Publicação
Explore light emitting diodes and photocatalytic surfaces to prevent biofilm formation in food industry
| Resumo: | Pathogenic microorganisms can contaminate food and food contact surfaces and form biofilms, aggregates of microorganisms from one or more species that are enclosed in a matrix of extracellular polymeric substances. The removal of biofilms is a very challenging task, and they can be the source of foodborne diseases and contribute to the deterioration of food contact surfaces. A protocol for biofilm production was optimized for Listeria monocytogenes, Escherichia coli, Salmonella enterica Typhimurium and Pseudomonas putida. Two different protocols, incubation times and temperatures were tested. Two different quantification protocols with crystal violet were also tested. This work aimed to explore the effectiveness of the inactivation of Listeria monocytogenes biofilms with ultraviolet light using the emergent technology of light emitting diodes that are an alternative to the mercury lamps. Listeria monocytogenes biofilms were produced at room temperature and at 4 ºC in stainless-steel discs and were analyzed before and after the exposure for 2.5 and 5 min to light emitting diodes that emit ultraviolet light at 265 nm. This treatment proved to be effective since we obtained a log reduction higher than 1 in all the inactivation condition tested. This disinfection method was tested to disinfect stainless-steel discs that were contaminated with a suspension of Listeria monocytogenes and Escherichia coli multidrug resistant. A log reduction of 2 was achieved after 5 min of exposure. Scanning electron microscope images were obtained before and after the exposure to ultraviolet light emitting diodes. Photocatalytic surfaces were also tested for biofilm removal. Stainless steel discs modified with a titanium dioxide solution were also used to produce Listeria monocytogenes biofilms and exposed to light emitting diodes. A log reduction of 0.8 was achieved in this experiment. These methods of disinfection proved to be promising approach to disinfect surfaces and could be used in food, medical and pharmaceutical industries. |
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| Autores principais: | Santos, Carolina de Brito |
| Assunto: | Desinfeção de superfícies Díodos emissores de luz ultravioleta Superfícies fotocatalíticas Listeria monocytogenes Escherichia coli multirresistente Teses de mestrado - 2022 |
| Ano: | 2022 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | Pathogenic microorganisms can contaminate food and food contact surfaces and form biofilms, aggregates of microorganisms from one or more species that are enclosed in a matrix of extracellular polymeric substances. The removal of biofilms is a very challenging task, and they can be the source of foodborne diseases and contribute to the deterioration of food contact surfaces. A protocol for biofilm production was optimized for Listeria monocytogenes, Escherichia coli, Salmonella enterica Typhimurium and Pseudomonas putida. Two different protocols, incubation times and temperatures were tested. Two different quantification protocols with crystal violet were also tested. This work aimed to explore the effectiveness of the inactivation of Listeria monocytogenes biofilms with ultraviolet light using the emergent technology of light emitting diodes that are an alternative to the mercury lamps. Listeria monocytogenes biofilms were produced at room temperature and at 4 ºC in stainless-steel discs and were analyzed before and after the exposure for 2.5 and 5 min to light emitting diodes that emit ultraviolet light at 265 nm. This treatment proved to be effective since we obtained a log reduction higher than 1 in all the inactivation condition tested. This disinfection method was tested to disinfect stainless-steel discs that were contaminated with a suspension of Listeria monocytogenes and Escherichia coli multidrug resistant. A log reduction of 2 was achieved after 5 min of exposure. Scanning electron microscope images were obtained before and after the exposure to ultraviolet light emitting diodes. Photocatalytic surfaces were also tested for biofilm removal. Stainless steel discs modified with a titanium dioxide solution were also used to produce Listeria monocytogenes biofilms and exposed to light emitting diodes. A log reduction of 0.8 was achieved in this experiment. These methods of disinfection proved to be promising approach to disinfect surfaces and could be used in food, medical and pharmaceutical industries. |
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