Objective
This experiment aimed to evaluate how two different grinders Grinder 1 and Grinder 2 influence the sweetness and acidity of coffee.
The focus was on grind consistency and particle distribution, using both subjective sensory cupping and objective Coffee Value Assessment (CVA) measurements.
Methodology
Grinders & Calibration
Both grinders were calibrated to achieve a 400–600 micron grind size range.
Sifting
Ground coffee was sifted using the Kruve sifter to separate fines (small particles) from coarse ones.
Cupping Procedure
Each grinder was tested using:
- 12 g of coffee
- 197 g of water
- 93 °C brewing temperature
Objective Measurements
- Particle distribution was measured via the Kruve sifter.
- CVA (Coffee Value Assessment) was used to objectively evaluate sweetness, acidity, and body.
Disclaimer:
The Kruve sifter provides a practical way to categorize particle sizes but does not match the precision of advanced technologies such as laser diffraction analyzers. Therefore, results should be interpreted as indicative rather than absolute.
Results
Grinder 1
- Produced a higher proportion of fines, leading to faster extraction.
- Pronounced acidity and bitterness in the first cups.
- Sweetness emerged later but remained less balanced overall.
Cupping results:
|
Cup |
Sweetness |
Acidity |
Overall Balance |
|
1 |
Medium–Low |
High |
Sharp and bright |
|
2 |
Medium |
Balanced |
Moderate |
|
3 |
Low |
Low |
Flat |
Grinder 2
- Generated a more uniform particle distribution, enabling even extraction.
- Produced a balanced cup with mellow acidity and consistent sweetness.
Cupping results:
|
Cup |
Sweetness |
Acidity |
Overall Balance |
|
1 |
Medium–Low |
Medium |
Smooth start |
|
2 |
Medium |
Mellow |
Well-balanced |
|
3 |
Low |
Low |
Mild and clean |
Particle Distribution Data
|
Grinder |
Sample |
Fines (g) |
Coarse (g) |
|
1 |
1 |
1.3 |
10.5 |
|
2 |
1.3 |
10.6 |
|
|
3 |
1.7 |
10.2 |
|
|
2 |
1 |
1.0 |
10.7 |
|
2 |
1.1 |
10.9 |
|
|
3 |
1.8 |
10.2 |
Analysis
Grinder 1
The higher amount of fines led to over-extraction, producing sharp acidity and bitterness in the first cups.
As extraction continued, larger particles contributed sweetness, but the profile remained acid-dominant.
Grinder 2
With fewer fines and a tighter grind distribution, Grinder 2 allowed even extraction across the brew bed.
The result was a smoother, more harmonious cup, balancing sweetness and acidity consistently across cups.
Conclusion
- Grinder 1: More fines → faster extraction → higher acidity and bitterness.
- Grinder 2: More uniform grind → even extraction → balanced sweetness and acidity.
While the Kruve sifter proved valuable for categorizing particles, future experiments using laser diffraction or other advanced analysis tools could offer deeper insights into how particle uniformity directly affects flavor balance.