Understanding Coffee Extraction - Get The Perfect Coffee Cup
What is Extraction?
Extraction is the process through which we dissolve the flavors and other components of roasted and ground coffee in water. During coffee brewing, hundreds of unique compounds are extracted from the ground beans, which shapes your daily cup. These compounds directly affect the flavor and aroma of coffee, including caffeine (bitterness), acids (sour and/or sweet flavors), lipids (viscosity), sugars (sweetness, viscosity) and carbohydrates (viscosity, bitterness).
How does Extraction Affect Flavor?
Coffee compounds are extracted at different times: first the fruity and acidic notes, then the sweet and balanced notes, and finally the bitterness. An under-extracted coffee will lack the sweetness and slight bitterness necessary for balance, resulting in a sour taste. On the other hand, an over-extracted preparation will be bitter, since the compounds that create the sweetness and acidity will be overshadowed.
What is the Ideal Level of Extraction?
Extraction percentages and the ideal level of Total Dissolved Solids (TDS) are usually 18-22%. However, every coffee has a different character, so instead of looking for a “perfect” number, focus on obtaining the highest extraction percentage at which you still like your coffee.
How to Control Extraction
To get the best flavors from your coffee, you need the right level of extraction. If your coffee tastes too sour, it could be under-extracted, so you should try a slower extraction or a finer grind. If it is bitter, it may be over-extracted, so you should try a coarser grind or a shorter extraction time.
Variables Influencing Extraction
Several factors affect the solubility and extraction of coffee, including:
Grind Size:
Extraction occurs more rapidly with fine grind coffee than with coarse grind. A fine grind has greater potential for bitterness, while a coarse grind can result in greater acidity.
Extraction Time:
Short extractions are more acidic and longer extractions are more bitter. An espresso has a short extraction time, while a French press has a longer time.
Water Temperature and Quality:
The ideal water temperature for brewing coffee is between 195-205℉ (91-96 ℃). Warmer water extracts compounds more quickly, while colder water may result in incomplete extraction.
Coffee Bed Depth:
A uniform coffee bed is crucial for consistent extraction. If the grind is not evenly distributed or steeped, the water will create channels, leading to inconsistent extraction.
Experiment and Enjoy
Coffee extraction is a balance between many variables. Adjusting one factor affects the others, so take notes on grind size, extraction time, water temperature and other factors that may influence. Find a method that works for you and use it as a starting point for new experiments - don't be afraid to change your technique to discover the best in each new coffee!
