May 12, 2016

Coffee Science: What Affects The Flavour of Coffee?


Of all of our senses, taste interests me the most.

As a chef I’m biased, but my interest doesn’t stop at how things taste:  it extends to why things taste the way they do. After all, it is only with a better understanding of how taste works that we can make things tastier – especially coffee.

Until now, our efforts to improve coffee’s flavour experience have been hindered by a misunderstanding of how taste works. Unless we correct this, we aren’t maximising the enjoyment we get from our coffee.

So if you want to know how to make your coffee taste its best, let’s get started…

SPANISH VERSION: La Ciencia Del Café: ¿Qué Cosas Afectan el Sabor del Café?

Taste and Smell: Not Quite What They Seem

Before I became a chef, I was pre-med at Yale and fascinated with biochemistry and biophysics. And in my junior year, I learned something that altered my career course from medical to culinary.

Have you ever wondered why or how the same substance, prepared in the same manner, can taste entirely different on separate occasions?

The answer is simple: our palate, a combination of taste and smell, measures all flavours in relation to our environment and what immediately preceded that flavour.

A sour taste test with lemon and mint

A sour taste test. Credit:

Let’s say you put a thermometer into a hot bath, a warm bath and a cold bath. You know that you’ll get the same result every time you put that thermometer in that cold bath, even if you put it into the hot bath before. And for a long time, the assumption was that taste could be relied on to work in this way. We know now that this is the opposite of how taste works.

Perception of Taste: A Test

Let’s look at something sour or acidic, for example. Your tongue can’t tell you that a substance has a pH of 3 or 7. All it can tell you is that something is more or less sour than what you were tasting before.

If you want to experience this for yourself, simply have a few sips of water, bite into a lemon wedge, swish the juices around your mouth, and then re-taste the water. What is amazing is that the water will taste sweet, as if you’ve added a tablespoon of sugar.

But the water hasn’t changed at all – your palate’s reference point has.

It’s magnified the opposite flavour, so that the sequence of substances tricks your palate! Just imagine what that means for everyone drinking coffee with pancakes doused in maple syrup…

Pairing coffee with sweet flavour

Your morning pancakes. Credit: King’s Row Coffee

How Environment Affects Your Palate

There is another less obvious factor that alters our palate’s reference point – our physical setting.

Consider this: most of taste is smell. There is a significant difference between the smell of something that is not yet in your mouth (called orthonasal) and a substance that is in your mouth with the aroma climbing up into your sinus cavity (called retronasal). The same exact substance can have a different aromatic profile depending on those two situations.

So while your favourite coffee will have a consistent smell in an orthonasal situation, once tasted, the flavour you experience depends on the reference point of your palate  – which can be significantly altered by external aromas.

Drinking coffee can refine your palate

Coffee at the beach. Credit: King’s Row Coffee

If you can, brew a coffee that you know well and pay attention to how it tastes at the beach. Here the heavy salt smell in the air will tire out your taste buds and alter your perception of the taste.

You can also try it on farms or in gardens, where earthy aromas enter your nose to distort your palate’s reference point. Or even at high altitudes, where a combination of minimised odour receptors and a lower boiling point will both factor in.

In all of these situations, the coffee will be unsatisfactory. Not because of the coffee itself, but because of the role that that external environment plays on our taste perceptions – and even on the brewing process itself.

bag of King’s Row Coffee

Credit: King’s Row Coffee

Coffee: More Complex Than Wine

The most complex of fine wines rarely have more than 250 molecular compounds contributing to their remarkable bouquets. In comparison, the Maillard reactions (a reaction between amino acids and reducing sugars) in the roasting process of a fine coffee can produce more than 800 flavour and aroma compounds. Coffee can be a beverage of amazing richness and elegant complexity.

We can turn a £100 bottle of wine into a £10 tasting experience if it’s paired with the wrong dish. That’s precisely why sommeliers and chefs think about how a dish and wine will interact.

The same science applies to coffee. However, this ‘gastronomic’ mindset is completely absent in the selection and preparation of coffee, with most people focusing entirely on quality.

The point is, not everyone drinks their coffee in a vacuum – black, unaccompanied by food, in their kitchen, and at sea level.

Different roast profiles can influence the taste of coffee

Beautiful beans. Credit: Nousnou Iwasaki

Applying the Science at King’s Row Coffee

When I started King’s Row Coffee, I began with an understanding of the physiology of taste and a question: how can I achieve amazing coffee while in common settings that distort our palate’s reference point?

King’s Row recognises and addresses the external factors that alter our coffee experience, as well as considering the natural qualities and flavours.

It’s only been around 25 years since we began delving into the neurochemistry of taste and smell. There is still so much to learn, but what we do know with certainty is that flavour and aroma have a profound effect on what we experience next.

Crafting and consuming coffee without a better understanding of these principles limits the potential of our coffee satisfaction. Only by being aware of how the environment around us affects taste can we take the next step in making coffee even more enjoyable.

Now who wants to perform some coffee experiments?

SEE ALSO: Hydrosols: How to Make Brewing Water as Aromatic as Perfume

Edited by H. Paull.

Perfect Daily Grind.