You’ve bought good beans, put them in your fully automatic machine, and the coffee still tastes flat, sour, or bitter. This doesn't have to be a reflection of quality. A fully automatic machine works differently than a portafilter or a manual filter, and not every good bean is suited to this process.
In short: For fully automatic machines, medium to medium-dark espresso roasts with a dry, matte surface are usually best. Very light filter roasts often taste sour in them, while very dark, oily beans can promote residue in the grinder. Fresh beans, the right grind size, and the appropriate amount of coffee do the rest. In Munich, using a water filter is also recommended due to the hard tap water.
Why not every good bean is suitable for a fully automatic machine
A fully automatic machine grinds, doses, and brews in a set process. You can adjust the grind size, coffee quantity, and often the temperature in steps. However, the machine itself largely determines how the water flows through the coffee and how long it takes.
Light, fruity filter coffees require exactly this control. In a manual filter, they reveal floral and fruity notes, whereas in a fully automatic machine, this often manifests primarily as acidity.
That is why we divide our coffees into two lines. I roast the Espresso Line for portafilters and fully automatic machines, and the Filter Line for manual filters, AeroPress, and French Press. Light filter roasts are therefore not the easiest choice for starting out with a fully automatic machine. Not because the bean is bad, but because it was roasted for a different brewing method. How well it works anyway depends on your machine, your settings, and your personal taste.
The roast level: medium to medium-dark
Too light: Light roasts are harder to extract. To ensure their acidity is fruity rather than sharp, the grind, temperature, and coffee-to-water ratio often need to be precisely adjusted. Many fully automatic machines offer only limited settings for this, which is why light roasts often taste thin or sour in them.
Too dark: The darker the roast, the more coffee oil tends to reach the surface of the bean over time. You can see this by the shine. Oily beans can stick together in the hopper, feed poorly, and promote deposits in the grinder. This means cleaning more frequently.
In between: Medium to medium-dark roasts are the safest range for most fully automatic machines. In our Espresso Line, these are:
| Coffee | Roast level | Flavors | Type |
|---|---|---|---|
| KICK OFF | medium-dark | Dark chocolate, nutty, caramel | Single Origin, Brazil |
| CALCIO | medium-dark | Dark chocolate, nougat, nutty | Blend, Brazil and India |
| MATCH DAY | medium | Milk chocolate, hazelnut, caramel | Single Origin, Brazil |
| BOX 2 BOX | medium | Caramel, mandarin, cocoa | Blend, Brazil and Costa Rica |
For a fully automatic machine, I recommend starting with KICK OFF or CALCIO. They are roasted slightly darker and are therefore more forgiving if the machine isn't perfectly adjusted. MATCH DAY and BOX 2 BOX also work, though their more delicate notes are usually clearer in a portafilter.
We roast on a small drum roaster in batches of around 12 kilograms.
Single Origin or Blend?
For a fully automatic machine, the label "Single Origin" or "Blend" is less important than the roast level and the flavor profile you are looking for. A Single Origin like MATCH DAY shows an origin very clearly, while a blend like BOX 2 BOX combines two origins into a unique profile. Both can work well in a fully automatic machine if the roast level is right.
If a lot of crema is important to you: Robusta beans often contribute more to the crema and body in espresso blends. Our CALCIO contains a portion of Indian Robusta. The other coffees in the table aim more at sweetness and balance than at maximizing crema.
How fresh should beans for a fully automatic machine be?
Coffee gradually loses its aroma after roasting. Therefore, pay attention to the roast date when buying, not just the "best before" date. We print the roast date on every bag.
Shortly after roasting, coffee releases a lot of carbon dioxide. That's why it's worth not using espresso roasts on the very day they were roasted. The ideal waiting time depends on the roast level, packaging, and storage.
In practical terms, this means: only buy as much as you will use in a few weeks. Store the beans in an airtight container, in a cool, dark place, but not in the refrigerator. And only fill the bean hopper with as much as you need for the next few days.
Coffee from the machine tastes bitter or sour? Three common causes
If the roast level and freshness are correct, the issue is usually the grind size, coffee amount, or water. Always change only one setting and then try again. Otherwise, you won't know what actually helped.
1. Grind size
If ground too fine, the water flows through more slowly, and the coffee may taste bitter or dry. If ground too coarse, it flows through faster, and the coffee tends to taste sour or thin. Adjust the grind size in small increments. How and when you are allowed to adjust it is explained in your machine's manual.
2. Coffee amount
Many machines are set to a medium or low coffee strength by default. Too little coffee for the amount of water quickly results in a thin cup that can still taste unpleasantly bitter. Try setting the coffee strength one level higher or the water amount slightly lower before you adjust the grind.
3. Water
Munich tap water is hard. According to the drinking water analysis by Stadtwerke München (as of January 2026), the average total hardness is 15.8 °dH. That is good drinking water, but quite a lot for coffee. In particular, high carbonate hardness can dampen acidity and fine aromas, and limescale deposits build up in the heating system of the fully automatic machine. Set the correct water hardness in your machine's menu so that it reminds you to descale at the right time. The descaling indicator usually doesn't measure scale directly but calculates it based on factors like the set water hardness and the amount of water used. If you use a water filter in the machine, activate it according to the instructions and replace it in time. You can read more about this in the article Water for Coffee in Munich.
Frequently asked questions about coffee beans for fully automatic machines
Which roast level is best for fully automatic machines?
Usually medium to medium-dark. Very light roasts often taste sour in a fully automatic machine, while very dark, oily beans can put more strain on the grinder.
Are oily beans bad for a fully automatic machine?
Significantly oily beans are not a good choice for many machines, as they can promote deposits in the bean hopper and grinder. Beans with a matte surface are the safer choice.
Can I use filter coffee beans in a fully automatic machine?
You can, but light filter roasts often taste sour or thin. Espresso roasts in the medium to medium-dark range are a better fit.
Are Single Origin beans suitable for fully automatic machines?
Yes, if the roast level is right. Whether it is a Single Origin or a blend is less decisive than the roast level and flavor profile.
How often should I clean my fully automatic machine?
According to the manufacturer's specifications. You can wipe out the bean hopper regularly with a dry cloth. With dark, oilier roasts, it is worth checking more often.
Do I have to descale the machine more often in Munich?
Because of the hard tap water, probably yes. It is important that the correct water hardness is set in the machine, as the descaling indicator is usually based on this. If you use a water filter, activate it in the menu and replace it according to the instructions.
Why does coffee from a fully automatic machine taste sour?
Common reasons include beans roasted too lightly, a grind that is too coarse, or too little coffee for the volume of water.
Conclusion
You don't need a rare bean for your fully automatic machine; you need the right one: medium to medium-dark roasted, matte rather than oily, and as fresh as possible. Add a few minutes of fine-tuning the machine and, in Munich, a water filter, and you are very close to a great cup of coffee. If you want to compare several profiles, you can also find KICK OFF, MATCH DAY, and BOX 2 BOX together in our Espresso Tasting Pack.
About the author: Jovana is a roaster, coffeeologist, and founder of Nine Fine Roastery in Munich. She roasts the coffee for Nine Fine herself. She is also a professional soccer player.
Sources: Stadtwerke München – Munich drinking water analysis values, as of January 2026 · Nine Fine Roastery – Espresso Line product data
