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Advisor(s)
Abstract(s)
Compreender a forma como o oxigénio afeta o vinho, nas diferentes operações de produção, é um fator determinante para a elaboração de vinhos. Numa perspetiva química, a presença de oxigénio dissolvido no vinho poderá resultar numa oxidação, diminuindo a sua qualidade e consequentemente o seu tempo de vida útil. Controlar as etapas nas quais há uma maior probabilidade de entrada de oxigénio no vinho assim como o controlo dos níveis de oxigénio dissolvido é de fundamental importância.
O presente relatório resulta do trabalho realizado na Adega Cooperativa de Favaios (ACF), tendo como objetivo identificar quais os processos responsáveis pela maior introdução de oxigénio dissolvido no vinho. Devido ao período da realização deste trabalho, só foi possível realizar as medições do teor de oxigénio nos processos de trasfega. Os estudos foram efetuados em vinhos brancos, tintos, licorosos (Porto tinto, Porto branco e Moscatel) e espumantes. Além deste estudo, foi também realizada a monitorização de 4 vinhos tintos, no processo de micro-oxigenação (MO), que é uma das técnicas utilizadas na Adega Cooperativa de Favaios.
Quanto aos resultados obtidos, pudemos observar que em algumas trasfegas o aumento do teor de oxigénio foi significativo. Verificou-se que na trasfega onde houve a necessidade de mudar as mangueiras, a fim de completar o processo, houve um aumento de dissolução de oxigénio significativo. Outro caso em que se registou um ponto crítico foi na trasfega em que o troço final da mangueira foi colocado no topo do depósito.
Em relação à técnica da de micro-oxigenação efetuada nos 4 vinhos tintos, os objetivos foram alcançados ao nível da cor onde houve um aumento das tonalidades vermelhas, no aroma em que se verificou um aumento dos aromas frutados e no sabor em que se detetou uma diminuição significativa da adstringência e dos sabores herbáceos. Quanto à dose de oxigénio utilizada para esse fim, foi utilizada uma dose 2,0 mg/L/mês durante 43 dias, e com a temperatura das cubas regulada para os 16ºC.
Understanding how oxygen affects wine, in the different production operations, is a determining factor for winemaking. From a chemical perspective, the presence of dissolved oxygen in the wine may result in oxidation, reducing its quality and consequently its shelf life. Controlling the steps in which there is a greater possibility of oxygen entry into the wine as well as the control of the levels of dissolved oxygen is very important. This report is the result of the work carried out at Favaios Cooperative Winery, in order to identify the processes responsible for the increased introduction of dissolved oxygen into wine. Due to the period of this work, it was only possible to carry out measurements of the oxygen content in the transfer processes. The studies were carried out on white, red, Port (red and white), Moscatel, and sparkling wines. In addition to this study, four red wines were also monitored in the micro oxygenation process, which is one of the techniques used at Favaios Cooperative Winery. Regarding the results obtained, we could observe that in some racking operations the increase in the oxygen content was significant. It was found that in the transfer where there was a need to change the tubes in order to complete the process, there was a significant increase in oxygen dissolution. Another case where there was a critical point was in the transfer where the final section of the tubes was placed on the top of the tank. Regarding the technique of micro-oxygenation, carried out in the 4 red wines, the objectives were reached at the color level where there was an increase of the red tones, in the aroma in which there was an increase of the fruity aromas and in the flavor in which a decrease was detected of astringency and herbaceous flavors. The oxygen dose used for this purpose was 2.0 mg/ L/month, applied for 43 days, and the tank temperature was set at 16 °C.
Understanding how oxygen affects wine, in the different production operations, is a determining factor for winemaking. From a chemical perspective, the presence of dissolved oxygen in the wine may result in oxidation, reducing its quality and consequently its shelf life. Controlling the steps in which there is a greater possibility of oxygen entry into the wine as well as the control of the levels of dissolved oxygen is very important. This report is the result of the work carried out at Favaios Cooperative Winery, in order to identify the processes responsible for the increased introduction of dissolved oxygen into wine. Due to the period of this work, it was only possible to carry out measurements of the oxygen content in the transfer processes. The studies were carried out on white, red, Port (red and white), Moscatel, and sparkling wines. In addition to this study, four red wines were also monitored in the micro oxygenation process, which is one of the techniques used at Favaios Cooperative Winery. Regarding the results obtained, we could observe that in some racking operations the increase in the oxygen content was significant. It was found that in the transfer where there was a need to change the tubes in order to complete the process, there was a significant increase in oxygen dissolution. Another case where there was a critical point was in the transfer where the final section of the tubes was placed on the top of the tank. Regarding the technique of micro-oxygenation, carried out in the 4 red wines, the objectives were reached at the color level where there was an increase of the red tones, in the aroma in which there was an increase of the fruity aromas and in the flavor in which a decrease was detected of astringency and herbaceous flavors. The oxygen dose used for this purpose was 2.0 mg/ L/month, applied for 43 days, and the tank temperature was set at 16 °C.
Description
Keywords
Vinho Trasfega Oxigénio dissolvido Micro-oxigenação