It's one of those things that you've heard, but you don't remember when or where or why. It was also one of those things that you never remember at the appropriate time.
Then one day it all came together. I was sitting in a hotel in Vancouver, and took a sip of their bitter and burnt coffee and set my mug down right next to the salt shaker. After some back and forth in my mind, I did it... I took the plunge. I sprinkled a tiny bit of salt into the mug. I stirred it around, and went in for another taste, expecting to taste bitter and burnt with a side of salt.
Unbelievably, that's not what happened at all. The bitterness was nearly gone, and the coffee went from hard to drink to smooth. Now, it still had the burnt taste, and was still hotel coffee.... but it was transformed into something drinkable. I was blown away.
Why does this happen? SCIENCE! Basically there is a biological mechanism that's triggered when your tongue tastes something bitter. Calcium ion is released, which tells your brain "hey... this bitter". For some unknown reason, adding salt to the equation stops that release, and your brain says "hey... this smooth".
WHEN should you use this? This is a trick that you have to be careful about. If you start with great quality coffee, brewed correctly, there's no need to use this trick. It will just make your coffee taste salty. The mild bitterness of a great cup of coffee adds to the flavour. If, however, you're stuck with a badly made cup of coffee that's harsh to drink, give this trick a try.
Like we always say... Don't Be Bitter.