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Descripción
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| The ageing on lees involves prolonged contact between the wine and the lees. The cell autolysis is produced during this particular ageing that involves the release of cell components into the wine that interacts with the wine?s physico-chemical and sensory characteristics. These modifications are of special interest to obtain high quality red wines. The main drawback is that it is a slow process. Nine months are necessary to obtain perceptible effects in wines. This work evaluated several ultrasound techniques to accelerate the ageing on lees process. In addition, a comparative study of commercial barrels was done to obtain information about the best barrel for this ageing. The sonication of red wines and model media allowed the acceleration of yeast autolysis. This was identified by a 50% increase in the polysaccharide content. Some chemical parameters of the wine were clearly altered by the ultrasound treatment. A decrease of total pigments content around 50% and an increase of dissolved oxygen content up to 3.7 mg/L were identified during the ultrasound treatment. In addition, these wines showed a bad quality identified by a taste panel. In the other hand, the addition of previously sonicated lees accelerated the yeast autolysis avoiding the detrimental effects which were produced by wine sonication. The antioxidant capacity and the polysaccharides content were increased by 20 %. A greater quantity of pigments was preserved without significant variation in the fermentative volatile fraction, total polyphenol index and tonality. In addition, the combination of this technique with the addition of oak chips resulted in complex wines with high quality according to the expert taste panel. The application of this technique on a large scale entailed the annulation of the antioxidant capacity of the lees. The analyses only showed small differences with respect to the control wine. The comparative study of oak barrels resulted in wines with different aromatic profile. These results indicated that, in addition to the information provided by the cooperage, other parameters must be taken into account, such as the quantification of volatile compounds from oak wood. Keywords: ageing on lees, ultrasound, polysaccharides, dissolved oxygen, anthocyanins and pyranoanthocyanins, fermentative volatile compounds, oak wood volatile compounds. | |
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Internacional
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Si |
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ISBN
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Tipo de Tesis
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Doctoral |
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Calificación
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Sobresaliente cum laude |
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Fecha
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22/02/2019 |