Guide · 23 October 2026
Beans, Cup, Milk: Small Rules with a Big Effect
How to store your beans, why freshly roasted is not best straight away, why the cup is warmed up and how hot the milk may get. — by Dieter Eitz
The grind size, dose and time are right, and yet your espresso tastes round one day and flat the next? Often the cause lies in things that happen before and after the shot: how the beans are stored, how old they are, how warm the cup is and how hot the milk gets. These small rules take hardly any time and make a big difference.
1. Store your beans properly
Coffee loses aroma through air, light, heat and moisture. So keep the beans airtight, dark and at room temperature, ideally in the original bag with a valve or in a sealed, opaque tin. The fridge is not a good place: when you take the cold bag out, moisture from the room air condenses on the beans, and they pick up smells from the fridge. It is better to buy amounts you will use within a few weeks, and to grind only shortly before the shot.
2. Freshly roasted does not mean best straight away
Roasting produces carbon dioxide, which the beans release in the days that follow. Very freshly roasted coffee degasses heavily: the shot foams up, the gas disturbs the even contact between water and ground coffee, and the espresso tastes unsettled. Many roasters therefore recommend letting coffee rest for a few days after the roast date for espresso, often one to two weeks. After that the coffee keeps its aroma well for a while. A look at the roast date on the bag helps you hit the right window.
3. Adjust the grinder when the shot changes
Even with the same beans, the shot can change from day to day. If the beans keep ageing, or the room climate changes noticeably, the espresso sometimes runs faster or slower than yesterday. Then the familiar rule of thumb applies: if it runs too fast and tastes sour, grind a little finer; if it runs too slowly and tastes bitter, a little coarser. Small corrections to the grind size are normal and not a sign that something is broken.
4. Warm up the cup
A single espresso is only around 25 to 30 millilitres. A cold porcelain cup immediately draws noticeable heat out of this small amount, and the espresso quickly turns merely lukewarm. So warm the cup beforehand: on the machine's cup tray or rinsed briefly with hot water. Thick-walled cups keep the heat longer, because they have more mass and porcelain gives off heat only slowly. Small cups suit espresso: it stays hot longer in them, and the crema does not spread over a large surface.
5. Milk: warm, not hot
Milk tastes sweetest when it is about 55 to 65 °C. If it gets much hotter, above roughly 70 °C, the taste moves towards boiled milk, and the foam collapses faster. The sweetness does not come from added sugar: warm milk simply tastes sweeter than cold or boiling hot milk. A milk thermometer helps at the beginning; later your hand on the jug is often enough. When the jug becomes too hot to hold, the milk is in the target range: turn off the steam.
For fine, glossy microfoam you need less air than many people think. Draw in air only for the first few seconds, keeping the tip of the steam wand just below the surface. Then lower it a little deeper, so that the milk swirls in the jug. This whirlpool distributes the air into tiny bubbles. Many oat drinks sold as barista versions can be frothed this way, too.
Your next step
Pick one rule and try it for a week, for example the warmed cup or the milk that you switch off as soon as the jug becomes too hot to hold. If you change only one thing at a time, you can taste what it does.
Beans → airtight, dark, room temperature, not in the fridge
Roast date → let freshly roasted coffee rest for a few days
Grinder → when the shot changes, adjust in small steps
Cup → warm it up, small and thick-walled
Milk → 55 to 65 °C, draw in air briefly, then let it swirl
