Something about mass spectrometry

Me, in front of my baby, the mass spectrometer (called PTR-MS)

In a previous post I wrote about the fact that mass spectrometry is one of the tools used by food chemists.

Now, I want to share with you a scientific article I recently published regarding coffee aroma.

The story started when Nicky, a Thai student, came to our lab in Italy. She arrived with thousands of Arabica coffee beans harvested in Thailand. Thailand is one of the top 20 producers of coffee in the world. Robusta coffee is harvested in southern Thailand, on the contrary Arabica is grown in the North.

We were interested in understanding if and how the harvesting altitude, the fermentation time and the roasting degree have an effect on the aroma of coffee.

Let’s start with the easiest feature: the roasting degree. Depending on the extent of roasting, coffee is commercially categorized as light, medium or dark. The roasting process generates a lot of volatile organic compounds (or VOCs). VOC is a strange name to indicate those molecules, which confer aroma and flavor to food. As you all know from your experience, a light roasted coffee is more delicate compared to a dark roasted coffee. We were able to identify which molecules are more present in the light roasted coffee and which ones are more present in the dark roasted one.

During the fermentation of coffee beans microorganisms are inoculated into the beans. These microorganisms produce VOCs, which can affect the final aroma of coffee. We discovered that beans fermented for a prolonged time (72 hours) are less acidic, more delicate and aromatic.

Finally we discovered that beans harvested at lower altitude (900 m asl, compared to 1500 m asl) are characterized by fruity, green and more delicate.

These findings can help the coffee industry to sell coffee based on consumer’s preferences. Do you prefer a delicate coffee? Then the coffee been should be harvested at 900 m asl, fermented for 72 h and light roasted. On the contrary, if you prefer a more intense and strong aroma, then the coffee been should be harvested at 1500 m asl, fermented for 24 h and dark roasted.


Bodner et al., “Effect of harvesting altitude, fermentation time and roasting degree on the aroma released by coffee powder monitored by proton transfer reaction mass spectrometry”, European Food Research and Technology, 2019, 245:1499-1506,

If you want to know more about coffee in Thailand:

Or about the mass spectrometer PTR-MS:


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