recently, nitrogen-doped
titanium dioxide (N-TiO2) coatings are among the possible forms to enhance food contact surfaces performance
in terms of higher hygiene and easier sanitation. In this context, the present work aimed at
evaluating the bactericidal activity of an N-TiO2 coating on glass and stainless steel under two different
sources of visible light – fluorescent and incandescent – and ultraviolet (UV) irradiation. Listeria monocytogenes
was chosen as representative of major foodborne pathogens and its survival was tested on
N-TiO2 coated coupons. In terms of survival percentage, good results were obtained after exposure of
coated surfaces to all light types since, apart from the value obtained after exposing glass to fluorescent
light (56.3%), survival rates were always below 50%. However, no effective disinfection was obtained,
given that for a disinfectant or sanitizing agent to be claimed as effective it needs to be able to promote
at least a 3-log reduction of the microbial load, which was not observed for any of the experimental
conditions assessed. Even so, UV irradiation was the most successful on eliminating cells on coated surfaces,
since the amount of bacteria was reduced to 1.49
×
106 CFU/ml on glass and 2.37
×
107 on stainless
steel. In contrast, both visible light sources had only slightly decreased the amount of viable cells, which
remained in the range of 8 log CFU/ml. Hence, although some bactericidal effect was accomplished under
visible light, UV was the most effective light source on promoting photocatalytic reactions on N-TiO2
coated coupons and none of the experimental conditions have reached a satisfactory disinfection level.
Thus, this surface coating needs further research and improvement in order to become truly effective
against foodborne pathogens and, ultimately, become a useful tool towards food safety in general.
