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Implementação dos métodos de deteção de Cronobacter spp. e enumeração de fungos em géneros alimentícios no laboratório MicroChem
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Com o passar dos anos, verificou-se uma crescente preocupação da população com a
segurança alimentar, gerando várias discussões para determinar medidas de prevenção e
controlo de perigos na cadeia alimentar. Uma das medidas consiste na realização de análises
microbiológicas de determinados microrganismos – Cronobacter, bolores e leveduras. O
Cronobacter é um bacilo gram-negativo, não produtor de esporos, da família Enterobacteriaceae,
associado a infeções em neonatos em virtude do consumo de fórmulas infantis desidratadas.
Apesar de não existirem muitos surtos de Cronobacter documentados, este é associado ao
desenvolvimento de doenças graves, apresentando uma taxa de mortalidade de 40-80%. Desta
forma, a deteção deste microrganismo em alimentos, implica que o resultado seja
imediatamente considerado não satisfatório. Os bolores e leveduras são organismos eucariotas
heterotróficos pluricelulares e unicelulares, respetivamente. Estes são fungos que podem ser
benéficos ou prejudiciais ao homem, na medida em que podem produzir metabolitos tóxicos
e/ou causar deterioração alimentar, havendo a necessidade da sua enumeração para avaliação
da qualidade alimentar.
Os principais objetivos do estágio, realizado no laboratório MicroChem, passam pela
implementação de dois métodos, um método qualitativo para a deteção de Cronobacter spp.,
baseado na ISO 22964:2017, e um método quantitativo, para a enumeração de fungos em
géneros alimentícios, ISO 21527-2:2008. Os resultados da implementação das metodologias
foram de encontro ao esperado, permitindo a deteção de Cronobacter com elevado grau de
confiança e enumerar os bolores e leveduras permitindo contabilizar e diferenciar
macroscopicamente os fungos no meio DG18, na qual se determinou a incerteza do método
(Uexp=0,16) e o critério de precisão (Cp=0,25). Os métodos foram implementados com sucesso,
utilizando amostras artificialmente contaminadas e amostras dos ensaios interlaboratoriais.
Foram obtidos mais de 30 ensaios válidos, em duplicado e em paralelo, e foram efetuados dois
ensaios interlaboratoriais válidos, indicativo da precisão, exatidão e reprodutibilidade dos
resultados.
Over the years, there has been a growing concern of the population with food safety, generating several discussions to determine measures to prevent hazards in the food chain. One of these measures consists of performing microbiological analyses of certain microorganisms - Cronobacter, moulds and yeasts. Cronobacter is a gram-negative, non-spore- producing bacillus of the Enterobacteriaceae family associated with infections in neonates due to the consumption of dehydrated infant formulas. Although there are not many documented outbreaks of Cronobacter, it is associated with the development of serious diseases, with a mortality rate of 40-80%. Therefore, the detection of this microrganism in foodstuffs means that the result is immediately considered unsatisfactory. Moulds and yeasts are heterotrophic eukaryotic organisms, multicellular and single-celled, respectively. These are fungi that can be beneficial or harmful to humans as they can produce toxic metabolites and/or cause food deterioration, so it is necessary to enumerate them for food quality evaluation. The main objectives of the internship, carried out in the MicroChem laboratory, involves the implementation of two methods, a qualitative method for the detection of Cronobacter spp. based on ISO 22964:2017, and a quantitative method, for the enumeration of fungi in foodstuffs, ISO 21527 2:2008. The results of the implementation of the methodology were as expected, allowing the detection of Cronobacter with a high degree of confidence and the enumeration of moulds and yeasts, enabling the fungi to be counted and differentiated macroscopically in DG18 medium, in which the uncertainty of the method (U=0.16) and the precision criterion (CP=0.25) were determined. The methods were successfully implemented using artificially contaminated samples and interlaboratory samples. More than 30 valid duplicate and parallel tests were obtained and two valid interlaboratory tests were performed, indicating the precision, accuracy, and reproducibility of the results.
Over the years, there has been a growing concern of the population with food safety, generating several discussions to determine measures to prevent hazards in the food chain. One of these measures consists of performing microbiological analyses of certain microorganisms - Cronobacter, moulds and yeasts. Cronobacter is a gram-negative, non-spore- producing bacillus of the Enterobacteriaceae family associated with infections in neonates due to the consumption of dehydrated infant formulas. Although there are not many documented outbreaks of Cronobacter, it is associated with the development of serious diseases, with a mortality rate of 40-80%. Therefore, the detection of this microrganism in foodstuffs means that the result is immediately considered unsatisfactory. Moulds and yeasts are heterotrophic eukaryotic organisms, multicellular and single-celled, respectively. These are fungi that can be beneficial or harmful to humans as they can produce toxic metabolites and/or cause food deterioration, so it is necessary to enumerate them for food quality evaluation. The main objectives of the internship, carried out in the MicroChem laboratory, involves the implementation of two methods, a qualitative method for the detection of Cronobacter spp. based on ISO 22964:2017, and a quantitative method, for the enumeration of fungi in foodstuffs, ISO 21527 2:2008. The results of the implementation of the methodology were as expected, allowing the detection of Cronobacter with a high degree of confidence and the enumeration of moulds and yeasts, enabling the fungi to be counted and differentiated macroscopically in DG18 medium, in which the uncertainty of the method (U=0.16) and the precision criterion (CP=0.25) were determined. The methods were successfully implemented using artificially contaminated samples and interlaboratory samples. More than 30 valid duplicate and parallel tests were obtained and two valid interlaboratory tests were performed, indicating the precision, accuracy, and reproducibility of the results.
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Cronobacter spp. Bolores Leveduras Implementação de método ISO 21527- 2:2008 ISO 22964:2017