Coffee Extraction

Brewing Coffee is a straight-forward chemistry experiment that can be measured and controlled. Hot water and coffee grounds are combined to create a simple solution. Below, we will describe how this process can be controlled and perfected!

 

Total Dissolved Solids (TDS) is a measure of the dissolved combined content of substances present in a liquid can be used to understand extraction of coffee.  Factors that Influence TDS and coffee extraction are:

Ratio: the amount of water compared to the amount of coffee

Brew Time: The amount of time the water is dripping through or immersed in the coffee grounds

Water Temperature: The temperature of the brewing water

Grind Size: The measure of coffee partial size which affects the surface area available for the water to interact with the ground coffee (the smaller the grind size the greater the surface area and the faster/higher the extraction)

Pressure: to make espresso, water is often forced through coffee grounds which are closely packed together. Pressure changes the interaction of the water and coffee ground, which impacts the extraction.

Method

TDS

Ratio

Time

Temp

Grind Size

Drip

1.3

18:1

4 min.

205F

700

V60

1.3

18:1

4 min.

205F

700

Chemex

1.3

18:1

4 min.

205F

900

Percolator

1.3

18:1

4 min.

205F

700

French Press

1.4

18:1

4 min.

205F

1000

Moka Pot/Espresso

1.2

18:1

2 min.

212F

400

Cold Brew

3-3.5

15:1

24-hours

60F

1100

 

 

Stages of Coffee Extraction

Coffee Has 3 distinct stages of flavor development. If you isolate the liquor (coffee) that has dripped through a standard drip brewing process into 3 cups (the beginning, middle, and end of the brewing process) you will create dramatically different taste sensations in each cup.

 

Stage 1: Strong/Fruity.

At the beginning of the extraction process, a lot is happening. The highly soluble compounds are being extracted, including caffeine.  The liquor is very strong and tastes very acidic. Most of the winey or fruity notes are extracted at this stage.

Stage 2: Medium/Sweet.

At the middle stage of the brewing process, a lot of the compounds formed during roasting are extracted.  The liquor has a medium body, limited flavor, and often shows a mild sweetness similar to brown sugar due to the maillard browning and caramelization that occurred during roasting.

Stage 3: Weak/Bitter

The final stage of the brewing process extracts the least soluble compounds consisting mainly of long chain acids.  When isolated, it tastes weak and often bitter.

 

Coffee extraction follows a timeline: any one stage when isolated is not representative of the finished product.  These three stages of coffee extraction combine harmoniously to produce a balanced cup of coffee.  Remember to check out our Brew Methods page to learn how to make the best cup using your favorite brew style.

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