Browsing by Author "Moreira, N."
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- Aroma precursors of grapes: contribution of variety and vineyard traning system to port wine aromaPublication . Sousa, L.; Moreira, N.; Queiroz, J.; Oliveira, M.B.; Santos, C.; Oliveira, C.; Ferreira, A. C. Silva; Pinho, P. Guedes deIn order to evaluate the influence of the vine training system in the composition in terpenes, norisoprenoids and their precursors (carotenoids and glycosidic molecules), these compounds were quantified in grapes and Port wines belonging to two varieties: Touriga Nacional and Touriga Franca from Douro Region. The double cordon LYS 2/3 system was compared with the traditional method, the vertical shoot positioning VSP system. Touriga Nacional grapes and wines have higher contents in carotenoids, free and glycosylated fractions of terpenic and norisoprenoids compounds than Touriga Franca. In general, LYS 2/3 training system produced grapes and wines with high content in glycosylated fractions of terpenes and nor-isoprenoids, being more appropriate to the production of Port wines, which are submitted to an aging process.
- Aroma precursors of grapes: contribution of variety and vineyard traning system to port wine aromaPublication . Sousa, L.; Moreira, N.; Queiroz, J.; Oliveira, M. B.; Santos, C.; Oliveira, C.; Ferreira, A. C. Silva; Pinho, P. Guedes de
- Características aromáticas de Vinhos Verdes produzidos com diferentes estirpes de LevedurasPublication . Moreira, N.; M. T. Herdeiro, M. T.; Martins, M. C. P.; Revel, G. de; Vasconcelos, I.; Moura, F.; Pereira, O.
- Effect of malolactic fermentation on the volatile profile of winesPublication . Moreira, N.; Ruão, P.; Couto, J. A.; Vasconcelos, I.; Pinho, P. Guedes de
- Effect of malolactic fermentation on the volatile profile of winesPublication . Moreira, N.; Ruão, P.; Couto, J. A.; Vasconcelos, I.; Pinho, P. Guedes deThis work aimed to evaluate the influence of malolactic fermentation (MLF) on the composition of the volatile fraction of wines (alcohols, esters, fatty acids and heavy sulphur compounds). Red grape must vinifications were performed at industrial scale from a single grape cultivar (Touriga Franca-TF) and a mixture of cultivars (MC) of the Douro Region. Wine samples were collected before and after spontaneous MLF. Results show that the concentration of certain volatile compounds was clearly affected by the MLF. It was found that the content of 2-phenylethyl acetate, hexyl acetate, ethyl hexanoate, ethyl lactate and methionol increased while the levels of total ethyl esters and S-(methylthio)acetate decreased in both wines. The impact of MLF in some compounds was found to be wine dependent. For example, the concentration of 3-mercapto-1-propanol increased in the MC wine while it decreased in TF wine. No significant differences were observed for trans-2-methyltetrahydrothiophene-3-ol, 4-(methylthio)-1-butanol and 3-(ethylthio)-1-propanol.
- Etude de l'influence de la levure d'implantation et de la composition chimique du moût sur les caracteristiques aromatiques des vins blancs issus de cinq cepages portugaisPublication . Vasconcelos, I.; Moura, F.; Herdeiro, M. T.; Martins, M. C. P.; Moreira, N.; Pereira, O.; Revel, G. de
- Heavy sulphur compounds, higher alcohols and esters production profile of Hanseniaspora uvarum and Hanseniaspora guilliermondii grown as pure and mixed cultures in grape mustPublication . Moreira, N.; Mendes, F.; Pinho, P. Guedes de; Hogg, T.; Vasconcelos, I.Hanseniaspora guilliermondii and Hanseniaspora uvarum were tested in grape must fermentations as pure and mixed starter cultures with Saccharomyces cerevisiae. In pure cultures, the specific growth rates found were 0.29 h⁻¹ for H. uvarum, 0.23 h⁻¹ for H. guilliermondii and 0.18 h⁻¹ for S. cerevisiae. No significant differences were observed between these values and those obtained in mixed cultures. Results presented in this work show that growth of apiculate yeasts during the first days of fermentation enhances the production of desirable compounds, such as esters, and may not have a negative influence on the production of higher alcohols and undesirable heavy sulphur compounds. Growth of apiculate yeasts reduced the total content of higher alcohols in wines, when compared to those produced by a pure culture of S. cerevisiae. Furthermore, the highest levels of 2-phenylethyl acetate were obtained when H. guilliermondii was inoculated in grape musts, whereas H. uvarum increased the isoamyl acetate content of wines. Apiculate yeasts produced high amounts of ethyl acetate; however, the level of this compound decreased in mixed cultures of apiculate yeasts and S. cerevisiae. When S. cerevisiae was used as a starter culture, wines showed higher concentrations of glycerol, 2-phenylethanol and ethyl hexanoate. In mixed cultures of apiculate yeasts and S. cerevisiae, wines presented amounts of methionol, acetic acid-3-(methylthio)propyl ester, 4-(methylthio)-1-butanol, 2-mercaptoethanol and cis-2-methyltetrahydro-thiophen-3-ol similar to those produced by a pure culture of S. cerevisiae. An increase in the amounts of 3-(ethylthio)-1-propanol, trans-2-methyltetrahydro-thiophen-3-ol and 3- mercapto-1-propanol was obtained in wines produced from mixed cultures with H. guilliermondii.
- Method for analysis of heavy sulphur compounds using gas chromatography with flame photometric detectionPublication . Moreira, N.; Pinho, P. Guedes de; Vasconcelos, I.A method for analysis of heavy sulphur compounds in wines, based on gas chromatography (GC) with flame photometric detection, is reported. Wine samples preparation includes a dichloromethane liquid–liquid extraction followed by concentration under a nitrogen atmosphere. The extracted fraction was also analysed by GC–mass spectrometry. The method enables high recovery of sulphur compounds in wine and satisfies the requirements of repeatability and sensitivity. Applications of the method to red, white and Port wines are reported.
- Pesquisa de compostos voláteis de enxofre varietais em vinhos brancos elementares de castas portuguesasPublication . Ferreira, D.; Moreira, N.; Vasconcelos, I.; Silva, J. M. Ricardo da; Pinho, P. Guedes de
- Preliminary study of sulfur-containing compounds produced by saccharomyces and non-saccharomyces yeast strains in different fermentation mediaPublication . Moreira, N.; Mendes, F.; Guedes, P.; Vasconcelos, I.