Describe acidity more precisely
Before correcting a sour espresso, describe its acidity more precisely. Fruity and juicy is different from sharp, brief and then empty. Acidity can be part of a bean’s intended character. Taste, recipe and brewing behaviour together help you decide whether to work on preparation or choose a different coffee style.
Collect the starting data
Record dose, drink yield, time and pre-infusion. Check that the machine and portafilter are ready for use. A first extraction from a system that is not yet sufficiently prepared is no fair comparison with later shots.
Stir the espresso and taste it after it has cooled a little. Tasting only the crema or taking a very hot sip tells you little about the whole drink.
A sensible order
- Check the bean description and cleanliness. Are you expecting a style this roast is actually aiming for?
- Check for a suitable dose and even preparation.
- If the shot flows unusually fast and seems thin, try one small step finer with the same beverage yield.
- If the flow is even, alternatively test a slightly larger beverage quantity with the grind unchanged.
- Compare only one change at a time and record the better version.
Why a longer extraction can help
A larger drink yield means more water flows through the puck. That can change the balance and reduce intensity. It is an experiment, not a guarantee. If extraction is already uneven, running it longer may not solve the problem.
Do not forget water
Water's buffering capacity affects perceived acidity. If the same bean suddenly tastes much sharper in another setting, comparing water can help. Use only water that suits the machine. An arbitrary switch to distilled water is not a general solution.
When you actually want a different style
Sometimes the recipe works yet the coffee still does not suit your preferences. If you want less fruit and more classic roast or cocoa notes, a different bean may make more sense than ever more extreme settings. Taste is not a test of courage.
An example for your notes
A useful note might read: “18 grams in, 36 grams out; fast flow; sharp and thin.” For the next trial, keep 18 to 36 unchanged and only make the grind slightly finer. If you also extend the drink to 45 grams, you cannot clearly attribute the difference to one change afterwards.
If no change helps consistently
First repeat the same clean procedure. Fluctuating results suggest a different problem from a consistently unsuitable setting. Then check distribution, dose variation and appliance function. A servicing problem should not be hidden by constant readjustment.