Browsing by Author "Cosme, Fernanda"
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- Characterization and Quantification of Proanthocyanidins in Grapes and Wines: A ReviewPublication . Jordão, António M.; Cosme, FernandaGrapes have long been appreciated for their rich content of phenolic compounds such as gallic acid, (+)-catechin, anthocyanins and resveratrol, and a wide diversity of proanthocyanidins (PAs). In the grape berries, the flavan-3-ols ((+)-catechins and PAs) are present in the solid parts of grapes (stems, skins and particularly seeds) and exist with different degrees of polymerization (dimers, trimmers, tetramers and polymers). Several factors could determine the grape PA content, namely, grape variety, viticulture practices and environment conditions. On the other hand, during winemaking process, the extraction rate from grape to must during maceration and alcoholic fermentation, depends on several factors, such as concentration of PAs in grape, alcohol content, sulphur dioxide content, maceration time and temperature. Also, several winemaking techniques could enhance their extraction, such as, cold soak, must freezing with dry ice and treatments using pectolytic enzymes. However, the application of protein fining agents, mannoproteins or oenological tannins could also have an important impact on the wine PAs concentration and composition. Thus, the main purpose of this chapter is to show a review about the structural characteristics and composition of PAs in grapes and wines, including the main factors that could determine PAs concentration.
- Efeito da aplicação de taninos enológicos na evolução das características fenólicas e sensoriais de um vinho tintoPublication . Muxagata, Sara; Fontes, Luisa; Correia, Ana C.; Nunes, Fernando M.; Cosme, Fernanda; Jordão, António M.
- Effect of the addition of different types of oenological commercial tannins on phenolic and sensorial red wine characteristics evolutionPublication . Jordão, António; Muxagata, Sara; Fontes, Luísa; Correia, Ana Cristina; Nunes, Fernando; Cosme, FernandaThe main objective of this work was to understand the effect of the addition of different commercial types of oenological tannins on red wine phenolic compounds and sensorial characteristics evolution. So, six different commercial oenological tannins obtained from different sources at an average dosage recommended by the manufactures were added to a red wine. During 120 wine aging days several phenolic parameters were analyzed (including several individual phenolic compounds by HPLC) and also the sensorial characteristics of the wines. Wines treated with oenological tannins showed higher total phenols and flavonoid phenols and lesser color degradation during the aging time considered. After 120 aging days, wines aged with oenological tannins showed After 120 aging days, wines aged with oenological tannins showed more total and individual anthocyanins and significantly more red color that induced significantly color differences in relation to the untreated wine (especially for the wines treated with condensed tannins). From a sensorial point of view it was also possible to detect a clear differentiation between the wines.
- Evolução das características sensoriais de vinhos brancos da casta encruzado conservados em diferentes tipos de barricas de madeira de carvalhoPublication . Nunes, Paulo; Muxagata, Sara; Correia, Ana C.; Nunes, Fernando M.; Cosme, Fernanda; Jordão, António M.
- Evolução do perfil fenólico de um vinho tinto conservado com alternativos de acácia e de cerejeira.Publication . Costa, Andreia; Cosme, Fernanda; Nunes, Fernando M.; Jordão, António M.Novas tendências têm ocorrido através da utilização de madeiras que não de carvalho, para utilização enológica, como seja a madeira de cerejeira e de acácia. Assim, o objetivo deste trabalho consistiu em avaliar o perfil fenólico durante 65 dias de um vinho tinto conservado com aparas de madeira de acácia e cerejeira. Efetuou-se ainda uma análise comparativa com os resultados obtidos para o mesmo vinho, mas conservado com diferentes aparas de madeira de carvalho. Os resultados obtidos não permitiram evidenciar uma clara diferenciação no perfil fenólico do vinho conservado em contacto com as diferentes aparas de madeira. Porem, o contacto com aparas de madeira de acácia pareceu induzir a uma maior tendência para o vinho apresentar valores signi cativamente mais elevados em compostos fenólicos não avonóides e de intensidade da cor. O vinho estagiado em contacto com aparas de acácia, apresentou ainda valores significativamente mais elevados em ácido trans-caftárico, ácido coutárico e ácido cafeíco, enquanto que o vinho conservado com aparas de cerejeira apresentou no geral, valores significativamente mais elevados de ácido gálhico e de (+)-catequina.
- Grape and Wine Metabolites: Biotechnological Approaches to Improve Wine QualityPublication . Cosme, Fernanda; Gonçalves, Berta; Inês, António; Jordão, António M.; Vilela, AliceGrape metabolites can be affected by many extrinsic and intrinsic factors, such as grape variety, ripening stage, growing regions, vineyard management practices, and edaphoclimatic conditions. However, there is still much about the in vivo formation of grape metabolites that need to be investigated. The winemaking process also can create distinct wines. Nowadays, wine fermentations are driven mostly by single-strain inoculations, allowing greater control of fermentation. Pure cultures of selected yeast strains, mostly Saccharomyces cerevisiae, are added to grape must, leading to more predictable outcomes and decreasing the risk of spoilage. Besides yeasts, lactic acid bacteria also play an important role, in the final wine quality. Thus, this chapter attempts to present an overview of grape berry physiology and metabolome to provide a deep understanding of the primary and secondary metabolites accumulated in the grape berries and their potential impact in wine quality. In addition, biotechnological approaches for wine quality practiced during wine alcoholic and malolactic fermentation will also be discussed.
- Volatile components of vine leaves from two Portuguese grape varieties (Vitis vinifera L.), Touriga Nacional and Tinta Roriz, analysed by solid-phase microextractionPublication . Fernandes, Bruno; Correia, Ana; Cosme, Fernanda; Nunes, Fernando; Jordão, AntónioThe purpose of this work was to study the volatile composition of vine leaves and vine leaf infusion prepared from vine leaves collected at 30 and 60 days after grape harvest of two Vitis vinifera L. species. Eighteen volatile compounds were identified by gas chromatography–mass spectrometry in vine leaves and in vine leaf infusions. It was observed that the volatile compounds present in vine leaves are dependent on the time of harvest, with benzaldehyde being the major volatile present in vine leaves collected at 30 days after harvesting. There are significant differences in the volatile composition of the leaves from the two grape cultivars, especially in the sample collected at 60 days after grape harvest. This is not reflected in the volatile composition of the vine leaf infusion made from this two cultivars, the more important being the harvesting date for the volatile profile of vine leaf infusion than the vine leaves grape cultivar.
- Wine phenolics: looking for a smooth mouthfeelPublication . Vilela, Alice; Jordão, António M.; Cosme, FernandaEach grape variety has its own phenolic profile. However, the concentration of the phenolic compounds present in wine mainly dependson winemaking processes. Phenolic compounds influence wine sensorial characteristics namely taste or mouthfeel, bitterness, astringency and color. Humans can perceive six basic tastes: sweet, salty; sour; umami; fat-taste and bitter taste. This last basic taste is considered as a defense mechanism against the ingestion of potential poisons. Some of the genes,encoding G-protein-coupled receptors - TAS2Rs, which translate for these distinct bitter compounds detectors have been identified. Different phenolic compounds activate distinguished combination of TAS2Rs. Astringency in wine is primarily driven by proanthocyanidins, soluble protein-proanthocyanidins complexes which diminish the protective salivary film and bind to the salivary pellicle; insoluble protein-proanthocyanidins complex and proanthocyanidins are rejected against salivary film and trigger astringency sensation via increasing friction. Thus, the aim of this review is to expand the knowledge about the role of wine phenolic compounds in wine sensorial properties, namely in bitterness and astringency phenomenon’s.