dossier

Alternative woods

[vc_row full_screen_section_height=”no”][vc_column][vc_column_text]The iconographic image of quality wine has always been linked to the presence of wooden containers, barriques and barrels of various shapes and sizes. However, wood is not a simple material for building a traditional container, but rather plays a technically important role in defining what will be the aromatic and gustatory profile, as well as the balance of the wine it will house.

Since the mid-90s, the use of wood in alternative forms has spread in the New World countries. It has therefore moved from its use as a container to its use as a technological means added to the wine inside the concrete or steel storage tanks.

In reality, it is not a real technological evolution, but an adaptation to the wine sector of a common and widespread practice in the wine sector. Spirits in particular of Brandy (wine distillates) and Rum. Paradoxically, having such experience at one's disposal has created a delay in the development of a specific know-how for wine, with consequences that are still felt today and which we will discuss in more detail later.

At a regulatory level, the use of “pieces of oak wood in the processing of wines” was authorised by the European Union approximately 10 years ago with EC Regulation 1507/2006 of 11 October 2006.

With a controversial Ministerial Decree the Italian government immediately (2 November 2006) placed a very significant limit on the use of alternative woods by prohibiting their use in the production of all VQPRD wines (DOC and DOCG) with the declared aim of protecting the quality and image of these typical Italian products.

Still within the regulatory framework, the EU has established specific requirements for “pieces of oak wood” (more commonly known as woody fragments o shavings, or shavings, or parts, or again chips, staves, etc…).

 

 

In particular:

  • The botanical origin must be exclusively oak. Therefore, woods of all species of the genus are permitted. Quercus;
  • They are left in their natural state or heated in a defined light, medium or strong way, but they must not have undergone combustion even on the surface and must not be carbonaceous or brittle to the touch;
  • They must not have undergone chemical, enzymatic or physical treatments other than heating;
  • They must not be added with products intended to increase their natural flavouring power or their extractable phenolic compounds;
  • The size of the wood particles must be such that at least 95% by weight is retained by a sieve with 2 mm mesh:
  • They must not release substances in concentrations such as to pose any health risks;
  • Their use must be recorded in the cellar records.

 

-Evolution of commercial terminology-

Typically the reference is to the botanical species / area of ​​origin, the degree of roasting and the size of the wood fragments.
For example fine untoasted American oak chips rather than High toasted French oak barrels or medium toasted American oak cube...

In defining dimensions, common language is quite precise:

  • Drugs o Staves à boards with a thickness of 6 to 20 mm and dimensions of 80-100 cm in length and 4-8 cm in width
  • Demi-slats, mini Staves, Sticks à tablets smaller than staves, possibly joined together to be used as inserts for wooden barrels
  • Cubes, dice, blocks à small dice of about 1-2 cm on each side
  • Chips or Copeaux à oak wood fragments from about 0,5 to 2 cm
  • Rice grain, granules, tobacco à finer fragments up to the limits of the minimum authorised size

As for the conventional classification of toasting, borrowed from the terminology relating to barriques and widely accepted, it actually hides many more inaccuracies and approximations than it might seem. First of all, there is no homogeneous definition of the degree of toasting: what for one producer may be a strong toasting, for another may be medium.

Thanks to the research work and application know-how generated by the main producers and users, for some years now we have been able to define commercial typologies no longer based on production characteristics, but rather focused on the aromatic profile obtained (for example Vanilla, Mocha, Spice, etc.) or more generally on the oenological objective sought or result achieved (sweetness, structure, freshness, etc.).


-Variability of the raw material-

The in-depth study of the raw material and the modern analytical technique have allowed us to highlight the variability of the composition of oak wood in terms of structure, extractable substances, phenolic compounds, aromatic component.

The margin of variability between different trees within the same forest, as well as between different parts of the same tree, is in fact so high that it effectively cancels out the “typicality” of the region traditionally adopted as the main parameter for defining the quality of barriques.

Normally this variability would be a negative factor, being the cause of product inhomogeneity and variability of the effect of its application in wine.

The systems traditionally adopted by the cooperage to homogenize and standardize the final product they rely on the practice of mixing the different batches of raw material. It is evident that as the dimensions decrease, from staves, to cubes, to chips, the possibility of homogenization increases, which allows for a much higher standardization.

Furthermore, the possibility of controlling the incoming raw material with modern analytical and sampling techniques allows us to exploit natural variability (for example in the content of extractable tannins and aromatic substances originating from wood such as lactones) to direct different raw materials to different production lines, rather than passively undergoing it.


-The maturing-

Seasoning is of great importance for quality purposes as it induces chemical and structural changes. The practice of seasoning is traditionally adopted by barrel makers because on the one hand it allows to reduce future variations in the volume of the wood, ensuring a better seal of the barrel, and on the other because it allows the elimination of some negative characteristics of fresh oak wood (excess tannin, unpleasant aromas).

The seasoning of the wood takes place in piles of staves stored outdoors and raised from the ground so that the rain can leach the tannins and the wood undergoes periodic contractions in volume due to wetting and subsequent drying as well as temperature variations. It normally lasts from 18 to 36 months depending on the thickness of the stave and the characteristics of the raw material.

 

 

 

 

– Effect of seasoning-

From a structural point of view, the transformations that occur facilitate the release of compounds from the wood, making it more permeable.

The chemical-physical transformations reduce the concentration of tannins and therefore the sensation of astringency detectable in the wines that will be aged in/with that wood. Furthermore, the presence of compounds with an unpleasant vegetal aroma is reduced, first of all trans-2-nonenal which gives the wood a hint of fresh wet wood – bedbug. Without a correct seasoning period it is in no way possible to eliminate these defects from oak wood.

During the seasoning process, however, there is no degradation of the most important original aromatic component of oak wood, whisky-lactone (β-methyl-γ-octalactone), which is why at the end of the seasoning process the typical coconut notes will be more evident.

Finally, there is a reduction in acidic characteristics and dryness of taste.


-The roasting-

In the production of barrels according to the French technique of bending the staves over a direct flame, the internal surface of the barrel undergoes toasting due to contact with the flame which gives it typical aromatic characteristics.

In the production of alternatives, since curvature is not necessary, other methods of roasting heat transmission can also be used:

  • Conduction à the wood is toasted through contact with a heated surface
  • Convection à the wood is toasted by air heated by a flame. There is no direct contact between the flame and the wood
  • Irradiation à Infrared radiation allows for superficial roasting, but is not able to penetrate deeply into the wood fragment.
  • Direct fire is in fact only usable in the production of staves

 

 -Roasting effect-

During roasting, under the effect of heat, some basic constituents of wood such as lignin and hemicellulose are degraded and give rise to volatile substances and other organoleptically active constituents.

From the transformation of lignin derives teaspoon vanilla extract (hints of vanilla and pastry) and eugenolor (spicy, clove) and many other compounds constituting the aromatic bouquet.

From the transformation of hemicellulose, pentose and hexose monosaccharides originate which, following the continuation of the heat treatment, are transformed into the so-called furanic aldehydes (furfural, 5-methylfurfural and hydroxymethylfurfural) which provide hints of toasted almond and hazelnut and caramel.

 

 

 

 

So far nothing new emerges with respect to what is already well known in the production of barrique. However, the great flexibility of use of chips presents us with new application possibilities, much more precise and targeted in terms of effect and objective sought.

 

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