Browsing by Author "Pereira, Paula"
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- Supercritical fluid extracts with antioxidant and antimicrobial activities from myrtle (Myrtus communis L.) leaves. Response surface optimizationPublication . Pereira, Paula; Bernardo-Gil, Maria Gabriela; Cebola, M. João; Mauricio, Elisabete; Romano, AnabelaSupercritical Fluid Extraction (SFE) was used to obtain myrtle leaf extracts, and to study the antioxidant capacity (AOC) and in vitro antimicrobial activity of those extracts. To optimize the SFE operational conditions, the response surface methodology (RSM) was adopted. The parameters studied were: pressure (P), within the range 10 to 30 MPa; temperature (T), between 35 C and 60 C and supercritical carbon dioxide (SCCO2) flow rate (Q) within the range 0.15 to 0.45 kg h-1. The results show a good fit to the proposed model and the optimal conditions obtained (23 MPa, 45 C, and SCCO 2 flow rate of 0.3 kg h-1) were within the experimental range. The predicted values agreed with experimental ones, thus indicating the suitability of the RSM model for the optimization of the extraction conditions being investigated. With those values remaining constant, ethanol as a co-solvent was then studied. There was an observed rise in AOC as the amount of ethanol increased, within the range studied (0-30 wt% ethanol). The extract with the highest AOC was tested for its antimicrobial activity against gram-positive and gram-negative bacteria. The minimum inhibitory concentration (MIC) values obtained showed significant inhibitory effect against gram-positive bacteria.
- The market features of imported non-indigenous polychactes in Portugal and consequent ecological concernsPublication . Costa, Pedro Fidalgo E.; Gil, João; Passos, Ana Maria; Pereira, Paula; Melo, Pedro; Batista, Frederico; Cancela Da Fonseca, LuísThe importance of the market for polychaetes dramatically increased after the discovery of their potential as food in aquaculture. In Portugal, the gathering of polychaetes solely front natural populations is not sufficient to meet market demand, both as bait for sea anglers and as a food item in aquaculture. The requests for worms to polychaete dealers by Portuguese and Spanish seafarms have increased during recent years. Due to the lack Of intensive Culture of these worms in Portugal and the proximity of southern Spanish farms, a large component of imported polychaetes that arrive in Portugal at Lisbon Airport go directly to Spain by road. fit 2002 and 2003 a total of 12,728,379 and 16,866,839 polychaetes respectively were imported to Europe via Lisbon Airport from China and the USA. In 2003 the imports from China and the USA realised 716,180 and 291,845 US dollars respectively. Two species were reported to have been imported in these years, namely the Korean blue ragworm Perinereis aibuhitensis and the American bloodworm Glycera dibranchiata. Imports of non-indigenous species, which are traded and sold alive. may increase the risk of accidental introduction into the wild. This is of special concern as Perinereis aibuhitensis has been successfully reared in captivity within the range of environmental conditions existing in the Ria Formosa coastal lagoon. Other risks associated with introduced species are the transport of foreign pathogens and other associated non-native organisms, which may act as carriers of disease.