Of Oak and Wine (Part I)

This is one of the more important and hotly debated topics in the world of wine: how does oak influence taste and is that influence for the better or worse? Knowing about the affects of oak on wine is one of those fascinating details to which I alluded at the end of “All You Need To Know.” It can go a long way towards helping you appreciate what you are tasting and why. It’s such an involved topic I’m going to approach it in two installments: Part I, Where does the oak influence come from? and Part II, What does it do to a wine? Here is the first installment. I’ll post the second next Friday.

Some winemakers, particularly when it comes to white wines, believe
oak is a “fruit killer” and should never be allowed to touch them. But
they are in somewhat of a minority, albeit an influential and vocal one.
Most are from Europe, especially from Germany and France. Most
German wines, and many white wines from Burgundy or the Loire
Valley, have very little contact with oak. Most other winemakers argue
over how much oak is a good thing and how much oak is too much oak.
This ultimately involves questions as to just how, when, and for what
length of time a wine ought to be exposed to it. Meanwhile, a strong
consensus has developed amongst quality wine consumers that there is
too much of an oak influence in many wines, especially in California
Chardonnay. I tend to agree with this.

There are two stages in the wine making process where oak can come
into play: during fermentation and during aging.

Fermentation, the process of turning grape sugar into alcohol, can take
place in either stainless steel or oak vats. If stainless steel is used the
wine is subject to no “outside” influences. The only thing determining
taste is the flavor of the grapes. If oak vats are used, then depending on
their size and age, they can to varying degrees influence a wine’s taste
and character. But in general this vat influence, while similar to that of
aging wines in oak barrels, is much less pronounced. An exception is
what is called “barrel fermentation,” which means fermentation itself
takes place in small barrels. This is a more costly and labor-intensive
process than vat fermentation and is relatively rare. In the case of barrel
fermentation the effects of the oak on the wine can be very pronounced.
But again, these influences are of the same kind and nature as those that
occur during barrel aging, so barrel aging is what I will concentrate on.

It is during the aging process that oak traditionally exercises its most
consequential influences. I’m sure most of us have either visited a
winery, or seen pictures like the one above, and marveled at the view of
row after row of neatly aligned barrels. Usually these barrels are of a
standard size, what the French call a barrique or piece. They hold about
60 gallons, or around 300 bottles, in case you’re wondering. Wine can
remain in them for as short a time as a few months or for as long as five
years. The norm, I’d say, is from twelve to twenty-four months. Thus
the influence of barrel aging can range from minor to profound.

The five factors that determine the affects barrel aging has on a wine are
1) the size of the barrel, 2) the age of the barrel, 3) the wood from which
the barrel is made, 4) the “toast” of the barrel, and finally, 5) the length
of time the wine remains in the barrel. We’ll take them in order.

1.) The effects of barrel size is the inverse of what many people assume.
They think a bigger barrel means more influence, but the truth is it’s the
opposite. The smaller the barrel the more impact it has. This is because
the ratio of wine to wood is smaller, which means proportionately more
wine is in direct contact with the barrel and so the more influences it
will draw from the wood. (For the mathematically challenged, trust me
on this one.) The influence of oak comes about as the result of leaching,
meaning the wine slowly draws elements out of the wood and into itself.

2.) Barrels are hard to make and so expensive to buy. For this reason
most wineries can not afford new barrels every year, although all the
good wineries try to purchase a certain percentage of new ones every
year. So barrels are used more than once (the upper limit is 5 times) and
each time a barrel is used it has fewer and fewer additives remaining to
leach into the wine. It’s a bit like a tea bag, the more you use it the
weaker the results.

3.) The kinds of wood from which the barrel is made is by far the most
influential variable. Just about every species of hard wood in the world
has been used to make barrels, and many of the softer woods as well.
However we will concentrate on oak, because through hundreds of years
of trial and error it has shown itself to be the best by far when it comes
to enhancing the flavor of wine.

But what variety of oak? And from where? There is American oak,
French oak, Spanish oak, and other oaks from which a winemaker can
choose. French oak is considered by many the best, but here again the
question becomes: Oak from which forest? -- that of Limousin, Allier,
Nevers, Vosges, or Troncas? It’s enough to give one a headache.

So, does it really make a difference which forest the oak comes from? I
use to think it couldn’t possibly until a winemaker had me taste from
barrels the absolutely identical wine, the only difference being one
barrel was Nevers oak and the other Allier. It was astounding how
different they tasted. The winemaker went on to explain the obvious,
i.e., that trees, like grape vines, are living things and the character of
their wood is determined by the conditions in which they grow. From a
winemaker’s perspective, the most consequential difference between
oaks is the size and compactness of their wood grain. Large-grained, or
less dense wood, imparts more flavor more quickly than small, tight-
grained wood. Think of a paper towel as compared to the page of a
magazine -- the larger, looser weave (or grain) of the first allows it to
absorb more of a liquid more quickly. In the same way, a larger, more
porous grained wood allows more wine to seep into it and so its leeching
affect is increased. So the type of oak involved has a marked influence
on what it does to the wine that comes into contact with it.

4.) The individual wood slats that form a barrel are called staves and
they must be bent into shape before they are assembled. To do this the
barrel maker (called a cooper) heats the staves over an open fire. This is
referred to as toasting, and obviously the longer the wood is exposed to
the flame the more toasted it becomes. Because it is the toasted surface
of the wood that comes into contact with the wine, and because toasting
influences the flavors imparted to the wine, the degree of barrel toasting
is a significant factor. At the extremes, heavy barrel toasting can impart
a caramelized taste to wine, while a light toast might impart a subtle hint
of vanilla, smoke, or yes, even toast.

5.) Common sense tells us the longer a wine is kept in contact with
wood the more pronounced the results. There are a number of factors
that influence a winemaker’s decision as to how long to leave the wine
in barrels, but in general the “bigger” the wine the longer it will need to
stay in wood in order for the affects to register. If the final product is to
be one featuring a blend of grape varieties, like a Bordeaux or Chianti,
the winemaker must decided if he or she wants to mix the individual
wines together before or after putting them into barrels to age. If they
are aged separately, the winemaker must decide how long to leave each
individual wine in wood to achieve the desired taste or style once they
are finally blended together. Clearly a complex series of decisions and,
needless to say, a winemaker must monitor developments very carefully

So, now you have a little background concerning those neatly stacked
barrels. More thought has gone into their making, selection and use
than might first appear. They do not simply make a pretty picture, but
play a decisive role in how a wine will taste and age. It is in the use of
oak that a winemaker can exert his or her biggest stylistic influence. So,
in terms of taste and character, just what are these influences? We’ll
address that in Part II.