The science of taste

You can see a threat, smell danger, hear an alarm and feel an injury. But did you know that your sense of taste ranks right up there as one of your most effective defence mechanisms?

As the gateway to your body, your mouth has the responsibility of ensuring that it only allows good, and not bad ingredients to enter your system. Good choices mean highly nutritious foods that keep us healthy and make us stronger. Bad choices mean wasting energy on food that is poor in nutrients or even poisonous to us. As humans evolved our sense of taste helped us choose which foods to consume and which ones to avoid.

Taste is not flavour. We can distinguish about 100,000 flavours, which is the combination of all the senses when experiencing food. We not only taste but smell odour, and feel texture when we experience food.  Even sound and sight can contribute to flavour. 

Taste begins as soon as food breaks down in your mouth.  As you chew, enzymes in saliva reduce food to identifiable molecules. The job of analysing those molecules falls to the taste buds, flower bud like receptors found within papillae (puh-pil-ee), those tiny bumps found on the tongue and throughout the mouth.

Taste buds are made up of about 10 to 15 cells grouped together in bunches similar to orange segments. Tiny finger-like hairs stick out from the cells reaching out to direct molecules into taste pores where they are analysed.

Once a molecule has been identified nerve fibres at the bottom of the each taste cell transmit signals to larger cranial nerves that then carry those taste sensations to the brain. At the base of the brain taste signals are processed and sent along to higher brain areas where the decision is made to either accept or reject the food.

Receptors in your mouth identify five specific tastes: sweet, salty, bitter, sour and savoury. Sweet signifies a source of sugar, which means energy. Sour might indicate a source of vitamin C, a substance we need but do not produce. Bitter may indicate a toxic danger. Papillae at the back of the throat are most sensitive to bitter, and can cause a gagging reflex in response to the potential poison.

Human tongue. Taste receptors of the tongue are present in papillae, and are the receptors of taste. basic tastes sweet, sour, bitter and salty.

Scientists continue to look for taste receptors and they may soon find those that identify fat, alkaline (the opposite of sour), metallic, starch, calcium and water.

We have anywhere from 2,000 to 10,000 taste buds in our mouths and numbers vary from person to person.  While taste buds are the only part of the nervous system that can completely regenerate they do become less sensitive as we age. That may be why foods you don’t like as a child become more acceptable as you get older.

Are you a supertaster?

Do you have strong likes or dislikes for different foods? You may belong to the quarter of the population that are supertasters, people with more taste buds than most. You can test this by swabbing a Q-Tip covered in blue food colouring on your tongue. Taste buds will remain pink and can be counted more easily. If you can see 35 or more in a ¼ inch diameter circle (the hole in a piece of loose-leaf) then you are a supertaster. Count fewer than 15 and you are a non-taster!

Article originally published in Brainspace Magazine Fall 2019

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