The influence of incubation periods on photosynthesis–irradiance curves

In phytoplankton primary production studies, samples for the determination of photosynthesis versus irradiance relationship ( P–I) are usually incubated at several irradiance levels during a fixed time period, commonly 2–4 h. However, it is not clear if the use of this fixed incubation time is appropriate to study the P–I relationship in any given ecosystem. The aim of this work was to study the influence of incubation time on the P–I relationship in natural phytoplankton populations from three different coastal ecosystems: an open coastal area, an estuary, and a coastal lagoon. Physical and chemical variables, phytoplankton biomass, species composition, and P–I curves were analysed. The results showed that, in the coastal area and in the estuary, P–I relationships were time dependent, whereas in the coastal lagoon different incubation periods produced the same P–I curve. An underestimation of daily primary production, ranging from 13% to 42.5%, was calculated when data from standard incubation times (2–4 h) were used in ecosystems where P–I curves present a dynamic time-dependent behaviour. This work suggests that the response of the P–I curves to the incubation time varies with the characteristics of the ecosystem and is related to the light regime to which phytoplankton cells are adapted. D 2002 Elsevier Science B.V. All rights reserved

The influence of incubation periods on photosynthesis–irradiance curves

In phytoplankton primary production studies, samples for the determination of photosynthesis versus irradiance relationship ( P–I) are usually incubated at several irradiance levels during a fixed time period, commonly 2–4 h. However, it is not clear if the use of this fixed incubation time is appropriate to study the P–I relationship in any given ecosystem. The aim of this work was to study the influence of incubation time on the P–I relationship in natural phytoplankton populations from three different coastal ecosystems: an open coastal area, an estuary, and a coastal lagoon. Physical and chemical variables, phytoplankton biomass, species composition, and P–I curves were analysed. The results showed that, in the coastal area and in the estuary, P–I relationships were time dependent, whereas in the coastal lagoon different incubation periods produced the same P–I curve. An underestimation of daily primary production, ranging from 13% to 42.5%, was calculated when data from standard incubation times (2–4 h) were used in ecosystems where P–I curves present a dynamic time-dependent behaviour. This work suggests that the response of the P–I curves to the incubation time varies with the characteristics of the ecosystem and is related to the light regime to which phytoplankton cells are adapted. D 2002 Elsevier Science B.V. All rights reserved

Otimização da extração de azeite de azeitona ‘Cobrançosa’ por adição de adjuvantes tecnológicos

Realizaram-se ensaios de modelação e otimização das condições operatórias de extração de azeite, utilizando a metodologia das superfícies de resposta, segundo uma matriz central compósita rotativa, em função da concentração adicionada de adjuvantes na termobatedura – preparação enzimática Endozym Olea AS (0,04-0,24%) e microtalco FC8 (0,12-0,68%) – a um lote de azeitona Cobrançosa com um índice de maturação de 3,05. Os ensaios de extração foram efetuados em equipamento Abencor, calculando o rendimento pelo índice de extratabilidade e o teor de gordura dos bagaços. Os resultados obtidos mostram que o rendimento da extração depende do teor de talco, mas é independente da concentração de enzima adicionada, nos valores testados. Nem os pigmentos clorofilinos nem os critérios de qualidade do azeite foram afetados pela presença de adjuvantes

Microencapsulation of bioactives for food applications

Health issues are an emerging concern to the world population, and therefore the food industry is searching for novel food products containing health-promoting bioactive compounds, with little or no synthetic ingredients. However, there are some challenges in the development of functional foods, particularly in which the direct use of some bioactives is involved. They can show problems of instability, react with other food matrix ingredients or present strong odour and/or flavours. In this context, microencapsulation emerges as a potential approach to overcome these problems and, additionally, to provide controlled or targeted delivery or release. This work intends to contribute to the field of functional food development by performing a comprehensive review on the microencapsulation methods and materials, the bioactives used (extracts and isolated compounds) and the final application development. Although several studies dealing with microencapsulation of bioactives exist, they are mainly focused on the process development and the majority lack proof of concept for final applications. These factors, together with the lack of regulation, in Europe and in the United States, delay the development of new functional foods and, consequently, their market entry. In conclusion, the potential of microencapsulation to protect bioactive compounds ensuring their bioavailability is shown, but further studies are required, considering both its applicability and incentives by regulatory agencies.The authors are grateful to Fundação para a Ciência e a Tecnologia (FCT, Portugal) for financial support to CIMO (strategic project PEst-OE/AGR/UI0690/2011) and LSRE (PEst-C/EQB/LA0020/2011), and M.I. Dias grant (SFRH/BD/84485/2012)

Adding molecules to food, pros and cons – A review on synthetic and natural food additives

The pressing issue to feed the increasing world population has created a demand to enhance food production, which has to be cheaper, but at the same time must meet high quality standards. Taste, appearance, texture, and microbiological safety are required to be preserved within a foodstuff for the longest period of time. Although considerable improvements have been achieved in terms of food additives, some are still enveloped in controversy. The lack of uniformity in worldwide laws regarding additives, along with conflicting results of many studies help foster this controversy. In this report the most important preservatives, nutritional additives, coloring, flavoring, texturizing, and miscellaneous agents are analyzed in terms of safety and toxicity. Natural additives and extracts, which are gaining interest due to changes in consumer habits are also evaluated in terms of their benefits to health and combined effects. Technologies, like edible coatings and films which have helped overcome some drawbacks of additives, but still pose some disadvantages, are briefly addressed. Future trends like nanoencapsulation and the development of “smart” additives and packages, specific vaccines for intolerance to additives, use of fungi to produce additives, and DNA recombinant technologies are summarized.The authors are grateful to Proder nº 46577 PlantLact for financial support of this work, to Fundação para a Ciência e a Tecnologia (FCT, Portugal) and COMPETE/QREN/EU for CIMO strategic project PEst-OE/AGR/UI0690/2011 and LSRE strategic project PEst-C/EQB/LA0020/2011. The authors also state that they do not have any conflicts of interest

Anti-inflammatory potential of mushroom extracts and isolated metabolites

Background: In the recent years natural resources are being in focus due to their great potential to be exploited in the discovery/development of novel bioactive compounds and, among them, mushrooms can be highlighted as alternative sources of anti-inflammatory agents. Scope and approach: The present review reports the anti-inflammatory activity of mushroom extracts and of their bioactive metabolites involved in this bioactive action. Additionally the most common assays used to evaluate mushrooms anti-inflammatory activity were also reviewed, including in vitro studies in cell lines, as well as in animal models in vivo. Key findings and conclusions: The anti-inflammatory compounds identified in mushrooms include polysaccharides, terpenes, phenolic acids, steroids, fatty acids and other metabolites. Among them, polysaccharides, terpenoids and phenolic compounds seem to be the most important contributors to the anti-inflammatory activity of mushrooms as demonstrated by numerous studies. However, clinical trials need to be conducted in order to confirm the effectiveness of some of these mushroom compounds namely, inhibitors of NF-κB pathway and of cyclooxygenase related with the expression of many inflammatory mediators

Water-based polyurethane dispersions: chemistry, technology and applications

Over the past few decades, polyurethane-polyurea aqueous dispersions (PUDs) have developed a solid reputation for high performance applications, particularly in the field of adhesives and coatings. PUDs are mostly environmentally compatible products; they are totally devoid or contain only low amounts of volatile organic compounds (VOC). This is an important feature in view of the present environmental policies where governments and internal agencies are placing emphasis on developing sustainable processes, improving work conditions and reducing emissions of toxic and polluting substances into the atmosphere. In the past years, our research group has been involved in the development of polyurethane-polyurea aqueous dispersions for two main applications (footwear and indirect food contact). With this work we intend to review this theme and describe some of the achieved developments. Characterization of commercial dispersions will be presented and examples of synthesis will be described, following a modified pre-polymer process developed in our group

Microencapsulação de extratos aquosos de funcho e camomila para funcionalização de requeijões

Introdução: Os extratos derivados de plantas são ingredientes muito procurados para funcionalizar alimentos. Foeniculum vulgare Mill. (funcho) e Matricaria recutita L. (camomila) são exemplos de plantas ricas em compostos fenólicos, que apresentam propriedades antioxidantes e antimicrobianas. No entanto o uso de extraias naturais como aditivos alimentares pode ser limitado uma vez que, após extração são suscetíveis de degradação. Assim, a microencapsutação surge como uma forma de superar estas limitações uma vez que, protege os extratos da ação de diversos fatores ambientais, tais como oxigénio, luz, humidade ou calor, assegurando um aumento da sua estabilidade. Objetivos: Neste trabalho, incorporaram-se em requeijões microesferas contendo extratos de plantas, de forma a preservar a sua atividade antioxidante que no caso de requeijões aditivados com extratos livres diminuía ao fim de 7 dias. Material e métodos: Os extraias aquosos de funcho e camomila foram tiofilizados e utilizados como Princípío ativo. As microesferas foram preparadas utilizando uma técnica de atomização/coagulação utilizando alginato de cálcio como material de matriz. As microsferas foram caracterizadas quanto à sua morfologia e tamanho através de microscopia ótica (MO), durante e após a atomízação. Para verificar a efetiva incorporação do extraio na matriz de alginato foi usado o FTIR. A eficiência de encapsulação (EE) foi avaliada por HPLC-DAD. Os extratos livres e microencapsulados foram incorporados em amostras de requeijão que, posteriormente, foram analisadas nutricionalmente e no que concerne ao seu potencial antioxidante, imediatamente após a incorporação, e após 7 e 14 dias de armazenamento a 4°C. Resultado e discussão: A análise por MO permitiu concluir que a incorporação dos extratos foi eficaz e com uma distribuição homogénea no interior das microesferas. A presença dos extratos no interior das microesferas foi confirmada por FTIR e a EE foi próxima de 100% para ambas as amostras. Em termos nutricionais, os requeijões funcionalizados não apresentaram alterações significativas em relação ao controlo e a atividade antioxidante aumentou ao longo do tempo, tendo sido preservada no caso das amostras com o extraio microencapsulado. Conclusão: Verificou-se que a técnica de atomização permitiu a produção de microesferas viáveis para incorporação em requeijões capazes de preservar a atividade antioxidante de extratos naturais

Ingredientes conservantes e bioativos à base de Foeniculum vulgare Mill. e Matricaria recutita L.: caracterização química, estabilização e estudos de aplicação em diferentes alimentos

Assiste-se a uma tendência globalizada para a procura de alimentos mais saudáveis, minimamente processados e onde os aditivos artificiais se encontrem em quantidades reduzidas ou, de preferência, estejam ausentes. Neste trabalho, foram desenvolvidos ingredientes naturais à base de extratos aquosos de Foeniculum vulgare Mill. (funcho) e Matricaria recutita L. (camomila), obtidos por decocção, e aplicados na funcionalização de diferentes alimentos (requeijões, iogurtes e biscoitos) devido às suas propriedades conservantes (antioxidantes e antimicrobianas) e bioativas, também validadas no âmbito do presente trabalho. A incorporação em requeijões permitiu aumentar o seu tempo de prateleira sem alterar significativamente as características nutricionais dos produtos finais e, simultaneamente, conferir propriedades bioativas.1.2 No entanto, essa atividade começou a diminuir após 7 dias de armazenamento, o que nos levou a estabilizar os ingredientes desenvolvidos recorrendo com sucesso à técnica de microencapsulação.3 Os efeitos conservantes foram confirmados em outras matrizes alimentares: iogurtes4 e biscoitos;5 e comparados com aditivos artificiais utilizados nesses alimentos: sorbato de potássio (E202) e hidroxianisol butilado (BHA; E320), respetivamente. Em ambos os casos, a incorporação de aditivos, naturais ou sintéticos, não alterou significativamente o valor nutricional dos produtos finais. No entanto, quando funcionalizados com as decocções das duas plantas, os iogurtes apresentaram maior atividade antioxidante do que quando incorporados com E202. Já nos biscoitos, as decocções garantiram uma atividade semelhante ao BHA, mas constituem uma opção mais saudável. Até ao momento podemos concluir que os extratos aquosos de funcho e camomila, podem ser uma alternativa para o desenvolvimento de aditivos naturais para aplicação em produtos alimentares substituindo os antioxidantes e antimicrobianos artificiais massivamente usados na indústria alimentar. Futuramente pretendemos avançar para a testes de avaliação sensorial e de aceitabilidade dos novos produtos desenvolvidos.info:eu-repo/semantics/publishedVersio