Sour Espresso Shot Checklist

Step 1: Name the taste precisely

Before changing anything, write down what you taste. Useful words:

• Sour: sharp, tart, citrus-like, mouth-watering.
• Salty: a savoury edge that often accompanies under-extraction.
• Thin: watery body, quick finish.
• Hollow: sweet at the start, then empty.

If the shot is sour *and* harsh or drying at the same time, that is not simple under-extraction; it suggests uneven flow. In that case, read the channeling guide first.

Step 2: Compare against your recipe

You need a reference. Record dose, yield, and time. If you do not have a recipe yet, start with a dose that fits your basket, a yield around twice the dose by weight, and a time in the range your grinder and machine produce. These are starting points, not laws.

Ask:

• Did the shot run much faster than usual?
• Did I stop it early at a lower yield?
• Did I change beans since the last good shot?

A sour shot that ran 18 seconds is a different problem from a sour shot that ran 32 seconds.

Step 3: Check the easy causes first

1. Bean age. Very fresh coffee can taste sharp and gassy. Coffee that is extremely old can taste flat and sour in a stale way. Check the roast date and note it.
2. Dose too low for the basket. A small dose in a large basket leaves a shallow bed that water passes through quickly.
3. Water temperature. If your machine allows temperature adjustment, a low setting can under-extract. Change it only after grind and dose are sane.
4. Basket and screen. A partially blocked screen or a basket with damaged holes can disturb flow.

Step 4: Adjust grind, one step at a time

This is the highest-leverage change for a sour shot. Grinding finer increases resistance and contact time. Make one small adjustment, then pull a shot with the same dose and target yield. Do not also change the dose or temperature in the same shot.

If the grinder's steps are large, you may need to compensate with dose. Note which direction and how many steps you moved. A common mistake is to jump several steps at once, overshoot into bitterness, and then lose track of where the good setting was.

Step 5: Increase yield within reason

If grinding finer makes the shot slow and muddy, try a slightly longer yield instead. More water through the same dose extracts more. This is a useful lever for light roasts that stay sour even at a fine grind. Stop the shot at a higher weight and taste again.

Keep a note of both changes. "Finer by one step" and "longer by 4 g" are different fixes and should not be blended into a vague memory.

Step 6: Consider the coffee itself

If the shot is balanced, sweet, and simply has a bright acidity, it may be correct. Coffees from high-altitude growing regions and light roasts often carry noticeable acidity. Before chasing it away, taste the same coffee brewed another way, or compare it with a darker roast you know. If the brightness is pleasant and supported by sweetness, stop adjusting.

A quick decision table

Logging the result

Write the change and the outcome in the same row:

Two or three disciplined shots usually tell you whether you are moving in the right direction. If five shots in a row are still sour and you have moved grind and yield, revisit bean age and water before continuing.

Bottom line

Confirm the taste, compare with your recipe, then adjust grind first and yield second. Change one variable per shot, log it, and accept that some brightness belongs to the coffee. If sourness comes with harshness, treat it as a distribution problem rather than an extraction-time problem.