Influence of oak barrel aging on the quality of red wines

Resumen

Winemaking is a process involving several stages, with the barrel aging period having great importance in red wine quality. Wine in contact with oak wood undergoes important changes due to the contribution of numerous components characteristic of oak, mainly aromatic and polyphenolic compounds. Moreover, wood is a porous material that allows wine micro-oxygenation, so the barrel favors a series of chemical processes of oxidative type, which affect the polyphenolic content. During barrel aging, the wine increases its aromatic complexity and improves its stability, both of which increase its organoleptic quality. The extraction process of volatile and polyphenol compounds that takes place in oak barrels is very complex and depends on many factors, among which stand out: wood composition (related to the species and origin of the oak, the cooperage and the use of the barrels), the wine composition and the contact time between wine and wood. Moreover, a very important aspect is the age of the barrel, since ethylphenols can be formed as a consequence of the accumulation of undesirable microorganisms on wood, especially Brettanomyces/Dekkera. These ethylphenols are compounds with very unpleasant smells that negatively affect the sensory quality of wines. Furthermore, the repeated use of barrels plugs up the wood pores with the consequent reduction in micro-oxygenation. Barrel aging is a slow process, with a high economic cost that affects the final price of wines. For this reason, alternative techniques have emerged, faster and less expensive, such as the use of oak chips. Nowadays, there is a wide range of products available (types of oak, toasting, size, etc.) and different possibilities regarding the timing of oak chips addition, contact time, dose, application of micro-oxygenation jointly with this addition, etc. Depending on the type of wine to be obtained, these factors can be optimized to achieve the most quality wines. However, it should be noted that with the accelerated aging methods, quality wines can be obtained but the results provided by the barrel can be difficult to achieve. Therefore, in this chapter we have compiled the studies carried out to now on the aspects that can best influence the quality of aged wine. For this reason, this chapter is structured as follows: first we study the oak composition and the cooperage. Secondly, we discuss the influence of different parameters, such as the type of barrel (origin and oak species), the number of barrel uses or the wood-wine contact time, on the quality of this kind of wines. Next, we study the formation of ethylphenols in wines aged in oak barrels. And finally, we discuss the different aspects related to the use of new technologies for the aging of wine. © 2011 by Nova Science Publishers, Inc. All rights reserved.