"Why does that taste better today"
Did my wife just ask that? 😞 Actually, Mr. Jerky Wine Dweeb, it's a valid and common question. It might also be phrased as "Why did the taste of that wine change?" I just didn't expect the question in my household. Luckily one of my now adult children stepped in and and mentioned that the 24 hours it had been open had let the wine oxygenate, allowing nature to start doing it's stuff - which eventually results in wine vinegar. However, we don't have time for a wine class to explain that process and I'm not the correct leader of it anyway. Then again, U.C.Davis is only an hour away, perhaps even closer via the Internet. As an aside, that comment reminded me of a moment in 2015 while in France. I was both amused, and proud, when both my kids explained to my wife that Chateauneuf-du-Pape is a wine growing region - not the name of the winery we were going to visit that day! Ahh, the last 14 years of owning a wine shop haven't been a complete failure after all.
Square Peg - Round Hole?
Anyway, the rather bold, somewhat Tannic Pinot Noir she was reacting to had softened and fleshed out somewhat since the night before. My wife was absolutely correct that it was smoother and richer with less bitterness - making it a more enjoyable wine on night two.
This is not uncommon for wine , primarily reds which have longer skin contact during the winemaking process as well as often having exposure to oak barrels. Quite a few red wines can benefit from some oxygen exposure through early opening, decanting or time in the glass. What is hard to know is which will truly benefit as many may change a bit but not necessarily to the better.
The easy rule of thumb is that younger wines made from "bolder" grapes and often exposed to more Oak (barrels hopefully) change more when opened. Examples: Caberet, Syrah, Sangiovese, Mourvedre).
Other "mllder" reds such as those from Pinot Noir, Grenache, Zinfandel, are not generally not as harsh or astringent. Although they to can still change in reaction to oxygen.
Of course, things are much more complex than such a rule of thumb but so is the rest of life. If you feel like clicking a second link, along with the one on Tannin above, head over to Decanter Magazine for a bit more on the subject:
Also, feel free to ask us if we think a wine might benefit from a breath of Oxygen when you stop by for something.