6. Grinding Coffee & the Effect of Grinding on Extraction
COFFEE GRIND & EXTRACTION
The foundational understanding for all brewers is that coffee grind is fixed by the brewer used. Coffee grind setting follows the general pattern below to ensure proper extraction within the brewing parameters.
For example a French Press (immersion style) with a metal filter requires a coarse grind for a few reasons. Coarse coffee can use more time while coffee particles are suspended in water in order to dissolve. Also because they are coarse they will not pass through the holes of the metal screen when plunged.
In contrast an espresso machine (pressure brew) has a more fine metal filter but requires a fine ground coffee. The fine ground coffee creates more back pressure which helps it to extract more quickly into the cup.
Time also has a direct correlation with the grind used for specific brewing devices. The SCA has provided the general framework below for brewing according, though it should be noted that these are only loose guidelines.
Fine ground coffee: Less than 4 minutes
- Espresso approx. 20-30 seconds
- Aeropress approx. 1.5-2.5 minutes
- Syphon brewer approx. 3-4 minutes
Medium ground coffee: 4-6 minutes
- Auto gravity/drip filter brew approx. 4 minutes
- V60 approx. 3 minutes
- Chemex approx. 4-5 minutes
Coarse ground coffee: 6+ minutes
- French Press approx. 4-6 minutes
- Cold brew approx. 18-24 hours
Troubleshooting your grind.
What happens if I grind my coffee too fine for the chosen brewer?
- Water flows slower than it should... so that brew time is lengthened.
- More coffee is dissolved in the process of brewing.
- The brew extracts faster and is over extracted.
What happens if I grind my coffee too coarse for the chosen brewer.
- Water flows faster than it should... so that brew time is shortened.
- Less coffee is dissolved in the process of brewing.
- The brew extracts slower and is under extracted.
Water flow rate is a leading indicator when using a gravity drip brewer.
Nice work! You're already starting to pull together the 7 Essential Elements for a great Brew Plan. We'll keep unpacking more of the variables in the coming slides. The logic should be stacking for you now. As some elements increase so does extraction in a direct relationship. Other elements may increase while extraction decreases in an inverse relationship.
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