Purdue Wine Grape Team Newsletter

Dear Indiana Winemakers


Much like good wine, we all seem to get better with age.  However, many of our wines may also benefit from being bottled sooner rather than later, especially if they age in polyethylene or flexible top tanks, in an rather temperate production environment, or if you don't have the option to sparge your tanks on a regular base with nitrogen, and if you need to create fermentation capacity for the upcoming crush.


One of the basic stabilization techniques we use to make a wine look glorious in the bottle is to "cold stabilize" it.  By chilling the wine prior to bottling, we remove any excess of the grape's natural potassium bitartrate which otherwise may precipitate into glass-like crystals when stored in a consumer's fridge.  Two factors are important for success:

  1. Crucial to complete cold-stability is a solid refrigeration system for jacketed tanks or a cold room that can get the wine down close to its freezing temperature, i.e. about 25°F.
  2. And you have to be patient: without seeding, it takes about 4 weeks to stabilize a wine, and much electricity is spent on fixing this purely cosmetic instability.

Testing techniques for cold stability vary substantially.  We will discuss the pertinent Conductivity Test at another time.


You can download our PWGT Extension brochure on the topic for free from the Purdue Education Store: Wine Cold Stability Issues


E-mail me if you have further questions.
And best of luck at the
INDY next week!

34 out of 80 Indiana wineries have submitted their wines already.
There are still 5 days left to enter!



Christian Butzke

Professor of Enology


Jeanette Merritt
Christian Butzke

Jill Blume

Bruce Bordelon