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- Influence of the structural features of commercial mannoproteins in white wine protein stabilization and chemical and sensory propertiesPublication . Ribeiro, Tânia Isabel Monteiro; Fernandes, Conceição; Nunes, Fernando M.; Filipe-Ribeiro, Luis; Cosme, FernandaThe cloudy aspect formed in white wines due to protein instability is a visual defect. Sodium bentonite is the most commonly used fining agent to treat this instability, but has usually a negative impact on the wine’s physicochemical and sensory characteristics. Aiming to find suitable alternatives, eleven commercial mannoproteins were chemically characterized concerning their sugar composition and protein content, and their effectiveness on wine protein stabilization. Also, their effect on the amount and nature of phenolic compounds, browning potential, chromatic and sensory characteristic was evaluated. Protein stabilization effectiveness was related to their chemical composition, namely their high mannose to glucose ratio. Additionally, some mannoproteins decreased the browning potential. Thus, mannoproteins could be an effective alternative for protein stabilization, preserving or even improving wine 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.
- 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 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 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.