Thesis (doctoral)--University of Helsinki, 2009. / Includes bibliographical references. Also available on the World Wide Web.

Salmonella spp é um dos microrganismos patogênicos de relevância em alimentos. Sua detecção em alimentos por metodologia de cultura é trabalhosa e demorada, o que explica a grande variedade de sistemas automatizados e kits para detecção rápida desse patógeno existentes no mercado. Muitos desses métodos alternativos são validados por organizações internacionalmente reconhecidas, mas tais validações têm sido efetuadas em condições laboratoriais artificiais e com matrizes alimentares experimentalmente contaminadas, dificilmente refletindo a realidade de um laboratório de rotina de análises microbiológicas de alimentos. Nesse trabalho, avaliou-se o desempenho de sete métodos rápidos alternativos genotípicos e imunológicos, usados simultaneamente para detecção de Salmonella spp em 244 amostras de alimentos sem contaminação experimental, empregando o método de cultura ISO 6579:2002 como método de referência. Os métodos avaliados foram BAX Salmonella,VIDAS Salmonella (SLM),Transia Plate Salmonella Gold,VIP Salmonella,TECRA UNQUIQUE SALMONELLA,Singlepath Salmonella e 1-2 Test. O nível de detecção para cada método também foi determinado, trabalhando-se com três matrizes alimentares diferentes, experimentalmente contaminadas com cinco níveis de inóculo. O método de referência detectou 50 amostras (20,5%) positivas para Salmonella spp. Nas condições em que o trabalho foi realizado, a porcentagem de concordância dos resultados positivos obtidos pelos métodos alternativos avaliados em relação aos resultados positivos obtidos pelo método ISO 6579:2002 variou de 42,3% a 100% nas amostras sem contaminação experimental e de 75% a 100% nas amostras artificialmente contaminadas, dependendo do método avaliado e da matriz alimentar analisada. Todos os métodos rápidos avaliados apresentaram resultados falso-positivos e falso-negativos, em freqüências dependentes também do método avaliado e da matriz alimentar analisada. Os resultados obtidos evidenciaram que os métodos rápidos avaliados devem ser utilizados unicamente para fins de triagem, podendo haver um risco intrínseco na escolha de um método rápido para detectar Salmonella spp em determinada matriz alimentar. A seleção de um método rápido, em particular, só deve ser feita após a determinação do grau de risco que se queira assumir. / Salmonella spp is an important foodborne pathogen. The detection in foods by the cultural methodology takes at least five days to be completed and several automated systems and kits are available in the market for rapid detection of this pathogen. Most rapid methods are validated by internationally recognized organizations, but most validations have been conducted in artificial laboratory conditions, working with inoculated food samples, hardly reflecting the real conditions of a routine testing laboratory. In this study, seven immunological and genotypic rapid methods were used simultaneously for the detection of Salmonella spp in 244 non-inoculated food samples, and compared to the ISO 6754:2002 cultural method, used as reference. The rapid methods evaluated were BAX Salmonella, VIDAS Salmonella (SLM), Transia Plate Salmonella Gold, TECRA UNIQUE SALMONELLA, VIP Salmonella, Singlepath Salmonella and 1-2 Test. The lowest detection level for each method was also determined using three different food matrices experimentally contaminated with five levels of inoculum. Based on results obtained by the ISO 6754:2002 method, 50 (20.5%) samples were positive for Salmonella spp. In the conditions of the study, the agreement percentage of positive results obtained by each rapid method when compared to the positive results of the reference method varied between 42.3% and 100% in the non-inoculated food samples and between 75% and 100% in the experimentally contaminated samples, depending on the method and the tested food matrix. All rapid methods presented false-positive and false-negative results, and their frequency varied according to the method and the tested food matrix. Results confirmed that these rapids methods should be used for screening exclusively, and the selection of a rapid method for detection of Salmonella spp in foods may have an intrinsic risk. The degree of this risk needs to be determined before a particular method is selected.

No description available.

The potential applicability of Fourier transform infrared (FM) spectroscopy for the study of biomolecules, has been investigated through the investigation of three specific applications. Two of the applications selected involve the classification of whole cells, whereas the third concerns the study of peptides and proteins isolated from tissues as well as synthetic peptides. In the microbiological application, for the differentiation of bacteria on the basis of their FTIR spectra, it has been found that classification is most efficiently achieved through the utilisation of artificial neural networks, and that a wide, variety of bacteria can be correctly identified with minimal sample preparation after being grown on a single growth medium. The suitability of low-cost, disposable materials as supports for the deposition of bacteria samples has also been demonstrated. In contrast to the successful classification of bacteria, it has been found that the examination of cytological smears by FTIR spectroscopy does not allow the classification of cervical cell populations into the recognised diagnostic categories. In a microscopic investigation of the same cell populations utilising infrared imaging, localised areas of the smear were found to exhibit distinct characteristics not observed in the spectra of the entire population. This indicates that infrared imaging system may be required for this type of application because the infrared spectrum recorded from a whole cervical smear does not allow the detection of the small spectral features arising from the molecular changes associated with a localised pathological state. Finally, the investigation of factors affecting the stability of peptides related to amyloidosis has shown that temperatures above 70°C, hydrostatic pressure greater than 6 kbar, and alkaline pH promote the disaggregation of the typical intermolecular beta-sheet structure of amyloid peptides. Peptides utilised as model systems for amyloidosis showed

The infrared spectra of 14 bacteria were recorded by Fourier Transform Infrared (FTIR) spectroscopy. The effects of changes in growth conditions, such as temperature, growth medium, and incubation time, sampling conditions on the reproducibility of the spectra were investigated. The spectra of bacteria suspended in saline solution, in D$ sb2$O-saline and on plate films were obtained and stored in separate spectral libraries. The application of library search routines for differentiation and identification of the 14 bacteria was investigated. The spectral regions used for the library search include 1750-1560 cm$ sp{-1}$ and 1480-960 cm$ sp{-1}$, which contain bands mainly associated with proteins (secondary structure), lipids, and polysaccharides. An index produced by the library search, which indicates how much an "unknown spectrum" matches a library spectrum, is suggested as a criterion for the differentiation and identification of bacteria. A correct identification of five unknown samples shows the feasibility of using spectral library searching routines for identification of bacteria down to the species level by FTIR spectroscopy. This technique is rapid, easier, and more efficient than conventional microbiological and biochemical methods. Quantitative analysis of a mixture of Escherichia coli and Staphylococcus aureus by the partial-lest-square (PLS) technique was also evaluated. The analytical error was about 10%.

Orientador: Jose Luiz Pereira / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-17T12:12:24Z (GMT). No. of bitstreams: 1 Constantino_CristinadeAbreu_M.pdf: 2114819 bytes, checksum: 189ec1c7fa681707e31ce5dc34bc0e27 (MD5) Previous issue date: 2011 / Resumo: No Brasil, a Portaria MS nº. 518/2004 do Ministério da Saúde estabelece, entre outros parâmetros, a análise de coliformes totais, termotolerantes ou Escherichia coli (E. coli) e de bactérias heterotróficos para análise de água para consumo humano, em toda e qualquer situação, incluindo fontes individuais como poços, minas e nascentes. A Agência de Proteção Ambiental dos Estados Unidos (EPA) avalia métodos para diferentes aplicações ambientais, entre outras, para análise de água potável, que se aprovados, são publicados como métodos oficiais no Standard Methods for the Examination of Water and Wastewater. Este manual recomenda muitos princípios de reações e métodos para análise de água potável e é muito importantes que se compreendam as limitações e benefícios destes métodos antes de utilizá-los, para garantir a segurança e qualidade microbiológica da água de consumo humano. Os métodos convencionais de análise microbiológica de água para consumo humano requerem um mínimo de 24 horas de incubação, seguidos por procedimentos de confirmação dos resultados positivos, que duram entre 24-48 horas, o que gera uma demanda de métodos mais rápidos de análise. O uso das Placas 3M¿ Petrifilm¿ não está aprovado pela EPA, e, consequentemente, não está publicada no Standard Methods for the Examination of Water and Wastewater. Este estudo apresenta resultados comparativos do desempenho da tecnologia 3MTM Placas PetrifilmTM para contagem de Coliformes e E. coli (EC) e Contagem de Aeróbios (AC) contra as metodologias convencionais para as análises de bactérias do grupo coliformes (Endo) e para contagem padrão de bactérias heterotróficas (PCA), através do método de membrana filtrante e técnica de plaqueamento em profundidade, respectivamente, seguindo os procedimentos descritos no protocolo 821-B-03-004, da EPA. As amostras foram obtidas de dois rios que suprem o fornecimento de água potável (antes e após o tratamento na estação de abastecimento), dois poços e duas fontes na região da cidade de Campinas, estado de São Paulo, Brasil. A água bruta dos rios foi utilizada para contaminar a água potável, e em seguida, foi realizado estresse por cloração, (0.1mg/L ¿ 5 minutos); a água dos poços e fontes estava naturalmente contaminada. Parâmetros físico-químicos foram avaliados. A mediana das contagens de coliformes e E. coli para água de consumo humano oriunda das estações de tratamento, com as 3MTM Placas Petrifilm EC foi igual a 1,9085 e para o meio Endo igual a 1,8603. O resultado do teste de Mann-Whitney foi W = 2786,5 o que demonstrou que não se pode rejeitar a igualdade dos métodos, já que W é maior do que 2525,0. O método Petrifilm EC apresentou menor variabilidade com pvalor = 0,014, com menor desvio padrão para o método EC (0,16), do que o método Endo (0,29) e maior precisão, com Coeficiente de variação (CV) = 8,43 para EC x CV = 15,91 para ENDO. Para amostras de água de fontes e poços não tratados, 40 resultados de contagens de coliformes foram avaliados e o método 3MTM Petrifilm EC apresentou recuperação estatisticamente inferior do que o método de referência, porém com maior precisão com CV=12, 26 para o método EC x CV = 16,44 para o método ENDO. Para contagens de bactérias heterotróficas, as amostras das três matrizes água foram analisadas conjuntamente. Não houve diferença na recuperação com o método 3MTM Petrifilm AC, pois W = 8455,5 é maior do que 8145, 0, com medianas de 2,0294 e 2,0212 para o método PCA, com p-valor de 0,253. O desvio padrão de 0,40 para o 3MTM Petrifilm AC e 0,49 para o método PCA demonstram que os métodos apresentaram recuperação muito similar das colônias e superioridade na precisão do método 3MTM Petrifilm AC, com CV = 19,78 x CV = 25,76 para o método PCA. Observou-se que não houve diferença estatística significativa e que há uma forte correlação entre os métodos convencionais e as placas 3MTM Petrifilm. A técnica 3MTM Petrifilm é rápida, padronizada, confirmatória e precisa e com base nestes resultados sugere-se que pode ser utilizada como um método prático para análise de bactérias heterotróficas, coliformes e E. coli em água de consumo humano, alternativamente à metodologia convencional, atendendo à demanda das empresas de alimentos, bebidas e abastecimento de água / Abstract: In Brazil the normative MS nº. 518/2004 of Health Agency establishes, among others parameters, the analysis of total, thermotolerant coliforms or Escherichia coli (E coli) and of heterotrophic bacteria for drinking water, including springs, wells and other sources of human drink water. Many principles of reactions are recommended for water potability analysis in the Standard Methods for the Examination of Water and Wastewater that proclaim the validated method for water analysis, sand are very important to understand the limitations and benefits of these methods before the use of these, to guarantee the security and microbiological quality of the human drinking water. The US Environmental Protection Agency (EPA) evaluates methods for many environmental uses, between others, to drinking water analysis, that been approved will be published as official methods in the Standard Methods for the Examination of Water and Wastewater. This Standard recommend that many reaction principle¿s and methods for drinking water analysis and is very important that be understood the limits and benefits of those methods before using it, for warranty the safety and microbiological quality of human drinking water. The conventional methods of microbiological water analysis of human consumption requires a minimum of 24 hour of incubation, followed for confirmatory procedures of the positive results, that last between 24-48 hours, what it generates a demand of faster methods of analysis. The use of 3M¿ Petrifilm¿ Plates is not approved by the EPA and consequently is not published in the Standard Methods for the Examination of Water and Wastewater. This study shows comparative results from the performance of the technology 3MTM PetrifilmTM Plates for counting of coliforms and E. coli (EC) and counting of aerobic organisms (AC) versus the conventional methodologies for the analyses of coliforms bacteria (Endo) and for standard counting of heterotrophic bacteria (PCA), through the method of membrane filtration and pour plate technique, respectively, following the protocol EPA 821-B-03-004 procedures. Samples were obtained from two rivers that are suppliers of drinking water (prior and after the supplier station treatment), two wells and two fountains in the Campinas city region, São Paulo state/ Brazil. The raw river water was used to spike drinking water, after chlorination stress [0.1mg/L ¿ 5 minutes]; wells and fountains were naturally contaminated. Physical-chemical parameters were evaluated. Median was EC = 1,9085 and Endo = 1,8603. The result from Mann-Whitney test was W = 2786,5, that shows the equality between methods can not be reject since W is > 2525,0. Petrifilm method shows lower variability with p-value = 0,014, with lower Standard Deviation to EC (0,16) than Endo (0,29) and higher precision, with CV = 8,43 for EC vs. CV = 15,91 for ENDO. For the untreated water from wells and fountains, 40 coliforms results were evaluated and EC results were statistically different and lower than the reference method, bur higher precision with Coefficient of Variation (CV) = 12, 26 for EC method vs. CV = 16,44 to ENDO method. For heterotrophic counts, the samples for 3 matrices were analyzed together. There is no recovery difference for 3MTM Petrifilm AC method since W = 8455,5 greater than 8145,0 with medians of 2,0294 and 2,0212 for PCA method, with a p- Value of 0,253. The Standard Deviation of 0,40 for 3MTM Petrifilm AC and 0,49 for PCA method shows that both methods presents a very similar recover of colonies and the superiority of precision of the 3MTM Petrifilm AC method, with CV = 19,78 vs. CV = 25,76 for PCA method. Was observed that there is no statistic significant difference and there is a strong correlation between the traditional and 3MTM Petrifilm Plates. The 3MTM Petrifilm technique is rapid, standardized, confirmatory and precise and based in these results should be suggested that it can be used as a practical method for heterotrophic bacteria, coliforms and E. coli analysis in human drinking water, alternatively to the conventional methodology, attending the demand of the companies of food, beverages and water supply stations / Mestrado / Engenharia de Alimentos / Mestre em Ciência de Alimentos

Salmonella spp é um dos microrganismos patogênicos de relevância em alimentos. Sua detecção em alimentos por metodologia de cultura é trabalhosa e demorada, o que explica a grande variedade de sistemas automatizados e kits para detecção rápida desse patógeno existentes no mercado. Muitos desses métodos alternativos são validados por organizações internacionalmente reconhecidas, mas tais validações têm sido efetuadas em condições laboratoriais artificiais e com matrizes alimentares experimentalmente contaminadas, dificilmente refletindo a realidade de um laboratório de rotina de análises microbiológicas de alimentos. Nesse trabalho, avaliou-se o desempenho de sete métodos rápidos alternativos genotípicos e imunológicos, usados simultaneamente para detecção de Salmonella spp em 244 amostras de alimentos sem contaminação experimental, empregando o método de cultura ISO 6579:2002 como método de referência. Os métodos avaliados foram BAX Salmonella,VIDAS Salmonella (SLM),Transia Plate Salmonella Gold,VIP Salmonella,TECRA UNQUIQUE SALMONELLA,Singlepath Salmonella e 1-2 Test. O nível de detecção para cada método também foi determinado, trabalhando-se com três matrizes alimentares diferentes, experimentalmente contaminadas com cinco níveis de inóculo. O método de referência detectou 50 amostras (20,5%) positivas para Salmonella spp. Nas condições em que o trabalho foi realizado, a porcentagem de concordância dos resultados positivos obtidos pelos métodos alternativos avaliados em relação aos resultados positivos obtidos pelo método ISO 6579:2002 variou de 42,3% a 100% nas amostras sem contaminação experimental e de 75% a 100% nas amostras artificialmente contaminadas, dependendo do método avaliado e da matriz alimentar analisada. Todos os métodos rápidos avaliados apresentaram resultados falso-positivos e falso-negativos, em freqüências dependentes também do método avaliado e da matriz alimentar analisada. Os resultados obtidos evidenciaram que os métodos rápidos avaliados devem ser utilizados unicamente para fins de triagem, podendo haver um risco intrínseco na escolha de um método rápido para detectar Salmonella spp em determinada matriz alimentar. A seleção de um método rápido, em particular, só deve ser feita após a determinação do grau de risco que se queira assumir. / Salmonella spp is an important foodborne pathogen. The detection in foods by the cultural methodology takes at least five days to be completed and several automated systems and kits are available in the market for rapid detection of this pathogen. Most rapid methods are validated by internationally recognized organizations, but most validations have been conducted in artificial laboratory conditions, working with inoculated food samples, hardly reflecting the real conditions of a routine testing laboratory. In this study, seven immunological and genotypic rapid methods were used simultaneously for the detection of Salmonella spp in 244 non-inoculated food samples, and compared to the ISO 6754:2002 cultural method, used as reference. The rapid methods evaluated were BAX Salmonella, VIDAS Salmonella (SLM), Transia Plate Salmonella Gold, TECRA UNIQUE SALMONELLA, VIP Salmonella, Singlepath Salmonella and 1-2 Test. The lowest detection level for each method was also determined using three different food matrices experimentally contaminated with five levels of inoculum. Based on results obtained by the ISO 6754:2002 method, 50 (20.5%) samples were positive for Salmonella spp. In the conditions of the study, the agreement percentage of positive results obtained by each rapid method when compared to the positive results of the reference method varied between 42.3% and 100% in the non-inoculated food samples and between 75% and 100% in the experimentally contaminated samples, depending on the method and the tested food matrix. All rapid methods presented false-positive and false-negative results, and their frequency varied according to the method and the tested food matrix. Results confirmed that these rapids methods should be used for screening exclusively, and the selection of a rapid method for detection of Salmonella spp in foods may have an intrinsic risk. The degree of this risk needs to be determined before a particular method is selected.

No description available.

Master of Science / Food Science Institute / Daniel Y.C. Fung / ECA Check® Easygel® Plus (ECA) is a pectin-based gelling system that reacts with calcium ions bound to a pre-treated Petri dish, eliminating autoclaving prior to use. It can chromogenically and/or fluorogenically distinguish three organisms: Escherichia coli, Salmonella spp., and coliforms. This study compared the recovery of these organisms to conventional media using stock culture, inoculated, and non-inoculated ground beef and ground turkey. ECA was compared to Violet Red Bile Agar (VRB), Violet Red Bile Agar with 4-methylumbelliferyl-β-D-glucuronide (VRB-MUG), Xylose Lysine Desoxycholate Agar (XLD), Escherichia coli/Coliform (ECC) Count Plate Petrifilm™, and Tryptic Soy Agar (TSA). The stock culture recovery of Salmonella Typhimurium for ECA, TSA, and XLD were 8.62, 8.69, and 6.82 log CFU/ml, respectively. There was very little difference between the media in the recovery of Escherichia coli and Cronobacter spp., formerly referred to as Enterobacter sakazakii. Mean counts of presumptive E. coli in ground beef were 7.24 and 7.41 logs for ECA and VRB-MUG. Total coliform mean counts were 7.43, 7.63, and 7.37 logs for ECA, Petrifilm™, and VRB. Presumptive Salmonella means were 6.68 and 6.21 logs on ECA and XLD, while total aerobic counts were 7.84 and 6.51 logs on ECA and TSA. At 6.72 logs, ECA recovered considerably more Salmonella than XLD (5.71 logs) from the inoculated ground turkey; ECA recovered 7.62 logs total aerobic count which was significantly more than TSA at 6.89 logs. Total counts for both non-inoculated ground meats resulted in significant differences between TSA recovery and all other media. ECA also recovered significantly more than Petrifilm™ from both non-inoculated foods. The randomly selected organisms recovered from ECA were identified using BBL™ Crystal™ Enteric/Nonfermenter ID or Gram-Positive kits, and correlated precisely to the chromogenic reaction of the colonies. ECA Check® Easygel® was efficient, less labor-intensive, comparable to, and, in some instances, better than conventional media at recovering target organisms.

Orientador: Jose Luiz Pereira / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-05T16:44:43Z (GMT). No. of bitstreams: 1 Maistro_LilianeCorrea_D.pdf: 46681351 bytes, checksum: ad9a87ef59bfce7cfb07b758fe4a075f (MD5) Previous issue date: 2006 / Resumo: O resumo poderá ser visualizado no texto completo da tese digital / Abstract: The abstract is available with the full electronic document / Doutorado / Doutor em Ciência de Alimentos