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- 1,3-Propanediol continuous production by Clostridium butyricum VP1 1718: effect of dilution rate and substrate concentrationPublication . Gonzalez-Pajuelo, M.; Ribeiro-Cruz, A. P.; Sousa- Monagas, C. M.; Andrade, J. C.; Vasconcelos, I.
- Effet de la souche de levure sur les proprietes organoleptiques des vins issus de cinq cepages blancs portugaisPublication . Vasconcelos, I.; Moura, F.; Martins, M. C. P.; Herdeiro, M. T.; Pereira, O.; Castro, A.; Revel, G. deNeuf souches de levures commerciales, appartenant au genre Saccharomyces (six souches de S. cerevisiae et trois souches de S. bayanus), ont ete testees lors de la fermentation de moths issus de cinq cepages portugais: Loureiro, Trajadura, Pedernk Azal e Avesso. Pour un même cepage la levure d'implantation semble ne pas avoir d'influence sur la teneur en alcool et sur l'acidité totale des vins produits. Les variations des quantites produites en esters ethyliques d'acides gras (BRAG) et acetates d'alcools superieurs (AAS) peuvent varier d'un facteur 2.1 et 4.3 respectivement, pour un même cepages les teneurs maximales en AAS sont observêes avec les deux mêmes souches pour tour les cepages, a une exception pres. En ce qui concerne les alcools superieurs, les souches plus ou moths productrices different pour chaque cépage. Une etude statistique a permis d'etablir une correlation entre l'analyse chimique et l'analyse sensorielle. D'un point de vue organoleptique, les vins prefer-es sont riches en acides gras et en EEAG mais relativement pauvres en AAS.
- Production of 1,3-propanediol by Clostridium butyricum VPI 3266 using a synthetic medium and raw glycerolPublication . González-Pajuelo, M.; Andrade, J. C.; Vasconcelos, I.Growth inhibition of Clostridium butyricum VPI 3266 by raw glycerol, obtained from the biodiesel production process, was evaluated. C. butyricum presents the same tolerance to raw and to commercial glycerol, when both are of similar grade, i.e. above 87% (w/v). A 39% increase of growth inhibition was observed in the presence of 100 g l 1 of a lower grade raw glycerol (65% w/v). Furthermore, 1,3-propanediol production from two raw glycerol types (65% w/v and 92% w/v), without any prior purification, was observed in batch and continuous cultures, on a synthetic medium. No significant differences were found in C. butyricum fermentation patterns on raw and commercial glycerol as the sole carbon source. In every case, 1,3-propanediol yield was around 0.60 mol/mol glycerol consumed.
- Production of 1,3-Propanediol by Clostridium butyricum VPI 3266 in continuous cultures with high yield and productivityPublication . González-Pajuelo, M.; Andrade, J. C.; Vasconcelos, I.The effects of dilution rate and substrate feed concentration on continuous glycerol fermentation by Clostridium butyricum VPI 3266, a natural 1,3-propanediol producer, were evaluated in this work. A high and constant 1,3-propanediol yield (around 0.65 mol/mol), close to the theoretical value, was obtained irrespective of substrate feed concentration or dilution rate. Improvement of 1,3-propanediol volumetric productivity was achieved by increasing the dilution rate, at a fixed feed substrate concentration of 30, 60 or 70 g l-1. Higher 1,3-propanediol final concentrations and volumetric productivities were also obtained when glycerol feed concentration was increased from 30 to 60 g l-1, at D=0.05–0.3 h-1, and from 60–70 g l-1, at D=0.05 and 0.1 h-1. 30 g l-1 of 1,3-propanediol and the highest reported value of productivity, 10.3 g l-1 h-1, was achieved at D=0.30 h-1 and 60 g l-1 of feed glycerol. A switch to an acetate/butyrate ratio higher than one was observed for 60 g l-1 of feed glycerol and a dilution rate higher than 0.10 h-1; moreover, at D=0.30 h-1 3-hydroxypropionaldehyde accumulation was observed for the first time in the fermentation broth of C. butyricum.
- 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.
- Influência das características aromáticas da casta e do seu estado de maturação nas propriedades dos vinhos da região do DãoPublication . Santos, S.; Guedes, P.; Pina, C. M. G.; Santos, C.; Hogg, T.; Vasconcelos, I.
- 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.
- 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.
- Fermentation of Low Grade Glycerol by Clostridium butyricum and Clostridum acetobutyllcum StrainsPublication . Gonzalez-Paluelo, M.; Andrade, J.C.; Vasconcelos, I.