This has nothing to do with anyone but Canadians.
One on our national pass time is cheering on hockey games and drinking Timmies. That’s why I perked up a bit when a friend asked me about why there’s a onion after taste in their new dark roast coffee.
Being a passionate cook and coffee enthusiast, my first reaction was: “WTF are you talking about? I do not believe you.” Still, he asked me to look into it when I have time since I have a lot more research knowledge on coffee than anyone he knows.
So, during one of these dark raining days, I bought one and drank it. Nothing, no onion taste. I finished the drink and went back to work. If only the story stopped there, I’d have saved one whole day.
As a habit in dry climates, I lick my lips from time to time during work to make sure it doesn’t cake up. So imagine my surprise when it tasted like onion… but I didn’t eat anything since I wome up!!! The only thing I’ve downed is that coffee… Damn it.
So, what could cause an onion flavor? It’s only on my lips and not in the coffee, which means that it is a chemical reaction with either my saliva on my lips or oxygen in the air. If it is saliva, then holding the coffee in my mouth would’ve given me the same taste.
So what chemical can react with oxygen to give an onion flavor? After much google foo. The potential candidate is: sulfur.
But how can sulfur get into coffee? That’s insane. The only reported instance I can find, was that of stale water used during pulping. Weird.
This led me down a wild chase on where Tim Horton’s dark roast came from. Believe me when I say it was hard to find. This kind of info should’ve been everywhere.
So to save you the trouble, it was from Cuaca region high up in the mountains of Columbia. If look up videos from that region, you’d find out that it is a volcanic region with lots of volcanic ash in the soil. Rainfall is rare between May to June and most coffee farms are boutique farms with small operations.
The story fits and I left it at that. Without my friend first warning me about it, I would never have figured out the connection. The reactions with oxygen in the cup takes time and the onion flavor won’t be strong enough until 30 minutes later so it does not affect any flavor profile of the food or drinks you are having. It will big those who drinks a lot of coffee and have a heightened sense of coffee flavor though. But if you are the latter crowd, you probably rarely drink timmies unless you are spectating a hockey game.