What is coffee extraction?

At Unity, we believe that great coffee starts with understanding.
Every cup we serve is the result of countless small decisions — from sourcing and roasting to how we brew it in our cafés. And one of the most important parts of that process is extraction.

Whether you're a barista, a home brewer, or just coffee-curious, knowing how extraction works can transform the way you taste and brew coffee. Here’s a breakdown of the science behind it — clear, simple, and grounded in real-world practice.

Extraction is the process of dissolving soluble compounds from ground coffee into water during brewing.
It’s what transforms dry coffee into a beverage — using hot water as the solvent.

During brewing, the majority of soluble compounds are extracted at the beginning, and fewer toward the end.

We can measure this process using a special tool called a refractometer. It measures the amount of total dissolved solids — TDS — in the brewed coffee.
The ideal range for TDS in coffee shops is 1.15%–1.45%.

The ideal extraction yield range is 18–22%.
The maximum possible extraction yield is 27–35%, depending on the type of coffee bean.

How is extraction yield calculated?

Ex = TDS × beverage yield / dose of ground coffee

Once we measure TDS and calculate the extraction yield, we can use a control brew chart to determine if our brew is within the ideal range.

But before we do that, we need to understand the key variables that affect coffee brewing:

• Coffee-to-water ratio
  

• Grind size
  

• Brew time
  

• Turbulence
  

• Water temperature
  
  

Coffee-to-water ratio

• Minimum: 50 g of coffee per 1 liter of water
  

• Optimal: 50–65 g per 1 liter, but this varies by national preference
  
  

Grind size

• Affects brew time
  

• Affects how quickly water passes through the coffee
  
  

Brew time

• Filter methods: 4–6 minutes
  

• Single-cup filter: 1–3 minutes
  

• Espresso: 20–30 seconds
  
  

Turbulence

Turbulence is the movement of water during brewing:

• Controlled turbulence: water flow from the kettle follows a stable, consistent pattern
  

• Uncontrolled turbulence: chaotic or random water movement
  
  

Water temperature

If the water is too hot or not hot enough, extraction will be incorrect:

1. Too hot — over-extraction (bitter taste)
   

2. Too cool — under-extraction (flat, empty taste)

Understanding extraction is the key to brewing consistent, delicious, and well-balanced coffee. It’s not magic — it’s science, grounded in measurement, observation, and fine-tuning.

Great coffee is the result of a mindful process:

• the right ratio,

• proper timing,

• precise temperature,

• full control over every step.

When you understand what is being extracted and when, you stop guessing — and start crafting.
Experiment, measure, adjust — and the cup will reward you with flavor.