What is Coffee Over-Extraction? How Does Over-Extracted Pour-Over Coffee Taste? How to Determine if Coffee is Over-Extracted

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When making pour-over coffee, have you ever encountered this situation: the coffee has obvious bitterness and astringency, making it difficult to swallow? This is a sign of over-extraction! In this article, FrontStreet Coffee will discuss what coffee over-extraction is and what to do when your coffee is over-extracted.

What is Coffee Over-Extraction?

Over-extraction refers to when coffee grounds remain in contact with water for too long, extracting too many undesirable compounds. When you taste it, your tongue can clearly perceive bitterness that lingers at the back of your tongue, masking other coffee flavors. There's obvious and prolonged astringency that makes you resist the coffee. You'll experience flatness and what's called a "hollow sensation" - after drinking the coffee, you feel like you've had coffee, but no distinct flavors or tastes remain in your mouth.

Causes of Coffee Over-Extraction

Based on FrontStreet Coffee's years of brewing experience, there are two main causes of coffee over-extraction: excessively high brewing water temperature and coffee grounds ground too finely.

Please note: The extraction rate of compounds varies among coffee beans with different roast levels.

According to FrontStreet Coffee's roasting observations, coffee beans with shorter roasting times and lighter roast degrees typically have lower density after roasting, making it more difficult for flavor compounds to release into water.

Therefore, when brewing light to medium roast coffee beans, FrontStreet Coffee recommends using medium-fine grind (fine sugar size, 75-80% retention on China's #20 standard sieve) paired with 90-91°C water temperature for extraction.

Meanwhile, medium-dark to dark roast coffee beans, due to extended roasting times and reaching the second crack, have relatively looser structures, making compounds easier to release into water.

Therefore, when brewing dark roast coffee beans, FrontStreet Coffee recommends using medium-coarse grind (coarse sugar size, 65-70% retention on China's #20 standard sieve) paired with 88-89°C water temperature for extraction.

Pour-Over Coffee Ratio Recommendations

For FrontStreet Coffee's store preparations, regardless of the coffee bean's roast level, we use 15g of coffee grounds with a 1:15 coffee-to-water ratio for brewing. The total time for water to pass through the grounds is approximately 2 minutes to 2 minutes and 10 seconds.

If this total extraction time exceeds 5 seconds, there's a risk of over-extraction, which also indicates that the grind is too fine. You can slightly adjust the grinder setting coarser for the next brew to increase the coffee particle size.

If the extraction time is normal with this ratio but the coffee still has an uncomfortable dry bitterness, then the water temperature is too high. You need to lower the water temperature by 1-2 degrees for brewing! Alternatively, the coffee beans might be too old and have lost their flavor!

To achieve a balanced taste and rich layers in a cup of pour-over coffee, using freshly roasted coffee beans is very important. FrontStreet Coffee currently ships all coffee beans within 5 days of roasting, ensuring that the beans you receive are 100% freshly roasted.

The flavor window for coffee beans is 5-30 days from the roasting date. When storing, remember to seal them and place them in a cool, dry place!