Electrochemical study of butylate: application to the analysis of water

The electroactivity of butylate (BTL) is studied by cyclic voltammetry (CV) and square wave voltammetry (SWV) at a glassy carbon electrode (GCE) and a hanging mercury drop electrode (HMDE). Britton–Robinson buffer solutions of pH 1.9–11.5 are used as supporting electrolyte. CV voltammograms using GCE show a single anodic peak regarding the oxidation of BTL at +1.7V versus AgCl/ Ag, an irreversible process controlled by diffusion. Using a HMDE, a single cathodic peak is observed, at 1.0V versus AgCl/Ag. The reduction of BTL is irreversible and controlled by adsorption. Mechanism proposals are presented for these redox transformations. Optimisation is carried out univaryingly. Linearity ranges were 0.10–0.50 mmol L-1 and 2.0–9.0 µmolL-1 for anodic and cathodic peaks, respectively. The proposed method is applied to the determination of BTL in waters. Analytical results compare well with those obtained by an HPLC method

Mead production: selection and characterization assays of Saccharomyces cerevisiae strains

http://apps.isiknowledge.com/full_record.do?product=UA&search_mode=GeneralSearch&qid=10&SID=V12mKh9k9n8jHN@CK7o&page=1&doc=1&colname=WOSMead is a traditional drink, which results from the alcoholic fermentation of diluted honey carried out by yeasts. However, when it is produced in a homemade way, mead producers find several problems, namely, the lack of uniformity in the final product, delayed and arrested fermentations, and the production of “off-flavours” by the yeasts. These problems are usually associated with the inability of yeast strains to respond and adapt to unfavourable and stressful growth conditions. The main objectives of this work were to evaluate the capacity of Saccharomyces cerevisiae strains, isolated from honey of the Trás-os-Montes (Northeast Portugal), to produce mead. Five strains from honey, as well as one laboratory strain and one commercial wine strain, were evaluated in terms of their fermentation performance under ethanol, sulphur dioxide and osmotic stress. All the strains showed similar behaviour in these conditions. Two yeasts strains isolated from honey and the commercial wine strain were further tested for mead production, using two different honeys (a dark and a light honey), enriched with two supplements (one commercial and one developed by the research team), as fermentation media. The results obtained in this work show that S. cerevisiae strains isolated from honey, are appropriate for mead production. However it is of extreme importance to take into account the characteristics of the honey, and supplements used in the fermentation medium formulation, in order to achieve the best results in mead production

Potential of Portuguese vine shoot wastes as natural resources of bioactive compounds

Since annually a high amount of wastes is produced in vine pruning, the aim of this study was to evaluate the potential of vine shoots from two Portuguese grape varieties (Touriga Nacional - TN and Tinta Roriz - TR) to be used as a natural source of phenolic compounds. To reach this goal, three techniques were explored, namely microwave-assisted extraction (MAE), subcritical water extraction (SWE) and conventional extraction (CE). The phenolic composition of the extracts, antioxidant and biological activities were evaluated by spectrophotometry and chromatography. MAE and SWE produced the highest concentrated extracts. TR vine shoot variety had the highest antioxidant activity and total phenolic (32.1±0.9mggallicacidequivalents/g dry sample), as well as flavonoid content (18.7±1.2mgepicatechinequivalents/g dry sample). For the first time, the biological activity of the vine shoot extracts was tested. Results demonstrated that all of them had antimicrobial potential against different bacteria and yeasts, and the ability of inhibiting α-amylase and acetylcholinesterase enzymes, with MAE TR extracts being the most efficient. HPLC analysis enabled the identification of different phenolic compounds, with gallic acid, catechin, myricetin and kaempferol-3-O-rutinoside being the main contributors to the phenolic composition. Portuguese vine shoot wastes could serve as easily accessible source of natural antioxidants for the food or pharmaceutical industries.Manuela M. Moreira (SFRH/BPD/97049/2013) and M. F. Barroso (SFRH/BPD/78845/2011) are grateful for the postdoctoral fellowships financed by POPH-QREN – Tipologia 4.1 – Formação Avançada, subsidized by Fundo Social Europeu and Ministério da Ciência, Tecnologia e Ensino Superior. The authors are also grateful for the financial support from FCT/MEC through national funds and co-financed by FEDER, under the Partnership Agreement PT2020 through the project UID/QUI/50006/2013 - POCI/01/0145/FEDER/007265; the project 6818 - Transnational Cooperation, Agreement between Portugal (FCT) and Serbia (MSTD) is also acknowledged. This work was also supported by the strategic programme UID/BIA/04050/2013 (POCI-01-0145-FEDER-007569) funded by national funds through the FCT I.P. and by the ERDF through the COMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI). The supply of the vine shoots is acknowledged to Sogrape Vinhos, S.A.info:eu-repo/semantics/publishedVersio

Mead production improvements after using a factorial desing

Anex

Plant and soil metal concentrations in serpentine soils and their influence on the diet of extensive livestock animals

Background: Grazing circuits and resources consumed differ strongly throughout the year and within a territory. For this reason, animals’ diet composition, as well as their exposure to metals, is variable. No studies have been performed on how habitat use affects the metal concentrations to which sheep and goats reared in serpentine soil areas are exposed. Objective: The aim of the present study was to investigate the metal exposure of grazing animals raised in a serpentine soil area of the north-east of Portugal, taking into account the spatial distribution of metal concentrations in soils and plants. Methods: The habitat use and foraging behaviour of six flocks of sheep and goats were studied. The concentrations of Ca, Mg, Mn, Cr and Ni were determined in the soils and plant species most consumed by those animals. Results: The highest Mg, Mn, Cr and Ni concentrations were found in the soils of the ultramafic complex. Ni concentrations above the recommended threshold for agricultural soils (30 μg/g) were found in some sites. A positive correlation between Ni concentration in soils and plants was found (0.634). Ni concentrations higher than 10 μg/g were found in some samples of the following plant species: Sorghum × drummondii (Steud.) Millsp. & Chase,Quercus rotundifolia Lam., Cytisus multiflorus (L’Hér.) Sweet, Cistus ladanifer L. and Erica scoparia L. Significant differences (p ≤ 0.05) in metal concentrations of the plants most consumed by each flock were observed. Conclusion: Grazing circuits have an important role in the metal exposure of animals raised in this serpentine soil area.info:eu-repo/semantics/publishedVersio

Mead production: selection and characterization assays of Saccharomyces cerevisiae

Mead is a traditional alcoholic drink which results from the fermentation of diluted honey. Yeasts used in mead production are, usually, wine Saccharomyces cerevisiae strains. Most of these yeasts are not adapted to the conditions of mead production namely, high sugar levels, low pH values and reduced nitrogen concentrations. The inability of yeast strains to respond and adapt to unfavorable stressful growth conditions, leads to several problems, such as lack of uniformity of the final product, delays and “pouts” fermentations, as well as the production of off-flavors by the yeasts. Therefore, it is necessary to find yeast strains more suitable for mead production

Analysis of polycyclic aromatic hydrocarbons in fish: optimisation and validation of microwave-assisted extraction

An accurate and sensitive method for determination of 18 polycyclic aromatic hydrocarbons (PAHs) (16 PAHs considered by USEPA as priority pollutants, dibenzo[a,l]pyrene and benzo[j]fluoranthene) in fish samples was validated. Analysis was performed by microwave-assisted extraction and liquid chromatography with photodiode array and fluorescence detection. Response surface methodology was used to find the optimal extraction parameters. Validation of the overall methodology was performed by spiking assays at four levels and using SRM 2977. Quantification limits ranging from 0.15–27.16 ng/g wet weight were obtained. The established method was applied in edible tissues of three commonly consumed and commercially valuable fish species (sardine, chub mackerel and horse mackerel) originated from Atlantic Ocean. Variable levels of naphthalene (1.03–2.95 ng/g wet weight), fluorene (0.34–1.09 ng/g wet weight) and phenanthrene (0.34–3.54 ng/g wet weight) were detected in the analysed samples. None of the samples contained detectable amounts of benzo[a]pyrene, the marker used for evaluating the occurrence and carcinogenic effects of PAHs in food

Assessment of groundwater contamination in an agricultural peri-urban area (NW Portugal): an integrated approach

The excessive use of pesticides and fertilisers in agriculture has generated a decrease in groundwater and surface water quality in many regions of the EU, constituting a hazard for human health and the environment. Besides, on-site sewage disposal is an important source of groundwater contamination in urban and peri-urban areas. The assessment of groundwater vulnerability to contamination is an important tool to fulfil the demands of EU Directives. The purpose of this study is to assess the groundwater vulnerability to contamination related mainly to agricultural activities in a peri-urban area (Vila do Conde, NW Portugal). The hydrogeological framework is characterised mainly by fissured granitic basement and sedimentary cover. Water samples were collected and analysed for temperature, pH, electrical conductivity, chloride, phosphate, nitrate and nitrite. An evaluation of groundwater vulnerability to contamination was applied (GOD-S, Pesticide DRASTIC-Fm, SINTACS and SI) and the potential nitrate contamination risk was assessed, both on a hydrogeological GIS-based mapping. A principal component analysis was performed to characterised patterns of relationship among groundwater contamination, vulnerability, and the hydrogeological setting assessed. Levels of nitrate above legislation limits were detected in 75 % of the samples analysed. Alluvia units showed the highest nitrate concentrations and also the highest vulnerability and risk. Nitrate contamination is a serious problem affecting groundwater, particularly shallow aquifers, especially due to agriculture activities, livestock and cesspools. GIS-based cartography provided an accurate way to improve knowledge on water circulation models and global functioning of local aquifer systems. Finally, this study highlights the adequacy of an integrated approach, combining hydrogeochemical data, vulnerability assessments and multivariate analysis, to understand groundwater processes in peri-urban areas

Analysis of polycyclic aromatic hydrocarbons in fish: evaluation of a quick, easy, cheap, effective, rugged, and safe extraction method

QuEChERS method was evaluated for extraction of 16 PAHs from fish samples. For a selective measurement of the compounds, extracts were analysed by LC with fluorescence detection. The overall analytical procedure was validated by systematic recovery experiments at three levels and by using the standard reference material SRM 2977 (mussel tissue). The targeted contaminants, except naphthalene and acenaphthene, were successfully extracted from SRM 2977 with recoveries ranging from 63.5–110.0% with variation coefficients not exceeding 8%. The optimum QuEChERS conditions were the following: 5 g of homogenised fish sample, 10 mL of ACN, agitation performed by vortex during 3 min. Quantification limits ranging from 0.12– 1.90 ng/g wet weight (0.30–4.70 µg/L) were obtained. The optimized methodology was applied to assess the safety concerning PAHs contents of horse mackerel (Trachurus trachurus), chub mackerel (Scomber japonicus), sardine (Sardina pilchardus) and farmed seabass (Dicentrarchus labrax). Although benzo(a)pyrene, the marker used for evaluating the carcinogenic risk of PAHs in food, was not detected in the analysed samples (89 individuals corresponding to 27 homogenized samples), the overall mean concentration ranged from 2.52 l 1.20 ng/g in horse mackerel to 14.6 ± 2.8 ng/ g in farmed seabass. Significant differences were found between the mean PAHs concentrations of the four groups

Influência da dose de radiação gama na cor de castanhas de origem Portuguesa e Turca (Castanea sativa Mill.)

A produção mundial de castanha está estimada em 1,1 milhões de toneladas, distribuídas por uma superfície de aproximadamente 340 000 ha, contribuindo a Europa em cerca de 12% dessa produção. Portugal assume um papel importante, contribuindo com aproximadamente 3%. Contudo, só cerca de 15% da produção Portuguesa é absorvida pelo mercado nacional, sendo os restantes 85% exportados. Estes valores demonstram a importância que este fruto tem para o equilíbrio da balança comercial Portuguesa. Durante a conservação da castanha, os produtores e industriais do sector enfrentam diversos problemas, tais como: I) Perda de peso, resultado da elevada taxa de transpiração que este fruto apresenta, a qual acarreta importantes perdas económicas e de qualidade; II) Infestação por insectos, tais como o bichado e o gorgulho; e III) Desenvolvimento de fungos, alguns dos quais produtores de micotoxinas. Até há pouco tempo, a fumigação com brometo de metilo era uma das técnicas mais utilizadas para eliminar pragas, sendo utilizada em castanha para exportação. Contudo, este composto, por ser um agente tóxico de largo espectro, pode causar efeitos nocivos na saúde humana. Por outro lado, o Protocolo de Montreal, o qual Portugal subscreveu, declarou este produto como nocivo para a camada de ozono, tendo dado início a um procedimento para a sua eliminação. Por tal, a implementação de métodos alternativos assume assim particular importância. Neste contexto, o tratamento por irradiação surge como uma técnica possível a aplicar no futuro próximo, estando autorizado por entidades oficiais o uso de radiação gama (60Co e 137Cs), feixes de electrões e raios-X. A irradiação como técnica de conservação tem sido testada com sucesso em diversos produtos alimentares, tais como mangas, morangos, etc., e encontra-se regulamentada pela União Europeia (UE) através da Directiva (CE) nº 1999/2/EC. Contudo, elevadas doses de radiação gama podem afectar a integridade funcional de algumas biomoléculas, originando alterações nos produtos, o que obriga a um estudo de adequabilidade para cada alimento em particular. De forma a obter mais informação sobre o efeito do uso da radiação gama, como técnica de conservação em castanhas (Castanea sativa), no presente trabalho pretendeu-se estudar a influência da dose de radiação sobre a cor de frutos sujeitos a esse tratamento, tanto a nível exterior (fruto com casca) como interior (fruto sem película e fruto cortado), por se tratar de um parâmetro de grande importância para a futura aceitabilidade do produto por parte do consumidor. Adicionalmente, pretendeu-se verificar se os resultados obtidos eram ou não semelhantes ao utilizar castanha, Castanea sativa, proveniente da Turquia, a qual é um dos principais produtores mundiais deste fruto. De forma a atingir os objectivos propostos, castanhas (Castanea sativa) de origem Portuguesa foram irradiadas com doses de 0,25; 0,50; 1,0 e 3,0 kGy a um débito de dose de 0,8 kGy.h-1, usando uma câmara de radiação gama com quatro fontes de 60Co. As irradiações foram realizadas em triplicado. Após tratamento, as amostras foram armazenadas sob refrigeração (5 a 6ºC) e analisadas aos 0, 15 e 30 dias de armazenamento. Em simultâneo, foram processadas castanhas não sujeitas a qualquer tratamento (controlo). Para cada dose e tempo de armazenamento, a cor foi avaliada através de um colorímetro, tendo sido determinados os parâmetros de cor de Hunter (L, a, b). Estes parâmetros foram também determinados em castanhas tratadas com o mesmo tipo de radiação numa unidade industrial (Gamma-Pak Sterilizasyon) da Turquia, onde foram aplicadas as doses de 0,50 e 3,0 kGy. Em paralelo, algumas propriedades físicas das castanhas Portuguesas e Turcas foram avaliadas, designadamente: I) Dimensões axiais, correspondentes ao comprimento, largura e espessura; II) Diâmetro médio aritmético; III) Diâmetro médio geométrico; e IV) Esfericidade. Ao avaliar a cor de castanhas Portuguesas, Castanea sativa, com casca exterior sujeitas a várias doses de radiação gama, verificou-se que os parâmetros L (29,4+1,6 a 32,6+1,6), a (13,4+3,2 a 16,7+2,5) e b (8,4+2,4 a 13,4+2,4) não apresentaram qualquer relação com a dose aplicada e tempo de armazenamento. Em termos do interior do fruto, foram já observadas algumas diferenças. Em relação ao parâmetro L (82,1+2,6 a 87,2+0,5), este diminuiu ligeiramente após 30 dias de armazenamento, tendo sido esse decréscimo maior para as doses maiores (> 0,5 kGy). O parâmetro b variou pouco ao longo do tempo de armazenamento e com a dose, tendo sido, contudo, obtido o maior valor para a dose de 3,0 kGy e tempo de armazenamento de 30 dias (27,3+4,3). No entanto, este valor foi semelhante ao medido para a dose 0,25 kGy e igual tempo de armazenamento (27,2+4,9), o que sugere que doses maiores de radiação gama (até 3,0 kGy) parecem não provocar um maior amarelecimento do interior dos frutos. Em termos do parâmetro a, este pouco variou com a dose e tempo de armazenamento. Ao comparar as dimensões das castanhas Portuguesas e Turcas entre si, constatou-se que, em termos médios, a castanha Portuguesa apresentou um comprimento e esfericidade maiores em relação à castanha Turca. Pelo contrário, esta apresentou uma largura e espessura maiores, o que se traduziu em maiores diâmetros médios aritmético e geométrico. Em relação à cor da castanha Turca com casca, submetida aos vários ensaios - controlo e a diferentes doses da radiação gama -, constatou-se que os valores do parâmetro L medidos (29,3+2,20 a 33,0+2,07) foram semelhantes aos anteriormente referidos para a castanha Portuguesa, indicando que as duas castanhas são semelhantes em termos de brilho. Também para a castanha Turca não se observou qualquer relação entre este parâmetro e a dose aplicada ou tempo de armazenamento. Pelo contrário, no parâmetro a detectaram-se já algumas diferenças entre as duas castanhas. De facto, a castanha Turca apresentou menores valores, 9,3+2,6 a 11,9+1,6, quando comparada com a Portuguesa. Contudo, também para a castanha Turca não se observou qualquer relação entre este parâmetro e a dose ou tempo de armazenamento. Considerando os valores médios do parâmetro b para a castanha Turca, 6,8+2,8 a 12,2+2,8, verificou-se que esta apresentou sempre valores inferiores quando comparada com a Portuguesa, com excepção do valor obtido com a dose de 0,50 kGy no início do armazenamento (0 dias). Para ambas as castanhas verificou-se um ligeiro aumento do parâmetro b ao longo do tempo de armazenamento, tanto para o controlo como para as amostras sujeitas à dose 0,50 kGy. Contudo, para a radiação de 3,0 kGy, os valores obtidos foram semelhantes ao longo do tempo para ambas as castanhas. Em relação ao interior da castanha Turca, os valores para o parâmetro L (83,4+5,3 a 86,0+1,9) foram semelhantes aos determinados para a castanha Portuguesa, apresentando uma menor variação. Também não se detectaram diferenças entre doses aplicadas e tempo de armazenamento. Comportamento idêntico foi também observado para o parâmetro a. Ao contrário do observado com a castanha Portuguesa, com a castanha Turca observou-se um aumento no valor médio do parâmetro b ao longo do tempo de armazenamento: controlo 19,7+2,5 a 26,0+3,8 (0 e 30 dias), Dose = 0,50 kGy 20,5+3,2 a 26,0+6,1 (0 e 30 dias), Dose = 3,0 kGy 20,9+2,5 a 25,0+3,7 (0 e 30 dias). Ao comparar os valores obtidos no ensaio controlo e nos referentes às doses de 0,50 e 3,0 kGy no início e após 30 dias de armazenamento, os valores são semelhantes, indicando novamente que doses maiores de radiação gama (até 3,0 kGy) parecem não provocar um maior amarelecimento no interior dos frutos.Agroaguiar Lda. pela disponibilização das amostras; ON.2-QREN Project nº 13198/2010; A. L. Antonio agradece à Fundação para a Ciência e Tecnologia pela bolsa SFRH/PROTEC/67398/2010