The post below by Coffee Ad Astra goes into detail grind size affect and specific grinders. We have put together a summary of how it affects espresso extratgion and the key insights in the article
Espresso and Grind Size Affects
The grind size plays a crucial role in determining the taste of espresso. Let’s explore how:
- Extraction Rate: Finer grinds extract faster due to increased surface area. This results in a shorter extraction time and a more intense flavour. Coarser grinds extract slower, leading to a milder taste.
- Bitterness and Over-Extraction: If the grind is too fine, the coffee brew can become bitter. Over-extraction occurs when water spends too much time in contact with the coffee grounds, pulling out undesirable compounds.
- Sourness and Under-Extraction: Coarser grinds may lead to under-extraction, resulting in a sour taste. Insufficient extraction time means not all desirable flavours are extracted.
- Balance: The ideal grind size achieves a balance between extraction time and flavour. Adjusting the grind allows baristas to fine-tune the taste profile, emphasizing sweetness, acidity, or body.
Remember, consistency in grind size is essential for a uniform extraction and a delightful cup of espresso! ☕️.
Key Insights
Here are some key insights from the article:
- Particle Size Distribution (PSD): The PSD tells you about the volume contribution from particles at each different diameter in your ground coffee sample. It’s crucial for understanding the extraction dynamics of espresso because it affects mouthfeel, puck resistance, and potentially alignment.
- Fines and Boulders: The amount of fines (very small particles) and boulders (larger particles) produced by a grinder can significantly impact the taste. Fines can contribute to a more intense mouthfeel and puck resistance, while boulders can affect the uniformity of the grind and, consequently, the extraction.
- Unimodality vs. Uniformity: Grinders vary in their tendency to produce fines and boulders, which is described by their unimodality (how many fines they generate) and uniformity (how narrow the nominal particle size peak is). These factors are mapped out in the data to understand their influence on taste.
- Taste Correlation: The data suggests that grinders with middle-of-the-road unimodality and uniformity align with the Kaffeemacher team’s taste preferences. However, other factors beyond PSD, such as clumping or heating of the grounds, also play a role in the resulting taste of espresso.
- Grinder Comparison: Comparing a single PSD from different grinders is limited unless using the same coffee and measurement technique.
- Burr Types: Conical burrs were generally less unimodal and less uniform than flat burrs, on average.
These points highlight the complex relationship between grind size and espresso taste, emphasizing the importance of grinder settings and the physical properties of the ground coffee.
