Science explained: how do we taste?

We all have food and drinks we love, and a fair few that we don’t, and that’s largely down to their taste. We go through life consuming foods, and our tongue is perfectly equipped to tell us about them – whether they are sweet or sour, salty, bitter rich. But how does the tongue actually work? How and why do we taste? And why do the different things we taste, well, taste different?

Our tongue is covered with, on average, around 10,000 little sensory organs called tastebuds. Stick out your tongue, and you’ll notice a lot of tiny bumps – these are called papillae, and they contain our tastebuds. Tastebuds are a combination of cells, including between 10 and 50 taste receptor cells. These react to our food – some contain proteins on their surface that bind to some of the chemicals from our food, while others have ion channels that are activated by different chemicals. Once the receptors have picked up a particular chemical, the information is sent along a neural pathway to the brain, telling us what taste we’re experiencing.

What we know as ‘taste’ is, in fact, actually a bundle of different sensations. The qualities of taste perceived by the tongue is a significant part of it, but the smell, texture and temperature of a meal also factor in. The ‘colouring’ of a taste happens through the nose – one of the reasons that you’re encouraged to hold your nose before consuming something unpleasant like medicine. As you chew food, chemicals are released, which travel up to your nose and trigger the olfactory receptors, which work together with your tastebuds. You can test the pair yourself – hold your nose when you eat something, and then let it go. You’ll get some information, but you shouldn’t detect the full flavour until the pair are both allowed to process it.

The flavours you like may be informed quite heavily by your genes

Let’s shatter a couple of common taste myths. A map from school, indicating that certain areas of the tongue are responsible for particular taste sensations, is not accurate. There’s no flavour to hot or cold food, but our mouth does let us know about the temperature – it releases the TRP-V1 protein in reaction to heat, and the TRPM8 protein in reaction to cold foods like ice cream. That same protein is responsible for the cold feeling you get when you eat mint. There’s also not such a flavour as spicy – it is in fact a pain signal sent by the nerves that transmit touch and temperature sensations.

Why do we taste? The evolutionary reason is obvious – so we know what to eat. Taste was a means of identifying nutritious food items, and it clued our ancestors as to what things they could digest, both safely and quickly – sweetness implies calories, for example, while saltiness implies minerals. Their food choices carry down to us – the flavours you like may be informed quite heavily by your genes. This helps explain certain sensitivities. The sides of the tongue are overall more sensitive that the middle, with one exception – the back is very sensitive to bitter tastes, an evolutionary means of warning us to spit out poisonous or spoiled foods before they enter the throat.

There’s a lot to taste, and we barely even think about it. Next time you enjoy a meal, thank your tongue and your nose – they’re both doing a lot of work to help make that food appetising!