bitterness is a characteristic of coffee and there's sometimes a pleasant bitterness in the not so pleasant bitterness salt is a flavor mediator meaning it blocks certain taste receptors getting rid of that bitterness making the coffee smoother and more balanced

not only this the salt balances acidity so whether the coffee brewed is acidic or bitter a pinch of salt could be the solution by getting rid of that bitterness the natural compounds of the coffee become more noticeable

the coffee will taste sweeter and there will be more pronounced and noticeable flavors

you can make a simple cup of coffee all the better

usually the solid just pinch into the coffee afterwards but i decided to add it directly to the coffee

and i noticed the same effect so next time you go to a diner or restaurant or even

the coffee might be a bit bitter or sour add a pinch of salt it goes a long way