Bottles of Angry Orchard hard cider were recalled this week with their manufacturer warned that cider from two recent batches may result in bottles that overflow or, much more dramatically, literally burst. But what makes a bottle of otherwise ordinary cider explode?

The phenomenon that makes hard cider explode is actually the same phenomenon that makes it (or wine or beer) possible in the first place: Fermentation. But while some fermentation may result in drinks that are both tasty and—at least in your own mind—blessed with charm-enhancing powers, too much is a potentially explosive problem.

Advertisement

When fermenting—whether a cider or wine or beer—getting the timeline right is important, lest you end up with a product that is either a little too raw (not fermented enough) or slightly turned (fermented too long). Sometimes brewers will use an additive like sorbic acid or chill it down cold to stop fermentation in its tracks exactly where they want it, but just as often they just wait for the reaction to have finished before they move on to bottling.

Usually, that’s enough. But, sometimes, in a problem well-known to home-brewers, there’s enough residual sugars to kick off a second, unwanted and unplanned for fermentation, after the bottle has already been sealed. This problem has a name: refermentation in the bottle (for self-explanatory reasons). When the fermentation process kicks off again, carbon dioxide production kicks off into high gear, just like it did in the first fermentation cycle—only this time it’s sealed in a bottle with no way for the gas to easily escape.

When re-fermentation in the bottle happens to wine, you’ll occasionally get reactions so strong that it will pop the cork right out of the bottle. For those cider bottles, though, there was no cork to pop, letting the pressure in the increasingly fizzy cider just build and build, eventually to a level high enough to burst right through the glass.

Advertisement

But, there’s probably not much use in crying over that particular spilled cider—besides producing the extra carbon dioxide that’s responsible for blowing the tops off the bottles, bottle refermenation also often leaves the drink tasting pretty yeasty as well.

Image: Angry Orchard ciders