| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 3.56 MB | Adobe PDF |
Authors
Advisor(s)
Abstract(s)
As características físico-químicas do mosto e do vinho apresentam uma elevada relevância para os seus produtores. Estas características dão indicação sobre a qualidade, estabilidade, entre outras informações, destes produtos. Umas das formas de quantificar estes parâmetros é através de métodos espetrofotométricos. Através da utilização destas características é possível desenvolver modelos estatísticos, recorrendo à análise multivariável para a classificação das qualidades entre amostras, mostos e vinhos. As amostras analisadas foram obtidas durante o processo de controlo de maturação e durante a vindima (lotas de Vinho do Porto, ou seja, referem-se a amostras antes do processo fermentativo), nos anos de 2018 e 2019, na Symington Family Estates. Antes da análise das amostras pelos métodos espetrofotométricos (de absorção no infravermelho e visível), foi analisado o teor de dióxido de enxofre. Desta análise verificou-se que as amostras recolhidas durante o controlo de maturação se encontravam aptas para a análise multivariável, neste caso a análise de componentes principais (PCA), enquanto que a maioria das amostras de lotas de vinho do Porto apresentavam níveis de dióxido de enxofre elevados, superiores a 300 mg/L, sendo descartadas as análises destas últimas. Através da análise de PCA de semanas destintas do controlo de maturação de 2018 e 2019, em que a variação da densidade é de 3,14 %, expressa em ºBé, entre as semanas em estudo, verificou-se que as origens Bomfim e Malvedos apresentam maior quantidades de açúcares (maior grau de Baumé), maior pH e maior quantidades de nutrientes, em relação às restantes origens (Ataíde, Cavadinha, Roriz, Senhora da Ribeira, e Vesúvio).
The physical and chemical characteristics of must and wine are highly relevant for their producers. These characteristics give an indication of the quality, stability, and other information of these products. One of the ways of quantifying these parameters is through spectrophotometric methods. By using these characteristics, it is possible to develop statistical models, through multivariable analysis, for the classification of qualities between samples, musts and wines. The samples analysed were obtained during the maturation control process and during the harvest (Port lots) in 2018 and 2019 at Symington Family Estates. The grape must sulphur dioxide content was evaluated using the aspiration method before spectrophotometric characterization (infrared and visible absorption). The low variance in must [SO2] demonstrated that the samples taken during the ripening control were within acceptable values, adequate to proceed with robust multivariable analysis, in this case Principal Component Analysis (PCA). The majority of Port wine lot samples had excessively high levels of sulphur dioxide added to inhibit fermentation, over 300 mg/L, unacceptable for evaluation. PCA analysis of the samples obtained during the maturation control in 2018 and 2019, selected for their low comparable variation of 3,14 % in density, expressed in ºBé, showed that the origins Bomfim and Malvedos had higher sugar levels (increased degree of Baumé), higher pH and higher quantities of nutrients, in relation to the other origins (Ataíde, Cavadinha, Roriz, Senhora da Ribeira, e Vesúvio).
The physical and chemical characteristics of must and wine are highly relevant for their producers. These characteristics give an indication of the quality, stability, and other information of these products. One of the ways of quantifying these parameters is through spectrophotometric methods. By using these characteristics, it is possible to develop statistical models, through multivariable analysis, for the classification of qualities between samples, musts and wines. The samples analysed were obtained during the maturation control process and during the harvest (Port lots) in 2018 and 2019 at Symington Family Estates. The grape must sulphur dioxide content was evaluated using the aspiration method before spectrophotometric characterization (infrared and visible absorption). The low variance in must [SO2] demonstrated that the samples taken during the ripening control were within acceptable values, adequate to proceed with robust multivariable analysis, in this case Principal Component Analysis (PCA). The majority of Port wine lot samples had excessively high levels of sulphur dioxide added to inhibit fermentation, over 300 mg/L, unacceptable for evaluation. PCA analysis of the samples obtained during the maturation control in 2018 and 2019, selected for their low comparable variation of 3,14 % in density, expressed in ºBé, showed that the origins Bomfim and Malvedos had higher sugar levels (increased degree of Baumé), higher pH and higher quantities of nutrients, in relation to the other origins (Ataíde, Cavadinha, Roriz, Senhora da Ribeira, e Vesúvio).
Description
Keywords
Análise multivariável, Análise de Componentes principais Controlo de maturação Mosto Radiação eletromagnéticas Espetrofotometria de Infravermelho e Visível Vinho do Porto Multivariate analysis Principal components analysis Maturation control Must Port Wine Electromagnetic radiation Infrared and Visible Spectrophotometry