Techniques for improving or replacing ageing on lees of oak aged red wines: The effects on polysaccharides and the phenolic composition.

Alternative techniques to the ageing on lees are being looked for in order to guarantee the improvements provided by this technique but eliminating its disadvantages. The aim of this work was to study the effect of ageing on lees and other alternative techniques (addition of β-glucanase enzymes to the lees; use of different yeast commercial preparations with or without β-glucanase enzymes; use of non-toasted oak chips; and ageing on lees together with micro-oxygenation) on the phenolic compounds, colour, proteins, polysaccharides and sensorial characteristics of red wines during vinification and ageing in oak barrels for 6months on two consecutive vintages. Only the use of lees together with micro-oxygenation seemed to have a positive effect on the colour stability, due to the formation of new pigments that allows the intensity and blue notes of wines to be maintained during the barrel ageing process. All the techniques studied released total and neutral polysaccharides, although the type and content of these compounds depended on the technique used, and the yeast derivative added. No clear effect was observed with the use of β-glucanase enzymes. The sensory analysis showed that some of the wines treated were better valued than the control wines. The results obtained indicated that is difficult to select the technique that allows us to obtain the best quality wine.