Caracterização microbiológica de géneros alimentícios em estabelecimentos de restauração. Caracterização de alimentos e identificação de factores de risco

Mestrado em Engenharia Zootécnica - Produção Animal - Instituto Superior de Agronomia / Faculdade de Medicina Veterinária

Microflora of food products is greatly influenced by the production process and by intrinsic and extrinsic characteristics of the products. Contamination of foods can be of endogenous or of exogenous origin. The first dues to the commensal flora or pathogens presents in the raw material and, the second takes place at different stages of the food processing through contact with soil, water, waste water, environment, cross-contamination, inadequate heat treatment, inadequate storage, handlers, surfaces, animal feed, insects and pests. In order to reduce or eliminate contamination of food it is necessary the application of control measures to assure the food safety and the warranty of the public health. This objective can be achieved using physical factors such as temperature, irradiation or the acidification but mainly by the application of appropriate hygiene practices at all stages of the food production. Relevant microorganisms studied in this work were the foodborne pathogens. They present different characteristics in growth and survival conditions, toxins production, pathogenicity and symptoms of disease. Predominant species are: Staphylococcus spp., Clostridium perfringens, Clostridium botulinum, Bacillus cereus, Listeria monocytogenes, Salmonella spp., Shigella spp., Escherichia coli, Campylobacter spp., Vibrio spp. and Yersinia spp. These types of microorganisms are responsible for three types of foodborne diseases: intoxication - the microbial toxins are pre-formed in food; infection - ingestion of microorganisms, and toxi-nfection - ingestion of pathogens in high quantity, proliferation and production of toxins in the digestive tract of the individual. The scope of this study was the microbiological analysis of 1981 analytical surveys for samples of ready-to-eat foods served at a restaurant in 2006, seasonal analysis, identification of risk factors and identification of control measures. With this purpose was performed a database in the Microsoft Office Access software with the information of the microbiological parameters analyzed at the “Centro de Formação Profissional de Segurança Alimentar” (CFPSA). For the classification of the level of microbiological quality were considered the Guide Values of the National Health Institute Dr. Ricardo Jorge (INSA). These guide values are organized in three categories, G1 (Meals/sandwiches/cakes/desserts with fully cooked ingredients, or added with spices, dried herbs, dehydrated or treated with ionizing radiation, UHT products and industrialized mayonnaise), G2 (cooked meals/sandwiches/cakes/desserts added of raw ingredients and/or with own specific flora) and G3 (raw salads/vegetable/fruit. Data were entered on the following microbiological parameters, for 1174, 298 and 509 foods belonging to the groups G1, G2 and G3,respectively: mesophiles (ufc/g), molds (ufc/g), yeasts (ufc/g), total coliformes (ufc/g), Escherichia coli (ufc/g), coagulase-positive Staphylococcus (ufc/g), Salmonella (25g) e Listeria monocytogenes (25g). For statistical analysis was used the SAS software (SAS Institute, version 9.1, Cary, NC) and, for the comparison between levels of microbiological quality, was used the chi-square method, for a significance level of 0, 05. The results showed that most foods, regardless of group, and for all analyzed parameters showed satisfatory and acceptable levels of microbiological quality with a small proportion of unsatisfactory and unacceptable. The foods most frequently characterized as unsatisfactory were due to the numbers of total coliforms (21,10%) (mainly for the G1 (9,34%) and G3 (8,18%) groups), and mesophiles (12,57%) (with the majority being of G1 (9,49%) group); moulds and yeasts counts showed similar proportions and G3 was the food group for which the occurrence of molds was more frequent while for yeasts there was no food of the G3 group with counts at this level of quality, being the foods of G2 group the most common (2,22%); the foods with Escherichia coli (3,94%) were mostly belonging to the G1 group (2,52%); those with Staphylococcus coagulase-positive had lower proportions (1,26%). Foods classified as unacceptable were found: in a sample of roast beef with coagulase-positive Staphylococcus, a sample of “Frango à Brás” with Salmonella and 2.25% of the samples with Listeria monocytogenes (12, 7 e 6 of the G1, G2 e G3 groups, respectively). The seasonal analysis showed that foods with mesophilic, molds, yeasts and total coliforms mainly occurred in the second and third quarters of the year. The differences were significant for the G1 and G3, G1 and G2, G2 and G3 groups of foods, respectively. This difference may be associated with higher temperatures at this time of year In conclusion, it can be said that most foods, regardless of the group to which they belong, were satisfactory and acceptable and, despite the low proportion of unacceptable, these are a risk for the public health.----------------------------------------O âmbito deste estudo visou a caracterização microbiológica de alimentos, análise sazonal, identificação de factores de risco e formas de controlo. Considerando 1981 boletins analíticos (1174, 298 e 509 dos grupos G1, G2 e G3, respectivamente) do Centro de Formação Profissional de Segurança Alimentar relativos a 2006, criou-se uma base de dados em sistema informático Microsoft Office Access 2003. Os resultados foram analisados em programa informático SAS e método do Qui-quadrado baseando-se nos Valores Guia do Instituto Nacional de Saúde Dr. Ricardo Jorge. Verificou-se uma reduzida proporção de alimentos não satisfatórios e inaceitáveis. Tal deveu-se aos coliformes totais (21,10%) dos quais a Escherichia coli representou 3,94% (principalmente do G1), à flora mesófila (12,57%) (frequentemente no G1), a bolores e leveduras (3,63% e 3,33%, respectivamente) e a Staphylococcus coagulase-positiva (1,26%). Os inaceitáveis verificaram-se para Staphylococcus coagulase-positiva e Salmonella em carne assada e Frango à Brás, respectivamente; Listeria monocytogenes (2,25%) ocorreu em 12, 7 e 6 alimentos de G1, G2 e G3, respectivamente. A maior proporção de alimentos com mesófilos totais, bolores, leveduras, coliformes totais e Escherichia coli ocorreu no segundo e terceiro trimestres. Concluindo, a maioria dos alimentos foram satisfatórios e aceitáveis representando os inaceitáveis um risco para a saúde pública de gravidade considerável.