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A composição e a qualidade de um vinho estão intrinsecamente ligadas a vários fatores, tais como o cultivo da uva, as características da colheita, as condições de vinificação, as práticas de produção, o envelhecimento, a embalagem e as condições de estágio. O envelhecimento é um processo relevante, pois durante esse período, o vinho sofre complexas alterações químicas que podem afetar a sua composição aromática, sabor e cor. Vinhos como o Porto Vintage têm elevado potencial de envelhecimento, passando por um período de maturação em garrafa que pode durar anos ou até mesmo décadas. Este trabalho teve como objetivo avaliar a influência do tipo de rolha de cortiça natural (embutida ou bartop), a posição da garrafa (deitada ou na vertical) e o local de estágio (garrafeira climatizada ou com condições naturais) nas propriedades químicas e sensoriais de um Vinho do Porto Vintage em garrafa de vidro negro. Adicionalmente, foi avaliado o impacto destes fatores nas propriedades físico-mecânicas das rolhas. O projeto vai se prolongar por um período de 10 anos para apurar o impacto das variáveis em estudo no Vinho do Porto Vintage. Os resultados apresentados na dissertação, contemplam os primeiros 15 meses de estágio. Após o período em estudo, as rolhas de embutir não evidenciaram qualquer progressão capilar, enquanto que as bartop apresentaram uma capilaridade de cerca de 30% do seu comprimento, com maior intensidade de absorção nas garrafas em posição horizontal. As forças de extração das rolhas e embutir foram significativamente superiores nas garrafas conservadas em posição vertical e na garrafeira com maiores amplitudes de temperatura e de humidade (Castelo). Quanto à caracterização físico-química, observou-se um decréscimo do SO2 Total e uma evolução normal da cor do Vinho do Porto em todas as condições estudadas. Relativamente às antocianinas livres, constatou-se, como expectável, uma diminuição da sua concentração ao longo do estágio, independentemente do tipo de rolha, posição e local de estágio do vinho, apesar de não se observarem diferenças estatisticamente significativas. O poder tanante diminuiu ao longo do tempo, independentemente do tipo de rolha, posição e local de estágio dos vinhos. Foram observadas diferenças de compostos voláteis entre os vinhos em estudo. Apesar de não existirem diferenças cromáticas e sensoriais significativas, os vinhos conservados na garrafeira do Castelo estão um pouco mais evoluídos em prova, pois apresentaram menor teor de antocianinas e menor teor de vários compostos aromáticos, indicador de degradação térmica. Estas evidências estão relacionadas com o facto de os vinhos na garrafeira do Castelo estarem expostos a temperaturas mais elevadas que na garrafeira 5 e que pode afetar negativamente o seu envelhecimento. O prosseguimento do projeto no período preconizado é fundamental para apurar o impacto das variáveis em estudo e aumentar o conhecimento no âmbito das oxidações aleatórias no Vinho do Porto.
The composition and quality of a wine are intrinsically linked to several factors, such as grape growth, harvest characteristics, vinification conditions, production practices, aging, packaging or settings of the aging wine cellar. Aging is a relevant process, as during this period the wine undergoes complex chemical changes that may affect its aromatic composition, taste and color. Wines such as a Vintage Port have a high aging potential, as they are exposed to a maturing period which can last for years or even decades. The objective of this work was to evaluate how the natural cork (embossed or bartop cork), theposition of the bottle (lying down or in the upright position) and storage place (climatised or innatural conditions) can influence the chemical and sensory properties of a Vintage Port in a black glass bottle, as well as to evaluate the impact of these factors on the physical-mechanical properties of corks. The project will be extended for a period of 10 years, the results presented in this dissertation cover the first 15 months of aging. The embossed corks did not show any capillarity progression, while the bar top showed a capillarity of about 30% of its length, with greater intensity of absorption in the lying down bottles. The extraction forces of the embossed corks were significantly higher in the upright bottles and in thewine cellar (Castle), which presents higher temperature and humidity amplitudes. As for the physical-chemical characterisation, there was a decrease in total SO2 and a normal evolution of the colour of Port in all studied conditions. The free anthocyanin’s suffered a decrease along the bottle stage, irrespective of the type of cork, position and store cellar, even though no statistically significant differences were noticed. The tanning power decreased over time, regardless the type of cork, position and store cellar. Differences on the volatile compounds were detected among the wines under study. Given the inexistence of significant chromatic and sensorial differences, the wines preserved in the Castle wine cellar are slightly more evolved in the wine tasting, as they presented lower content of anthocyanins along with lower content of several aromatic compounds, indicative of thermal degradation. This evidence is related to the fact that the wines in the Castle wine cellar are exposed to higher temperatures than in cellar 5, which may affect negatively their aging.T he project continuity during the recommended period is fundamental in order to determine the impact of the wine in the variables under study and to increase knowledge about random oxidations in the Port Wine.”
The composition and quality of a wine are intrinsically linked to several factors, such as grape growth, harvest characteristics, vinification conditions, production practices, aging, packaging or settings of the aging wine cellar. Aging is a relevant process, as during this period the wine undergoes complex chemical changes that may affect its aromatic composition, taste and color. Wines such as a Vintage Port have a high aging potential, as they are exposed to a maturing period which can last for years or even decades. The objective of this work was to evaluate how the natural cork (embossed or bartop cork), theposition of the bottle (lying down or in the upright position) and storage place (climatised or innatural conditions) can influence the chemical and sensory properties of a Vintage Port in a black glass bottle, as well as to evaluate the impact of these factors on the physical-mechanical properties of corks. The project will be extended for a period of 10 years, the results presented in this dissertation cover the first 15 months of aging. The embossed corks did not show any capillarity progression, while the bar top showed a capillarity of about 30% of its length, with greater intensity of absorption in the lying down bottles. The extraction forces of the embossed corks were significantly higher in the upright bottles and in thewine cellar (Castle), which presents higher temperature and humidity amplitudes. As for the physical-chemical characterisation, there was a decrease in total SO2 and a normal evolution of the colour of Port in all studied conditions. The free anthocyanin’s suffered a decrease along the bottle stage, irrespective of the type of cork, position and store cellar, even though no statistically significant differences were noticed. The tanning power decreased over time, regardless the type of cork, position and store cellar. Differences on the volatile compounds were detected among the wines under study. Given the inexistence of significant chromatic and sensorial differences, the wines preserved in the Castle wine cellar are slightly more evolved in the wine tasting, as they presented lower content of anthocyanins along with lower content of several aromatic compounds, indicative of thermal degradation. This evidence is related to the fact that the wines in the Castle wine cellar are exposed to higher temperatures than in cellar 5, which may affect negatively their aging.T he project continuity during the recommended period is fundamental in order to determine the impact of the wine in the variables under study and to increase knowledge about random oxidations in the Port Wine.”
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Palavras-chave
Vinho do Porto Garrafa Rolha Garrafeira Port Wine Bottle Cork Cellar