What does it mean if a popped Champagne cork doesn't expand afterward?

Dear Dr. Vinny,

When a Champagne cork doesn't expand after it's popped, might that mean that it was stored incorrectly? Or counterfeit? I've noticed I frequently wake up with a headache when that happens.

—Morten R., Copenhagen

Dear Morten,

To get everyone up to speed, Champagne corks start out in a typical cylindrical shape. Because of all the pressure inside a bottle of bubbly, the corks are cut extra wide, and then squished firmly into the bottle, but only about two-thirds of the way in. It's then held into place by a metal cap tied down with wire, which is called the "cage."

Typically, when you open a bottle of sparkling wine, the part of the cork that was inside the neck of the bottle expands, giving it a sort-of swollen mushroom shape.

That’s what typically happens. But sometimes the base of the cork doesn’t expand much at all. Corks lose their elasticity and resilience over time, and a very old cork won't expand nearly as quickly or as fully as a fresh one. There's no scientific formula to it, but corks can start to lose their elasticity as early as age 5, but may keep their bounce for decades—that's part of the uncertainty of natural corks.

I don’t know if there's anything much more than that that you can draw from whether or not a Champagne cork expands after it's popped. It’s possible that some of the places you purchase your bubbly from move their inventory more swiftly than others, and the non-mushrooming corks are from older bottlings. I'm not aware of any correlation between counterfeit Champagne and corks that don't expand.

As far as giving you a headache, I don’t think a less-elastic cork is necessarily going to have any effect. If a cork starts to fail in a bottle of bubbly, it might cause the wine to become a little flat, or perhaps taste a bit oxidized—more like a bruised, nutty apple than a fresh one. But neither of those scenarios would make a bottle of bubbly more likely to cause a headache.

—Dr. Vinny