Espresso extraction is all about balance.

When brewing espresso, we are simply dissolving flavour from roasted coffee into water. Inside every coffee bean are acids, oils, sugars and fibrous plant material. These flavours extract in stages throughout the shot.

The brighter acidic compounds extract first, followed by sweetness and texture. Push extraction too far and the heavier woody compounds begin to dominate, creating bitterness, dryness and an ashy finish. Don’t extract enough and the espresso can taste sour, sharp, salty or thin.

This is where the terms under-extracted and over-extracted come from.

A common mistake in coffee is confusing sourness with bitterness. Many people describe any unpleasant flavour as “bitter”, however under-extraction is actually far more common in espresso than over-extraction.

A helpful way to think about it:

• Sour = lemon, grapefruit, sour milk
• Bitter = dark beer, burnt toast, citrus peel

The goal of espresso extraction is balance — enough brightness and acidity to create life and structure, balanced by sweetness, texture and body.

The exciting part is that espresso is highly adjustable. Small changes to your recipe and technique can dramatically shift the flavour in the cup.

A Simple Espresso Adjustment Guide

Variable	My espresso is too sour	My espresso is too bitter
Goal	Increase extraction	Decrease extraction
Grind size	Make finer	Make coarser
Water temperature	Increase temperature	Decrease temperature
Dose (g)	Decrease dose	Increase dose
Brew time	Increase time	Decrease time
Yield / beverage weight	Increase yield	Decrease yield

 

One of the biggest contributors to poor extraction is channeling. This happens when water finds a weak point in the coffee puck and rushes through unevenly rather than flowing evenly across all the coffee.

A channeled shot may:

• splash
• pour pale and watery
• run unevenly from the spouts
• taste both sour and bitter simultaneously

Good puck preparation helps minimise channeling. Consistent distribution, level tamping and an even coffee bed all contribute to better extraction.

Visual cues can also tell you a lot about a shot. Under-extracted espresso often pours quickly and thin like water, while over-extracted espresso may drip slowly or choke the machine. A well-balanced extraction typically flows somewhere between warm honey and olive oil in texture.

Coffee is constantly changing. Temperature, humidity, bean age and even the coffee crop itself all influence extraction. A recipe that worked perfectly yesterday may need small adjustments today.

That’s part of what makes espresso both frustrating and endlessly rewarding.

There is no single “perfect” espresso — only the version that tastes best to you. The beauty of espresso is that you have the ability to shape and influence the cup through small, thoughtful adjustments.