What is Taste?

For many of us, our sense of taste is extremely important. But what is taste? And do we all taste the same?

According to research, 25% of people are ‘nontasters’ (someone with less taste perception), 25% are described as ‘supertasters’ (someone with an increased taste perception), while the rest fall somewhere in the middle. As well as this, we all have a different number of taste buds in our mouths. Some people will have as few as 2,000 while others have up to 10,000. What’s more, if you’re a supertaster, you have more tastebuds and, the chances are, you might be a pickier eater as a result.

In this article, we’ll explore the fascinating sense that is taste.

What is taste?

Our sense of taste, also called ‘the gustatory system’, is our sensory system that is responsible in part for our taste (or flavour) perception. When we talk about taste, we talk about our perception of a substance that reacts chemically in our mouths with our taste buds and their receptor cells. Most of our taste buds are found on the tongue.

What truly determines our taste perception of a substance, is our taste receptors working alongside our sense of smell and the nerves in our mouths (trigeminal nerves) that register the substance’s temperature and texture.

When you look at a human tongue, you’ll notice thousands of tiny bumps. These are called papillae. Inside each papilla are tastebuds in their hundreds. Within each taste bud, you’ve also got between 50 and 100 taste receptor cells.

Can smell affect taste?

You might have already noticed, that when you have a cold and have the associated blocked nose, you can’t taste your food as well. This is because smell influences the taste of our food.

When a person chews and swallows, odour molecules from the food move along the palate and into the nasal cavity. When these arrive in the nasal cavity, they activate odour receptors – and there are almost 400 different ones!

This process goes by the name of retronasal olfaction. It is different from smelling your food by sniffing it before eating. The human brain will actually distinguish between odours reaching the odour receptors through eating and odours inhaled through the nose. If you lose your sense of smell for whatever reason, your sense of taste is disturbed too.

Though smell combined with our sense of taste will make up most of the experience we have on eating a food, our other senses (touch, hearing and sight) are involved too. There have been experiments showing how the food colour can affect our perception of the flavour, as can the sound it makes when we eat.

What are the different types of taste?

Our taste buds have five different taste receptors.

These are:

• Sweet.
• Sour.
• Salty.
• Bitter.
• Savoury (umami).

Let’s take a look at each of these in more detail.

Sweet

Generally speaking, we perceive sweetness when the food or drink contains a form of alcohol, sugar or certain amino acids.

It is believed that we have evolved to taste sweet foods (and to like them) because it helps us to recognise high-calorie foods. These foods often have high amounts of carbohydrates, which our bodies use as fuel. This is a mixture of simple carbohydrates and complex carbohydrates.

Simple carbohydrates are easily absorbed by the body and these increase our blood glucose levels. Because of this, they should be consumed in moderation. This is because they can contribute to chronic diseases if consumed in excess.

Complex carbohydrates absorb in the intestines quite quickly but, unlike simple carbohydrates, they are slower to increase our blood glucose levels. Examples of complex carbohydrates are bread, rice, and potatoes.

Yes, the reason you crave all those sweet things is down to evolution when we were trying to survive with little around.

Examples of things that taste sweet are:

• Strawberries.
• Fruit juice.
• Cake.
• Honey.
• Chocolate.

Sour

When we taste sour things, we’re tasting the acidity of a food, which is brought about by hydrogen ions.

We have actually evolved to identify sour foods because rotten or spoiled foods often have a sour taste. This evolution has helped us to identify the foods that could be potentially harmful to our health.

However, there are sour foods that are perfectly edible. These include:

• Lemon juice.
• Vinegar.
• Yoghurt.

Salty

A salty taste is usually caused by sodium chloride (table salt) that is in our food. It can also occur from mineral salts.

Sodium is an essential electrolyte in the body. We need it for fluid balance. This is why sports electrolyte drinks have a high salt content – we exert ourselves and sweat during exercise, which excretes salt from our bodies.

We are believed to have evolved to taste salt to ensure we get enough in our system.

Foods with a high salt content include:

• Fries (unless cooked without salt).
• Processed meat and foods.
• Preserved olives.
• Soy sauce.
• Crisps.
• Salted peanuts.
• Sauces like ketchup, brown sauce and gravy.
• Canned soup.
• Cheese.

Bitter

Tasting bitterness happens due to lots of different molecules. These are usually in plants.

Many bitter compounds are actually toxic. It’s believed we evolved to detect bitterness to recognise and ultimately avoid poisonous foods.

Not all things that are bitter are bad, however. Lots of people actually appreciate a bitter-tasting food or drink, especially if they’re combined with other flavours.

Here are some typically bitter foods and drinks:

• Wine.
• Coffee.
• Dark chocolate.

Savoury or ‘umami’

It is different amino acids that bring about a savoury taste. Typically, we can taste savouriness when a food contains glutamic acid or aspartic acid. We often hear people referring to this specific taste as ‘meaty’ or ‘umami’.

It is thought that we taste the savouriness of foods to control the digestion of protein and increase our appetite.

Here are some savoury tasting foods:

• Aged cheese.
• Meat broth.
• Asparagus.
• Ripened tomatoes.

What is umami taste?

For a long time, scientists believed we only had four taste groups. These were sweet, salty, bitter and sour. The savoury ‘umami’ flavour is described as the fifth taste and it wasn’t discovered until very recently. In fact, it wasn’t until the 1980s that it officially became a separate taste.

The word ‘umami’ means a ‘pleasant savoury taste’ in Japanese. It has been described as meaty or brothy. Umami is in foods containing high levels of an amino acid called glutamate. Human breast milk is high in these amino acids, which scientists believe could encourage a person to seek this flavour throughout their whole life.

Foods with an umami taste include parmesan cheese, miso, mushrooms and seaweed. It is described as being a mild taste but one that has a lasting aftertaste. It’s associated with a furriness sensation on the tongue as well as increased salivation. As a standalone flavour, many people don’t consider it to be desirable, but when it is added to other tastes, it adds complexity.

Researchers were able to prove that this was a separate taste that has its own taste receptors.

Umami foods

There are plenty of umami foods around but they’re often more popular in different places around the world. For example, there are lots of ‘umami’ foods in Japan like miso and other fermented foods like soy sauce.

In the UK, things like vegemite and marmite have that typical umami flavour as well as pork, beef, broths, gravies, cheeses and tomatoes.

Is there a difference between taste and flavour?

Lots of English words are used as synonyms and a lot of the time, it’s down to your own personal preference which one you use. Things like ‘to answer’ and ‘to respond’, ‘angry’ and ‘mad’ or ‘smart’ and ‘intelligent’.

Some people often use ‘flavour’ and ‘taste’ as synonyms but these actually have different meanings.

Taste is the process that happens inside the mouth and mostly involves the tongue (though there are taste buds in a few other areas like the soft palate). When a food reaches the tongue, the taste receptors in the taste buds pass on information to your brain and give you the ‘taste’.

Though taste does make up some of the flavour of a food, it is not all of it.

When we talk about flavour, we’re also incorporating a food’s aroma. The aroma of a food is essentially what we smell. This odour plays a huge part in how flavour is perceived.

According to research, somewhere between 75% and 95% of what we believe to be taste, is actually from the smell. This means that how a food smells will directly impact how we perceive it to taste.

Flavour also incorporates the other senses too like the feel of the food in our mouth, how it sounds when we eat it, and whether it has a ‘spicy’ effect like chillies or a ‘cooling’ effect like menthol.

How does taste work?

Taste is actually subjective. Who’s to say that chocolate tastes the same to me as it does to you? Some people inherit traits that make certain foods taste disgusting. For example, many people love the taste of coriander but to some people, it tastes like soap. This is because they have genetic differences in their taste receptors. Most people who hate coriander have a particular set of olfactory genes called OR6A2. These receptor genes can identify a specific chemical in coriander – one that is present in lots of soaps!

Let’s look into the science of how taste actually works.

From sensation to taste perception

When you put a food in your mouth and it hits your tongue, it comes into contact with the taste buds. Each taste bud has around 50 receptor cells as well as supporting and basal cells.

Taste buds are located inside the bumps on your tongue – called the papillae.

Each receptor cell has a gustatory hair protruding out of it. This ‘taste’ hair goes through a taste pore to reach the outside. Food molecules mix with your saliva and then enter the pore and come into contact with the gustatory hairs. This interaction stimulates the taste sensation.

When taste is activated, the receptor cells pass on electrical impulses along the nerves to an area of the brain called the cerebral cortex – specifically the gustatory area. It is at this point that your brain will interpret the sensation as taste.

Now, all this happens instantaneously! It’s hard to imagine just how quickly this process happens – and also how minute everything is!

How can your sense of taste be affected?

There are many things that can affect a person’s sense of taste.

Here are some of them:

• Age.
• Medication.
• Medical treatments.
• Illnesses.
• Smoking.

Let’s look at these in more detail:

Age

As people age, it becomes more difficult to notice different flavours. Some women might begin to lose tastebuds in their 40s, while for men it usually starts in their 50s.

As well as losing taste buds, the existing taste buds might become less sensitive and shrink. The first flavours to weaken are sweet and salty flavours. Later on, it’s sour and bitter flavours.

As we know, a person’s sense of smell affects the taste of foods. Your sense of smell is at its strongest between 30 years old and 60 years old. After this time, it starts to decline. Some older people lose their sense of smell completely.

It is not possible to reverse this age-related taste decline. However, it’s worth finding out if that’s what’s causing the loss of taste.

Medication

Different medications can affect our perception of taste. This happens because the chemicals in them can affect the saliva.

Here are some medicines that are known to affect the taste and smell:

• ACE inhibitors – These are ‘angiotensin-converting enzyme’ inhibitors and are used to treat heart failure and high blood pressure. They can make your taste buds less sensitive or they might leave a sweet, bitter, or metallic taste in your mouth.
• Antidepressants and antihistamines – These can alter your taste because they make your mouth dry. This prevents flavours from reaching the taste buds – saliva is an important part in taste.
• Beta-blockers – These are used to treat heart problems and they can alter your sense of smell and taste.

Medical treatments

As well as medicines, other medical treatments can affect a person’s taste.

This includes:

• Chemotherapy – Cancer-treating chemotherapy is known to affect the taste in around 50% of patients.
• Radiotherapy – Radiation can hurt the saliva glands and taste buds, and it also affects the sense of smell. Patients receiving radiotherapy often comment that foods taste different or bland, or that everything tastes similar. This is usually a temporary alteration during treatment.

Illnesses and medical conditions

There are many health problems and medical conditions that affect our sense of taste.

These include:

• The common cold.
• Influenza.
• Pneumonia.
• Covid-19.
• Ear problems.
• GERD (Gastroesophageal reflux disease).
• Injury.
• Dental problems.
• Mouth dryness.
• Vitamin B12 or Zinc deficiency.
• Glossitis.
• Sjogren’s syndrome.
• Bell’s palsy.
• Multiple Sclerosis (MS).
• Infection.

There are many reasons for a loss of taste and smell. If you have a common cold or Covid-19, for example, you’ll be able to determine why that is. However, a loss of taste is sometimes a sign that something serious is going on. It can be a symptom of a head injury, a stroke, a brain tumour or even the first sign of dementia.

Smoking

When you smoke cigarettes – or nicotine-containing substances – the nicotine suppresses your ability to taste flavours. Also, the reduced oxygen intake due to inhaling smoke also contributes to less flavour being perceived. What’s more, it also causes changes to the receptors responsible for satiety and hunger in the hypothalamus.

Final thoughts on: What is taste?

Who knew that taste was so complex – and that it can be affected by so many different things? As we’ve seen, taste is a complex process that depends on your sense of smell and health to be functioning properly. Though a sudden loss of taste can be put down to many self-limiting illnesses, if there’s no obvious cold or illness, it’s worth getting checked out by a GP to rule out other conditions.