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Efeito nas características físico-químicas de vinhos cv Touriga Nacional e Trincadeira de colagem com proteinas vegetais
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Orientador(es)
Resumo(s)
Currently, wine fining is still a common practice, in which, the mechanisms and consequences are not entirely defined. Considering the complexity of the phenomena and the difficulties related to the analysis of the main compounds involved (colloids, tannins, proteins), only a few authors cited proposed theories that explain these mechanisms.
The main goal is the clarification and decrease of phenolic compounds, regarding in particular the excess of astringency in wines. Protein fining agents used in Enology present a varied physico-chemical composition subsequently, the distribution of molecular weight and charge density influence their properties.
Meanwhile, the incresing problems during the 90s (last century) with the BSE desease, led the oenological industry, to a certain deal of concern, regarding the products used, particularly in fining agents used in wines. As a result, the subject of plant proteins for collage in wines followed the phases imposed by the OIV, Portuguese and European regulations.
The present work studied the effect of fining agents from vegetable and microbiological proteins on the physico-chemichal composition in wines, in particular anthocyanins. The results were compared with the ones obtained by using bentonite and egg albumin.
In the laboratory the following analyses had been made: measurements on the physico-chemical parameters of color, using Somers method, and assays of high pressure liquid chromatography (HPLC), to verify the effect of the finning treatment on total amount of anthocyanins.
In all fining agents used, there was a decrease in color intensity, total anthocyanins, colored anthocyans and tannins, although was more pronounced in non-traditional fining agents. For the chromatograms it was verified a decrease in the anthocyanin concentrations.
This results obtained with non conventional fining agents led to a smaller decrease then the results from the tradicional protein fining agents, concerning the anthocyanins parameters and the decreasing of tanins, involved in astringency.
Descrição
Mestrado em Viticultura e Enologia - Instituto Superior de Agronomia / Universidade do Porto. Faculdade de Ciências
Palavras-chave
wine Touriga Nacional Trincadeira anthocyanins yeast extract HPLC
Contexto Educativo
Citação
Romão, A.C.C.L. - Efeito nas caracteristicas fisico-quimicas de vinhos cv Touriga Nacional e Trincadeira de colagem com proteinas vegetais. Lisboa: ISA, 2012, 86 p.