An interesting tip from salt101.com. Adding a pinch of salt to regular cup of coffee enhances flavor, making more mellow and lessening bitterness.
Several linkedin members have different comments. Specially pointing out about the negative effects of excessive salt intake on health.
A more scientific reasoning. The sodium ion (Na+) reduces bitterness by interfering with the transduction mechanism of taste. It acts without manifesting the salt flavor itself. About 10 to 50 ppm is enough to alter human taste perception. Another tip, without adding salt and sugar, is to drop a slice of apple, but the slice should not be eaten after.
Adding a pinch of salt to cup of coffee is not a new thing to me. It was a tip from an old friend. A salt crystal dropped in a coffee cup will make it better. However, he never told that it also removes bitterness. I should have known that thing after few trials, but my taste buds are not sensitive enough to differentiate flavor differences.
Yet another interesting observation is the effect of salt to guyabano sour variety.