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- Enhancement of apparent resistance to ethanol in Lactobacillus hilgardiiPublication . Couto, José António; Pina, Cristina; Hogg, TimThe survival of Lactobacillus hilgardii, a highly ethanol-tolerant organism, after an ethanol challenge at 25% (v/v) for 10 min, increased by several log cycles when cells, grown in the absence of ethanol, were pre-treated with 10% (v/v) ethanol, 15% (v/v) methanol or 2% (v/v) butanol for 4 h. A temperature upshift (25 to 40°C) before ethanol challenge demonstrated a similar enhancement of apparent resistance to ethanol. Ethanol shock enhanced apparent resistance to methanol, butanol and heat challenges. The addition of chloramphenicol to cells prior to any pre-treatment did not significantly diminish the increase in ethanol tolerance, suggesting that de novo protein synthesis is not required for induced tolerance in this organism
- 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.
- Evaluation and insights into chitosan antimicrobial activity against anaerobic oral pathogensPublication . Costa, E.M.; Silva, S.; Pina, C.; Tavaria, F.K.; Pintado, M.M.The objective of this study was to assess the antimicrobial capability of non-chemically altered chitosan as an alternative to traditional antimicrobials used in the treatment of oral infections. The action mechanism of chitosan was also ascertained. High and low molecular weight chitosan showed antimicrobial activity at low concentrations for all tested bacteria with the MICs varying between 1 and 7 mg/ ml with a drop of efficacy relatively to the action of LMW chitosan. In addition chitosan showed also to be an effective bactericidal presenting bactericidal effect within 8 h at the latest. Additionally the evaluation of chitosan’s action mechanism showed that both MWs acted upon the bacterial cell wall and were not capable of interacting with the intracellular substances, as showed by the inefficacy obtained in the flocculation assay
- Industry/University collaboration in product focussed œnological research in Portugal - the SOGRAPE / UCP ESB partnership 1995 - 1998Publication . Guedes, P.; Pina, C.; Santos, C.; Vasconcelos, I.; Silva, M. C.; Couto, J.A.; Hogg, T.; Cabral, L.; Vieira, M.; Pessanha, M.; Graca, A.; Soares Franco, J. M.A innovative model of collaboration between a wine company and a university research group is presented. A protocol was established as a response to the perceived need to, on the part of the university, (i) focus research on specific scientific bottlenecks which would have a real impact in the producing industry and, on the part of the company, (ii) to have access to the scientific capacity to conduct in-depth studies to approach specific technical challenges. A closely managed programme was jointly established and the major characteristics are presented here together with the main results obtained during the first 2 and a half years of operation.
- Defining the uniqueness of monovarietal wines from native portuguese varieties of vitis viniferaPublication . Guedes, P.; Pina, C.; Santos, C.; Santos, S.; Vasconcelos, I.; Silva, M. C. M.; Hogg, T.
- Industry / university collaboration in product focussed oenological research in Portugal - the SOGRAPE / UCP ESB partnership 1995 - 1998Publication . Guedes, P.; Pina, C.; Santos, C.; Santos, S.; Vasconcelos, I.; Silva, M. C. M.; Hogg, T.
- Defining the uniqueness of monovarietal wines from native portuguese varieties of Vitis viniferaPublication . Guedes, P.; Pina, C.; Santos, C.; Vasconcelos, I.; Silva, M. C. M.; Hogg, T.; Cabral, L.; Vieira, M.; Pessanha, M.; Soares Franco, J. M.Studies have been carried out on red and white monovarietal wines vinified during the 1995, 1996 and 1997 harvests. The essential aim being to evaluate sensory quality, correlate it with chemical analytical data and relate these to the various winemaking options available. Hence selective native varieties from the Douro, Dao, Bairrada and Vinhos Verdes regions have been studied and the analytical / sensorial data correlated to such factors as grape maturation and maceration regime. Results are presented illustrating the quality effects of variety / winemaking practice combinations, both in terms of analytical data (sensory and chemical) and taster preferences.
- Caracterização química e sensorial de vinhos provenientes de castas nobres da região do DãoPublication . Guedes, P.; Pina, C.; Santos, C.; Santos, S.; Vasconcelos, I.; Cabral, L.; Vieira, M.; Hogg, T.
- Caracterização química e sensorial de vinhos provenientes de castas nobres da região do DãoPublication . Guedes, P.; Pina, C.; Santos, C.; Santos, S.; Vasconcelos, I.; Cabral, L.; Vieira, M.; Hogg, T.