Browsing by Author "Mendes, F."
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- Apiculate wine yeasts: growth kinetics and aroma compounds productionPublication . Moreira, N. E. O.; Silva, C. L. M.; Vasconcelos, I. M.; Mendes, F.; Hogg, T.
- 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.
- 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.
- Volatile compounds contribution of Hanseniaspora guilliermondii and Hanseniaspora uvarum during red wine vinificationsPublication . Moreira, N.; Pina, C.; Mendes, F.; Couto, J.A.; Hogg, T.; Vasconcelos, I.This work aims to investigate the contribution of a selected non-Saccharomyces yeast species, Hanseniaspora guilliermondii, to higher alcohols, esters, fatty acids and heavy sulphur compounds composition of red wine. Red grape must vinifications of 100 l were performed and an inoculated fermentation with H. guilliermondii was compared to a spontaneous fermentation. The presence of apiculate yeasts was observed in both fermentations; however, Hanseniaspora uvarum was the only apiculate yeast isolated from the spontaneous fermentation. Apiculate yeasts dominated the fermentation until an ethanol concentration of 6% (v/v) was attained and remained in considerable high levels for an ethanol concentration of 12.5% (v/v). The grape must inoculated with H. guilliermondii led to the production of wine with higher concentrations of 1-propanol, 2-phenylethyl acetate and 3-(methylthio)propionic acid, and lower amounts of ethyl hexanoate, pentanoic acid, free fatty acids, 2-methyltetrahydrothiophen-3- one and acetic acid-3-(methylthio)propyl ester, than wine resulting from the spontaneous fermentation. The present study shows that the use of specific apiculate yeasts in grape must fermentations may lead to the production of wines with different chemical profiles, emphasising the importance of Hanseniaspora yeasts as mixed starter cultures with Saccharomyces cerevisiae, in winemaking.
- Vulnerability in recreational settings: the city of Porto, PortugalPublication . Carvalho, M. C.; Araújo, I.; Brotto, A.; Gonçalves, S.; Pinto, M. J.; Rocha, I.; Rodrigues, T.; Soares, M.; Teixeira, J.; Brito, I.; Mendes, F.Between April and June 2015 a data collection process took place that aimed to contribute to the characterization of vulnerability in recreational settings in the city of Porto. These data contribute to a larger project that aims to characterize vulnerability in a number of Portuguese and Portuguese speaking cities. A total of 7 Porto nightlife areas were observed, including 4 downtown Porto sites (Piolho - outdoors, Piolho – indoors, Galerias – indoors, Túnel de Ceuta – indoors and outdoors), the Ribeira area, a party at a disco associated with university students at an industrial area, and a large scale annual festival for university students (Queima das Fitas). Data include over 53 images (photo voice), n=11 structured interviews, n=7 structured observation instruments and content of 1 focus group (world café) with participation of n=11 young adults (ages 20-28, graduate or post- graduate students, or recently graduated professionals). Data were analyzed through a content analysis procedure that identified vulnerability dimensions and recommendations offered to deal with those vulnerabilities. Ideal nights to go out varied from Thursday to Monday. The considerable growth of tourists in the city was identified as a major factor for the recent increase of nightlife offer.