Sour Coffee – Why Coffee Tastes Sour And How To Fix It

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While some acidity is generally regarded as a good thing in coffee, there is a fine line between a perfectly brewed cup’s bright and vibrant acidity and an off-putting and unpalatable sour taste caused by too much acidity.

Like many areas of domestic brewing, sourness can be a source of ongoing frustration without the means to address it. However, if you understand the elements that make coffee sour, fixing the issue need not be a difficult task.

This guide will address the issue of sour coffee and offer some simple fixes to work through each until you find a sweet spot (quite literally) of a beautiful coffee with just the right level of acidity, whatever your brewing method. Let’s get started.

Understanding Coffee Acidity And Sourness

A degree of acidity is good for coffee – or any food. However, there is a limit to the amount of acidity people can tolerate before coffee begins to taste sour. Therefore, finding the right balance is essential.

Coffee beans have naturally fruity flavors because they come from the cherries of coffee trees. The Specialty Coffee Association (SCA) attempted to help coffee lovers differentiate the flavors with its iconic Coffee Taster’s Flavor Wheel.

coffee-flavor

The wheel displays over 100 sensory flavors to help coffee drinkers understand and describe the flavors. In addition, the wheel contains many fruity descriptors, including apple, cherry, grape, peach, pear, pineapple, and pomegranate.

The flavors on the wheel are bright and vibrant, with enjoyable acidity. However, there are also some sour flavors, which are not desirable. Nevertheless, great acidity is often confused with sourness. The key is to brew coffee with the former rather than the latter.

Why Does Your Coffee Taste Sour?

The Coffee Beans

There are various reasons why coffee beans can affect acidity, including origin, variety, roast level, and how they are processed. Let’s look at the main factors.

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Coffee Type

Some beans naturally have more acidity than others. For example, arabica coffee grows and matures slower than Robusta beans, which ensures an improved development of flavor and higher acidity.

Therefore, Arabica beans are more likely to have pleasant acidity rather than sourness. In comparison, Robusta coffee naturally has a bitter taste.

Processing Method

There are two main ways to process coffee – natural or wet-processed.

Natural processing involves allowing the whole coffee cherry on mats, raised beds, or patios. On the other hand, wet-processed coffee involves putting the coffee cherries through a pulping machine to remove the outer skin. The seeds, which are covered in pulp, are then soaked in water until the pulp falls off. Then, the seeds ferment before they are rinsed and dried.

Wet processed coffee (washed coffee) typically emphasizes the quality of the coffee beans, making it the most reliable of the two methods for producing higher acidity or brightness.

Growing Region

Beans grown in regions with higher elevation, including Ethiopian and Kenyan, also typically have a higher acidity. They are great coffee, but if your taste buds don’t enjoy the sour coffee taste, avoid them.

Roast Level

The coffee roasting process affects the acidity, sweetness, and bitterness of your coffee.

Lighter roasted beans are usually higher in acidity than dark roast beans. If you usually use dark roast beans, you may find light roast coffee tasting sour even when the coffee is perfectly extracted. So, if your palate is particularly susceptible to sourness, use light roast beans instead.

light-roast-vs-dark-roast

The Extraction

When coffee grounds are extracted, acids and fats are the first compounds to extract. Sugars and plant fibers follow these. This is true regardless of the brewing method. Acid contributes sour flavors to the coffee, and, as it’s the compound extracted earliest, along with fats, that means that sourness will be one of the first things extracted into your cup of coffee.

Sugars are next because they’re more molecularly complex than acids, meaning water needs more time to dissolve them. Finally, the dry and bitter plant fibers are extracted for even longer.

Because of this order, that means under-extracted coffee will always be sour because it didn’t have the time it needed to extract the sugars to balance the sourness. At the same time, coffee tastes weak. On the other hand, over-extraction leads to bitter coffee because it has more dry and bitter plant fibers.

How To Fix Sour Coffee

Choose Low Acid Coffee Beans

When it comes to pH, coffee is acidic. Indeed, most black coffee has a pH of 5, whereas some have a lower acidic level with a pH closer to neutral 7. This depends on the growing environment, including soil, climate, and mineral composition.

Check out our best low-acid coffee beans collection.

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Generally, it’s worth keeping in mind that coffee beans grown at a low altitude are less acidic. Beans of this nature are grown in countries including Brazil, Sumatra, Mexico, and Peru. Therefore, choosing coffee from these regions is a good idea to avoid a sour cup of coffee.

On the other hand, while acidity flavor in the coffee is a good thing, it’s not for everyone. Therefore, it’s worth checking the label and opting for coffee with descriptors including nutty, chocolate, cinnamon, and caramel, rather than tropical fruit names.

Also, choosing dark roasts instead of light roasted beans also helps if you don’t want sour-tasting coffee.

Check out our best dark roasted coffee beans collection.

Fresh beans make coffee taste sweeter than stale coffee beans, grind before brewing can also fix sour coffee.

Adjust Your Coffee Brewing Method

Brewing coffee with pour-over increases the chances of producing sour coffee. That’s because the water and coffee have a shorter contact time, meaning it is more likely to be under-extracted – particularly if you’re inexperienced.

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If you are getting sour drip coffee, check your drip coffee maker. If it has strength option or temperature option, make use of it.

French press and cold brew are your best brewing method options to maximize your chances of reducing sour taste.

The extraction is the primary reason for the sourness in your coffee. As long as you’ve chosen the correct beans, under-extraction is the most significant reason why your coffee tastes sour. If you can address that issue, you should reduce the sourness considerably.

Let’s examine key areas where altering your brewing process can reduce coffee sourness.

1. Brew Time – Increase The Extraction Time

As we mentioned earlier, coffee extracted for longer offers more chance for the sweetness of the sugars to balance out the initial sourness. Therefore, extending the brewing time is one excellent way to brew less sour coffee.

So, the best options are brewing methods that allow more contact time between the coffee and water, including French press and cold brew. Simply let the coffee steep for longer.

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Of course, you can’t do much to change the brewing time of a drip coffee maker while you’re limited with pour-over, so it’s necessary to examine some other options to reduce sourness with those brewing methods.

2. Grind Size – Grind Finer

If you grind your beans and want to reduce the sourness in your beverage, try a finer grind size. The finer the grinds, the more surface areas the water will contact, and the more your coffee will extract.

It’s common knowledge that each brewing method has its own grind size. So, the French press uses coarse grinds, while espresso uses fine grinds at the other end of the scale.

So, whichever your base grind size is for your chosen brewing method, try grinding a little finer to ensure greater extraction and more sweetness and bitterness into the coffee to balance the acidity and sourness.

If you are getting sour cold brew coffee, in most cases, the coffee grounds you use are too coarse. You can try finer coffee grinds and darker roasts.

french-press-grind-size

3. Temperature – Use Hotter Water

It isn’t the most obvious solution, but the water temperature affects the extraction rate. If you’re a fan of cold brew coffee, this will be more apparent, as cold brew has to steep for between 12 and 24 hours to fully extract instead of just a few minutes for coffee brewed using hot water.

If you like hot coffee, it’s advisable to try using water at a hotter temperature. This is, of course, linked to the previous points. Namely, that under-extracted coffee taste sour. In addition, hotter water leads to a faster extraction. Therefore, the hotter the water you use, the more efficient the extraction.

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4. Ratio – Use More Coffee

Another potential reason for under-extracted coffee is the amount of ground coffee you’re using in your coffee recipes. If you’re not using enough coffee, there’s more chance the beverage will be under-extracted, causing it to taste sourer. But, again, increasing the quantity of coffee in the recipe could solve the issue.

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This is most likely an issue if you’re using an unfamiliar brewing method and haven’t yet found the perfect coffee-to-water ratio.

Try adding more coffee incrementally each time you brew your coffee until you find your sweet spot.

Conclusion

As this guide has shown, several elements can cause coffee to taste sour. While some are more obvious causes of sour flavor than others, there are simple enough ways to fix them if you know how.

Much of the process of domestic coffee brewing involves making incremental changes to various areas of the task until you find the correct levels for you, and eliminating sourness is no different.

So, if it’s not the coffee bean you’re using, it could be the water temperature. It could be another area, like grind size or coffee-to-water ratio, if it’s not that.

Everyone’s taste preferences are different, so there’s no correct answer to precisely what makes the perfect sour-free coffee. Therefore, the best idea is to simply make tweaks until you find the best levels for you. Before long, you can enjoy beautiful coffee with just the right amount of acidity and none of the sourness.