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- Influência da rega deficitária na evolução da maturação da variedade Tinta Roriz (Vitis vinifera L.)Publication . Ribeiro, A.C.; Sá, Alexandra; Andrade, João VerdialNa Região Demarcada do Douro, e em particular na sub-região do Douro Superior, a vinha é conduzida, durante uma parte significativa do seu ciclo vegetativo, em condições de défice hídrico acentuado associadas a altas temperaturas, elevado stresse radiativo e elevado défice de pressão de vapor. As práticas culturais implementadas para minimizar as condições adversas, e em particular o regime de rega, podem alterar substancialmente a fisiologia da videira afectando a produção e a composição do bago. O principal objectivo deste estudo foi o de avaliar o curso da maturação na variedade Tinta Roriz de Vitis vinífera L., através da monitorização dos principais parâmetros da maturação, quando submetida a dotações de rega moderadas.
- Importância dos inimigos associados à oliveira para azeitona de conserva no planalto mirandêsPublication . Bento, Albino; Andrade, João Verdial; Ribeiro, A.C.; Rodrigues, M.A.; Cabanas, J.E.; Pereira, J.A.Em Trás-os-Montes, a oliveira É uma das culturas mais importantes. Nesta região, a maioria da produção de azeitona e destinada à obtenção de azeite. Contudo, nos concelhos de Freixo de Espada à Cinta e Mogadouro, a quase totalidade da produção é destinada para azeitona de conserva podendo ser certificada como "Azeitona de Conserva Negrinha de Freixo" DOP.
- Pesquisa de resíduos de fungicidas no mosto e no vinhoPublication . Pinto, Miguel; Pereira, Sandra; Fernandes, Conceição; Andrade, João Verdial; Estevinho, Leticia M.
- Detecção de fenóis voláteis e leveduras do género Dekkera em vinhos de Trás-os-montesPublication . Rebelo, Fernanda; Estevinho, Leticia M.; Morais, Jorge Sá; Rocha, Amélia; Andrade, João VerdialOs fenóis voláteis são um grupo de compostos que podem estar presentes em vinhos exercendo urna forte influencia no seu aroma. Destacam-se neste grupo o 4-etil-fenol e o 4-etil-guaiacol, em vinhos tintos, e o 4-venil-fenol e 4-vinil-guaiacol em vinhos brancos. Estes compostos quando presentes em baixíssimas concentrações não prejudicam significativamente os aromas dos vinhos. No entanto, a medida que a concentração aumenta, sobretudo do 4-etil-fenol, começam a ser perceptiveis aromas que rapidamente levam a depreciagao dos vinhos, provocando consequenternente perdas económicas significativas aos produtores.
- Mead production: selection and characterization assays of Saccharomyces cerevisiaePublication . Pereira, Ana Paula; Dias, Teresa; Andrade, João Verdial; Ramalhosa, Elsa; Mendes-Ferreira, Ana; Mendes-Faia, Arlete; Estevinho, Leticia M.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.
- Segurança alimentar em vinhos: detecção de aminas biogénicasPublication . Correia, Daniela M.; Barros, Lillian; Andrade, João Verdial; Peres, António M.; Dias, L.G.As aminas biogénicas (AB) são bases orgânicas de baixo peso molecular, possuidoras de actividade biológica (Rivas et al., 2005). Estas, podem ser encontradas numa grande variedade de produtos alimentares de origem animal ou vegetal (Cinquina et al.,200ï), especialmente em alimentos ricos em proteínas (peixe e carne), alimentos fermentados (queijo. salame) e bebidos alcoólicas (vinho, cerveja) (Kovacs et al., 1999).
- Mead production: selection and characterization assays of Saccharomyces cerevisiae strainsPublication . Pereira, Ana Paula; Dias, Teresa; Andrade, João Verdial; Ramalhosa, Elsa; Estevinho, Leticia M.Mead 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.
- Toxicity effects of fungicide residues on the wine-producing processPublication . Calhelha, Ricardo C.; Andrade, João Verdial; Ferreira, Isabel C.F.R.; Estevinho, Leticia M.We report the detection of several fungicide residues (Dichlofluanid, Benomyl, Iprodione, Procymidone and Vinclozolin) in red and white bottled wines from two Portuguese wine-producing zones. Studies were done in order to evaluate the active compound transfer percentage from grapes to the final product along fermentation process. We also investigated their effects in Saccharomyces and non-Saccharomyces yeasts as well as their influence on the physical, chemical and organoleptic wine properties. All the tested fungicides had a negative effect on in vitro yeast growth, with Dichlofluanid and Benomyl being the most toxic. Zygosaccharomyces rouxii and Saccharomyces cerevisiae were the most resistant yeasts while Rhodotorula glutinis was the most susceptible. Microvinification experiments carried out in the presence of fungicides produced wine samples with unaltered physical, chemical and organoleptic properties, though Benomyl, a slight delay in the initiation of fermentation process was observed.