Browsing by Author "Cosme, Fernanda"
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- Avaliação do efeito da aplicação de manoproteínas comerciais no incremento da qualidade de vinhos brancosPublication . Ribeiro, Tânia; Fernandes, Conceição; Filipe-Ribeiro, Luis; Nunes, Fernando M.; Cosme, FernandaFace à exigência dos consumidores atuais, as características sensoriais de um vinho, assim como a sua estabilidade, são fatores determinantes para a sua aceitabilidade no mercado. A instabilidade proteica do vinho e consequente desnaturação/precipitação das proteínas depende de fatores (intrínsecos e extrínsecos) e é responsável pelo aparecimento de turvação nos vinhos brancos. Para prevenir a instabilidade proteica são usados vários produtos enológicos, com objetivo de remover as proteínas instáveis, no entanto com várias limitações, tais como eficiência e modificação das características físico-químicas e sensoriais no vinho. Nos últimos anos têm surgido diversos aditivos comerciais à base de manoproteínas, já que as mesmas podem ser uma via alternativa para a estabilização proteica do vinho. Neste trabalho foram selecionadas onze manoproteínas comerciais para avaliar o seu efeito na estabilização proteica, bem como o seu efeito na composição fenólica e nas características cromáticas e sensoriais num vinho branco. Os resultados obtidos mostraram que 9 das 11 manoproteínas testadas apresentaram efeito positivo na estabilização proteica do vinho. Além disso, todas as manoproteínas diminuíram o potencial de acastanhamento dos vinhos, e de um modo geral conduziram a um aumento da luminosidade. Na análise sensorial, apesar de não haver diferenças significativas relativamente ao vinho controlo, tendencialmente os vinhos mais pontuados foram os tratados com manoproteínas, nomeadamente ao nível da diminuição da cor, equilíbrio gustativo e na componente aromática, frutado e floral. Pelos resultados obtidos neste trabalho, podemos concluir que as manoproteínas parecem ser uma alternativa eficiente na estabilização proteica de vinhos brancos e que podem simultaneamente melhorar as características sensoriais do vinho, porém, convém salientar que estes resultados devem ser encarados como preliminares, sendo necessário realizar mais estudos com outros tipos de vinhos.
- Avaliação do efeito da aplicação de manoproteínas comerciais no incremento da qualidade de vinhos brancosPublication . Ribeiro, Tânia; Fernandes, Conceição; Filipe-Ribeiro, Luis; Nunes, Fernando M.; Cosme, FernandaA estabilidade e as características sensoriais dum vinho são fatores determinantes para a sua aceitabilidade. Neste trabalho testaram-se manoproteínas comerciais, verificando-se que estas podem ser uma alternativa eficiente na estabilização proteica de vinhos brancos, melhorando simultaneamente as suas características sensoriais.
- Comparison of ion exchange resins at industrial scale and enological stabilizers treatments for tartaric stabilization of white Port wine: Impact on wine physicochemical and sensory profilePublication . Moreira, Daniela; Fernandes, Conceição; Borges, Rita; Marques, Celeste; Matos, Carlos; Vilela, Alice; Filipe-Ribeiro, Luis; Nunes, Fernando M.; Cosme, FernandaA frequent cause cause of stability loss in awine is the formation of crystalline salts of potassium bitartrate (KHT) that appears mainly at low temperatures, temperatures, as a consequence of a large decrease in its itssolubility solubility [1,2]. Port wine is a Portuguese fortified wine produced exclusively in the Douro Valley demarcated region. There are only only few few studies regarding white Port wine tartaric stabilization, although its importance for consumers acceptance.
- Comparison of ion exchange resins at industrial scale and enological stabilizers treatments for tartaric stabilization of white Port wine: Impact on wine physicochemical and sensory profile.Publication . Moreira, Daniela; Fernandes, Conceição; Borges, Rita; Marques, Celeste; Matos, Carlos; Vilela, Alice; Filipe-Ribeiro, Luis; Nunes, Fernando M.; Cosme, FernandaA frequent cause of stability loss in a wine is the formation of crystalline salts of potassium bitartrate (KHT) that appears mainly at low temperatures, as a consequence of a large decrease in its solubility [1, 2]. Although important for consumer’s acceptance, there are only few studies regarding white Port wine tartaric stabilization. Therefore, tartaric stabilization has been carried out in a white Port wine by ion exchange resins, at an industrial scale, and by the addition of enological stabilizers, with the main objective of comparing the impact of these treatments on wine physicochemical and sensory profile. Port wine is a Portuguese fortified wine produced exclusively in the Douro Valley demarcated region. In this study, a white Port wine from the 2015 vintage from Gran Cruz winery, Portugal was used and almost 20% from the total wine volume was treated by ion exchange resins (pH-Stab®). The stabilizers used were metatartaric acid and carboxymethylcellulose (CMC1 5%, CMC2 20%; CMC3 solid) with different structural characteristics. Wine tartaric stability was measured by the mini contact test. Wines phenolic composition - total phenols, flavonoid and non-flavonoid compounds, as well as the chromatic characteristics by the CIELab method, were also evaluated. Sensory analysis was performed by a panel of eight trained tasters. Twenty-one attributes were selected and were quantified using a five-point intensity scale. As expected, all treatments assayed stabilized the white Port wine. All the samples presented a slight decrease in total phenolic compounds and non-flavonoid phenolic compounds. Concerning sensory analysis, wine treatment with ion exchange resins was more scored for the visual limpidity attribute and for the aroma attributes citrus and tea.
- Effect of different fining agents and additives in white wine protein stabilityPublication . Ribeiro, Tânia Isabel Monteiro; Cosme, Fernanda; Filipe-Ribeiro, Luis; Fernandes, Conceição; Mendes-Faia, ArleteProteins in white wine could become insoluble and precipitate causing the appearance of a haze in bottled wine. Protein instability may be due to intrinsically or extrinsically factor such as protein molecular weight, isoelectric point, ionic strength, alcohol degree and wine pH or storage temperature. These modifications may occur during aging, storage or when diverse wines are blended. The type and concentration of proteins in the wine depends on grape variety, maturation degree and winemaking operations (pre-fem1entative grape maceration, application of tannins, enzymes or bentonite fining). Usually, the treatment for wine protein instability is sodium bentonite fining. The adsorption of wine proteins onto bentonite is due to the cationic exchange capacity of bentonite, which carries a net negative charge and the wine proteins are mostly positive charged at wine pH, and thus can be exchanged onto bentonite. Sometimes even with high level of sodium bentonite wines do not stabilize. Thus, the main purpose of this work is to understand the interaction of different types of bentonites, tannins, carboxylmethylcellulose (CMC) and mannoproteins on white wine protein stability, to get new approaches to stabilize them. Some trials were performed in four white wines with high protein instability. Preliminary results showed that sodium bentonite and mannoproteins increase protein stability, in opposition, CMC and tannins seems to increase turbidity after stability tests, which means more instability. Final results could provide important information to the wine industry to select alternative treatments to remove unstable proteins to maintain or improve wine quality.
- Effect of different fining agents and additives in white wine protein stabilityPublication . Ribeiro, Tânia Isabel Monteiro; Fernandes, Conceição; Filipe-Ribeiro, Luis; Cosme, Fernanda; Mendes-Faia, ArleteOne of the most common physical instability is the development of protein hazes in white wines. Bentonite (B) is widely used for the treatment of protein instability however in excess it adversely affects its sensorial properties. Thus, the main objective of this study was to compare the efficiency of different B and mannoproteins (MP) on removal protein hazes, and then developing new strategies for protein stabilization. Two tests have been used to assess the stability of wines: heat-test and TCA-test. The effects of treatments on phenolic compounds, chromatic and sensory characteristics of wines were evaluated. Results showed that both B and MP increased protein stability but, MP also improved the sensorial characteristics of wines, indicating that can be an alternative to stabilize wine proteins.
- Effect of ion exchange resins on white and red wine pH: Impact on wine sensory characteristicsPublication . Borges, Rita; Fernandes, Conceição; Marques, Celeste; Matos, Carlos; Vilela, Alice; Filipe-Ribeiro, Luis; Nunes, Fernando M.; Cosme, FernandaThe pH control during winemaking is a fundamental parameter by their influence on color, freshness and to achieve wine microbiological stability. The most common acidify correction performed in wineries is addition of natural tartaric acid; however, in some cases, this operation increases the risks of potassium bitartrate precipitations [1, 2]. The application of ion exchange resins for wine acidification is based on ability of exchanging ions fixed on functional groups, namely by exchanging cations, such as potassium, with hydrogen ions. Nevertheless, there is an important lack of knowledge on the impact of this operation on wine sensory characteristics. To adjust wine pH, a certain amount of treated wine by ion exchange resins is mixed with the untreated wine [3]. According to OIV [4], treatment must not lower the pH of wine below 3.0 and the decrease should not exceed 0.3 pH units. Anion exchangers are not allowed by the OIV [3] due to the negative effects on the wine sensory quality [5,6]. Therefore, the aim of this work was to evaluate the effect of cation exchange resins, authorized by the OIV, according to Resolution 43/2000 [3] on wine pH control and to evaluate their impact on wine sensory quality at industrial scale. In this study a white and a red wine from the Douro Valley region, 2015 vintage, was used. In this work ion exchange resin treated white wine was almost 20% from total white wine volume and red wine was almost 30% from total red wine volume. The present study indicated that there were no considerable changes in sensory attributes, although a slight improvement in the aroma and taste, as a result of the ion-exchange pH adjustment. These results show that the application of ion exchange resins process to wine could be an interesting tool for white and red wine pH adjustment, without interfering with wine sensorial quality.
- Effect of ion exchange resins on white and red wine pH: Impact on wine sensory characteristicsPublication . Borges, Rita; Fernandes, Conceição; Marques, Celeste; Matos, Carlos; Vilela, Alice; Filipe-Ribeiro, Luis; Nunes, Fernando M.; Cosme, FernandaThe pH control during winemaking is a fundamental parameter by their influence on colour, freshness and to achieve wine microbiological stability. The application of ion exchange resins for wine acidification is based on ability of exchanging ions fixed on functional groups, namely by exchanging cations, such as potassium, with hydrogen ions. Nevertheless, there is an important lack of knowledge on the impact of this operation on wine sensory characteristics. Therefore, the aim of this work was to evaluate the effect of cation exchange resins, on wine pH control and to evaluate their impact on wine sensory quality at industrial scale. In this study a white and a red wine, both from the Douro Valley demarcated region, 2015 vintage, were used. The ion exchange resin treated wine was almost 20% from total white wine volume and almost 30% from total red wine volume. The results obtained in the present study indicated that there were no considerable changes in sensory attributes, although a slight improvement in the aroma and taste, as a result of the ion-exchange pH adjustment. Therefore, the application of ion exchange resins process to wine could be an interesting tool for white and red wine pH adjustment, without interfering with wine sensory quality.
- Effect of ion exchange resins on white and red wine pH: impact on wine sensory characteristicsPublication . Borges, Rita; Fernandes, Conceição; Marques, Celeste; Matos, Carlos; Vilela, Alice; Filipe-Ribeiro, Luis; Nunes, Fernando M.; Cosme, FernandaThe pH control during winemaking is a fundamental parameter by their influence on color, freshness and to achieve wine microbiological stability. The most common acidify correction performed in wineries is addition of natural tartaric acid; however, in some cases, this operation increases the risks of potassium bitartrate precipitations [1, 2]. The application of ion exchange resins for wine acidification is based on ability of exchanging ions fixed on functional groups, namely by exchanging cations, such as potassium, with hydrogen ions. Nevertheless, there is an important lack of knowledge on the impact of this operation on wine sensory characteristics. To adjust wine pH, a certain amount of treated wine by ion exchange resins is mixed with the untreated wine [3]. According to OIV [4], treatment must not lower the pH of wine below 3.0 and the decrease should not exceed 0.3 pH units. Anion exchangers are not allowed by the OIV [3] due to the negative effects on the wine sensory quality [5,6]. Therefore, the aim of this work was to evaluate the effect of cation exchange resins, authorized by the OIV, according to Resolution 43/2000 [3] on wine pH control and to evaluate their impact on wine sensory quality at industrial scale. In this study a white and a red wine from the Douro Valley region, 2015 vintage, was used. In this work ion exchange resin treated white wine was almost 20% from total white wine volume and red wine was almost 30% from total red wine volume. The present study indicated that there were no considerable changes in sensory attributes, although a slight improvement in the aroma and taste, as a result of the ion-exchange pH adjustment. These results show that the application of ion exchange resins process to wine could be an interesting tool for white and red wine pH adjustment, without interfering with wine sensorial quality.
- Estabilização proteica de vinhos brancos por adição de manoproteínas e impacto na qualidadePublication . Ribeiro, Tânia Isabel Monteiro; Fernandes, Conceição; Nunes, Fernando M.; Filipe-Ribeiro, Luis; Cosme, FernandaA instabilidade proteica é um defeito que pode conduzir à rejeição do vinho. A desnaturação e precipitação das proteínas instáveis, podem afetar a limpidez e/ou originar depósitos amorfos. A concentração e composição das proteínas, dependem da casta, condições climáticas, estado de maturação das uvas e da vinificação. A colagem com bentonite é o processo mais comum na prevenção desta instabilidade, mas apresenta limitações, particularmente quando aplicada em doses elevadas. Assim, têm sido estudadas alternativas, como por exemplo as manoproteínas.
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