The kinetics of coffee aroma extraction

• Extraction kinetics of 20 key odorants from a coffee bed were monitored.
• Higher polar odorants were released faster than lower polar ones.
• The odorants' volatility did not seem to play a role in the extraction kinetics.

To obtain a cup of coffee with a balanced aroma, every step in the coffee production chain is crucial, including the final brew preparation, in order to achieve the optimal result in-cup. In this study, the role of the physico-chemical properties (volatility and polarity) of coffee odorants during extraction was investigated. The extraction kinetics of 20 key coffee odorants from a coffee bed were measured using quantitative in-cup aroma analysis. The kinetics differed depending on the coffee odorants' properties. The extraction speed could be correlated with the odorants' polarity. Higher polar components, such as 2,3-butanedione, were released much faster from the coffee bed as compared to lower polar ones such as β-damascenone. In contrast, the odorants' volatility did not seem to play a major role. Due to the different kinetics of extraction of the coffee odorants, the in-cup aroma balance changed continuously as more water passed through the coffee bed.