HAMBURG (Germany) – The German Coffee Association and the Research Association of the German Food Industry (FEI) finalized an interdisciplinary research project on coffee in May 2023. The aim of the project was to use a mathematical model to describe the change in concentration of sensory active components during the preparation of the coffee beverage. Key variables are temperature, pressure/flow rate, and particle size.
German Coffee Association presents the research project on espresso extraction
Extraction is the last intervention possibility to guide the sensory perception of the beverage in a specific direction and to adapt it to the consumer’s taste. Previous studies showed that water temperature, pressure or flow rate, and particle size impact the taste.
Overall, experts observed that the influence of all three control variables on the sensory-relevant components within the investigated range was small.
The effects of temperature differed depending on the substance and were very small to non-significant; for aroma substances, experts detected a slightly higher concentration in some cases at higher temperatures.
An intensification of the sour taste with an increase in temperature and a more pronounced fruity flavor impression at the lowest temperature (80 °C) were observed. Increasing the flow rate resulted in lower concentrations of aromatics and non-volatiles. The degree of grinding had either no or a non-monotonic influence on the substance concentrations. Experiments with deviating water quality, roasting and when using decaffeinated coffee showed similar results.
Based on the model predictions, an Espresso Brewing Control Chart was created that allows the prediction and comparison of the studied extraction kinetics at different temperatures and flow rates.
To transfer the research results to a commercial application, experts are working on an Espresso Brewing Control App. In the form of a graphical user interface, it shows the results in a playful way. The app and the knowledge gained in this project enable a more targeted control of espresso extraction, e.g., to determine an optimal target beverage quantity at a given flow rate and temperature.
About the German Coffee Association
For over 50 years, the German Coffee Association has represented the interests of companies and organizations that trade, process, or otherwise deal with coffee in Germany.
It unites more than 360 companies along the coffee value chain – including sustainability organizations, coffee traders and brokers, coffee roasters, soluble coffee producers, decaffeination industries, coffee and roasting machine manufacturers, logisticians, and laboratories. In 2014 and 2018, the German Coffee Association was named “Association of the Year” by the German Association Management Association (DGVM).
About the Research Association of the German Food Industry (FEI)
The Research Association of the German Food Industry (FEI) is a non-profit, registered association supporting research projects in food science, food technology, and nutritional science. The financing is provided by private funding (corporates and industrial associations) and public funding (Federal Ministry for Economic Affairs and Climate Action). Please let me know if you have any queries.
