Guide · Espresso machines
Why is my espresso sour? Under-extraction causes and how to fix them
Sour espresso almost always means under-extraction. Here's how to spot it, the order to fix things in, and what Sage and De'Longhi's manuals say.
If you’re asking why is my espresso sour, the answer is nearly always under-extraction: the water has rushed through the coffee before it could pull out enough of the sweeter, heavier flavours. The usual causes are a grind that’s too coarse, too little coffee in the basket, or a light tamp. We haven’t tested this in person. This guide draws on Sage’s Barista Express and Bambino manuals and De’Longhi’s Dedica manual, so the fixes come from the makers rather than guesswork. Read how we compare.
Why is my espresso sour? The signs of under-extraction
Sage’s extraction guide for the Barista Express describes an under-extracted shot like this:
- Flow starts after only 1 to 3 seconds and pours “fast like water”.
- The crema is thin and pale.
- The espresso is pale brown.
- It tastes sharp, weak and watery. Sage’s chart labels this end “underdeveloped, sour”.
For comparison, Sage’s target is a shot that starts to flow after 4 to 7 seconds, runs “like warm honey” and takes 25 to 35 seconds in total. Anything under about 20 seconds sits in its sour zone.
Another clue is the puck. Sage says that if the used coffee puck is wet and sloppy when you knock it out, look at the under-extraction section.
The fix, in the right order
Change one thing at a time, then pull another shot. This order follows Sage’s troubleshooting.
- Grind finer. This is the main fix. Sage’s advice for a fast, sour shot is to turn the grind size finer and re-test. On the Barista Express, Sage suggests starting at grind setting 8 and adjusting from there.
- Check the dose. Sage’s optimum is 8 to 11g of coffee for a single basket and 16 to 19g for a double. Too little coffee lets water through too quickly. As a guide, the top of the tamper cap should sit level with the rim of the basket after tamping.
- Tamp firmly and evenly. Sage recommends 15 to 20kg of pressure. A light or lopsided tamp lets water find a quick channel through the coffee.
- Look at the beans. Sage recommends beans with a “roasted on” date and suggests using them 5 to 20 days after roasting. Its Bambino manual says stale coffee “may pour too quickly” and taste “bitter and watery”.
- Heat everything up. Cooler water extracts less, so a cold machine can push a shot towards sour. Let the machine heat fully, run a little water through the group head first and warm your cup.
Who it isn’t for: anyone using a pressurised (dual-wall) basket with pre-ground coffee. Those baskets mask grind problems, so most of the grind advice above has less effect.
Machine-specific notes
Sage Bambino and Bambino Plus
Sage’s Bambino manual says espresso should start to flow after 8 to 12 seconds (it calls this infusion time). If it starts in less than 7 seconds, you’ve either under-dosed the basket or the grind is too coarse, and that’s an under-extracted shot. Sage also suggests running a short flow of water through the group head before you lock in the portafilter, to stabilise the temperature. See our Sage Bambino review for more on the machine.
Sage Barista Express and Express Impress
Use the built-in grinder’s dial: one step finer at a time, then re-test. Sage says single-wall baskets are for freshly ground beans and dual-wall baskets are for pre-ground coffee. If you’re grinding fresh, use the single-wall ones, or the grind changes won’t show.
De’Longhi Dedica EC685
The Dedica doesn’t have a grinder, so the fixes are different. De’Longhi’s troubleshooting table says that if coffee comes out too fast and light, the ground coffee may not be pressed down firmly enough, there may not be enough of it, or it may be too coarse. Its fix for the last one is to “use only pre-ground coffee for espresso coffee makers”. The Dedica also has a coffee temperature setting in its menu, and De’Longhi’s tips for hotter espresso include raising that setting and warming the cups first. Our Dedica EC685 review covers the machine in more detail.
Who it isn’t for: anyone with a bean-to-cup machine. Those grind and dose automatically, so the main fix is the grind setting in the menu.
When it’s sour and bitter at once
Sage lists “bitter/sharp” in its under-extraction box, which surprises people. A fast shot can taste sharp and harsh at the same time, especially if the grind is uneven. Get the shot time into the 25 to 35 second range first, then judge the taste again. If it’s still bitter once the timing is right, see why is my espresso bitter.
Where to go next
Our guide to how to make espresso at home covers the whole routine, and grind size for espresso goes deeper on grinding. A machine full of scale can run cooler and slower, so it’s worth knowing how to descale a Sage Bambino or a Sage Barista Express. Still choosing a machine? Browse our espresso machine guides.
FAQ
Is sour espresso under-extracted or over-extracted? Under-extracted, in almost every case. The shot ran too fast, usually because the grind was too coarse or the dose too small.
How long should an espresso shot take? Sage’s Barista Express guide aims for 25 to 35 seconds in total, with flow starting after 4 to 7 seconds.
Can fresh beans make espresso sour? Bean age matters. Sage suggests using beans 5 to 20 days after their roast date. Sage’s Bambino manual says stale coffee may pour too quickly and taste bitter and watery.
Will a finer grind always fix sour espresso? It’s the first thing to try, but check dose and tamp too. If the shot starts to choke or drip, you’ve gone too fine.