How minerals affect our sense of taste

You might be surprised by this but... we don't actually know how exactly ions like magnesium and calcium affect the taste of coffee!

We do know a lot about the sensory regions of the tongue (taste buds), and that minerals like magnesium sulfate can be used as benchmarks for bitterness, saltiness, etc.

But, it's not quite clear exactly how magnesium ions and others stimulate the taste buds.

You might be familiar with this kind of diagram, which is misleading:

This is not the case!

In fact, ALL of our tongue senses EVERY flavour. Each taste bud has receptors/cells that are involved in many sensations.

Here's a typical diagram of a taste bud:

Notice how cells that sense all flavour types are present in one group.

So, indeed you sense flavour all over your tongue.

However, some areas of your tongue have a lower "threshold sensitivity" to certain flavours.

Meaning that certain parts of your tongue tend to react more easily to a certain flavour type, so flavours can feel more intense in that area.

This is because there are a few variations of taste buds across the tongue.

These differences are quite small, but noticeable, since our brain is pretty good at computing and deciphering the nerve stimulation coming in.

Here's what these differences might look like:

From this we can see that:

• The front of our tongue over-expresses sensations of saltiness and umami vs the others
• The sides of our tongue taste strongly in general, in all ways, but with umami less expressed than the others
• The back of our tongue senses saltiness less that hte others, and bitterness much more than the others

So, taste buds aside, how does mineral composition affect taste?

This is something which is quite complex but probably has to do with how mineral ions coincidentally stimulate other taste buds.

If you're interested, this article has a great summary of the different taste receptors and how they work.