Does your coffee taste 'off'? There could be mould in your machine

Good coffee does not only depend on how you make it, but how you handle your machine. A decent sense of hygiene will improve the coffee's taste and can also help avoid mould. – Photo: Christin Klose/dpa

Did your coffee taste 'off' this morning? Kind of musty? It might not be the beans. Instead, it could be due to limescale and old coffee in your coffee machine.

There are two more good reasons to clean your coffee or espresso machine a little more often: mould growth and energy costs.

"A coffee machine with a build-up of calcium and limescale produces is forced to work harder, producing water that is too hot," says Holger Preibisch, CEO of the German Coffee Association. "The buildup means the machine can no longer maintain the water temperature."

Limescale buildup occurs wherever water is used. That is why experts as well as coffee machine manufacturers advise emptying the water tank even at the end of each day and wiping it dry.

Changing the water has another advantage: Fresh water does not negatively affect the taste of the coffee.

Mould and germs can form

Even if the taste of the coffee seems to be the most important thing, there is a much better reason to really get to grips with your machine every day: If you don't, mould and limescale can build up and germs can multiply.

Moist coffee residues go mouldy in the bottom chamber (e.g. of a moka pot), the coffee grounds container and in the drip tray. In addition, oil and fat from the coffee get deposited here.

In the case of capsule and pad machines, the tray should therefore be emptied after each use, recommends Theresa Seitz, a consultant for small household appliances at the German Electro and Digital Industry Association (ZVEI).

According to Holger Preibisch of the German Coffee Association, this also applies to filters, which should not be left in the holder after the brewing process.

Even the pots of filter machines are best emptied daily when you've finished drinking coffee for the day. Otherwise, the coffee will dry up and the pot will be harder to clean.

Manufacturers and coffee experts advise cleaning the water reservoir daily. – Photo: Karolin Krämer/dpa

The milk nozzle and tank are particularly prone to mould

The milk nozzle, the water tank and tubes are particularly tricky: "Germs develop wherever milk is used and not removed," says Holger Preibisch.

The steam wand on the side of portafilter espresso machines and fully automatic coffee machines, for example, can often be unscrewed and left to soak in cleaning agent and then rinsed with clear water. Some machines notify when you need to do this. However, in the expert's view, any milk tank in an espresso machine should be rinsed out daily. The same applies to the tubes, which are rinsed through with hot water from the coffee machine.

The machine should also be descaled about once a month, which is quite an easy process. Usually, you add a liquid descaler to the filled water tank and start a cleaning program or the usual operation program.

Do not use acidic cleaners

Theresa Seitz advises against vinegar and citric acid, which are often used in the household to get rid of limescale. "Citric acid reduces the lifespan of the machines, while the strong acidity can attack seals and tubes." Vinegar should also be be kept away from coffee machines. "It's too harsh and can damage the plastics in the machine."

In addition, all coffee machines should be given a basic cleaning on a regular basis. Fully automatic machines and many other coffee machines remind you when to to clean them and often offer corresponding programs. – By Evelyn Steinbach/dpa