Sour or Bitter Espresso: What to Check, in Order

Espresso, Explained · Part 6

Reach for the grinder first and you will never find the cause. Check whether water passed evenly, then how much you extracted, then how strong the cup is, in that order.

01 You need a fixed order of operations

When a shot tastes wrong, most people move the grind first.

Shot time changes, so it feels like progress. If the cause was somewhere else, the problem stays put and your settings are now scrambled as well.

There are three checks, in sequence.

Did water pass through evenly, how much did you pull out of the coffee, and how strong is the cup. If the first one has failed, you cannot judge the other two.

Change one thing at a time.

Move the grind and the yield together and you learn nothing about either. Write down what you changed and how it tasted, and the next coffee takes half the time to dial in.

02 Step one: did water pass evenly

If this is broken, every later judgement is wrong.

A shot where water escaped down one path tastes sour and bitter at the same time. Adjust the grind in that state and it only gets stranger.

Look at the stream and the puck.

Check whether the flow sprays to one side or stops and restarts, and whether the spent puck has a hole or a collapsed edge. If something here is off, go back to how you fill the basket.

Normal shot time proves nothing.

Water can take a shortcut and still finish on schedule. Numbers right, cup wrong, means come back to this step.

03 Step two: how much did you extract

Under-extracted shots are sour and saline, and the finish disappears quickly.

Raise the yield or grind finer. Raising water temperature slightly is another route, but use the first two before you touch it.

Over-extracted shots are bitter and drying.

Lower the yield or grind coarser. Before either, check whether you kept collecting after the stream turned pale.

Sour and bitter together sends you back to step one.

Two opposite flavours in one cup means different parts of the bed extracted differently. That is not a question of how much you pulled.

04 Step three: how strong is it

If the first two are fine and the cup still tastes weak, this is a strength problem.

Take slightly less liquid or raise the dose. In an americano you can also set it with the water you pour.

Strength does not change direction.

Try to solve sour or bitter with water and you get a weakly sour or weakly bitter cup. Direction belongs to step two, intensity to step three.

What you taste	Which step	What to do first
Sour and bitter together	Step one	Review how the basket is filled and levelled
Sour with a short finish	Step two	Raise the yield or grind finer
Bitter and drying in the mouth	Step two	Lower the yield or grind coarser
Fine, but tastes like water	Step three	Take less liquid or raise the dose

05 If the three steps do not settle it, look at the coffee and the water

Same routine as yesterday, different result today, usually means the coffee moved.

Check the roast date. Very fresh coffee carries a lot of gas and runs unevenly, while older coffee has lost aroma and tastes flat. Settings are supposed to shift on the day you open a new bag.

Water changes the cup too.

Most of what is in the cup is water, so filtration shows up directly. If the filter has not been changed in a long time, start there.

Keep one reference shot on paper.

Record the dose, yield, time and grind setting from a day it tasted right. On a strange day you will see immediately what moved. Memory does not give you a comparison.

First Penguin Coffee Company We roast to order and ship afterwards. Every bag carries its roast date, which makes it easier to tell when your settings are about to shift. Our coffees are listed under Beans in the top menu. Enquiries: 010-3444-1721

Also in Korean This article is also published in Korean. The original series it draws on, 50 parts on café practice, runs on our Naver blog. Read the Korean series

Next: iced americano, and how to account for the ice as it melts.