When espresso is sour?

by John Herriott

When espresso tastes sour, it is often an indication of under-extraction. Under-extraction occurs when hot water has not been in contact with the coffee grounds for a sufficient amount of time to extract the desirable flavors. This can result in the extraction of sour or acidic compounds without fully developing the sweet, bitter, and balanced flavors that make a well-brewed espresso.

Here are common reasons why espresso may taste sour and some potential solutions:

  1. Grind Size:

    • Issue: The coffee grounds may be too coarse, leading to a faster extraction and under-extraction.
    • Solution: Adjust the grind size to make it finer. A finer grind slows down the extraction process, allowing for better flavor development.

  2. Brewing Time:

    • Issue: The brewing time may be too short, and the water is not in contact with the coffee grounds long enough.
    • Solution: Increase the brewing time by adjusting the grind size, tamping pressure, or the amount of coffee in the portafilter.

  3. Tamping Pressure:

    • Issue: Inconsistent or too-light tamping may result in uneven extraction.
    • Solution: Ensure a consistent and firm tamp. Uniform tamping helps create an even bed of coffee for water to pass through during extraction.

  4. Coffee Dose:

    • Issue: Using too little coffee in the portafilter can lead to under-extraction.
    • Solution: Increase the coffee dose to ensure there is enough coffee for proper extraction.

  5. Water Temperature:

    • Issue: Water that is too cool may not extract the coffee properly.
    • Solution: Check and adjust the water temperature to ensure it falls within the recommended range (around 195–205°F or 90–96°C).

  6. Quality of Coffee Beans:

    • Issue: Low-quality or stale coffee beans may contribute to undesirable flavors.
    • Solution: Use fresh, high-quality coffee beans that are suited for espresso.

  7. Machine Calibration:

    • Issue: Inconsistent machine calibration or issues with the espresso machine.
    • Solution: Ensure that your espresso machine is calibrated properly. If there are issues, consider consulting a professional technician for maintenance or adjustments.

It's important to note that achieving the right balance in espresso extraction requires some experimentation. Small adjustments to variables such as grind size, dose, and brewing time can have a significant impact on the flavor profile. As you make adjustments, taste the espresso regularly to find the optimal combination that results in a well-balanced and flavorful shot.

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