I find the best way to preserve wine short term is simply to pour what’s left from its full 750 ml bottle into an empty 375 ml half bottle and seal it tightly with a cork. The idea is to expose the wine to as little oxygen as possible to avoid the chemical changes that oxygen induces. In addition, opened wine is susceptible to bacterial contamination that produces undesirable acetic acid.
Ronn Wiegand, one of the few in the world to hold the titles of both Master of Wine and Master Sommelier, swears by freezing wine as a method of preservation. In “Wine Secrets” by Marnie Old, Wiegand says, “I know it sounds ridiculous, but for more than 30 years, I’ve been freezing opened wine with incredible results.”
The so-called “Wiegand method” involves storing the wine upright with a clean cork. Some harmless sediment will form during freezing. Young wines do best, and reds tend to last longer than whites. Do not use this method for sparkling wines as they can explode.
The frozen wine may be thawed in a matter of a few hours at room temperature, but a few moments in the microwave works just as well (make sure the tin capsule is removed).
Wiegand claims freezing is the only way to preserve opened wine for days, weeks, months, or even years.