Why Is My Moka Pot Coffee Sour|Bitter|Burnt? &How To Fix It


Why does my moka pot coffee taste Sour_Bitter_Burnt header image

Brewing good coffee in a moka pot does require some practice and experimentation. Along the way, you might discover you’re getting some tastes that you don’t particularly enjoy like, sour, bitter and burnt. What can you do to fix this?

A sour or bitter taste is usually the result of under or over extraction respectively. Making the grind size a little smaller if it’s sour and bigger if your brew is bitter is the first thing to improve your moka pot coffee. Keeping the heat of your stove to medium can prevent burnt tasting coffee.

The solutions above are just the most important things you can try to improve the taste of your moka pot coffee. There are a few other things that can improve the taste. You can find them below.


Why is my moka pot coffee sour?

One of the most common problems with moka pot coffee is a sour taste. Coffee and Arabica in particular has quite a few acidic notes. The same compounds in coffee that give your coffee a wonderful acidity that you enjoy can make your coffee taste sour.

The acidity isn’t a bad thing but if it’s too sour, it means there is too much of it or, (more likely) it’s not balanced out by other tastes. Think about lemonade. Straight lemon juice is way too sour to enjoy. Add sugar and suddenly you’ve got a great drink. The lemon juice didn’t become less sour, it’s just that the acidity is balanced out by the sweetness of the sugar.

A similar thing happens with coffee. While there is no sugar in black coffee, you can still balance out the acidity with other tastes that are also present in the coffee grounds. It’s just a case of getting out those tastes so you get a well-balanced cup.

When brewing coffee, you start with water and ground coffee. Then you have to get the compounds in the ground coffee into the water. That process is called: extraction.

The compounds in ground coffee that are the easiest to get out are the ones that taste sour. The other compounds that balance out the taste need a bit more encouragement to get out of the grounds. So if your coffee tastes sour, it’s usually the result of the coffee being under-extracted. So you’ve got the sour compounds but not the compounds that balance out the taste or at least not enough of those.

Untamped grounds in a moka pot

In a moka pot there are a few things you can do to increase the extraction of your grounds and therefore making it taste less sour;

  • Grind size: The first place to look is the grind size you use. For a moka pot you need a grind that’s a bit coarser than an espresso grind. If you buy ground coffee that’s meant to be used with paper filters, it’s probably a bit too coarse. If you have your own grinder, don’t be afraid to try out a finer setting if your moka pot coffee is sour. A finer grind means the grounds have more surface area. More surface area means more contact with water which increases the extraction.
  • Ratio: Finally, the ratio of coffee grounds to water can have an impact. Try using a little less grounds for the same amount of water. Using less coffee means you can extract the grounds that are there better. It’s a good idea to keep track of how much water and grounds you use with a scale and write down what the results are. This way you can track the changes you made and which changes actually make things more to your taste.
  • Coffee: Of course the coffee you’re using has a big impact on the final taste. Some coffees are more acidic than others. However, if you’re using coffee that’s reasonably high quality and fresh, you should look into the factors outlined above before buying new coffee. Of course if you’re using 3 months old ground coffee from the supermarket (and you’ve got no idea how long it has been on the shelf there) it’s a good idea to look into some higher quality whole bean coffee.

To get the same cup of coffee every time, you’ll get the best results with a scale. A coffee scale might seem over the top but it’s the best way to get the same ratio every time.


Why is my moka pot coffee bitter?

Moka pot coffee can have a tendency to taste a bit bitter. Bitter coffee is often on the other end of sour coffee. Many people tend to confuse the two tastes because coffee is often only reffered to as bitter so if someone doesn’t like the taste, they say it’s bitter. However, it’s really important to really taste and think if it’s sour or bitter. That’s because the solutions are going to be the opposite of sour coffee.

Just like sourness has a lot to do with extraction, bitterness does as well. Where sourness is often the result of under extraction, bitterness is often the result of over extraction. You want to extract certain compounds from your grounds but not too much. Sour compounds tend to dissolve into the water easier while bitter compounds take a bit longer. However, if you extract too much, you get too many bitter compounds.

To influence the extraction of your grounds in a moka pot, there are a few things you can do to reduce the extraction and make your coffee taste better;

  • Grind: The first thing to do is increasing the grind size a little. You’re shooting for something a bit coarser than an espresso grind but since this is all personal taste, you can go a bit coarser if you like less bitterness.
  • Ratio: Use a little bit more coffee grounds (if it fits in the basket of your moka pot). Having the same amount of water for more grounds will lower the overall extraction of the coffee. Measure both grounds and water precisely and keep track of what the results are so you can be consistent in your changes and see what changes bring you closer to the taste you want.
  • Coffee: Of course the coffee you use also has a big impact on the final taste. If your coffee also turns out sour while using other methods than a moka pot, the coffee itself could be the problem. Try buying fresh 100% Arabica beans. Robusta tends to be more bitter and many blended coffees will have some Robusta beans in the mix unless it specifically mention 100% Arabica.

Why does my moka pot coffee taste burnt?

In some cases moka pot coffee can have a burnt taste. This is a bit different than bitter although it does have it similarities in taste.

The biggest reason this happens is that the coffee grounds get too hot. When the grounds get too hot, they can actually get burned and this will translate into your coffee tasting burnt. Because a moka pot is made from aluminum and the filter basket is as well, heat from the stove easily gets transferred into the grounds.

Also, pressurized water boils at a higher temperature. Since a moka pot creates pressure, the more pressure you create, the higher the boiling point the hotter the steam. This is why temperature control is quite important with a moka pot. At first, there will be just atmospheric pressure in the boiler of the moka pot. However, once the water starts turning into steam, the pressure rises and therefore the boiling point and the temperature of the steam.

A moka pot can create up to 2 bar of pressure which means the boiling point of the water will be around 120 degrees Celsius. Your stovetop can heat water to that temperature without any issues so if you keep your moka pot on the heat, the steam will keep getting hotter through the brewing process.

That’s why it’s important to reduce the heat or even take the moka pot off the heat once the coffee starts flowing through the tower. It’s a balance of heat and pressure.

So if you’re keeping the stove on and your moka pot on the same heat for the whole brewing process, here’s what you can try;

  • Start with hot water in the moka pot: This reduces the time on the stove. This helps reduce the total brew time and reduce the heat transfer to the coffee grounds through the metal.
  • Set the stove to medium heat.
  • Keep the top lid open so you can see when the coffee starts flowing.
  • Once the coffee starts flowing, reduce the heat to low. The goal is to keep the coffee gently flowing without shooting out of the tower. If this improves the taste but not enough, try turning off the stove and just using the residual heat in the hob.

Favorite Moka Pot Products

You don’t need many things to brew good coffee with a Moka pot. Here are the few things you need to make the best possible coffee.

  • Moka Pot: Just buy a high quality Moka pot from the get go. The cheaper ones can be messy when brewing. Bialetti is the original and still one of the best with it’s classic looks. They cost a bit more than the cheap ones but these can last for decades and the parts that wear out are easily available for the Bialetti Moka pots. The 3 cup size is good for a single person (Amazon)
  • Beans: Good coffee starts with good beans. You can’t make bad beans taste good. Espresso roast beans are good for a Moka pot and will get you closer to that typical espresso taste. Peet’s coffee does a great 100$ Arabica espresso roast. Give it a try, you can get it here on Amazon
  • Grinder: Using whole beans means you need to grind them at home. This improves the taste because the grounds are much fresher. A Hario Slim (Amazon) is a great starting point for the starting home barista. If you want a good hand grinder for a good price, check out the TimeMore C2 (Amazon)
  • Scales: To get consistent results, a set of accurate scales is essential. Check out this Apexstone scale (Amazon). I’ve been using it for more than a year and while it doesn’t look the sleekest, it’s cheap and just as accurate as more expensive coffee scales. It just reacts a little slower.

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