Chemistry of coffee

My favorite mug

Tomorrow I will start again to work on my PhD thesis.

That means only one thing: coffee!!!

In a previous post, I talked about my scientific paper regarding the possibility of using mass spectrometry to check the quality of coffee.

Now, I will talk about some of the molecules responsible for the taste and the aroma of coffee.

First of all, it is important to distinguish between Arabica and Robusta coffee.

Arabica coffee beans are harvested at high altitudes (between 600 and 2200 m asl) and medium-low temperatures, about 20 °C. Arabica coffee is characterized by sweet caramel notes. The molecules responsible for this sweet aroma are furanones. Among them:

Molecules responsible for the sweet aroma of Arabica coffee

Robusta coffee is produced at low altitudes (at max 800 m asl) and high temperatures, around 30 °C. Robusta coffee is characterized by spicy and earthy notes. The molecules responsible for this strong aroma are mainly pyrazines:

Other key compounds are:

Phenols, for example guaiacol, are responsible for the bitterness typical of dark coffee.

Citric acid is one of the compounds responsible for coffee acidity and astringency.

And, of course, last but not least:

Caffeine binds to adenosine receptors in the brain. That is the signal that triggers nerve cell activity and therefore the release of adrenaline. That is why we drink coffee to have more energy.

Coffee is addicting because caffeine works on the same brain receptors as amphetamines and cocaine.

What is your favorite type of coffee? Espresso or brewed? Arabica or Robusta?

Reference:

Sunarharum et al., “Complexity of coffee flavor: A compositional and sensory perspective”, Food Research International, (2014), 62:315-325, https://doi.org/10.1016/j.foodres.2014.02.030

Published by Martina Bodner

Biotechnologist, PhD Student in Food Chemistry, High school science teacher, STEM and autism advocate, mother.

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