Why Does Coffee Turn Sour?

Coffee is a sophisticated beverage. When properly brewed, it offers a delightful and smooth taste. However, the smallest error can transform this enjoyable beverage into an unpalatable one. Every phase of the brewing process demands meticulous care to ensure an impeccable outcome.

But you should not worry much if your coffee turns sour because it can happen to anyone. Even professionals can make this mistake. However, many times a cup full of unpleasant flavors gives you dissatisfaction. You get to wonder what goes wrong with your coffee. So, here you will discover the factors that make a coffee turn sour.

Presence of Acidity in Coffee

Acidity is naturally present in coffee. It is a vital ingredient of coffee. Therefore, the presence of acidity in coffee is important. Many people confuse acidity with a sour taste. Without acidity in coffee, your coffee will become dull and muted.

You will not feel any exciting taste in coffee if acidity is not present in it. There is a remarkable difference between acidity and sourness. Therefore, you should not mix the acidity of the coffee with sourness. There are different types of acids present in coffee. These different acids include;

  • Citric acids
  • Malic acids
  • Phosphoric acids
  • Acetic acids

Different coffee has different acid levels in it. This acidity contributes flavor to a cup. If this acidity gets too much, then it is also not good. The coffee can turn sour if the amount of acid in it gets high.

Reason Why Coffee Tastes Sour

The sour taste in coffee is a tragedy. No one wants to experience that taste of coffee. There are many reasons due to which your coffee tastes sour. These different reasons include;

Less Brew Time & Method

Brew time is also a very important factor. Many ingredients are present in a cup of coffee. Coffee contains oils, sugars, acids and many different flavours. When you mix coffee and water, then coffee flavours dissolve in water. If the flavors dissolve completely, then they give you an outstanding result.

It is because, during mixing, the acids are extracted firstly. Due to which at the start of brewing, the coffee is very sour. When time passes, these natural acids are then balanced by other flavours of coffee.

If you brew the coffee for a short time, the coffee remains under extraction. At that time, the other flavors of coffee are not dissolved to balance the natural acid in coffee. Due to this, you get a sour taste of coffee. It is because you do not give enough time to coffee to dissolve all flavours.

So, if you think about why your coffee gets sour, then under extraction might be a problem. You can fix it quickly by doing a good extraction. Apart from brew time, the brewing process also matters. Therefore, you should also focus on the brewing method.

Water Ratio

In coffee, the water ratio matters a lot. The coffee to water ratio is different for different coffees. It is essential to keep the ratio of water and coffee balanced. According to the traditional methods, two tablespoons of coffee and 8 ounces of water can give you good results.

Today there are a lot of variations and flavours that come in coffee. However, some coffees get too sour with the traditional method. So, for today’s coffee, you cannot use this traditional method. With the help of a water ratio, you can easily control the flavour of your coffee.

If you want a strong coffee taste, then you should add less water. Adding less water will give you a more concentrated brew. If you like weak coffee, then you should add more water to it. Adding more water will give you a less concentrated brew.

When you add more water, then it also increases the brewing time. When you brew more, it gives you a cup of coffee with a bit of acidity and sweet taste. Also, check that the water temperature is suitable while doing this.

Fresh Beans

Fresh beans are another reason due to which coffee tastes sour. If you roast the fresh beans and then brew them, the cup of coffee will get sour. After roasting the beans, their flavors get enhanced.

Before you roast the fresh beans, place them for some time. By placing them for some time, the flavour gets balanced. Because just after roasting, the flavors in the beans do not completely dissolve in water. These flavors are unable to balance the acidity in coffee.

Due to this, you will get sour coffee tastes. Coffee beans require some days to settle down. So that when you brew them, you get the desired result. If you keep them for about a week, then you will get better flavors and taste.

Roasting Coffee Beans

Many times, due to improper roasting, we do not get the taste that we expect. Under and over roasting coffee beans can make your coffee sour.

  • Under Roasted Beans: When you start roasting, most of the coffee beans are green in colour. With the help of sensible heat, these green beans transform into the coffee of your desired taste. Due to different reactions, the coffee turns brown. If you roast the beans under less heat, the flavour will not come out, due to which you will experience a sour taste in coffee. If you experience that taste in coffee, then it is due to under roasted beans.
  • Over Roasted Beans: Over-roasted coffee can also cause sourness in coffee. Due to over roasting, the beans turn out too dark. When you mix the coffee beans with water, the dark beans bring sourness to coffee due to over roasting. So, if you want a perfect coffee, you have to avoid over roasting beans. You can also use coffee grounds to prepare extracted coffee.

Too Large Particle Size

Not grinding the coffee beans well can also bring sourness in taste. Make sure that the grind size is accurate. If your coffee remains under extraction, then the particle size might be too large.

When the size of particles is more significant, then it takes a lot of time. Larger coffee particles do not get quickly saturated with water. It means that the flavours of the coffee are not entirely extracted from the bean.

If your coffee tastes sour, then you need to grind the particles well. Grinding the coffee beans well will help you overcome the sour taste of coffee.


If you are not familiar with why your coffee tastes sour, then this article is for you. Here, you will find the reasons that cause coffee to taste sour. By removing the given concerns, you can get a sweet and delicious coffee with ease.

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