Wooden containers in wine

Some Aspects of the Wooden Container as a Factor in Wine Maturation... 

The relationship of modern wine styles to aging wines in wooden barrels is described. The physical and chemical characteristics of different woods lead to the conclusion that white oak is best for wine cooperage. European cooperage oak samples had 161% of the extractable solids of North American samples and 154% of the phenol per unit of extractable solids, but American oak contributed more oak flavor to wine per unit of extract. Data are presented on the density and extractable phenol content of summer and spring oak wood, the characteristics of rapidly vs. slowly grown oak, the surface per unit volume effects of container size and shape, the variability among trees in flavor and extract content, the analysis of wood extract in wine, and the depth of penetration of wine into staves. 

Cor a long time wooden containers were probably the most common type of storage vessel for bulk wine. Under proper conditions, they still may be very desirable wine cooperage for a number of reasons. However, wooden containers are relatively permeable and are subject to leakage and contamination unless very carefully made and maintained. For these reasons, with the development of stainless steel and other relatively inert and impervious tanks or tank linings, some wineries, at least in the United States, boast that they use no wooden containers for any of their wines. 

Singleton, V. L. (1974). Some aspects of wooden container as a factor in wine maturation. In "Chemistry of Winemaking", A. D. Webb (Ed.), pp. 254-277. American Chemical society, Washington, DC. 

Vats, or balseiros, are wooden containers of larger capacity, between 10,000 and 100,000 L (Fig. 5.8). They are used to age full-bodies and fruity wines such as ruby, LBV, and vintage ports. The wines age more slowly than those conserved in wooden casks, retaining their structure and fresh fruity aromas that are the main characteristics of these wines (Guichard etal., 2003). 

Traditionally, maturation of red wines generally occurs in barrels or other wooden containers of various volumes. The wood provides special conditions for maturation that are favorable to the development of the wines character (Del Alamo Sanza et al., 2004 Perez-Coello and Diaz-Maroto, 2009). These usually include limited oxidation. Wood porosity together with filling and refilling operations ensure both a slow continuous and periodic incorporation of oxygen into the wine. The oxygen favors... 

Slow and controlled oxidation occurs in wooden containers. The use of wood in the refinement of wines furnishes volatile and non-volatile compounds, including polysaccharides and polyphenols that, together with a slow oxygenation process, help to stabilize the wine colour. 

Hydrolyzable tannins are not naturally found in grapes. On the other hand, they are the main commercial tannins legally authorized as wine additives. Ellagic acid in wine originates either from wooden containers or from the addition of enological tannins. On the other hand, gallic acid from the skins and seeds is always present in wine. 

Acetic bacteria are present everywhere on grapes, in wineries, on walls and floors, as well as inside empty wooden containers. Even if steps are taken to minimize contamination, wine always contains small quantities of bacteria, especially if it is not sulfured. If a young wine is allowed to remain in contact with air, it starts to produce a bloom (Section 8.3.4) and then acetic spoilage occurs. In older wines, spoilage occurs immediately. Consequently, it is essential to keep wine under conditions where bacterial development is as limited as possible. 

The objective of this operation is to separate clear wine from the sediment at the bottom of the container, and also from deposits on the sides, especially in wooden barrels. The wine is transferred to another, clean container and the free SO2 concentration is adjusted. Oxygenatiou occurs uaturally duriug this operatiou. 

Molds are capable of growth on the outer and inner surfaces of wooden storage containers and on cork in bottled wines where seepage has occurred. Aside from esthetic problems of growth on these surfaces, molds produce sensorially powerful metabolites that are perceivable at parts-per-billion or parts-per-trillion concentrations. As such, these compounds can play a significant role in wine quality (Section 4.5.3). 

Wakbukton s method of effecting the purification of rape oil is by treatment with caustic alkali, ia which, the albuminous and other impurities are soluble, and are. separated, associated with soapy matters. In a suitable vessel, containing fifty-two parts of. caustic soda solution, of specific gravity 1-010, are to be put one hundred pounds of the refined oil those are to be stirred with a wooden ladle till well mixed. The mixture is then allowed to stand twenty-four hours undisturbed, in a cold place, after which it is then slowly warmed, and again well stirred. After twenty-four hours subsidence all the oil will have separated if such should not bo entirely the case, the complete separation may be effected by the addition of a small quantity of spirit of wine. The oil drawn off from the liquor is afterwards well washed with hot water, till the pure oil is obtained without taste or color, and if desired, may be passed through a filter. The soap which deposits may be used as an ordinary detergent... 

The question arises as to how much aging can take place in an air-impervious container such as metal or concrete. In a wooden tank, the air transfer through the wood pores to the wine takes place slowly, but in a metal or concrete tank there is essentially none. How does aging take place Is aging necessary or desirable for Interior Valley table wines First, we note... 

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