In regards storing your opened can of concentrate, I would freeze it. Dump the remains into a Tupperware or other freezer-safe storage container and stick it in your freezer. The high sugar content might actually prevent all of the liquid from freezing, but the cold temperatures will halt any chemical reactions or microbial growth that could degrade the concentrate. Try to use it within six months if you can, just to be sure the quality of those delicate aromatic compounds remains intact.
How can I best save an open container of grape juice concentrate?
TroubleShooting
John Spencevia — e-mail asks,
Dear Wine Wizard,
In the Spring 2000 issue of WineMaker, there was an article about using concentrates as adjunct to grape wines. I make small batches of country wines that call for minced yellow raisins or white wine concentrate. I can measure the cup of raisins, but now I have an open container of concentrate. I don’t know how to protect this $65 can of concentrate from being destroyed by air, bug, and fermentation. Your help is needed.