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Master's Dissertation
DOI
10.11606/D.9.2017.tde-25072017-152400
Document
Author
Full name
Cristiano Andrigheto
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2000
Supervisor
Committee
Franco, Bernadette Dora Gombossy de Melo (President)
Landgraf, Mariza
Mayer, Marcia Pinto Alves
Title in Portuguese
Disseminação de Listeria monocytogenes em uma linha de produção de "nuggets" congelados de frango
Keywords in Portuguese
Alimentos (Microbiologia)
Alimentos de origem animal
Linha de processamento
Listeria monocytogenes
RAPO
Tipagem molecular
\"Nuggets\" de frango
Abstract in Portuguese
A presente pesquisa teve por objetivo avaliar as fontes de contaminação por Listeria monocytogenes em uma linha de processamento de "nuggets" congelados de frango. Linhagens de L. monocytogenes isoladas de diferentes pontos de uma usina de processamento industrial nas diversas etapas do processamento foram avaliadas quanto à sua diversidade genética. A técnica empregada foi o RAPO com metodologia modificada da Organização Mundial da Saúde (OMS/WHO). Os perfis RAPO gerados com os "primers" M13 e UBC155 foram agrupados, combinados e analisados quanto à sua similaridade. As cepas foram também sorotipadas e 189 pertenciam ao sorogrupo 1 e 63 ao sorogrupo 4. A correlação entre a diversidade genética e a distribuição do microrganismo na linha de processamento foi estabelecida. As 252 L. monocytogenes estudadas puderam ser divididas em dois grandes "clusters" cada qual dividido em dois grupos. Os resultados da análise de "clusters" foram relacionados aos da sorologia, determinando sete subtipos. Verificou-se que três subtipos são introduzidos no ambiente de processamento juntamente com a matériaprima. Um deles foi encontrado somente na matéria-prima e os outros dois também foram detectados em superfícies de equipamentos e no ambiente de processamento. Outros subtipos encontrados em superfícies de equipamentos e no ambiente foram encontrados no produto em etapas subseqüentes. A contaminação da matéria-prima por cepas diferentes daquelas encontradas no ambiente de processamento mostra a sua importância como fonte de contaminação. Formas de controle da presença de L. monocytogenes na matéria-prima devem ser buscadas assim como o controle da contaminação ambiente.
Title in English
Dissemination of Listeria monocytogenes in a chicken frozen nuggets production line
Keywords in English
Chicken nuggets
Food (Microbiology)
Food of animal origin
Listeria monocytogenes
Molecular typing
Processing line
RAPO
Abstract in English
This research was carried out in order to evaluate the sources of Listeria monocytogenes contamination in a frozen chicken nugget processing line. Strains of L. monocytogenes from different origins and isolated from different steps of the processing line were analysed for their genetic diversity. RAPO methodology modified from a WHO protocol was used. The RAPO profiles generated by primers UBC155 and M13 were grouped, combined and the similarities analysed. The strains were also serotyped and 189 belonged to serogroup 1 and 63 to serogroup 4. The correlation between genetic diversity and the strain distribution along the processing line was established. The 252 L. monocytogenes strains analysed were divided in two clusters, each of them containing 2 groups. Seven subtypes could be determined when the results of RAPO and serotyping were combined. It could be established that from the three sub-types of L. monocytogenes that belonged to the raw material, two could establish themselves in the processing line. These sub-types were detected latter in the environmental samples (food contact and non-food contact surfaces). On the other hand, other sub-types found initially in environmental samples were detected in the product in subsequent steps. The introduction of L. monocytogenes into the plant by raw material highlights its importance as a contamination source. Measures must be taken to control the presence of L. monocytogenes in the raw material as well as in the processing environment.
 
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Publishing Date
2017-07-25
 
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