The science of flavour

What if I asked you, what is your favourite food? Can you pick just one?

Now what if I asked you, WHY is it your favourite?

“Easy” – you’d probably say, “because I like the way it tastes”. But could you describe the flavour of this food (and why it pleases you) to a person that has never eaten that food before?

It is harder than you think – we eat or avoid foods without really stopping to think about why we like or dislike them. The flavours of foods are complicated and when eating we don’t just taste, we use all our senses.

Taste – not as complex as you think

How many things can a human taste? Actually, our tastebuds only recognise six tastes: bitter, salty, sweet, sour, umami (savoury) and oleogustus (fat).

All of our tastebuds can detect all six tastes, but we now think the tastebuds at the back of the tongue, which sit on domed structures called circumvallate papillae, are more sensitive to bitterness. A strong bitter taste can invoke the gag reflex to stop us from swallowing something toxic.

When at least two tastes come together, we get a taste interaction. Taste interactions can be enhancing or suppressing. Typically, if you have a sweet food, adding salt or acid will suppress the sweetness (think salt with sweet caramel or acidic raspberries with sweet white chocolate).

Salty and sweet both suppress bitterness (for example, salty chips with bitter beer). Umami enhances all the other tastes, which is why umami-rich food additive monosodium glutamate (MSG) is also known as ‘flavour enhancer E621’.

Every culture has its own taste bias which is probably partially genetic and partially influenced by locally available food. Many food companies, including Coca-Cola, change their product formula to conform to these cultural biases. It turns out that Germans like their Coke spicy, Mexicans prefer it more acidic and Italians want a little bitterness.

Aroma – you can’t smell tastes

There is a lot more to flavour than your tastebuds. In fact, many food flavours have no taste at all, like vanilla.

Vanilla is not sweet, bitter, sour, umami or fatty, yet it is easily recognisable and most people would say that it is sweet. However, this is just the brain making an association between the distinctive smell and the taste that you would normally associate with it.

In fact, around 80 per cent of our flavour experience is determined by our sense of smell. Many of the flavours that we describe for food, like fruity, spicy, herbal, earthy etc are actually aromas that we perceive retronasally (through an opening to the nasal cavity at the back of our throat).

These scent flavours all come from Volatile Organic Compounds (VOCs). When you chew food you release VOCs into the air in your mouth, and they are pulled up into your nasal cavity where the volatile compounds react with the olfactory bulb to register the aroma.

Foods like coffee have hundreds of different volatiles, although these won’t all be present in the same cup. You might prefer your coffee earthy, spicy or fruity, and different beans and processing techniques will give different combinations of VOCs, giving each type of coffee its individual aromas and flavours.

Mouthfeel – some like it hot!

Nerves in your mouth detect the texture, temperature and other somatosensory (touch) information – like crispness, smoothness and viscosity – from the foods we eat.

Spicy is often described as a taste, but is actually a pain signal. Menthol (which is felt as cool – think peppermint, alcohol) is also a pain response.

The temperature of food also influences taste and aroma. Warm foods taste sweeter, more bitter or more umami because the taste receptor cells are heat regulated. Warm foods also have a stronger smell because at warmer temperatures VOCs have increased emissions.

If you have trouble getting your kids to eat their veggies, serve them hot. Many foods taste less bitter when consumed hot because of the taste interaction between sweet sugars that suppress the bitterness in the food (and so is less likely to trigger that nasty gag reaction).

Eating with our brain

The link between smell and taste is so strong that we associate certain smells with a specific taste. For instance, the smell of caramel ‘tastes’ sweet, and the smell of lemon ‘tastes’ sour.

The food industry makes use of this by adding barely detectable ‘phantom aromas’ into food, that our brain perceives as tastes. An example is adding vanilla to ice cream to enhance the sweetness without adding more sugar.

It is not just smell that we associate with taste but colour and sound as well. For instance, red is associated with sweet, green with sour and brown with bitter.

A recent scientific study has even reported that certain odours are matched to the pitch and instrument class of music. The smells of iris flowers and candied orange were matched to a higher pitch than the smell of roast coffee and musk.

Eating with our eyes

There have been numerous studies on the appearance of food and our desire to eat it.

The saying “you eat with your eyes” is quite true – we are more likely to consume more and have a more favourable liking for food that is presented well, than the same food presented in a less Instagram-worthy way.

Everything about the presentation will affect our preference for, and consumption of food, from the size and colour of the plate it is served on to the way the food is placed and even the orientation of the food on the plate.

Perfect pairings – congruent or complimentary

Have you ever wondered why some ingredients seem to have a natural affinity while other combinations just taste wrong?

A perfect pairing will be either congruent or complimentary.

Two (or more) ingredients are congruent when they share key components. An example is the beautiful match of strawberries and cream; they share several aromatic compounds including acetoin (described as caramel and creamy).

Congruent works best with matching aromas, because if we match the tastes – like sweet with sweet or bitter with bitter – it can make them overpowering and unbalanced.

Western foods tend to be congruent, with matching aromas, whereas Asian cuisine tends to be complementary.

Complimentary foods have different components that go together well. A good example is fish and lemon – the creaminess of the fish protein balances the acidity of the lemon.

Pairing is also about getting the mouthfeel right. A mixture of textures will help to excite the senses and enhance the dining experience.

So next time you are preparing your favourite meal, think about incorporating components to stimulate every sense – this will improve your eating experience and help you enjoy your meal considerably more.

Bon Appetit!

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