Ever wonder why certain foods seem to hang around after you swallow them? Aftertaste is generally classified as any taste that remains in your mouth after your food or drink has been swallowed or spit out. The exact mechanism that causes these sensations isn’t fully understood. In fact, understanding how our brains perceive specifics tastes is still a subject of debate.
The current leading theory of taste is that it’s the perceived combination of several different sensory systems that include smell, flavour and what has been referred to as somatosensation. Basically meaning a combination of sensory input like temperature and texture.
Aftertaste is thought to be the left over flavour of whatever food or drink was consumed without the input of the other sensory systems. The result of the chemicals in food and drink continuing to interact with the specific taste receptor cells within our taste buds. To understand why this leading theory has no real competitors, let’s look at what flavour actually is and how our bodies combine it with other senses to create what we refer to as taste.
There are 5 basic flavours our taste buds perceive. They are: sweet, salt, sour, bitter and umami (the flavour that comes from glutamate like MSG {monosodium glutamate}). The idea we have a taste-map on our tongues where specific areas are responsible for specific flavours is false. All taste buds have the potential for perceiving the differing flavours.
Taste buds are a grouping together of around 50-150 flavour cells, known as gustatory cells. These buds are dispersed throughout the tongue in three different types of structures called papillae. The three papillae types are; fungiform, foliate, and circumvallate.
Your gustatory cells contain within them hairs that have proteins on them. Those proteins react to the chemicals in our food and drink to bind them to the cell. These cells have neuron-like properties (namely depolarization) that can cause the release of neurotransmitters. It’s these neurotransmitters that are perceived by the brain as flavour.
About half of the flavour cells within each taste bud react to several of the five basic flavours. These reactions vary in sensitivity to each of the five types. A specific cell might react strongly to sweet, but poorly to salt. The cell next to it may react strongly to salt and poorly to sweet. Those reactions are classified in levels of intensity from 1-10.
The other half of flavour cells within a taste bud are specialised and react to only one flavour. This is why some taste buds react, overall, to salty foods more than sweet.
When you combine these flavours, and variance of intensity of flavour between tastebuds, with how the food or drink smells, feels and its temperature, there are countless different tastes that can be perceived by our brains.
Most adults have around 2000-4000 taste buds. While many people think they reside only on the tongue, they’re also found in the back of your throat, epiglottis, nasal cavity and the upper part of your esophagus.
As mentioned before, how our brains perceive this taste is still not well understood. What we think is that our brains perceive taste by taking in input from several different senses and combining them to create the sensation of taste. For example, the smell of a food affects its taste because our olfactory sensors can perceive thousands more odours than our taste buds can flavours — fruity, nutty, garlic and burnt to name a few. The differing senses of odour, when combined with the flavour of food or drink, will affect overall taste. This is why when your nose is stuffed up, foods tend to taste differently.
Aftertaste is thought to be remaining chemicals from food or drink still affecting the gustatory cells on the tongue, back of the throat, epiglottis and the upper part of your oesophagus. This taste then is the sensation left over after the other factors of overall taste, like smell and texture, are no longer affecting the brain.
While the mechanisms of taste and aftertaste continue to be debated, scientists have begun to understand which chemicals within food and drink cause what type of aftertaste flavour. One example being iron.
Bonus Facts:
- Many people have noticed a fishy aftertaste to wine when you pare it with seafood. Studies have shown this aftertaste is most likely related to the levels of iron within the wine. Specifically the ferrous ion. The higher the ferrous ion amount, the more pronounced the aftertaste.
- Scientists have also found ways to block certain types of flavour. In 2010, researchers found a chemical that will block a person’s ability to sense aftertastes that are bitter. A molecule, known as GIV 3737 will target and block the taste receptors responsible for bitterness.
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