Dissertations / Theses on the topic 'Microbiological hazards'

Orientador: Arnaldo Yoshiteru Kuaye
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: As doenças transmitidas por alimentos (DTAs) colocam em risco o bem estar e a vida de muitas pessoas todos os dias, apresentando maior severidade em pessoas com estado de saúde mais debilitado, como crianças hospitalizadas. Para esta população alvo, uma das principais fontes de perigos é a alimentação preparada nos lactários dos hospitais. Assim é evidente a importância de um sistema preventivo de controle de qualidade que garanta a segurança dos alimentos fornecidos para esses pacientes. Este trabalho teve o objetivo de avaliar perigos microbiológicos existentes no preparo de fórmulas infantis em lactário de hospital público, a fim de adequar o estabelecimento aos pré-requisitos necessários para posterior implantação do sistema Análise de Perigos e Pontos Críticos de Controle (APPCC). Esta avaliação foi feita através do diagnóstico das condições higiênico-sanitárias do estabelecimento e do estudo do fluxograma de preparo da fórmula láctea infantil (FLI) reconstituída, onde foram estabelecidos dez pontos amostrais, nos quais foram realizadas análises microbiológicas do ar, de equipamento e utensílios e da FLI em pó e reconstituída. As amostras foram coletadas em seis lotes de preparação, compondo um total de 60 amostras às quais foram realizadas determinações de coliformes totais e fecais, estafilococos coagulase positiva, Bacillus cereus, Salmonella, enterobactérias, e microrganismos aeróbios mesófilos e psicrotróficos totais. Os resultados das análises microbiológicas mostraram uma grande variação nas contagens dos microrganismos indicadores, porém nenhum dos microrganismos patogênicos analisados foi detectado pelos métodos utilizados. Todas as amostras da FLI em pó se mostraram adequadas para o consumo de acordo com a resolução legal vigente, porém as amostras das FLI reconstituída apresentaram contagens elevadas para a maioria dos microrganismos indicadores. A colher foi o único utensílio que se mostrou adequadamente higienizado em todas as determinações realizadas. As etapas de aquisição da matéria-prima; armazenamento sob refrigeração e aquecimento para distribuição, foram determinadas como pontos críticos de controle do processo. Com este estudo é possível concluir que a falta de pré-requisitos higiênico-sanitários durante o preparo da FLI reconstituída para lactentes, resulta em um produto microbiologicamente inadequado para crianças em estado de saúde debilitado e que a implantação do sistema APPCC só será possível se o estabelecimento se adequar a esses pré-requisitos
Abstract: Every day foodborne diseases put a lot of people's lives at risk, this being more severe in people with weakened health conditions, such as hospitalized children. For this target population, one of the main sources of foodborne diseases is the food prepared in the hospital lactaries. Thus the importance of a quality control preventive system that guarantees the safety of foods destined for these patients is evident. This work aimed to evaluate microbiological hazards existent in the preparation of infant formula in the lactary of a public hospital, in order to adapt the establishment to the necessary prerequisites for the subsequent implantation of the Hazard Analysis and Critical Control Point system (HACCP). This evaluation was made by diagnosing the hygienic conditions of the establishment and by studying the preparation flowchart of the reconstituted infant dairy formula (IDF), for which ten sampling points were established so as to make microbiological analyses of the air, equipment and utensils, and powdered and reconstituted IDF. The samples were collected in six preparation batches, giving a total of 60 samples, which were analysed for total and faecal coliformes, coagulase negative staphylococci, Bacillus cereus, Salmonella, enterobacteriae, and the total aerobic mesophilic and psycrotrophic microrganisms. The results of the microbiological analyses showed considerable variation in the quantity of the indicative microorganisms, but no pathogens were found by the methods used. All of the powdered IDF samples were appropriate for consumption according to the norms in force, but the reconstituted IDF samples presented high quantities of all the indicative microorganisms, except for faecal coliformes. The spoon was the only utensil that was found to be appropriately clean. The stages: acquisition of the powdered formula; storage under refrigeration and heating for distribution, were identified as the critical control points of the process. From this study it was concluded that the lack of hygienic prerequisites during the preparation of the reconstituted IDF for infants resulted in a microbiologically inadequate product for children in a weakened health condition, and that implantation of the HACCP system would only be possible after the establishment had adjusted itself to attend these prerequisites
Mestrado
Mestre em Tecnologia de Alimentos

Dissertation submitted in fulfilment of the requirements for the degree Master of Technology: Environmental Health in the Faculty of Applied Sciences at the Cape Peninsula University of Technology, 2011
The retail sector in South Africa is increasingly evolving into a dynamic industry, driven by changes in technology, saturating markets and globalisation. A major phenomenon in South Africa has been the evolution of hypermarkets, which sell large quantities of almost all consumer goods on a self-service basis. The South African consumers are becoming increasingly health conscious and, as such, the demand for wellness foods, health and convenience food has escalated. Convenience foods are expected to remain popular with consumers and supermarkets and will therefore increase the amount of ready-to-eat food items offered. As the retail industry has changed over the last two decades, so has the epidemiology of foodborne illnesses, with an increase in the incidence of bacterial infections caused by emerging organisms. In addition, there are certain food safety issues specifically associated with ready-to-eat foods. In recent years, incidences of enteric diseases associated with meat consumption have risen. The emergence of several new foodborne diseases has led to an increased focus attention on the issue of food safety by consumers and the industry. The most commonly implicated foods in these disease outbreaks have been meat and dairy products. The microbial load of eight convenience food manufacturing plants was determined by firstly sampling stainless steel food contact surfaces after they had been cleaned and sanitised at the end of a day‘s shift. The samples were analysed for Total Plate Count (TPC), Escherichia coli, Salmonella species and Staphylococcus aureus and Listeria. The results showed that 59 % of the total areas sampled for TPC failed to comply with the legal requirements for food surfaces specified in the South African Health Act (< 100 cfu.cm-2). Listeria was detected in 23 % of the samples taken and E.coli was found in 1.3 % of the samples, while S. aureus was not detected in any of the samples. Fifty percent of the plants applied conventional cleaning methods for cleaning and sanitation and the remaining 50 % used the low-pressure foam (LPF) method. The bacterial results of the two cleaning methods were statistically compared and a statistically significant difference (P ≤ 0.05) was found between the TPC means of the cleaning methods after cleaning. No statistically significant difference (P > 0.05) was found in terms of the Listeria species counts after both cleaning processes. The LPF method proved to be the superior cleaning option for reducing TPC counts. Secondly surface samples were collected from washed and sanitised dominant hands of food handlers and analysed for the presence of total plate counts, S. aureus and E. coli. The study aimed to evaluate the efficacy of hand washing practices and sanitation before commencing work. A total of 230 samples were collected, involving 100 % of the food handlers in selected convenience food outlets. The highest bacterial count taken from handswas 7.4 x 10-3 cfu.cm-2 and the lowest showed no detectable growth. Forty percent of the TPC analysed complied with the legal limit of < 100 cfu.cm-2 and only 18 % of the food handlers had no detectable bacteria present on their hands. One hand sample tested positive for E. coli, which is generally viewed as an indication of faecal contamination. S. aureus could not be detected on the hands of any of the food handlers. The results of this study indicated that hand hygiene is unsatisfactory and underlined the importance of further training to improve food handlers‘ knowledge of good hand washing practices. The study also aimed to present data on the food hygiene knowledge and practices of food handlers based on a representative sample from convenience food outlets in the Gauteng area. The management, as well as food handlers, were interviewed without prior announcement and managers were interviewed prior to starting their shifts, followed by food handlers, after they had passed through the change room and hand wash facilities. Although the majority of food handlers adhered to basic hygiene principles, the results highlighted a need for proper and continuous training in hygiene practices, not only for food handlers, but also for management. Furthermore, all food handlers should adhere to a formal cleaning schedule and specific courses should be planned for food handlers. Most training is done away from the workplace and the workers might find it difficult to translate theory into practice. Although food safety training programmes are essential, behavioural changes will not occur merely as a result of having received training but rather continuous development of food handlers. In conclusion, the popularity of convenience food is bound to increase with the growing appeal for modern foods. Consumers in South Africa nowadays demand good quality and safe products at a reasonable cost. Due to continuous time constraints, convenience food is the food of the future for the working mother. It is clear that managing foodborne disease is a challenge and an economic problem subject to various constraints. Food safety has too often become a hit-or-miss gamble, with parents obliged to roll the dice when it comes to the safety of their children‘s food and consumers in general. The food industry therefore needs to improve food safety processes to prevent the contamination of foods and use methods to ensure safe food for consumers. Better training, more testing and better methods of tracking food must be utilised to verify that the processes are working. This study endeavoured to add to the understanding and improvement of hygiene processes as well as food handlers‘ practices in the convenience food industry in the Gauteng Province.

A poluição, alteração física do habitat e a introdução de espécies invasoras via água de lastro, representam os maiores impactos antropogênicos para os ambientes costeiros. Foram pesquisadas em amostras da região costeira de S. Paulo, regiões portuárias brasileiras e de tanques de lastro de navios, bactérias das espécies Vibrio cholerae (Vc), V. parahaemolyticus (Vp) e V. vulnificus (Vv) que são as que têm maior implicação na saúde pública. As amostras foram avaliadas levando-se em conta parâmetros físico-químicos e microbiológicos e suas relações com a presença de Vc, Vp e Vv. As relações clonais foram verificadas através das técnicas de ERIC, BOX e REP-PCR. Foram identificadas 90 cepas de Vp e 11 de Vc. Foram observadas correlações entre alguns parâmetros microbiológicos e a presença de vibrios. A análise clonal permitiu verificar a alta diversidade das cepas. Concluiu-se que Vc e Vp são autóctones do ambiente costeiro brasileiro e podem ser tornar reservatórios para determinados fatores associados à virulência, gerando cepas com potencial epidêmico.
Pollution, physical alteration of habitat and the introduction of alien species through ballast water constitute the biggest anthropogenic impacts on coastal environments. We examined samples taken from the coastal region of S. Paulo state, Brazilian ports and ship ballast tanks, for bacteria of the species Vibrio cholerae (Vc), V. parahaemolyticus (Vp) and V. vulnificus (Vv) which have the most significant implication for public health. The samples were evaluated for microbiological and physical-chemical parameters as well as the presence of Vc, Vp and Vv. Clonal relationships of bacterial isolates were determined through ERIC, BOX and REP-PCR. A total of 90 strains of Vp and 11 of Vc were identified. Correlations between some microbiological parameters and the presence of vibrios were observed. The clonal analysis revealed extensive strain diversity. We concluded that Vc and Vp are autochthonous bacteria of the Brazilian coastal environment that can become reservoirs for factors associated with virulence, and are capable of generating strains with epidemic potential.

This thesis deals with the Air to Ground Heat Exchangers (AGHEx) and their effects on the hygienic quality of the supplied air and the microbial microclimate in the interior of buildings. The theoretical part focuses on current findings and knowledge in the field of warm air heating, ventilation of the low-energy and energy passive houses and ground heat exchanger for the ventilation systems to family houses. The next chapter deals with the quality of the indoor environment and the influence on HVAC systems on the building microclimate. The experimental part of the thesis presents the results of energy simulations of operation of air to ground heat exchanger, obtained using the simplified model, and the data from long-term monitoring of experimental AGHEx built at FME BUT. Furthermore, the results of microbiological research of several already operating air to ground heat exchangers are evaluated. The research was carried out using two different sampling methods: the method using swabs taken from the pipe wall, and the sedimentation (gravimetric) method. The conclusion part mentions the practical experiences of users and knowledge of the author relating to the design, operation and use of air to ground heat exchangers.

Diarrhoeal diseases remain a main cause of preventable death, particularly among children under five years of age in developing countries. In addition, many studies related to infant diarrhoea causation have demonstrated that the level of contamination is higher in weaning foods than in drinking water. Furthermore, many studies addressed food microbiological contamination and its role in diarrhoea causation. But few of them resulted in an intervention. Although the Hazard Analysis, Critical Control Point (HACCP) approach has been developed and widely applied to food promotion in industrialised countries, and adapted to small and/or less Developed Businesses, few studies have examined its relevance to domestic preparation of food. However, these latter predicted that the implementation of the approach could lead to an improvement of household bacteriological food safety, but none of them completed the approach to find out how effective it is. Therefore, this study aimed to take that work one step further, and carried out a small-scale intervention developed on the basis of the HACCP approach. This latter has been extended to health district level in order to find out its impact on microbial reduction in weaning food. Experiment: The HACCP approach has been applied step by step, to two selected weaning foods prepared by 15 volunteer mothers in peri urban Mali. After setting Critical Control Point (CCP), actions were taken to control, reduce or eliminate microbial growth at these points. 432 food samples were collected and analysed in local Laboratory for FC count to assess the effectiveness of the approach. Lessons learnt were translated into messages delivered in a pilot study. Pilot study: Sample of 60 volunteer mothers selected randomly was split into two groups of 30, the first undergoing messages directed to actions implementation, and the second standing as a control. Bacteriological samples were taken and analysed and physical parameters were measured,· as in the experiment, in 60 households before the intervention and data collected set as baseline. After three weeks training, alongside with observations, foods samples were taken in both intervention and control households for Fe count in local Laboratory. Flow diag~ams of foods, Moni and Fish Soup indicated that they were exposed to contamination at all steps of their preparation and handling. The hazard analysis confirmed FC contamtnation of all suspected steps except cooking. Four CCPs were identified for each food (cooking, reheating, child service with cooled food after cooking, and child service with cooled food after reheating). The experiment showed that traditional cooking was very effective in FC elimination; reheating was as effective as cooking when adopted, because no difference existed between two operations' temperatures (P<0.0001). Behavioural corrective actions were effective in controlling FC contamination at remaining CCPs (child service after cooking and child service after reheating). In conclusion, the HACCP experiment improved significantly the bacterial safety of the two type of weaning foods studied. Thus its behavioural corrective actions were translated into educational messages for the following phase aiming to confirm the effectiveness of the HACCP approach in improving foods safety at household level. The pilot study data showed the effectiveness of cooking in FC elimination at CCPs considered. A comparison of seasonal variation of FC contamination levels at CCPs showed that these levels were higher at Moni cooking CCP in December (cold season) (P<0.0004) and in August (rainy season) (P<0.0002), compared to June (dry season). They were also higher at Fish Soup storage CCP in December compared to August (P< 0.0098). There was significant difference in FC contamination levels between cooking and storage CCPs, the latter was higher than the former, for both Moni and Fish Soup (P< 0.0001). A comparison of FC contamination levels before and after intervention showed that the intervention was very effective in FC contamination reduction at the two remaining CCPs (service after cooking and service after reheating), (P<0.0001). Indeed, at the end of the intervention, contamination levels were less than 10FC/g in more than 83% of cooled food samples (prior to child service) after cooking and about 96% of cooled food samples (prior to child service) after reheating. An assessment of the intervention mothers' ability to perform actions three months later resulted in a better effect, 83 % to 100% of food samples' FC contam.ination levels met the standard. The present research findings showed that not only was the HACCP approach effective in improving home food safety but also, it was relevant for food hygiene and safety promotion in low income community. Two research questions were highlighted: firstly, could food safety improvement achieved through the HACCP approach result in diarrhoea morbidity and mortality reduction among young children? And secondly, is the approach scalable and cost effective?

Filamentous moulds may cause spoilage in raw materials, foods and feeds. Some of them synthesize mycotoxins which are a risk for human and animal health. For this reason, from the food safety point of view, only mycotoxins, as chemical hazards, are important. Nevertheless, despite the absence of direct correlation between mould growth and mycotoxins production, the prevention of fungal growth in raw materials and foods leads invariably to the prevention of mycotoxins presence. Due to the fact that moulds can contaminate foods from raw materials till end products, different strategies could be used at the different steps in the food chain. Preharvest strategies include the use of resistant varieties, crop rotation, soil preparation, optimal irrigation, fertilizer, herbicides, insecticides and chemical and biological agents application. Post-harvest strategies include improved drying and storage conditions, together with the use of natural and chemical agents. Predictive models may be used as a strategy to predict and prevent mycotoxigenjc fungal growth and mycotoxins accumulation. The present PhD work focused in two main strategies: a) The use of antifungals of natural origin to prevent from mycotoxigenic fungi and mycotoxins Equisetum arvense and Stevia rebaudiana extracts were analized as possible natural agents to inhibit growth and mycotoxin accumulation in in vitro and in vivo experiments. Both extracts were effective against mycotoxigenic moulds and the mycotoxigenic Aspergillus and Fusarium isolates studied were completely inhibited by a 3% of E. arvense. However, the effect decreased in the in vivo test. In the last case, Equisetum was effective against Aspergillus section Flavi and Fusarium section Liseola growth at high water activity levels and with high infection levels, but mycotoxins levels were not significantly affected. b) The assessment of the usefulness of predictive models to manage the mycotoxin problem In an initial experiment, four particular points which deserved in depth study to assess the viability of predictive microbiology in the moulds field were identified: 1) models should be developed for longer time periods; 2) food and raw materials prone to mycotoxin contamination are usually stored under marginal conditions for mould growth, thus performance of models should be checked under such conditions; 3) the impact of the inoculum size in the performance of the models; and 4) the impact of the potential intraspecies variability among isolates in prediction performance. Prediction of time to growth by kinetic models was clearly linked to inoculum size. On the other hand, the performance of predictive models may be compromised under marginal conditions for fungal growth, the higher variability of results under these conditions results in the need for a higher number of replicates required, specifically for kinetic models. For last, a high intraspecific variability on growth and mycotoxin levels has proven to be wider for the both isolates studies: A. carbonarius and P. expansum. For this reason, a greater number of strains should be included to develop models under non optimal condition for both, growth and for mycotoxin production. A matrix was built from which the number of strains and replicates to be planned for new experiments can be assessed for a reliable estimation of growth parameters and we conclude that increasing the number of strains in an experiment increases the explained variability much more than including further replicates. Finally, a first attempt was done to model aflatoxins production as a function of growth parameters and time. Aflatoxins accumulation was shown to be better correlated to colony area than either colony diameter or fungal biomass. Luedeking-Piret model was used for this purpose, and reasonable percentages of variability were explained. To conclude, probability models applied either to mould growth or mycotoxin production might be a valuable tool in food safety management through the food chain.

Mestrado em Microbiologia
Nos últimos anos, observou-se um aumento do consumo de alimentos prontos a comer em estabelecimentos de restauração a nível mundial. Consequentemente, a vigilância microbiológica dos alimentos produzidos nestas unidades tornou-se uma área de grande interesse do ponto de vista da Saúde Publica. O objectivo deste estudo foi avaliar a qualidade microbiológica dos alimentos prontos a comer (alimentos cozinhados, alimentos mistos e saladas) servidos em restaurantes, escolas e lares do Distrito de Aveiro. Esta avaliação foi realizada de acordo com a legislação elaborada pelo Instituto Nacional de Saúde Dr. Ricardo Jorge. O período de estudo foi de sete anos (2004 a 2010). Foram estudadas 3295 amostras de alimentos e 2031 amostras de utensílios utilizados na confecção dos alimentos. Os alimentos e utensílios foram submetidos e avaliados através de análises microbiológicas de quantificação de microrganismos a 30°C, bolores e leveduras, coliformes totais, E. coli, S. aureus, Clostridium e presença de Listeria e Salmonella. Os resultados mostraram que os alimentos mistos foram os que apresentaram maior percentagem de amostras não satisfatórias (41%). Dos três tipos de instituições estudadas os restaurantes foram os que apresentaram alimentos com pior qualidade microbiológica (25% de amostras não satisfatórias) e os lares foram as que apresentaram menos amostras não satisfatórias (14% de amostras não satisfatórias). Nas escolas a percentagem de amostras não satisfatórias foi de 15%. Os microrganismos a 30°C foram os que mais frequentemente ultrapassaram o valor legislado (em 19% das amostras). Os microrganismos patogénicos mais implicados na má qualidade dos alimentos foram os Staphylococcus aureus (ultrapassaram o valor limite em 1% das amostras). Durante o período de estudo observou-se um aumento progressivo da qualidade microbiológica dos alimentos prontos a comer. Apesar da implementação do sistema HACCP nos estabelecimentos de restauração em Portugal em 1998, a percentagem de alimentos prontos a comer, servidos nestes estabelecimentos, que apresentam má qualidade microbiológica é ainda muito alta (18% em média).
In recent years, emerged a trend of increasing consumption of ready to eat food in catering establishments worldwide. Consequently, the microbiological surveillance of food produced in these units has become an area of great interest from the point of view of Public Health. The aim of this study was to evaluate the microbiological quality of ready to eat food (cooked food, mixed food and salads) served in restaurants, schools and nursing homes in the District of Aveiro. This evaluation was performed in accordance with the rules established by the National Institute of Health Dr. Ricardo Jorge. The study period was seven years (2004 to 2010), and were analyzed 3295 samples of food and 2031 samples of cooking utensils. The food and cooking utensils were evaluated through microbiological quantification of microorganisms at 30 ° C, yeasts and molds, total coliforms, E. coli, S. aureus, Clostridium and presence of Listeria and Salmonella. The results showed that mixed food presented the highest percentage of unsatisfactory samples (41%). Of the three types of institutions studied, the restaurants were those with the worst microbiological quality of food (25% of unsatisfactory samples) and old nursing homes showed the best quality (14% of unsatisfactory samples). In schools the percentage of unsatisfactory samples was 15%. Microorganisms at 30 ° C were the parameter that more often exceeded the legislated value (19% of samples). The pathogenic microorganisms most commonly implicated in the poor quality of food were Staphylococcus aureus (exceeded the limit in 1% of samples). During the study period there was a progressive increase in the microbiological quality of ready to eat food. Despite the implementation of HACCP in restaurants in Portugal in 1998, the percentage of ready to eat food served in these establishments that present a poor microbiological quality is still very high (18% on average).

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Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
The pulp processing is a possibility for use of fruits by traditional people like the quilombolas, inserted in a context in which native fruits are little consumed. Therefore, the hygienic and sanitary quality is essential in the production of safe food. This study aimed to evaluate the processing and hygienic and sanitary conditions of fruits and fruit pulps in quilombola community. The survey was conducted in the Community of the Remnant of Quilombo do Pombal, Goiás, Brazil. To evaluate the physical and functional conditions was applied a checklist before and after the implementation of structural adjustments, training and implementation of the Manual of Good Practices and Standard Operating Procedures. Data were categorized according to the percentage of adequacy. Microbiological analyzes of 32 samples were taken including, fruits of Cerrado found in the community and fruits and their pulps in different steps of the flowchart production. The hazards and critical control points were listed in the production flow chart. The physical and functional diagnostic performed indicated average compliance of blocks of 30.18%, being classified in Group 3, unsatisfactory. After interventions, there was 62.13% of compliance, with classification in Group 2, regular (p <0.05). The intervention effect was significant (p <0.05) for five of the seven blocks evaluated. Microbiological analysis indicated that all the native fruits collected are in accordance with the recommendations of the current health legislation. Fruits and pulps included into processing flowchart presented in accordance with sanitary standards for fecal coliform count and detection of Salmonella spp, however, the mold count and yeast in eight pulps analyzed indicated that five of them had counts above the established by legislation. The results suggest fruit contamination since the harvest and multiplication of such micro-organisms in the remaining stages. The washing and filling steps were able to reduce the load of molds and yeasts. It is understood that the physical and functional adaptations implemented were important to increase the percentage of adequacy of the items, however, the persistence of shortcomings in the work process may compromise the quality of the final product, stressing the need for compliance with good practices.
O processamento de polpas constitui uma possibilidade para utilização de frutos por povos tradicionais como os quilombolas, inseridos em um contexto no qual frutos nativos são pouco consumidos. Para tanto, a qualidade higienicossanitária é fundamental na produção de um alimento seguro. O objetivo deste estudo foi avaliar o processamento e as condições higienicossanitárias de frutos e polpas de frutas em comunidade quilombola. A pesquisa foi realizada na Comunidade dos Remanescentes do Quilombo do Pombal, Goiás, Brasil. Para avaliação das condições físico-funcionais foi aplicada lista de verificação antes e após a realização de adequações estruturais, capacitações e implementação do Manual de Boas Práticas e Procedimentos Operacionais Padronizados. Os dados foram categorizados de acordo com o percentual de adequação. Foram realizadas análises microbiológicas de 32 amostras incluindo, frutos do Cerrado encontrados na comunidade e frutos e suas polpas em diferentes etapas do fluxograma. Foram elencados os perigos e Pontos Críticos de Controle no fluxograma de produção. O diagnóstico físico-funcional realizado indicou média de conformidade dos blocos de 30,18%, sendo classificado no Grupo 3, insatisfatório. Após intervenções, verificou-se 62,13% de conformidade, com classificação no Grupo 2, regular (p<0.05). O efeito da intervenção foi significativo (p<0,05) para cincos dos sete blocos avaliados. A análise microbiológica indicou que todos os frutos nativos coletados estão em conformidade com as recomendações da legislação sanitária vigente. Os frutos e polpas inseridos no fluxograma de processamento apresentaram-se de acordo aos padrões sanitários para contagem de coliformes termotolerantes e pesquisa de Salmonella spp, porém, a contagem de bolores e leveduras em oito polpas analisadas, indicou que cinco apresentaram contagem acima do estabelecido pela legislação. Os resultados sugerem contaminação do fruto já na colheita e a multiplicação destes micro-organismos nas demais etapas, sendo que as etapas de lavagem e envase foram capazes de reduzir a carga de bolores e leveduras. Entende-se que as adequações físico-funcionais implementadas foram importantes para o aumento do percentual de adequação dos itens, contudo, a persistência de falhas no processo de trabalho pode comprometer a qualidade do produto final, ressaltando a necessidade de adequação às boas práticas.

Foodborne illnesses place a burden on the entire society. One strategy to lower the costs of foodborne illnesses is to reduce the prevalence of foodborne pathogens through interventions along the food supply chain. There is an ongoing trend that food safety systems are moving towards performance-based regimes, which rely on the implementation of food safety standards. However, the implementation of food safety standards has not garnered much interest in the Canadian policy environment. The assessment of food safety interventions to achieve a standard is challenging as the underlying biological processes are complex, the costs of administering such interventions are not abundantly clear and the set of available interventions is changing. This thesis investigates the cost-effectiveness of food safety interventions and specifically the applicability of a food safety standard. First, a theoretical model is developed to investigate how; in theory cost-minimization can be used to identify the most cost-effective way to reduce foodborne pathogens with the utilization of a food safety standard. Then, a specific framework is developed for Campylobacter in chicken that consists of interrelated simulation models that represent the level and flow of pathogens through a commodity supply chain, the impact of alternative interventions on pathogen load and their costs. The case study focus is Ontario, Canada. Different interventions are compared and evaluated based on their compliance with a food safety standard. The applicability of different cost-effectiveness measures is assessed.

In many countries, the authorities face extreme difficulties in monitoring and ensuring that food sold on the street is safe, that is, fit for human consumption. This is particularly the case in urban areas, where people buy food on the street because it is readily available and relatively inexpensive. The objective of this study was to determine the food safety knowledge and microbial hazard awareness of street food consumers, and to assess the bacteriological quality of selected ready-to-eat foods sold by street vendors in the Johannesburg municipality. A cross-sectional survey study was conducted and a total of 402 respondents who buy and consume street-vended foods were randomly selected at various street food vending locations. A total of 315 various street-vended samples were purchased from randomly selected street food vendors at different vending locations in Johannesburg metropolis, in order to investigate the bacteriological quality of street-vended foods. Results of the bacteriological analysis revealed that total aerobic counts ranged from 0.3*102 - 0.4*105 cfu/g in cereals and grain-based foods; 0.4*102 - 0.5*105 cfu/g in meat-, dairy- and fish-based foods and 0.7*102 - 0.9*104 cfu/g in fruit- and vegetable-based foods. None of the food samples tested positive for Salmonella spp and Staphylococcus aureus. Results of the survey showed that the majority of respondents were black males younger than 35 years. Individuals of different gender, race, level of education and monthly income groups significantly (p<0.05) differed in their responses regarding the frequency of purchasing and confidence in the safety of street-vended food. Better taste followed closely by affordability and accessibility were the most cited reasons for purchasing street-vended food
Life and Consumer Sciences
M. Sc. (Life Sciences)

"Salpicão de Vinhais" and "Chouriça de Vinhais" are traditional dry-fermented smoked meat sausages produced in Vinhais, a small region of Trás-os-Montes. The scientific knowledge of this sausage variety is limited. This work aims to collect scientific data that could, partially, fill the gaps in knowledge regarding these products, analyse the data and develop a risk-based study, according to an internationally accepted framework and finally, to explore the effect of hypothetical risk management measures on the safety of consumers, regarding traditional dry fermented meat smoked sausages. Seventy seven samples of ―Salpicão‖ and ―Chouriça de Vinhais‖ were purchased from producers, local markets and retail stores. Their microbiological and physical chemical characteristics were analyzed. The same analyses were performed on the products during the production processes. The raw materials and ingredients were also analyzed. Regarding the pathogenic flora, Staphylococcus aureus, spores of sulphite-reducing clostridia, Escherichia coli 0157:H7, Yersinia spp. and Salmonella spp., were not detected in any of the samples analyzed; Listeria monocytogenes was detected in 14.3% of the samples. The manufacturing process, namely fermentation, ripening/drying and smoking reduced the numbers of pathogen and hygiene indicator microorganisms. According to the Commission Regulation (EC) 2073/2005, 39% of the contaminated samples of ―Salpicão‖ and ―Chouriça de Vinhais‖ were able to support growth of L. monocytogenes. A quantitative microbiological risk assessment using a probabilistic model was developed. Considering the Portuguese population, with data obtained in this work, the calculated risk of listeriosis, for the intermediate age sub-population was 0.1297 cases per year, for the perinatal sub-population, 1.3695 cases per year, and elderly sub-population 0.1995 cases per year. This means that Traditional Dry Fermented Smoked Sausages constitute a low risk for the Intermediate Age and Elderly population (less than 1 case per annum) and an intermediate risk for the Perinatal populations, considering this last group of consumers as adult pregnant women (1-10 cases per annum). The effect of several putative risk management actions such as the adoption of a Performance Objective of 10 CFU/g, 1 CFU/g and 0.04 CFU/g reduced the risk of listeriosis for all sub-groups, at the end of shelf life, by 25.5%, 58.4% and 58.6%, respectively. The effect of bacteriocinogenic strain of Pediococcus acidilactici HA6111-2, previously isolated from ―alheira‖, was studied on both ―Salpicão‖ and ―Chouriça‖, in a challenge test against a cocktail of Listeria innocua, at pilot scale. A reduction of the numbers of Listeria innocua was achieved in all batches, being the biphasic equation the model that gave the better fit. The use of a bacteriocinogenic strain added to the batter reduced the risk of listeriosis for all sub-groups by 26.7%; obtaining a final product with aw below 0.92, supposedly below the growth limits of L. monocytogenes, reduces the risk by 8.6% in all sub-groups of population; the combination of the bacteriocinogenic strain and the limit of aw 0.92 reduces the risk by 41.0%. Traditional dry fermented smoked sausages present low to medium risk to the health of consumers. The use of more restrictive Performance Objectives during processing and/or distribution will result in a further reduction of risk. A more rigorous control of final product water activity and the use of a bacteriocinogenic bioprotective culture during production may contribute significantly to reducing the risk of listeriosis in consumers of these Traditional Dry Fermented Smoked Sausages (TDFSS).
O Salpicão de Vinhais e a Chouriça de Vinhais são enchidos fermentados, secos e fumados, produzidos em Vinhais, uma pequena região de Trás-os-Montes. Este trabalho pretende recolher dados científicos que possam preencher, ainda que parcialmente, os lapsos no conhecimento deste tipo de produtos, de acordo com uma abordagem aceite internacionalmente e, finalmente, explorar o efeito potencial que as medidas de gestão de risco podem ter na segurança dos consumidores, relativamente a enchidos tradicionais, fermentados, secos e fumados. Setenta e sete amostras de ―Salpicão‖ e ―Chouriça de Vinhais‖ foram compradas em produtores, mercados locais e hipermercados. As suas características microbiológicas e físico-químicas foram analizadas. As mesmas análises foram realizadas ao produto em curso, em diferentes fases do processo produtivo. As matérias-primas e ingredientes também foram analisadas. Relativamente à flora patogénica, não foram detectados esporos de Staphylococcus aureus, esporos do género Clostridia sulfito-redutores, Escherichia. coli 0157:H7, Yersinia spp. e Salmonella spp; Listeria monocytogenes foi detectada em 14.3% das amostras. O processo de fabrico, nomeadamente fermentação, maturação/secagem e fumagem reduziram o número de patogénicos e microrganismos indicadores de higiene. De acordo com o Regulamento da Comissão (CE) 2073/2005, 39% das amostras de ―Salpicão‖ e ―Chouriça de Vinhais‖ contaminadas eram capazes de permitir o crescimento de L. monocytogenes. Foi desenvolvida uma avaliação quantitativa de risco microbiológico. Considerando a população portuguesa, com os dados obtidos neste trabalho, o risco calculado de listeriose seria de 0.1297 casos por ano para a população de idade intermédia, 1.3695 casos por ano para a sub-população perinatal, e 0.1995 casos por ano para a sub-população sénior. Isto significa que Enchidos Tradicionais Secos, Fermentados e Fumados constituem um alimento de baixo risco para para a população de idade intermédia e população sénior (menos de 1 caso por ano) e são um alimento de risco intermédio para a população perinatal, ou seja, mulheres grávidas adultas (entre 1 a 10 casos por ano). A adopção de um Objectivo de ―Performance‖ de atingir 10 UFC/g, 1 UFC/g e 0,04 UFC/g no produto final reduziram o risco de listeriose para todos os sub-grupos da população, em 25.5%, 58.4% e 58.6%, respectivamente. O efeito da estirpe bacteriocinogénica de Pediococcus acidilactici HA6111-2, previamente isolada em alheira, foi estudada tanto no Salpicão como na Chourila de Vinhais, num ―challence test‖ contra um cocktail de Listeria innocua, à escala piloto. Foi observado, em todos os lotes, uma redução dos números de Listeria innocua, abaixo do limite de detecção (1.5 log UFC/g), A equação bifásica foi que forneceu o melhor ajuste da redução dos números de Listeria innocua, devido ao da estirpe bacteriocinogénica de Pediococcus acidilactici HA6111-2. A aplicação de uma estirpe bacteriocinogénica à adoba reduziu o risco de listeriose, em todos os sub-grupos populacionais em 26.7%; obter um produto final com aw inferior a 0.92 reduziu o risco de listeriose, em todos os sub-grupos populacionais em 8.6%; a combinação destes dois factores reduziu o risco de listeriose, em todos os sub-grupos populacionais em 41.0%. Os Enchidos Tradicionais Secos, Fermentados e Fumados apresentam um risco baixo ou médio para a saúde dos consumidores. A aplicação de Objectivos de ―Performance‖ durante o processamento e/ou distribuição resulta numa redução do risco. Um controlo mais rigoroso da actividade de água do produto final e o uso de uma cultura bioprotectiva bacteriocinogenica durante a produção, podem contribuir para reduzir significativamente o risco de listeriose nos consumidores deste tipo de produto tradicional.

In the following study, the potential role that microorganisms play in the removal of Mn (II) and Fe (II) was assessed using biofilter sand and water samples collected from a biofiltration system (operated by Umgeni Water in KwaZulu-Natal, Nottingham Road, at the Nottingham combined school, South Africa) treating borehole water containing manganese and iron. Initially the presence of Mn (II) and Fe (II) oxidizing bacteria was demonstrated in the biofiltration system. Thereafter, the contribution of individual microorganisms to the overall removal of manganese and iron was assessed in the laboratory by determining the difference in metal oxidation in the presence and absence of active bacteria at neutral pH, simulating conditions in the biofilter. Controls were run to verify the elimination via physiochemical reactions occurring within the biofiltration system. Finally a diversity snapshot of the bacteria present within the biofilter matrix was established via analysis of a clone library. Viable bacterial counts for the biofiltration system were established using MSVP (minimal salts vitamins pyruvate) medium - plus added manganese sulfate or iron sulfate targeting Mn (II) and Fe (II) oxidizing bacteria - and R2A for heterotrophic bacteria. In the first experimental chapter, batch tests using MSVP were employed to determine manganese oxidation, by measuring the pH and ORP (oxidation reduction potential) in experimental flasks and controls over time. There was a clear drop in pH and a concomitant increase in ORP when an isolated manganese oxidizing strain (designated LB1) was grown in MSVP plus added manganese sulfate, indicating manganese oxidation. Based on physiological characteristics established by the VITEK-2 system as well as by 16S rRNA gene sequence analysis and MALDI-TOF (Matrix assisted laser desorption ionization-time of flight mass spectrometry) mass spectrometry of cell extracts, the isolate was identified as a member of the genus Acinetobacter. EDX (energy dispersive X-ray analysis) analysis of crystals formed in batch culture tests, containing MSVP plus either added manganese or iron sulfate, confirmed the ability of the isolate to oxidize both Mn (II) and Fe (II). The leucoberbelin blue colorimetric assay and batch tests using MSVP both demonstrated that in the presence of the isolated strain, Acinetobacter sp. LB1, the rate of Mn (II) oxidation at neutral pH was enhanced as compared to abiotic controls. In the second experimental chapter the difference in Fe (II) oxidation between biological and abiological systems at neutral pH was determined using batch tests run with Acinetobacter sp. LB1 and Fe (II) in saline. In addition, the rate of Fe (II) oxidation was also determined at acidic pH and at alkaline pH in experimental and control flasks. To determine Fe (II) removal under conditions simulating those in the biofiltration system, batch tests were set up using borehole water freshly collected from the biofiltration system. In order to verify the contribution of native microorganisms in the borehole water to Fe (II) oxidation, these flasks were spiked with bacterial strains isolated from the biofiltration system - Acinetobacter sp. LB1 and Burkholderia sp. strain LB2 - and two known iron oxidizing strains Leptothrix mobilis (DSM 10617) and Sphaerotilus natans (DSM 565) were used to determine the contribution of reference iron oxidizers to Fe (II) oxidation. A separate set of the same flasks with the addition of filter sand was used to qualitatively demonstrate iron oxidation as it would occur within the biofiltration system. The ferrozine assay was employed to quantify the amount of Fe (II) in batch tests employing saline medium and in batch tests employing borehole water. EDX analysis was employed to confirm the presence of Fe (II) in oxidation products in the batch test flask with filter sand spiked with Acinetobacter sp. LB1. In the presence of Acinetobacter sp. LB1 at neutral pH in saline medium, the rate of Fe (II) oxidation was very similar to that in the abiological controls thus demonstrating that the presence of metabolically active microorganisms does not per se enhance the oxidation of Fe (II) like in the case of Mn (II) at neutral pH. Surprisingly, in the heat inactivated control, apparently the highest amount of Fe (II) was oxidized. As expected, at acidic pH very little oxidation of Fe (II) took place and at alkaline pH almost all Fe (II) in the flasks was removed and small amounts oxidized as determined by the amount of Fe (III) produced. Batch tests using borehole water proved that native microorganisms within the biofiltration system were more efficient in the oxidative removal of Fe (II) from the system, in comparison to the reference iron oxidizing strains. In the final experimental chapter, the presence of biofilms with actively metabolizing cells was examined on a pooled sample of biofilter matrix from the manganese and iron filter using CLSM (confocal laser scanning microscopy) image analysis. DNA was extracted from the biofilm material associated with biofilter matrix to establish a diversity snapshot of the bacteria present within the biofilter matrix. ARDRA (amplified “rDNA” restriction analysis) analysis of the clone library revealed the presence of 15 unique OTU’s (operational taxonomic unit) based upon restriction patterns of amplified 16S rRNA genes of a total of 100 randomly selected clones. The majority of the clones were closely related to the genera Nitrospira and Lactococcus. Overall, 42% of the clones were assigned to the phylum Proteobacteria, 13% to the phylum Actinobacteria, 24% to the phylum Firmicutes and 21% to the phylum Nitrospirae. Overall, the results demonstrate that bacteria present within an established biofiltration system at neutral pH can contribute to the oxidative removal of Mn (II) and, apparently only to a smaller degree, to that of Fe (II) present in borehole water and that species within the proteobacterial genus Acinetobacter are potentially involved in the geochemical cycling of these two metals. Keywords: Biofiltration, iron and manganese oxidation, Acinetobacter sp. LB1, batch tests, 16S rRNA, MALDI-TOF MS analysis, Mn (II) and Fe (II) colorimetric assays, EDX analysis, biofilm formation, CLSM image analysis, 16S rRNA clone library Abbreviations: MSVP (minimal salts vitamins pyruvate), ORP (oxidation reduction potential), EDX (energy dispersive X-ray analysis), MALDI-TOF MS (Matrix assisted laser desorption ionization-time of flight mass spectrometry), rRNA (ribosomal RNA), ARDRA (amplified “rDNA” restriction analysis), CLSM (confocal laser scanning microscopy), OTU (operational taxonomic unit)
Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.