Why does canned wine smell like rotten eggs?

A group of researchers at Cornell University said they have figured out why canned wine, aka the new boxed wine, sometimes has a rotten egg smell. 

Gavin Sacks and Julie Goddard, professors in the College of Agriculture and Life Sciences, led a team to solve the malodorous mystery after several winemakers approached Sacks asking for help. 

In a Cornell Chronicle article, Sacks said, “The initial focus was defining what the problem compounds were, what was causing corrosion and off aromas, and why was this happening in wines, but not in sodas? Why doesn’t Coca-Cola have a problem?”

It came down to a compound. When the “molecular” form of sulfur dioxide, which winemakers routinely use as an antioxidant and antimicrobial, interacted with the aluminum can it produced hydrogen sulfide — the source of the unpleasant smell. The research, which has now been published in the American Journal of Enology and Viticulture, began with a series of experiments to characterize the chemical makeup of commercial wines. Then the researchers stored samples in a variety of cans with different coatings for up to eight months, while incubating others. 

The team determined using a smaller amount of sulfur dioxide in the wine produced and using thicker epoxy liners in the cans could help eliminate the foul scent.