Good coffee can have many different tasting notes: chocolate, roasted nuts, caramel, cranberry, fruity acidity, and so on. One thing is for sure, though: “sour” isn’t a word used to describe tasty coffee. Few things can ruin a good morning like getting a sour taste from what should be a delicious cup of joe.
There are a handful of reasons why your coffee might taste sour, and below, we’re going to discuss what those are as well as offer fixes. By the end, you should know how to get your coffee experience back on track and enjoyable. Let’s get started!
First, Why is My Coffee Sour?
Sour coffee can be cured in many ways, but there’s one main reason it tastes sour to begin with: extraction. When you mix hot or boiling water with coffee grounds, you start extracting a bunch of different compounds from your coffee. These compounds include oils, acids, sugars, and eventually plant fibers. These compounds make their way into your finished coffee in this sequence during brewing.
The Extraction Process
Fats and acids are extracted first, and these lead to a strong sour taste in your coffee. Sugars come next and, of course, lead to a sweetness that often balances out the acidity. Lastly, the plant fibers that are extracted produce a bitter taste. Bitterness can also smooth out acidity, but too much bitterness will lead to overly bitter coffee.
As we’re sure you can guess, sour coffee results from ending the extraction process too early. If you under extract your coffee, you won’t get the sweetness from the sugars or the bitterness from the plant fibers to balance the acidity and sourness.
This extraction sequence remains the same no matter what brewing method you use, so whether you prefer French press, espresso, pour over, or some other method, your coffee will taste sour if it’s under-extracted. So, how do you fix it?
How to Fix Sour Coffee
1. Make Your Grind Size Smaller
If you grind your own coffee, the first thing you can do to fix sour coffee is to make your grind size finer. The finer your grounds are, the more surface area the hot water will have to interact with, and the more extraction you’ll achieve.
You may already know that different brewing methods call for different grind sizes — French press grounds are coarser than drip grounds, which are coarser than espresso grounds. This coarser grind size is because these methods maintain contact between the hot water and coffee for varying times. Therefore, if you keep using the same brewing method but grind your coffee more finely, you’ll end up with better extraction. A finer grind size will allow you to get some sweetness and bitterness into your coffee to balance the acidity and sourness.
For those who buy pre-ground coffee, you’ll have to use a different strategy to get rid of that sour taste in your coffee.
2. Water Temperature
You may already be aware that the rate of extraction in your brewing coffee is directly related to your water temperature. Many people know this because, while hot coffee takes only a few minutes to brew, cold brew, which is made with room temperature or refrigerated water, takes 24-48 hours on average! The hotter the water you use for brewing is, the faster the extraction will take place.
Increasing the water temperature you use will increase the rate of extraction, so if all other variables — like brewing time and grind size — are kept the same, hotter water will result in less sour coffee.
A water temperature between 205° and 210° Fahrenheit is the sweet spot for us. This temperature will allow for your extraction to include some sugars and plant fibers to balance the sourness from earlier in your extraction.
Water will only ever reach 212° Fahrenheit or 100° Celsius because, after that point, water is converted to steam. If you’re using boiling water already, you won’t get the temperature any higher and will have to use another option for reducing sourness.
3. Brewing Time
Another easy way to extend beyond the “sour phase” of extraction in your coffee is simply to extend the brewing time. Letting hot water interact for a more extended period with your grounds will let the extraction continue, resulting in some sweetness and bitterness getting into your coffee.
Extending the brew time is most easily done with immersion brewing methods like French press, Kalita wave (semi-immersion), or even cold brew, as you can just let the grounds steep for longer in hot water. Brewing time for drip coffee machines is usually dictated by your coffee maker and can’t be changed, so a different option for ridding of sourness in your coffee will be necessary.
Brewing time for methods like pour over can be adjusted a little with technique (like not pouring down the sides of your pour over coffee dripper), but for the most part, will be more easily adjusted with grind size or water temperature adjustments.
The last method for reducing sourness on our list is adjusting your recipe. With most brewing methods, your coffee to water ratio will determine your coffee’s strength rather than extraction, but under extraction can occur if you don’t use enough coffee.
If you’re following a recipe and weighing or measuring coffee and water carefully, chances are this isn’t your main issue. However, if you’re new to a particular brewing method, under extraction could be occurring because you’re not using proper water to coffee ratios. Adding water to your recipe could solve your sour coffee problem!
The process of getting rid of that nasty, sour taste in your coffee may seem like a mystery to you, but the problem boils down — pun definitely intended — to one thing: extraction. When hot water meets coffee grounds, the extraction that takes place leads to extraction, in order, of acidic and sour compounds, sweet compounds, and finally, bitter compounds.
Under extracted, sour coffee is the result of not getting enough extraction, which doesn’t allow sweet or bitter flavors into your coffee to balance out sourness. To fix this, you can make your grind size finer, make your water hotter, brew for longer, or use more water in your recipe. Your equipment and brewing method will dictate which is best and easiest, but no matter what, the result will be delicious coffee that’s free of unpleasant, sour flavors.
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