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The Science Behind A Cup Of Coffee – Caffeine & Trigonelline

Tuesday, March 17, 2015

Coffee is without doubt one of the nation’s favourite beverages – but how many of us actually know about the chemistry that goes into making a delicious brew?


Indeed, although producing a cup of coffee might seem like a quick and simple task – there is a surprising amount of science going on behind the scenes.

And it has only been in recent years that scientists around the world have begun to unlock the scientific secrets present in coffee beans, for there are thousands of compounds which work together to give coffee its unique properties.

It is these many complex compounds that are behind the intricate flavour of coffee.

Some of these compounds are naturally present in the coffee beans while others are created during the chemical reaction when coffee beans are roasted.  

(As Walter White says, “Chemistry is, well technically, chemistry is the study of matter, but I prefer to see it as the study of change.”)

Of these compounds, perhaps the most important are called alkaloids.


One of the most important alkaloids goes by the name of 1,3,7-trimethylxanthine… or caffeine.

A typical cup of coffee (200ml) will contain around 50 to 75 milligrams of caffeine, although this will vary depending on the type of coffee bean (for instance Robusta coffee contains almost twice as much caffeine as Arabica) and the method of preparation.

Caffeine, which evolved in plants as a defence mechanism (it’s toxic to fungi and insects), is absorbed rapidly by humans and is distributed throughout the body in under an hour.

During the three hour biological half-life of caffeine, it acts as a cardiac muscle stimulant, smooth muscle relaxant and central nervous system stimulant.

Caffeine stimulates neurons and also acts as a diuretic, stimulates gastric acid secretions and increases plasma glucose and free fatty acid concentrations.


Another alkaloid present in coffee beans which is less well known than caffeine is trigonelline.

Trigonelline, which is present in a lower concentration than caffeine, produces the flavour of coffee that we know and love – that is, the sweet, caramel and earthy aromas of roasted beans.

This flavour is produced during roasting when 60pc of trigonelline decomposes and forms carbon dioxide, water and aromatic compounds called pyridines.

Researchers have also discovered that trigonelline prevents certain acids adhering to teeth, and so can reduce tooth decay.

Signing Off

So, there we have it, two important compounds – or alkaloids if you’ve been paying attention to this article – that go into making coffee such a special drink.

Remember, if you have any comments or questions, remember to get in touch with us here at the Cafe2U blog.

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