Why is Pour-Over Coffee Too Sour and How to Adjust It? Is It Normal for Fresh Coffee Beans to Have Sour Taste?

Understanding Acidity in Light-Roast Coffee: Common Extraction Issues

Light-roast coffee is known for its fruit-like acidity, but today FrontStreet Coffee isn't discussing this desirable acidity. Instead, we're examining the sharp, unpleasant sourness that results from under-extraction during brewing. FrontStreet Coffee will analyze several case studies based on recent feedback from friends.

Case 1: Water Temperature Issues

During one customer service encounter, a customer ordered a pour-over of Yirgacheffe coffee. After tasting, he said: "I bought this coffee bean from your shop, but why is mine so sour when I brew it at home, while yours is perfectly balanced?"

After some discussion, it was discovered that he was using 86°C water for brewing, and in his own words, this was already after he had deliberately increased the temperature because it was light-roast coffee.

From this case, we understand that temperature influences the direction of coffee flavor. Generally, higher water temperatures extract more substances, making the coffee trend toward sweetness (or bitterness). Lower water temperatures extract fewer substances, making the coffee taste more acidic.

When brewing light-roast coffee like Yirgacheffe, FrontStreet Coffee typically uses 91°C, which is also a common water temperature for brewing light-roast coffee. In this case, if all other parameters were the same as FrontStreet Coffee's but only the water temperature was lower at 86°C, the resulting coffee flavor would be the sharp sourness of under-extraction.

Similarly, if brewing dark-roast coffee with a temperature of 91°C, it would also develop bitterness due to over-extraction. FrontStreet Coffee recommends using water temperatures of 90-93°C for medium-light roast coffee and 86-89°C for medium-dark roast coffee.

Case 2: Improper Pouring Technique

Improper pouring techniques during brewing can also cause under-extraction and sourness. Once, a friend reported: "I bought the Jushi Estate Blueberry from FrontStreet Coffee, and when I brewed it, it smelled wonderfully of blueberries, but tasted very acidic when I drank it." This Blueberry coffee bean uses anaerobic honey processing and should be quite sweet.

So FrontStreet Coffee discussed this with the friend, and during our conversation, we found nothing wrong with the brewing parameters—until he showed a picture of the coffee grounds after brewing, when the truth became clear.

It turned out that during brewing, the coffee grounds wall had been broken. The ribs in a coffee filter serve to guide water flow into the lower pot and prevent clogging. When the grounds wall is intact, water flows along the ribs through the filter, passing through much of the coffee grounds, extracting substances from them.

However, if the coffee grounds wall is broken during brewing, water in the filter will flow along the ribs where the wall was broken directly into the lower pot. This water hasn't passed through the coffee grounds, resulting in under-extraction, which manifests as sharp acidity, astringency, watery texture, and flatness in flavor.

Generally, unstable water flow, excessive flow rate, or too wide a pouring circle can easily break the grounds wall. If you're experiencing this issue, try maintaining stable water temperature, keeping the water stream vertical, and avoiding pouring on the outermost circle. This should significantly improve the situation.

Case 3: Brewing Time

A friend once reported to FrontStreet Coffee: "Why is my Mandheling sour? Is there a problem with the roasting?" FrontStreet Coffee first compared it with our sample and had him send photos of the coffee beans, finding nothing unusual. Through conversation, we learned that this friend was using a siphon pot to brew coffee.

When it comes to siphon brewing, there are three challenging parameters to master. The first is water temperature—the temperature of the rising water in a siphon is approximately 88-90°C, but if heating continues, the water temperature in the upper chamber will still rise.

The second is stirring—improper stirring can easily lead to bitterness or off-flavors and sourness from uneven extraction. The third is time. Many siphon brewers fear burning the coffee and typically choose a very conservative time limit of about 50-70 seconds. If the first two issues aren't handled properly, limiting the time can easily result in under-extraction and sourness.

The same applies to pour-over coffee. Try grinding very coarsely and brewing with water below 80°C, and you'll taste the under-extraction acidity, weakness, and lack of flavor in medium-dark roast coffee. This is why FrontStreet Coffee consistently recommends a brewing time of about 2 minutes for a standard 15-gram dose of coffee.

Important Notice :

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FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473