Understanding Extraction

Understanding Espresso Extraction

Extraction is the foundation of great espresso. It's the process of dissolving soluble compounds from roasted coffee grounds using hot water under pressure. Mastering extraction is the key to unlocking the full potential of your coffee beans.

What is Extraction?

When hot water passes through ground coffee, it dissolves various compounds:

• First to extract: Acids and fruity compounds (bright, sour notes)
• Middle extraction: Sugars and caramelized compounds (sweetness, body)
• Last to extract: Bitter compounds and tannins (bitterness, astringency)

The goal is to extract the right balance of these compounds. Too little extraction gives you a sour, thin shot. Too much extraction results in harsh bitterness.

Extraction Yield Explained

Extraction yield measures what percentage of the coffee's soluble material ended up in your cup. Most specialty coffee professionals target:

• 18-22% extraction yield for espresso
• Sweet spot: Around 20% for most coffees

How Variables Affect Extraction

Variable	Increase Extraction	Decrease Extraction
Grind size	Finer	Coarser
Water temperature	Hotter	Cooler
Brew time	Longer	Shorter
Pressure	Higher (to a point)	Lower
Dose	Lower (less coffee)	Higher (more coffee)

Under-Extraction: Signs and Causes

Under-extracted espresso hasn't dissolved enough of the coffee's goodness. You'll notice:

Taste Indicators

• Sour or acidic taste (not pleasant acidity)
• Salty notes
• Thin, watery body
• Quick, sharp finish
• Lack of sweetness

Visual Indicators

• Pale, blonde crema
• Fast flow through portafilter
• Shot finishes in under 20 seconds

Common Causes

1. Grind too coarse
2. Water temperature too low
3. Dose too high for the basket
4. Channeling (water finding easy paths)
5. Insufficient tamping pressure

Over-Extraction: Signs and Causes

Over-extracted espresso has pulled too many compounds, including undesirable ones:

Taste Indicators

• Harsh bitterness (not pleasant coffee bitterness)
• Dry, astringent mouthfeel
• Empty, hollow flavor
• Burnt or ashy notes
• Unpleasant lingering aftertaste

Visual Indicators

• Dark brown or muddy crema
• Very slow or "choking" flow
• Shot takes over 35-40 seconds

Common Causes

1. Grind too fine
2. Water temperature too high
3. Dose too low
4. Brew time too long
5. Over-tamping

Finding the Sweet Spot

The perfect extraction balances all flavor compounds for a shot that's:

• Sweet with pleasant complexity
• Balanced acidity (bright but not sour)
• Full-bodied with good texture
• Clean finish without harsh aftertaste

The Dial-In Process

1. Start with a baseline recipe: 18g in, 36g out, 25-30 seconds
2. Taste and evaluate: Is it sour? Bitter? Balanced?
3. Make ONE adjustment at a time
4. Taste again and compare
5. Repeat until you hit the sweet spot

Quick Reference Guide

Problem	Likely Cause	Solution
Sour, thin	Under-extraction	Grind finer
Bitter, harsh	Over-extraction	Grind coarser
Sour AND bitter	Channeling	Improve puck prep
Weak flavor	Low extraction	Increase temp/time
Too intense	High extraction	Decrease temp/dose

Advanced Concepts

Total Dissolved Solids (TDS)

TDS measures the concentration of your espresso—how much dissolved coffee is in your cup. Typical espresso ranges from 8-12% TDS:

• Higher TDS = More intense, concentrated
• Lower TDS = More delicate, tea-like

The Extraction-TDS Relationship

You can have the same extraction yield with different TDS:

• High TDS + High Extraction: Ristretto style
• Lower TDS + High Extraction: Lungo style
• High TDS + Low Extraction: Under-extracted but concentrated (common mistake)

Pressure Profiling

Modern machines allow pressure control during extraction:

• Pre-infusion (low pressure): Saturates the puck evenly
• Peak pressure (9 bar): Main extraction phase
• Declining pressure: Gentler extraction, reduces channeling

Practical Tips

Daily Consistency

1. Purge your grinder with a small amount of coffee each morning
2. Use a scale for both dose and yield
3. Time your shots consistently
4. Taste deliberately - develop your palate

Seasonal Adjustments

Coffee changes over time after roasting:

• Fresh roast (1-7 days): More CO2, may need coarser grind
• Peak (7-21 days): Most balanced, easiest to dial in
• Aging (21+ days): Less CO2, may need finer grind

Environmental Factors

• Humidity affects grind—adjust finer on humid days
• Temperature changes affect extraction—morning shots may differ from afternoon
• Bean temperature matters—room temp beans extract more consistently

Summary

Great extraction comes from understanding the relationship between all variables and making thoughtful adjustments. Remember:

1. Taste is the final judge—trust your palate
2. Change one variable at a time—isolate your adjustments
3. Keep notes—track what works for each coffee
4. Be patient—dialing in takes practice

Master extraction, and you'll unlock flavors you never knew existed in your coffee.