Resumo

BELCHIOR, A.P.; ALMEIDA, Tânia G.T.; MATEUS, Ana M.  e  CANAS, Sara. Extraction kinetics of low molecular weigtht compounds from wood to brandy in laboratorial scale . Ciência Téc. Vitiv. [online]. 2003, vol.18, n.1, pp.29-41. ISSN 0254-0223.

The objective of this work was the laboratorial study of the extraction kinetics of low molecular weight compounds in brandies. For this purpose the experimental units of 5 dm³ were filled with the same Lourinhã brandy and then added with oak or chestnut woods, in the form of microchips or stumps, with or without oxygenation. Physical and chemical analysis consisted of Total Phenolic Index (A280 nm), colour intensity (A440nm), chromatic characteristics (Cielab) and dry extract. In the last sampling time it was also performed the determination of low molecular weight compounds by HPLC and the dissolved oxygen. The results obtained show that the higher extraction rate of phenolic compounds and colour intensity occur in the first hours. The maximum was reach at about 72 hours, followed by a slower extraction rate up to the end, curves with less pronounced slope, particularly in the brandies that were in contact with micro-chips. This kinetic seems to be of logarithmic type, while it is closer to polynomial type in brandies that were in contact with stumps. The oxygenation seems to be inefficient on the colour intensity, although it affects the phenolic content and the dry extract of the brandies. As expected, the ageing time has a significant effect in all analytical parameters. The analysis of low molecular weight compounds allow us to conclude that brandies aged in oak wood are richer than those aged in chestnut wood in the majority of the studied compounds. This aspect contradicts previous results obtained at EVN, except for the richness of chestnut aged brandies in gallic acid.

Palavras-chave : Aguardentes; madeiras; cinéticas; extracção; fenólicas.

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