Monitorização da qualidade da água de barragens com redes neuronais artificiais

The water quality control of dams is fundamental, since these constitute indispensable renewable water resources for a variety of purposes. A feasible low cost approach for monitoring water quality bio-optical quantities is to use satellite spectral measurements that allow to continuously and globally follow the evolution of the water surface spectral reflectance. The present approach takes advantage of the Medium Resolution Imaging Spectrometer (MERIS) measurements, onboard ENVISAT satellite, as well as of the in situ samples of chlorophyll-a, cyanobacteria and total suspended solids (TSS), regularly collected and analysed. The method is applied to Alqueva dam the largest artificial lake in Europe in terms of surface area (250 km2), located in the south of Portugal (Alentejo). It is based on the use of a neural network that, after trained with a proper set of data, is capable of predicting the concentrations of the bio-optical parameters from the atmospherically corrected satellite spectral radiance

Role of Starter Cultures on the safety of fermented meat products

Starters are microbial cultures used to promote and conduct the fermentation of meat products. Bacteria, particularly lactic acid bacteria (LAB) and coagulase-negative staphylococci (CNS), as well as yeasts and molds, may be used as starters. They can increase the safety of fermented meat products by means of rapid matrix acidification or due to the production of antimicrobial substances, such as bacteriocins. Besides, starters may help to standardize product properties and shorten ripening times. Safety of fermented meat products may be jeopardized by microbiological, namely foodborne pathogens (Salmonella spp., Listeria spp., etc), and chemical hazards, particularly biogenic amines, nitrosamines, polycyclic aromatic hydrocarbons (PAH), and mycotoxins. Biogenic amines (BA) are potentially unsafe nitrogenous compounds that result from the decarboxylation of some amino acids. Some microorganisms may be responsible for their formation. Starters can cause a fast pH decrease, inhibiting the development of microorganisms with amino acid decarboxylative ability, thus preventing the accumulation of BA in fermented meat products. Besides, starters can compete with the autochthonous, non-starter microbiota throughout ripening and storage, thus reducing BA production. Some strains of Lactobacillus sakei and Lactobacillus plantarum have been shown to reduce the formation/accumulation of BA. On the other hand, Staphylococcus xylosus and Debaryomyces hansenii strains have been reported to degrade BA in food. PAH are organic compounds containing multiple aromatic rings and produced by the incomplete combustion of organic matter, such as the wood used for smoking meat. Mixed starters containing Lactobacillus spp., Gram-positive catalase-positive cocci and yeasts have been used in the manufacturing of traditional meat sausages. However, the effect of starters on reducing the accumulation of PAH is poorly understood. Starters may also be engaged in competitive exclusion, outcompeting the spoiling or deteriorating autochthonous microbiota. For example, Pediococcus acidilactici has been shown to inhibit Listeria monocytogenes in meat products. Additionally, the role of molds, such as Penicillium nalgiovense in the competitive exclusion of undesired filamentous fungi, has also been demonstrated. Most of these undesired fungi produce mycotoxins, secondary metabolites capable of causing disease. The current review addresses the role of starters on the microbiological and chemical safety of fermented meat products

Qualidade do Leite de Ovelha

O Regulamento (CE) nº 853/2004, que estabelece as regras de higiene específicas para os produtos de origem animal, na Secção IX – III do Anexo III, define os critérios microbiológicos a que deve obedecer o leite cru. Segundo este Regulamento, para o leite de vaca, são estabelecidos critérios para a carga microbiológica, mesófilos viáveis totais (MVT) e para a conta gem de células somá cas (CCS). Já no que se refere a outros leites que não de vaca, onde se inclui o leite de pequenos ruminantes, só é definido um critério para a carga microbio lógica, não havendo qualquer referência a CCS.Parece nos fundamental que seja estabelecido um critério para a CCS no leite de ovelha, pois será a única forma de garan r que o leite que entra na cadeia alimentar não é proveniente de animais com mas te. Eventualmente, pode rão ser implementados incen vos económicos que sirvam de es mulo aos produtores

Animal Health, Biosafety and Food Safety

Pork meat and processed pork meat products may carry some hazards that threaten the consumer’s health. These hazards are related with animal health or with the way in which the raw materials are manipulated during slaughtering and manufacturing until the consumption. Substances having anabolic effects, the residues of veterinary drugs and chemical contaminants, some of them with origin in animal production but others produced during the transformation processes should be considered among chemical hazards. Concerning biological hazards, we can mention some parasites like Toxoplasma gondii, Trichinella spiralis, Taenia solium and also some bacteria like Salmonella spp., Campylobacter spp., Yersinia enterocolitica and Listeria monocytogenes. The physicochemical characteristics of fresh meat further facilitate the growth of various microorganisms, other than those mentioned above, which turns it into a highly perishable product. Several transformation processes of the raw material, provide different food products to consumers and constitute ways to increase its shelf-life. Drying, fermentation and cure are among these processing methods. In Portugal there is a wide variety of processed meat products, such as Chouriço, Paio, Presunto, Salsichão and Catalão many of them manufactured according to traditional techniques of their regions of origin. Some of these products have been studied at the Universidade de Évora. Some results, which show the favourable effect of a range of transformation processes in controlling some of the mentioned biological hazards, will be presented

Addition of vinegar to "cabeça de xara" made from Alentejano pig meat increases shelf life

“Cabeça de xara” is a very typical product from Alentejo region. It’s a very particular type of galantine, made from meat, tongue and connective tissue removed from Alentejano pig breed heads. Usually this product has a parallelepiped shape, as those used in the present study, with 40 cm length and 14 cm height. The aim of this study was to evaluate the use of vinegar to increase the products’ shelf life without negatively affecting the physicochemical and microbiological parameters, as well as its sensorial attributes. Two different treatments were compared, namely control and vinegar, for three months using end product “cabeças de xara”. Three batches with two replicates per treatment were used. One-Way ANOVA was used for statistical analyses. The mean pH of the “cabeças de xara” with vinegar (5.48) was lower than the pH of the control treatment (6.05). However, no significant differences were observed between control and vinegar treatments regarding water activity (aw). The microbiological flora of the “cabeças de xara” showed no significant differences regarding yeasts and moulds. The counts of total mesophiles, psychrophiles, psychrophilic anaerobes and enterobacteria were higher in the control treatment. Only a few samples showed a minor contamination with Listeria monocytogenes. As expected, the counts for all microbial groups increased with time. Regarding sensorial analysis, panellists generally gave higher scores to the control “cabeças de xara”, however no differences were observed between control and vinegar “cabeças de xara” concerning the attributes marbled and colour and aroma intensity. Considering the results of the end product at three months shelf life, the vinegar “cabeças de xara” showed lower microbial counts, probably due to the lower pH values. Our data suggest that the sensorial panel prefers the control “cabeças de xara”; however, the panellists did not taste some of the control products due to contamination with Listeria monocytogenes. To our knowledge, this is the first report on the physicochemical, microbiological and sensorial characteristics of such a traditional product. Acknowledgements This work was supported by national funds through project PRODER (QREN/PRODER/Medida 4.1) and funded by FEDER Funds through the COMPETE and National Funds through FCT under the Strategic Project PEst-C/AGR/UI0115/2011. The authors thank PALADARES ALENTEJANOS, Lda. for their collaboration and A. Oliveira and G. Pias for their technical assistance

Safety conditions and native microbial flora of three processing units in Alentejo , Portugal

Portugal as other Mediterranean countries has a great diversity of dry fermented sausages. This traditional sausage production is highly diverse and products possess very particular organoleptic characteristics, which please consumers. These sensory characteristics are related not only to the manufacturing process, but also to the house microbial flora. On the other hand, the safety of fermented products is always difficult to achieve due to their processing technology and final characteristics, as the process does not have any step able to undoubtedly eliminate pathogens, according to HACCP approach. In this kind of products, coagulase negative staphylococci (CNS) and lactic acid bacteria (LAB) are present in high levels. These bacteria are responsible for the particular taste and flavour and also for extending the shelf life of sausages. LAB are useful particularly for the ability to produce bacteriocins that are generally active towards several foodborne pathogens, such as Escherichia coli, Listeria monocytogenes and Salmonella sp., while CNS are mainly nitrate reducers, thus contributing to flavour development. The aim of this study was to determine the occurrence of Salmonella sp., L. monocytogenes and E. coli in different surfaces of the three visited processing units as well as in meat batters, half ripened and final products (Portuguese traditional sausages). Furthermore, we also evaluated the total number of mesophiles in each surface and product, as well as the number of CNS and LAB. Surfaces were generally well hygienised, only a few presenting with low contamination levels by L. monocytogenes and E. coli. No contamination with Salmonella sp. was detected in the diverse analysed products independently of their processing stage. However, different contaminations levels with L. monocytogenes and E. coli were found in distinct processing units

MEDIÇÃO ESPECTRAL DO COEFICIENTE DE ATENUAÇÃO DE ÁGUAS INTERIORES

Changes in the water surface composition may affect the optical properties of the water column. In addition, the light penetration in the water body is affected by absorption and scattering processes resulting in spectral intensity changes along the water column. Underwater measurements of spectral downwelling radiance were performed at several depths in order to compute the water column spectral attenuation coefficient. Results show that the spectral downwelling radiance is highly dependent on solar zenith angle, water composition and wind speed. Spectral attenuation coefficient was computed whenever a stable logarithmic profile of downwelling radiance was achieved

QUALIDADE DA ÁGUA DA ALBUFEIRA DE ALQUEVA

The water quality control of reservoirs is fundamental since these constitute indispensable renewable water resources for a variety of purposes. A feasible low cost approach that allows for, continuously and globally, monitoring water quality bio-optical quantities was developed through the combination of satellite retrieved water surface spectral reflectance and limnological laboratory analyses. The present approach takes advantage of the Medium Resolution Imaging Spectrometer (MERIS) measurements, onboard ENVISAT satellite, as well as of the in situ samples of chlorophyll a, cyanobacteria and turbidity, regularly collected and analysed. The method is applied to Alqueva reservoir with a surface area of 250 km2, located in the south of Portugal (Alentejo)

Campylobacteriosis in beef cattle in Alentejo – preliminary assessment

The aim of this study was to assess the prevalence of infection by Campylobacter fetus in beef cattle reared in extensive systems in Alentejo region by direct fluorescent antibody test (DFAT), a technique widely used for determining the prevalence of this disease

Qualidade e Segurança Alimentar em unidades fabris produtoras de enchidos no Alentejo

Portugal, tal como outros países do Mediterrâneo, tem uma grande diversidade de enchidos secos fermentados. A produção tradicional de enchidos é muito diversa e os produtos possuem caraterísticas organoléticas muito particulares que agradam aos consumidores. Estas caraterísticas sensoriais estão relacionadas não só com os processos de fabrico, mas também com a flora microbiana autóctone. Por outro lado, a segurança dos produtos fermentados nem sempre se atinge com facilidade uma vez que no seu processamento não existe uma etapa que elimine os agentes patogénicos. Neste tipo de produtos estão normalmente presentes bactérias benéficas como estafilococos coagulase negativos e bactérias do ácido lático (BAL). Estes grupos bacterianos são responsáveis pelo sabor e aroma caraterísticos dos enchidos e também por aumentarem o seu tempo de vida de prateleira. De um modo geral, as estirpes dos referidos grupos bacterianos têm um papel muito importante para a segurança alimentar porque, se bem adaptados aos substratos, por exclusão competitiva condicionam o crescimento de microrganismos patogénicos e alterantes. As BAL são particularmente úteis pela sua capacidade produtora de ácido láctico e, em alguns casos, de bacteriocinas geralmente ativas contra agentes patogénicos, tais como Escherichia coli, Listeria monocytogenes e Salmonella spp., enquanto os estafilococos coagulase negativos são principalmente redutores de nitratos, contribuindo assim para o desenvolvimento da cor. O objetivo deste trabalho foi determinar a ocorrência de Salmonella spp., L. monocytogenes e E. coli em diferentes superfícies (parede da sala de enchimento, picadora, misturadora e enchedora) de três fábricas, bem como em enchidos tradicionais Portugueses em diferentes fases de cura: massa, meio da cura e produto final. Adicionalmente foram avaliados o número de microrganismos mesófilos em cada superfície e produto, bem como o número de estafilococos coagulase negativos e BAL. Em geral as superfícies apresentavam-se higienizadas, no entanto algumas mostraram níveis baixos de contaminação com L. monocytogenes e E. coli. Não foi detetada qualquer contaminação com Salmonella spp. nos diversos produtos analisados, independentemente do estado de cura, mas foram encontrados diferentes níveis de contaminação com L. monocytogenes e E. coli. O número de BAL é geralmente superior ao de estafilococos coagulase negativos. Agradecimentos Este trabalho foi financiado por Fundos FEDER através do Programa Operacional Factores de Competitividade – COMPETE e por Fundos Nacionais através da FCT – Fundação para a Ciência e a Tecnologia no âmbito do projeto PTDC/AGR-ALI/119075/2010 e dos Projetos Estratégicos PEst-C/AGR/UI0115/2011 e PEst-OE/AGR/UI0115/2014. Os autores agradecem à empresa PALADARES ALENTEJANOS, Lda. a colaboração prestada no âmbito do projeto PRODER 13.021 (QREN/PRODER/Medida 4.1)