Does the quality and origin of the oak used for ageing wine matter when considering the flavour impact on the finished wine?  You bet it does.  Just as spices lend specific character to food dishes, the raw oak character and the barrel treatment used in maturing wine will influence the finished wine.  It's not just the type of wood that makes a difference, it is also how the barrels are made and to what specifications, the amount of time a wine spends in the barrel, and even the size and age of the barrel itself. 

Oak and wine have come a very long way from the days when the latter was sloshing about inside open wooden buckets in Egypt, circa 2700 BC.  Although it took another 2000 years and the arrival of the Iron Age (800-900BC) for man to produce fully-closed barrels, it only took half as long again (by the first century BC) for barrels to be widely adopted for holding wine, beer, milk, olive oil, and water.  As trade and transportation developed, shippers quickly discovered that sealed wooden containers were vastly superior to relatively fragile clay vessels. With that realization the craft of cooperage - or barrel-making - was born.



No doubt, oak barrels remained important for thousands of years as lightweight, high strength and impermeable storage vessels. However more recently, say the past 300 years, oak barrels have become integral in winemaking mainly as a tool to enhance the stability and flavour of wines. Even today the oenological evolution of oak usage continues with many winemakers opting to use oak staves and chips to give wine oaky notes.

Types of oak

All barrels begin their life in the forest, and as we all know, trees grow very slowly.  It has been said that the first generation of 'farmers' will sow the seeds and nurture the oak plant, the second generation grows it and it is the third generation that gets to harvest the 'fruit' of nature and man.

More than ten kinds of oak exist, though only four families of the genus Quercus oak are suitable for wine because of the desirable flavours that they impart: Quercus Alba (white American), Quercus Garryana (Oregon oak), Quercus Robur (English red oak) and Quercus Sessilis (European).  Oak suitable for wine is found throughout Europe from Spain, to France, to the Baltics, Slovenia and Russia.  However, France has Europe's largest forest area of mature oak that is suitable for wine maturation.

It is arguable whether French oak is necessarily the best.  Many consider it to be best by default over other oak species.  Certainly for some wines it this may be true, but not for all.  The quality of oak from French forests is compared to that of American oak, often with an underlying inference that French barrels are superior.  Though most winemakers are more concerned about "how much" oak influence rather than which kinds of oak, they cannot ignore that American oak has distinctive flavor compounds, reminiscent of dill and coconut, that impart unique characters on the finished wine. 

When speaking of "how much" oak influence there is another notable distinction between French and American oak.  The pores in American oak are denser, which brings about a coarser tannin structure to wine. This is not to imply that such a structure is inferior, only that it is different.  The tight grain of the American oak (Quercus Alba) is suited for long barrel ageing because its small wood pores will not impart too much tannin over time. With American oak, the wine takes up the wood flavours quickly, so time in barrel is required primarily to allow the flavours and aromas to settle.  Hence the Spanish, who aged their wines for long periods of time, have always opted to use American oak.

In comparison, French oak generally lends a wine aromatic character and is therefore a better choice with more subtly flavoured wines and wines to be released and consumed earlier.  French oak offers flavours such as toasted almond, nutmeg, cinnamon and allspice while giving a softer, more fine-grained tannin structure.  Again, not better just different. In the end, the winemaker's real challenge is to artfully match the type of oak used to the style of wine he/she is making. 

Here are some broad generalizations of the flavours imparted by oak species from various sources.

OAK ORIGIN	CHARACTER ACCENTUATED
Hungary	Fruity varietal flavor character, with light, woody overtones
Missouri	Sweet vanilla, coconut characters
Minnesota	Tighter grain with less coconut character
Kentucky and Virginia	Lemon cream character close to Bordeaux style
Oregon	Pungent, smoky with tannins
France	Toasted almond and spices

Yet making generalizations about oak influence by country alone is problematic.  To say that all French oak will give uniform character, or that all American oak will age a wine the same way, grossly oversimplifies the winemaker's task of selecting the best barrel material for a wine.  Indeed, the combinations and permutations for oak influences on wine increase considerably when one starts to consider wood from different forests in one country alone.

A case in point would be that wood from the Vosges forest is quite different from the Limousin region in France. Vosges oak confers structure as it is a fine-grained, Citeaux oak that suits less tannic red wines whilst Limousin oak is seldom used for white wines because its tannins can over-colour the wine.  Even then, what would be considered excessive oak influence on a white wine could well turn into a trend.  For awhile, it was fashionable to drink Limousin matured Chardonnay!  It is no wonder that winemakers distinguish amongst the various oak from the forests of Limousin, Nevers, Tronçais, Allier, Western Loire, Sarthe, Bourgogne and Vosges.  The same can be said for choosing American oak from different parts of the US.

As can be seen from the wide array of flavour descriptors and the differences in oak character within countries, the  winemaker has considerable flexibility in crafting his or her wine.  

The oak discussion will continue in my next installment, where I will carry on with details of barrel production and how the wine's flavour and stability are influenced by oak maturation. 

With that, Ed says... "To Be Continued!"  

Ed Soon 12/03/09