On occasion, when a bottle of wine
is opened, you will notice a crystalline deposit that looks like a cluster of
coarse salt at the bottom of the bottle or possibly glistening at the end of
the cork. The clear diamond-like crystals found in wine are potassium
bitartrate in crystalline form. This is basically the same stuff as the cream
of tartar in your kitchen pantry.
The principal acids found in
grapes, and hence wine, are tartaric and malic acids. These acids are produced by
the grape as it develops. Potassium also exists naturally in grapes. When the
wine is under chilly conditions, the tartaric acid and potassium bind together.
The marriage produces potassium bitartrate (KHT) crystals: wine diamonds. They
are completely harmless and quite natural. In Europe
these wine diamonds are accepted as a sign that the wine is a natural one. To
many these diamonds are even appreciated. Americans, however, are used to wine
being without the crystals.
The winery, in order to fulfill the
consumers’ expectations, forces a pre-crystallization at the winery. This
process is called “cold stabilization”. It beats the crap out of the wine! The
wine is chilled to just above freezing; generally 21º to 23º F. It is
held at this temperature for about two weeks. During that time, the KHT is
formed in the wine. In order to remove all the KHT, the wine is filtered at
this cold temperature. The KHT, and host of other things, are removed from the
wine at this cold temperature. During this handling, the wine also becomes
saturated with oxygen. That’s a no-no. After the cold filtration, the wine is
then run through a heat exchanger to bring it up to cellar temperature. But the
wine must now be sparged with nitrogen gas to remove the oxygen, and again, a few
other aromatic compounds. Any winemaker who has ever tasted any wine before and
after “cold stabilization” wants to cry. If the winemaker is patient, this same
removal of KHT will occur over a longer period of time at cellar temperature.
Most red wines left in barrels for 12 months or more are not subjected to this
abuse. Some wineries do not want any of their wines to become “cold stabilized”
in a hurried fashion. Bravo!
So, let’s marvel at these little
wine diamonds. If you’re lucky to find them, raise your glass and enjoy the
wine with the assurance that this wine has been handled as naturally and gently
as possible and allowed to attain the highest quality.
Taking the world one wine at a time.
George Vierra
Wine Crystals: Wine Diamonds
On occasion, when a bottle of wine
is opened, you will notice a crystalline deposit that looks like a cluster of
coarse salt at the bottom of the bottle or possibly glistening at the end of
the cork. The clear diamond-like crystals found in wine are potassium
bitartrate in crystalline form. This is basically the same stuff as the cream
of tartar in your kitchen pantry.
The principal acids found in
grapes, and hence wine, are tartaric and malic acids. These acids are produced by
the grape as it develops. Potassium also exists naturally in grapes. When the
wine is under chilly conditions, the tartaric acid and potassium bind together.
The marriage produces potassium bitartrate (KHT) crystals: wine diamonds. They
are completely harmless and quite natural. In Europe
these wine diamonds are accepted as a sign that the wine is a natural one. To
many these diamonds are even appreciated. Americans, however, are used to wine
being without the crystals.
The winery, in order to fulfill the
consumers’ expectations, forces a pre-crystallization at the winery. This
process is called “cold stabilization”. It beats the crap out of the wine! The
wine is chilled to just above freezing; generally 21º to 23º F. It is
held at this temperature for about two weeks. During that time, the KHT is
formed in the wine. In order to remove all the KHT, the wine is filtered at
this cold temperature. The KHT, and host of other things, are removed from the
wine at this cold temperature. During this handling, the wine also becomes
saturated with oxygen. That’s a no-no. After the cold filtration, the wine is
then run through a heat exchanger to bring it up to cellar temperature. But the
wine must now be sparged with nitrogen gas to remove the oxygen, and again, a few
other aromatic compounds. Any winemaker who has ever tasted any wine before and
after “cold stabilization” wants to cry. If the winemaker is patient, this same
removal of KHT will occur over a longer period of time at cellar temperature.
Most red wines left in barrels for 12 months or more are not subjected to this
abuse. Some wineries do not want any of their wines to become “cold stabilized”
in a hurried fashion. Bravo!
So, let’s marvel at these little
wine diamonds. If you’re lucky to find them, raise your glass and enjoy the
wine with the assurance that this wine has been handled as naturally and gently
as possible and allowed to attain the highest quality.
28
October 2004 George
Vierra WineCrystals