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Este trabalho foi realizado na “Quinta de Soalheiro” no concelho de Melgaço e teve como principal objetivo estudar a evolução oxidativa de vinhos Alvarinho com e sem a adição de sulfitos. A evolução oxidativa foi analisada sob duas perspetivas distintas, culminando na divisão do estudo em duas partes diferentes: • Parte I- Realização de uma análise vertical de modo a caracterizar, em termos colorimétricos e aromáticos, a evolução natural em adega de dois tipos de vinhos, um de vinificação normal (Soalheiro Alvarinho) e outro de vinificação natural (Soalheiro Nature). Para tal analisaram-se os vinhos “Soalheiro Alvarinho” (com adição de sulfitos) de 10 anos consecutivos, de 2010 a 2019 e analisaram-se os vinhos “Soalheiro Nature” (sem sulfitos adicionados) de 4 anos consecutivos, de 2016 a 2019. • Parte II- Os principais objetivos foram tentar prever a evolução oxidativa de dois vinhos (Soalheiro Alvarinho e Nature) ao longo do tempo e comparar a longevidade e resistência entre ambos, em termos colorimétricos e aromáticos. Assim, de modo a conseguir mimetizar o envelhecimento dos vinhos em garrafa ao longo do tempo e perceber, de um modo mais expedito, de que modo evolui a oxidação dos vinhos na presença e ausência de sulfitos, os vinhos foram sujeitos a um envelhecimento forçado através de um período de incubação de 2 meses a 50˚C. Estudaram-se dois tipos de vinhos, de dois anos de colheitas diferentes “Alvarinho Soalheiro 2018 e 2019” e “Soalheiro Nature 2018 e 2019”. De modo a concretizar estes objetivos, foram realizados diversos testes, nomeadamente espectofotométricos e de CIELab, para caracterizar a cor dos vinhos e estudos de análise sensorial, de modo a caracterizar o aroma. Após a análise dos resultados da parte I foi possível concluir que poderá existir uma correlação entre o Índice de polifenóis totais (IPT) e o grau de acastanhamento nos vinhos Alvarinho. Relativamente à parte II foi possível concluir que, vinhos com e sem a adição de sulfitos, com conteúdos baixos de polifenóis, apresentam uma resistência à degradação cromática e aromática semelhante, ao longo dos anos. Constatou-se, também, que os testes de envelhecimento forçado poderão simular o envelhecimento natural em adega durante quatro anos, em termos colorimétricos.
This thesis presents the results from a research work that was accomplished in “Quinta de Soalheiro” at Melgaço. The main objective of this investigation was to assess the oxidative evolution of Alvarinho wines with and without the addition of sulfites. The oxidative evolution was analysed in two different perspectives that led to the division of this work in two parts: • Part I- A vertical anlysis was performed in order to characterize, in terms of color and aroma, the natural evolution of two types of wine, more specifically, one with normal winemaking (Soalheiro Alvarinho) and one with natural winemaking (Soalheiro Nature). “Soalheiro Alvarinho” (with the addition of sulfites) of 10 consecutive years, from 2010 to 2019, and “Soalheiro Nature” (without the addition of sulfites) of 4 consecutive years, from 2016 to 2019, were analysed. • Parte II- The main objectives were to try to predict the oxidative evolution in time of two wines (Soalheiro Alvarinho e Nature) and compare their resistence and longevity, in chromatic and aromatic terms. For that reason, in order to mimic the aging of wines in bottle over time and understand, in a more expeditious way, how the oxidation of wine with or without sulfites evolves, the wines were subjected to forced aging tests with an incubation period at 50˚C. Two types of wine of two years of harvesting were studied “Soalheiro Alvarinho 2018 e 2019” and “Soalheiro Nature 2018 e 2019”. In order to accomplishe these goals, several tests were performed, namely spectrophotometric and CIELab tests to characterize color and sensorial analysis studies to characterize aroma. The results from Part I showed that their may be a relathion between the total polyphenolic index and the degree of browning of the Alvarinho wines. In terms of the results of Part II it was possible to conclude that wines with and without the addition of SO2, with low polyphenolic contents, have the same resistence to chromatic and aromatic degradation over time. It was also concluded that the foreced aging test may simulate, in chromatic terms, the aging of wines after four years in the cellar.
This thesis presents the results from a research work that was accomplished in “Quinta de Soalheiro” at Melgaço. The main objective of this investigation was to assess the oxidative evolution of Alvarinho wines with and without the addition of sulfites. The oxidative evolution was analysed in two different perspectives that led to the division of this work in two parts: • Part I- A vertical anlysis was performed in order to characterize, in terms of color and aroma, the natural evolution of two types of wine, more specifically, one with normal winemaking (Soalheiro Alvarinho) and one with natural winemaking (Soalheiro Nature). “Soalheiro Alvarinho” (with the addition of sulfites) of 10 consecutive years, from 2010 to 2019, and “Soalheiro Nature” (without the addition of sulfites) of 4 consecutive years, from 2016 to 2019, were analysed. • Parte II- The main objectives were to try to predict the oxidative evolution in time of two wines (Soalheiro Alvarinho e Nature) and compare their resistence and longevity, in chromatic and aromatic terms. For that reason, in order to mimic the aging of wines in bottle over time and understand, in a more expeditious way, how the oxidation of wine with or without sulfites evolves, the wines were subjected to forced aging tests with an incubation period at 50˚C. Two types of wine of two years of harvesting were studied “Soalheiro Alvarinho 2018 e 2019” and “Soalheiro Nature 2018 e 2019”. In order to accomplishe these goals, several tests were performed, namely spectrophotometric and CIELab tests to characterize color and sensorial analysis studies to characterize aroma. The results from Part I showed that their may be a relathion between the total polyphenolic index and the degree of browning of the Alvarinho wines. In terms of the results of Part II it was possible to conclude that wines with and without the addition of SO2, with low polyphenolic contents, have the same resistence to chromatic and aromatic degradation over time. It was also concluded that the foreced aging test may simulate, in chromatic terms, the aging of wines after four years in the cellar.
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Keywords
Qualidade do vinho Alvarinho Evolução oxidativa Sulfitos Wine quality Oxidative evolution Sulfites