WineRegionsOld WorldFranceBordeaux
Adding vin de presse
One vinification technique that is more characteristic of real wine making
in Bordeaux than in any other region is the addition of a certain amount
of vin de presse. This is produced after the wine has completed its alcoholic
fermentation and has undergone malolactic conversion. The wine is drawn
off its lees into casks and the residue of skin and pips at the bottom of
the vat is pressed.
Normally this requires two pressings: the first vin de presse is the best
and represents about ten per cent of the total wine produced, the second
provides a further five per cent. The vin de presse is relatively low in
alcohol and, because the residue mainly consists of grape skins, it is very
dark and rich in tannic acid. in a wine made for early drinking, vin de
presse would be harsh and unpleasant, but with the structure of a classic
oak matured Bordeaux, it gives extra body and increases longevity.
The "noble rot'
Yquem might be the ultimate, but many other great wines are made in these
two small areas tucked away in the Bordeaux backwaters. What gives all of
these wines their hallmark of complexity is, literally a lot of rot, namely
"noble rot", or the fungal growth botrytis cinerea. The low lying,
undulating hills of Sauternes and, to a lesser extent, of Barsac, together
with a naturally warm but humid climate, provide a natural breeding ground
for botrytis, the spores of which are indigenous to the area. These spores
remain dormant in the vineyard soil and on vine bark until they are activated
by suitable atmospheric conditions. These conditions are alternate moisture
and heat; the early morning mist is followed, day after day by hot mid morning
autumn sunshine. The spores latch on to the skin of each grape, replacing
its structure with a fungal growth and feeding on moisture from within the
grape. They also devour five sixths of the grape's acidity and one-third
of its sugar, but as the amount of water consumed is between one-half and
two-thirds, the effect is to concentrate the juice into a sticky, sugar-rich
pulp. A healthy ripe grape with a potential of 13 per cent alcohol is thus
converted into a mangy looking mess with a potential of between 17.5 percent
and 26 percent. The spread of botrytis through a vineyard is neither orderly,
nor regular, and the harvest may take as long as ten weeks to complete,
with the pickers making various sorties, or tries, through the vineyard.
On each try, only the affected grapes should be picked, but care must be
taken to leave some rot on each bunch to facilitate its spread.
THE "HIGH-CULTURE" SYSTEM
Entre-Deux-Mers in the late 1940s and early 1950s was a sorry place. the
wines were sold in bulk, ending up as anonymous Bordeaux blanc and much
of the decline in the Bordeaux region was centered on the district. But
the new post war generation of wine growers were not content with this state
of affairs. Although times were difficult and the economy was deteriorating,
the young, technically minded vignerons, realized that the district's
compressed boulbenes soil, which was choking the wines, could not be worked
by their fathers old methods and they therefore took a considerable financial
risk to rectify the situation. They grubbed up every other row of vines,
thus increasing the spacing between the rows, and trained the plants on
a "high-culture" system similar to that practised in Madiran and
Jurancon further south (also in Austria where it was originally conceived
and called the Lenz Moser system). This allowed machinery to work the land
and break up the soil. It also increased the canopy of foliage, intensifying
chlorophyll assimilation and improving ripening.
COOL FERMENTATION
In the 1970s university trained personnel at the well funded Entre-Deux-Mers
cooperatives invested in temperature controlled stainless-steel vats and
led the way in cool-fermentation techniques. Prior to this, fermentation
temperatures were often in excess of 28°C (83°F), but it was soon
discovered that the lower the temperature, the more aromatic compounds were
released. They found out that fermentation can take place at temperatures
as low as 4°C (39°F), but the risk of stuck fermentation was high.
It soon became clear that the ideal fermentation temperature, reckoned to
be somewhere between 10°C (50°F) and 18°C (64°F) (only
recently has it been confirmed that 18°C (64°F) is the optimum),
increased the yield of alcohol and important aromatic and flavor compounds.
It also reduced both the loss of carbonic gas and the presence of volatile
acidity and required less sulfur dioxide. Cool fermentation is now practiced
on a large scale throughout Bordeaux. In particular, the Sauvingnon blancs
of Graves have benifited from this technique.