Adding salt to coffee to reduce bitterness
Martin Lersch at khymos.org posted about the flavour benefits of adding a pinch of salt to coffee. He points to precedent in a few places:
There is a tradition for adding a pinch of salt to coffee in Northern Scandinavia, Sibir, Turkey and Hungary. And when available, such as in coastal areas where fresh water from rivers mixes with the salt sea, one would simply use brackish water when preparing coffee. This water typically has a salt content of 0.5-3%, which is lower than the average 3.5% in seawater. This results in a more intense taste and more foaming.
When I was a teenager, I worked in a convenience store in Sudbury. We always sprinkled the ground coffee with about 1/4 tsp (1 ml) 1/8 tsp (0.5 ml) salt before brewing. The owner told me adding salt was the secret to Tim Horton’s coffee. I don’t know if that was true (or still is), but it did seem to improve the coffee. A little at least. The coffee was, I’m sure, made from robusta beans (the cheap variety that grows at lower altitudes than arabica beans) and it sat in that forlorn carafe for hours–we certainly didn’t make a fresh pot every 20 minutes.
Lersch explains that sodium ions seem to interfere with the perception of bitter flavours, though the exact mechanism isn’t known. Here’s what he tasted, plus an extra tip:
The tests were very un-scientific, but the tiny amount of salt does dampen bitterness and change the coffee taste (but the coffee does not have a salty taste).
A secret tip BTW is to add a little coffee to your beef stocks for extra depth and richness – this works because coffee shares many impact flavors with browned meats due to the Maillard reaction.