What are those Crystals on the End of a Cork?

1 Comment

• 

  April 23, 2012

  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