Why Does My Coffee Taste Sour?

This is probably one of the most frequently asked questions asked by home baristas.

Coffee making is an art. It is never easy to learn how to make a good cup of coffee. As you might already know, there are more than 800 aromatic compounds in a small coffee bean and every single thing you do could influence the overall taste.

Without further ado, let us deep dive into these possible causes of the sour taste.

1. Under Extracted Coffee

One of the most common reasons for sour coffee is due to under extraction. Extraction is the process where water develops the coffee flavor from the coffee grinds during brewing.

Under extraction usually occurs when the flavors are not fully extracted from the ground coffee. As the acidity of the coffee bean is first developed and extracted at the first stage of the brewing process, under extracted coffee usually taste sour. As the extraction commences, more sugars are developed from the ground coffee, the brew usually tastes sweeter at the latter part of the brewing process. Alternatively, over extraction leads to an undesired bitter taste.

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To have a balanced extraction, you need to manage these three factors.

Brew Time

Premature brew time leads to under extraction of the coffee as the brew time is too short to fully extract the flavor from the ground coffee.

Brew Temperature

Low brew temperature leads to under extraction as the temperature is insufficient to fully extract the flavors from the coffee.

Grind Size

When you grind your coffee beans coarse, water filters through the ground coffee at a faster pace, leading to under extraction of the coffee. The required grind size of your ground coffee depends heavily on your brewing method. For example, if you are using an espresso pump where high pressure water is forced through the ground coffee, a finer grind size is recommended to delay the brewing process. If you are using a french press where the ground coffee is submerged in the hot water, a coarse grind size is recommended instead.

To achieve a good extraction, you can trial and test with these three factors so you can develop your own preferred brew taste.

2. Light Roasted Coffee Beans

Different types of coffee roasts produce different types of tastes.

In general, light roast has the highest acidity compared to medium and heavy roast. Most home baristas dont enjoy light roast as they find it to be painfully sour with a thin coffee body. If you prefer a more satisfying body with a growing bittersweet aftertaste, we will recommend you getting the medium dark roast.

Recommended Tips to Reduce Sour Taste in your Coffee

In the nut shell, here are some of our recommendations if you are still producing that undesirable sour coffee taste.

If you are brewing your coffee via a coffee drip or an espresso pump, use a slightly finer grind size for your ground coffee to extend the brew time.

If you are brewing your coffee via a French Press, it is recommended to use a coarse grind size to begin with since finer ground coffee will get stuck in the plunger filter. Hence, to counter the sour taste, you can extend your brew time to 4 minutes. 

Trial and Test

Coffee making is about trial and test. Even if you have the best coffee beans in Singapore, you need to learn how to produce a balanced extraction to brew a great cup of coffee.

We hope you have benefited from this article. What are your secret extraction techniques? Do share with us in the comment sections below.