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Advisor(s)
Abstract(s)
O vinho espumante é distinguido dos restantes por apresentar uma quantidade significativa de CO2 dissolvido, que lhe confere uma efervescência característica. Esta quantidade de CO2 depende diretamente da quantidade de açúcar adicionado na preparação do vinho nomeadamente aquando da segunda fermentação. A rolha de espumante deve garantir a estanquicidade da garrafa a líquidos e gases, assim como preservar as características do vinho. As rolhas de espumante apresentam a particularidade de aguentaram as elevadas pressões existentes neste tipo de vinhos. Atualmente, a rolha mais utilizada é constituída por um corpo aglomerado colado a dois discos de cortiça natural. O tema de estágio surgiu devido à procura de alternativas às típicas rolhas de discos para vinhos espumantes, com o objetivo de as incluir no portfólio da Amorim Cork. Para isso, foi desenvolvida uma rolha (RN XPÜR) 100% de microaglomerado que garanta a qualidade físico-mecânica e um bom desempenho como vedante de garrafas de vinho espumante para concorrer com as soluções atualmente em uso. Dessa forma, foi avaliada e comparada a sua performance físico-mecânica com a das rolhas já existentes no mercado, assim como avaliado o seu efeito na qualidade química e sensorial de vinhos espumantes ao longo de 10 meses de engarrafamento. A permeabilidade das rolhas de champanhe ao oxigénio constitui um grande desafio para a indústria corticeira uma vez que ainda existe pouca informação disponível sobre este assunto. Assim, foram realizadas experiências em soluções-modelo, em condições semelhantes às dos vinhos espumantes, com as rolhas em estudo para avaliar a sua permeabilidade aos gases (dióxido de carbono e oxigénio), bem como a monitorização da retenção do CO2. Foi desenvolvido e otimizado um método colorimétrico para a deteção da entrada de oxigénio, baseado na mudança de cor do azul de metileno que foi posteriormente comparado com um método comercial (PreSens). Os resultados obtidos através do novo método são parcialmente coincidentes com os do método comercial, embora sejam necessárias mais experiências para o aperfeiçoar.
Os dados recolhidos ao fim de 3, 7 e 10 meses em garrafa, permitiram observar as diferenças do comportamento físico-mecânico das rolhas em estudo. A rolha RN XPÜR registou, ao fim de 10 meses em estudo, valores intermédios de forças de descolamento, uma menor retenção de CO2 ao fim de 7 meses em garrafa e valores intermédios de entrada de oxigénio para a solução. Para estudar o impacto das diferentes rolhas na qualidade do vinho foi feito um engarrafamento, com as rolhas em estudo, de um vinho espumante produzido na região da Bairrada pelo método Charmat-Martinotti, do qual foram feitas análises químicas e sensoriais aos 7 e 10 meses em garrafa. Relativamente à análise sensorial realizada aos 7 e 10 meses, verificou-se que não existiram diferenças estatisticamente significativas na qualidade dos vinhos vedados com as rolhas em estudo, para um grau de significância de 95%. Os resultados das análises químicas mostraram que os vinhos vedados com a rolha RN XPÜR indicaram uma boa retenção de SO2 ao fim de 7 e 10 meses em garrafa. Em conclusão, a nova rolha desenvolvida demonstrou uma boa performance do ponto de vista físico-mecânico e enológico, permitindo que a Amorim Cork adicione esta rolha ao seu portfólio de produtos.
Sparkling wine is distinguished from others by having a significant amount of dissolved CO2, which gives it a characteristic effervescence. This amount of CO2 depends directly on the amount of sugar added during the preparation of the wine, namely during the second fermentation. The sparkling wine stopper must guarantee the bottle's impermeability to liquids and gases as well as preserve the wine's characteristics. Sparkling wine stoppers have the particularity of withstanding the high pressures existing in this type of wine. Currently, the most commonly used cork stopper consists of an agglomerated body glued to two natural cork disks. The internship topic was developed due to the search for alternatives to the typical disc stoppers for sparkling wines, with the purpose of including them in Amorim Cork's portfolio. To this end, a 100% microagglomerate stopper (RN XPÜR) that guarantees physical-mechanical quality and good performance as a seal for sparkling wine bottles was developed to compete with the solutions currently in use. Therefore, its physicalmechanical performance was evaluated and compared with that of stoppers already on the market, and its effect on the chemical and sensory quality of sparkling wines over 10 months bottled was also assessed. Currently, the oxygen permeability of champagne stoppers is a big challenge for the cork industry as there is still little information available on this subject. Therefore, experiments were conducted in model solutions, in conditions similar to those of sparkling wines, with the stoppers under study to assess their permeability to gases (CO2 and oxygen), and their CO2 retention was also monitored. A colorimetric method was developed and optimized for the detection of oxygen ingress, based on the color change of methylene blue, which was then compared with an existing commercial method (PreSens). The results obtained using the new method partially match those of the commercial method, although more experiments are needed to improve it. The results collected after 3, 7 and 10 months bottled allowed us to observe the differences in the physical-mechanical behavior of the corks under study. The RN XPÜR cork showed, after 10 months, intermediate values of detachment forces, a lower CO2 retention after 7 months in bottle, and intermediate values of oxygen ingress into the solution. A sparkling wine produced in the Bairrada region using the Charmat-Martinotti method was bottled using the different closures under study, of which chemical and sensory analyses were performed at 7 and 10 months in bottle, to study the impact of the different closures on the quality of the wine. Regarding the sensory analysis performed at 7 and 10 months, it was found that there were no statistically significant differences in the quality of wines sealed with the stoppers under study, for a significance level of 95%. The results of the chemical analysis showed that wines sealed with RN XPÜR cork indicated good SO2 retention after 7 and 10 months bottled. In conclusion, the new stopper developed has demonstrated good performance from a physical-mechanical and oenological point of view, allowing Amorim Cork to add this stopper to its product portfolio.
Sparkling wine is distinguished from others by having a significant amount of dissolved CO2, which gives it a characteristic effervescence. This amount of CO2 depends directly on the amount of sugar added during the preparation of the wine, namely during the second fermentation. The sparkling wine stopper must guarantee the bottle's impermeability to liquids and gases as well as preserve the wine's characteristics. Sparkling wine stoppers have the particularity of withstanding the high pressures existing in this type of wine. Currently, the most commonly used cork stopper consists of an agglomerated body glued to two natural cork disks. The internship topic was developed due to the search for alternatives to the typical disc stoppers for sparkling wines, with the purpose of including them in Amorim Cork's portfolio. To this end, a 100% microagglomerate stopper (RN XPÜR) that guarantees physical-mechanical quality and good performance as a seal for sparkling wine bottles was developed to compete with the solutions currently in use. Therefore, its physicalmechanical performance was evaluated and compared with that of stoppers already on the market, and its effect on the chemical and sensory quality of sparkling wines over 10 months bottled was also assessed. Currently, the oxygen permeability of champagne stoppers is a big challenge for the cork industry as there is still little information available on this subject. Therefore, experiments were conducted in model solutions, in conditions similar to those of sparkling wines, with the stoppers under study to assess their permeability to gases (CO2 and oxygen), and their CO2 retention was also monitored. A colorimetric method was developed and optimized for the detection of oxygen ingress, based on the color change of methylene blue, which was then compared with an existing commercial method (PreSens). The results obtained using the new method partially match those of the commercial method, although more experiments are needed to improve it. The results collected after 3, 7 and 10 months bottled allowed us to observe the differences in the physical-mechanical behavior of the corks under study. The RN XPÜR cork showed, after 10 months, intermediate values of detachment forces, a lower CO2 retention after 7 months in bottle, and intermediate values of oxygen ingress into the solution. A sparkling wine produced in the Bairrada region using the Charmat-Martinotti method was bottled using the different closures under study, of which chemical and sensory analyses were performed at 7 and 10 months in bottle, to study the impact of the different closures on the quality of the wine. Regarding the sensory analysis performed at 7 and 10 months, it was found that there were no statistically significant differences in the quality of wines sealed with the stoppers under study, for a significance level of 95%. The results of the chemical analysis showed that wines sealed with RN XPÜR cork indicated good SO2 retention after 7 and 10 months bottled. In conclusion, the new stopper developed has demonstrated good performance from a physical-mechanical and oenological point of view, allowing Amorim Cork to add this stopper to its product portfolio.
Description
Keywords
Vinho espumante Rolha de champanhe Rolha 100% de microaglomerado Retenção de pressão de CO2 Permeabilidade ao oxigénio Sparkling wine Champagne cork 100% microagglomerate stopper CO2 pressure retention Oxygen permeability