Scientists have just discovered a sixth taste to join salty, sweet, sour, bitter and umami

We're all familiar with the different basic tastes - sweet, sour, salty, bitter, and umami - but now scientists have found a sixth one where the tongue detects ammonium chloride.

Research from USC Dornsife has discovered that protein receptors on the tongue not only respond to sour taste but also to ammonium chloride as well.

Scientists were very much aware that the tongue responds to ammonium chloride, but haven't been able to specify which exact protein receptors... until now.

The protein OTOP1 is responsible for this which can be found in the cell membranes and forms a channel for hydrogen ions moving into the cell.

Whenever we taste anything that's particularly sour such as vinegar or lemon juice, OTOP1 is able to detect the acidity found in both of those.

Therefore, given that ammonium chloride similarly affects the concentration of hydrogen ions within a cell, research was carried out on whether OTOP1 protein would react to this too.

After lab-grown human cells with OTOP1 protein were created and exposed to acid or to ammonium chloride, the team found that ammonium chloride was a "strong activator" of OTOP1.

“We saw that ammonium chloride is a really strong activator of the OTOP1 channel. It activates as well or better than acids,” Dr Emily Liman, a professor of biological sciences at USC Dornsife and study author.

Now, perhaps you're wondering what ammonium chloride tastes like, one example of where it can be found is in salt liquorice candy which is popular in Nordic countries.

“If you live in a Scandinavian country, you will be familiar with and may like this taste,” Dr Liman added.

Though the flavour can be of an acquired taste and one that many may not be a fan of - but there is an explanation for this.

“Ammonium is found in waste products – think of fertilizer – and is somewhat toxic, so it makes sense we evolved taste mechanisms to detect it,” Dr Liman explained.

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