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Publication
Micro-oxygenation in Madeira Wine
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Abstract(s)
A micro-oxigenação consiste na adição deliberada e controlada de pequenas quantidades de oxigénio durante o processo de vinificação, com o intuito de melhorar as características organoléticas do vinho. Tendo em conta o carácter oxidativo do processo de envelhecimento do vinho Madeira, avaliou-se o impacto de três tratamentos de microoxigenação (t1- 66 mg/L por mês, antes da estufagem; t2 - 66 mg/L por mês, durante a estufagem; t3 – oxigénio dissolvido acima de 7 mg/L, durante a estufagem) no conteúdo de oxigénio dissolvido, parâmetros enológicos básicos, cor, polifenóis, furanos, composição volátil e características sensoriais. Em geral, a adição de um fluxo padrão de oxigénio não teve um impacto notável na cor, na composição polifenólica, nos furanos ou no perfil volátil, favorecendo, no entanto, o desenvolvimento de sotolon (até 97%) e de acetais heterocíclicos (até 95% para o trans-dioxolano). Já as condições de sobreoxigenação (t3) diminuíram consideravelmente a intensidade da cor (cerca de 41%) e o conteúdo polifenólico (até 29% durante a estufagem). Adicionalmente, este tratamento desacelerou a formação de furanos e de sotolon até cerca de 36%, comparativamente ao controlo. Para tal, foi desenvolvida uma metodologia para a determinação simultânea de sotolon e acetais heterocíclicos (cis- e trans-dioxano e cis- e trans-dioxolano), tendo por base a miniaturização da extração líquido-líquido e análise por GC-MS/SIM. Após otimização, o procedimento de extração foi validado relativamente ao sotolon, demonstrando ter boa sensibilidade (LOD e LOQ de 2,3 e 6,8 μg/L, respetivamente), linearidade (R2 de 0,999), precisão (desvios padrão para repetibilidade e reprodutibilidade inferiores a 8% e 10%, respetivamente) e exatidão (recuperação média de 105,4%), recorrendo a uma abordagem ecológica, rápida e de baixo custo. Relativamente aos acetais heterocíclicos, a metodologia foi avaliada em termos de precisão, com desvios padrão inferiores a 13% para a repetibilidade e a 17% para a reprodutibilidade.
Micro-oxygenation is the deliberate and controlled addition of small amounts of oxygen during the winemaking process, with the intent of improving the wine’s organoleptic characteristics. Given the oxidative nature of Madeira wine aging, the impact of three micro-oxygenation treatments (t1- 66 mg/L per month before estufagem; t2 - 66 mg/L per month during estufagem; t3 – DO above 7 mg/L during estufagem) on the dissolved oxygen content, basic oenological characteristics, color, polyphenolics, furans, volatiles and sensorial characteristics were verified. In general, standard oxygen flow addition did not have a noticeable impact on wine color, polyphenolic composition, furans or total volatile composition, but favored the development of sotolon (up to 97%) and heterocyclic acetals (up to 95% for trans-dioxolane). Over-oxygenation conditions (t3) considerably decreased color intensity (about 41%) and polyphenols (up to 29% during estufagem). Additionally, the t3 treatment slowed the development of furans and sotolon up to about 36%, comparing to the control. To accomplish this analysis, a methodology for the simultaneous evaluation of sotolon and heterocyclic acetals (cis- and trans-dioxane and cis- and trans- dioxolane) was developed, based on a miniaturized liquid-liquid extraction followed by GC-MS/SIM analysis. The optimized extraction procedure was fully validated for the analysis of sotolon, showing good sensitivity (LOD and LOQ of 2.3 and 6.8 µg/L, respectively), linearity (R2 of 0.999), precision (standard deviation for repeatability and reproducibility lower than 8% and 10%, respectively) and accuracy (average recovery of 105.4%), using an eco-friendly, fast and low-cost approach. In regards to the heterocyclic acetals, the methodology was assessed in terms of precision, with standard deviations lower than 13% for repeatability and lower than 17% for reproducibility.
Micro-oxygenation is the deliberate and controlled addition of small amounts of oxygen during the winemaking process, with the intent of improving the wine’s organoleptic characteristics. Given the oxidative nature of Madeira wine aging, the impact of three micro-oxygenation treatments (t1- 66 mg/L per month before estufagem; t2 - 66 mg/L per month during estufagem; t3 – DO above 7 mg/L during estufagem) on the dissolved oxygen content, basic oenological characteristics, color, polyphenolics, furans, volatiles and sensorial characteristics were verified. In general, standard oxygen flow addition did not have a noticeable impact on wine color, polyphenolic composition, furans or total volatile composition, but favored the development of sotolon (up to 97%) and heterocyclic acetals (up to 95% for trans-dioxolane). Over-oxygenation conditions (t3) considerably decreased color intensity (about 41%) and polyphenols (up to 29% during estufagem). Additionally, the t3 treatment slowed the development of furans and sotolon up to about 36%, comparing to the control. To accomplish this analysis, a methodology for the simultaneous evaluation of sotolon and heterocyclic acetals (cis- and trans-dioxane and cis- and trans- dioxolane) was developed, based on a miniaturized liquid-liquid extraction followed by GC-MS/SIM analysis. The optimized extraction procedure was fully validated for the analysis of sotolon, showing good sensitivity (LOD and LOQ of 2.3 and 6.8 µg/L, respectively), linearity (R2 of 0.999), precision (standard deviation for repeatability and reproducibility lower than 8% and 10%, respectively) and accuracy (average recovery of 105.4%), using an eco-friendly, fast and low-cost approach. In regards to the heterocyclic acetals, the methodology was assessed in terms of precision, with standard deviations lower than 13% for repeatability and lower than 17% for reproducibility.
Description
Keywords
Envelhecimento oxidativo Oxigénio dissolvido Cor Polifenóis Composição volátil Oxidative aging Dissolved oxygen Color Polyphenols Volatile composition Vinho Madeira Applied Biochemistry . Faculdade de Ciências Exatas e da Engenharia