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Acids in brewed coffees: Chemical composition and sensory threshold
Christina J Birke Rune1, Davide Giacalone1, Ida Steen2
1Department of Technology and Innovation, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark.
Current Research in Food Science
|April 10, 2023
Summary
This study investigated organic acids in light-roast coffee, finding that individual acid concentrations don't fully explain perceived acidity. Results suggest a more complex relationship between coffee composition and taste.
Area of Science:
- Food Science
- Sensory Science
- Analytical Chemistry
Background:
- Light-roast coffee's increasing popularity highlights the importance of acidity as a sensory characteristic.
- Acidity in coffee is linked to organic acid content, but literature on specific acid concentrations and their sensory impact is limited.
- Understanding the chemical basis of coffee acidity is crucial for specialty coffee production and consumer experience.
Purpose of the Study:
- To quantify organic acid and sugar concentrations in French-press brewed specialty coffee across a range of light to very light roasts.
- To determine the sensory detection and recognition thresholds for key organic acids found in coffee.
- To investigate the relationship between roast degree, geographical origin, and the concentration of organic acids and sugars in brewed coffee.
Main Methods:
- Analyzed acid and sugar concentrations in coffee brewed using the French-press method from beans of varying light roast degrees.
- Included coffee samples from Brazil, Bolivia, and Kenya to assess geographical influences.
- Conducted sensory analysis to establish detection and recognition thresholds for specific organic acids.
Main Results:
- Most organic acid concentrations (except formic acid) changed systematically with increasing roast degree, with sugar content decreasing.
- Sensory thresholds for malic, acetic, and lactic acids were higher than their concentrations in coffee, suggesting they are not individually perceptible.
- Citric acid was the only acid detected above its concentration threshold, with higher levels found in Brazilian coffees; however, coffee experts could not identify added acids.
- None of the tested organic acids were recognized by experts when added to coffee at average concentrations.
Conclusions:
- The study questions a direct, individual link between specific organic acids and perceived coffee acidity.
- Results indicate that perceived acidity in coffee is likely influenced by a complex interplay of compounds rather than single acids.
- Further research is needed to elucidate the complex chemical and sensory interactions that contribute to coffee's overall acidity profile.
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