Tasting Tannins
Tannins are one of the
most obvious flavour compounds in red wine. Tannins and polyphenols
in wine come from the skins, pips and stems of the grapes, as well
as from the ageing in wooden oak barrels.
Tannin produces a mouth
puckering sensation – imagine sucking on a popstick or drinking
black tea that has been left to stand. Tannins are essential for
great red wines, but drinking a young red wine destined for
greatness involves tasting a lot of tannins.
Tannins act as a
preservative in red wines. Over time, the tannins break down and
combine with other compounds in the wine to produce the complex wine
that is sought when ageing a red. In winemaking, the art is to make
a wine that has enough tannin to balance with the other flavour
elements to make a wine that will last, but which is approachable
whilst young. An aged shiraz or cabernet sauvignon will have to
have sufficient tannins whilst young to last the distance. That is
why some of the best wines for ageing are difficult to drink whilst
young. In some cases, the tannins overpower the fruit flavours.
In the old days, people
would buy a wine and lay it down in a cellar for seven to ten years
before drinking it. The winemaking at the time reflected this with
high tannins in the young wine. These days, however, with
statistics like 85% of wines are consumed within two hours of
purchase, winemaking has had to evolve to make wines more
approachable when young. Even at Killerby we work towards making
our reds drinkable upon release, but with sufficient tannin and
structure to be great wines in ten years time.
As a red wine gets older,
the tannins soften and the wine seems softer. The fruit flavours
start to transform into more complex characters. This is what is
known as “bottle development.” The art of the winemaker is to
create a wine that has sufficient tannins to preserve the wine, but
also sufficient fruit to last the distance and balance the tannins.
All too often we can be disappointed with a wine where the fruit has
faded and all that is left is the tannins.
In these days of immediate
consumption of wine, there are many commercial wines that are low in
tannin. Such wines make for easy drinking over a relatively short
lifespan of, say, three years. With more tannins, however, such
wines could have lived for ten to fifteen years.
Exercise: Tasting
Tannins
The easiest exercise in
the isolation and detection of tannins is to take a simple pot of
tea. Let the tea stand for ten minutes so that it stews. Then pour
a cup of black tea and take a mouthful. Stewed tea is not a
pleasant drink – and the reason is the high tannin content. The
sensation is strongest inside your cheeks and on the outside of your
gums.
Now that you have isolated
the mouth feel of tannin, try applying this to the wines that you
drink. To detect the most tannin, ask your wine retailer for a red
that will last for 15 years, but buy it whilst it is young (within
three years of vintage). Then buy a bottle of the same wine that is
10-15 years old. Compare both wines with a cheaper, more commercial
red that is not designed for cellaring. Notice that the cheaper,
commercial wine has none of the mouth puckering tannins that the
younger, better wine has. Notice also that the older wine has none
of the obvious tannins as the younger wine, but has many more
complex characters derived from the break down of the tannins with
age. Over time, the fruit and oak characters in the wine come to
the fore and dominate the tannins.
In terms of the tannin
content, it is generally true to say that pinot noirs are lower in
tannin than merlots, and merlots are lower in tannin that cabernet
sauvignons. Try a bottle of each from the same vintage (say three
years from vintage year) from the same producer and notice the
gradation in tannin content from the three varieties.
The main reason that
tannins are found more in red wine is that tannins derive from grape
skins, stems and pips and these are used more in red winemaking than
in white. If you ever pick up a red grape and squeeze it, out comes
white juice. So to get the red colour into red wine, the white
juice is left in contact with the red skins for several weeks. This
extracts the colour of the skins into the juice and at the same
time, transfers the tannins into the wine.
White Wines and Tannins
Some white wines can
produce a mouth sensation akin to that of tannic reds. This occurs
when the white grapes are pressed hard and the compounds from the
skins and pips are extracted. Whilst this may give a higher yield
of litres per tonne of grapes, the resulting flavours are quite
astringent.
Thickness of Grape
Skins
Different varieties of grapes
are different sub-species and so the thickness of the skins of the
grapes is also different. The general rule is that the thicker the
skin, the higher the tannin content of
the resulting wine. The same goes for the number of pips in the
grape.
Cabernet sauvignon and
shiraz both have thick skins and a higher pip content, so the
resulting wines naturally contain more tannins. But the amount of
tannin extracted from the grapes depends on the winemaking
technique. Generally, the longer the juice is left on skins at the
beginning of the winemaking process, the more tannic the resulting
wine will be.
Another source of tannin
is the oak barrels in which red wines are matured. The tannin in
the wood is extracted during the time that the wine is in barrel.
Red wines can be in barrel from between 12 months and 24 months.
The newer the oak barrel, the more tannins it has. It is usual for
winemakers to use a mix of barrels that are new, one-year old,
two-year old and up to five-year old. At Killerby, we only use new
and one-year old barrels for our wines. This means that the tannin
content would ordinarily be higher, so we age the wines for less
time in them. Whereas a mix of new to five-year old oak might take
24 months to mature in oak, a mix of new and one-year old oak only
takes 15 months to mature. Using newer oak makes the wines more
capable of lasting ten to fifteen years in the cellar. |
