Why Does My Pour-Over Coffee Taste Too Sour? How to Make Coffee Taste Sweeter? What Water Temperature for Light Roast Coffee?

Understanding Acidity in Coffee: Achieving the Perfect Balance

"Acidity" can be described as the prevailing flavor profile in today's coffee culture. Since the rise of specialty coffee, coffee roasting has shifted from dark to light, transforming flavors from consistently bitter to a vibrant spectrum of acidity. This has attracted many friends who couldn't tolerate the traditional "coffee taste" (bitterness) to begin exploring coffee and appreciating the fruity and floral acidity of light-roasted coffee.

However, many friends have discovered that the coffee they brew at home never achieves the same acidity as what they taste in coffee shops. Despite using the same coffee beans, the coffee brewed in shops is pleasantly sweet and sour, while their homemade coffee tastes uncomfortably acidic—sharp and intense, like biting into a raw lemon, both sour and astringent.

Obviously, such situations typically indicate that the coffee hasn't been fully extracted—what we commonly call under-extraction. FrontStreet Coffee often mentions that flavor compounds in coffee dissolve at different rates due to variations in molecular size and polarity. If we divide the coffee extraction process into three stages—early, middle, and late—the first stage primarily extracts acids, followed by sweetness and bitterness.

Flavors exist in mutual balance. The reason brewed coffee tastes sharply acidic is that sweetness and bitterness haven't been extracted. Think of lemons—their acidity is difficult to accept precisely because their sugar content is very low, creating a severe imbalance between acid and sweet. If we want to brew a coffee with pleasant acidity and sweetness, we need to extract appropriate amounts of flavors beyond just acidity. This is similar to various lemon desserts, where sugar is added to balance the sharp acidity of lemons. Achieving this balance isn't difficult—it only requires the proper use of three essential parameters: grind size, time, and water temperature.

1. Adjusting the Grind Finer

The fineness of the grind determines the surface area of coffee exposed to water. When the grind is finer, the coffee's surface area in contact with water increases, resulting in a faster dissolution rate of flavor compounds. The reverse is also true. If we want to achieve full extraction from coffee, we naturally need a sufficiently fine grind! While this is correct, how fine specifically should it be?

Similar to other parameters, the specific fineness of coffee grind primarily depends on whether it can complement other parameters such as water temperature, time, and extraction method. For example, FrontStreet Coffee uses a fine sugar grind for light-roasted coffee, with a 75-80% pass-through rate on a #20 sieve, because this grind size pairs well with 92°C water temperature and 2-minute extraction time to produce a good cup of coffee. If you can keep other brewing variables constant, you can find the grind size that suits you through gradual experimentation, as there's no fixed standard for grind fineness, and not everyone has a #20 sieve at home. If the coffee tastes sharply acidic, adjust the grind finer; if the coffee tastes bitter, adjust the grind coarser. This is the simplest and most practical method.

Initially, we can adjust as finely as possible because light-roasted coffee has higher density, making its flavor compounds more difficult to extract. As long as the coffee grounds don't become muddy after brewing, there generally won't be significant extraction problems.

2. Extending Extraction Time

As FrontStreet Coffee mentioned earlier, the coffee tastes sharply acidic because we ended the extraction before sweetness and bitterness could be extracted in large quantities. Therefore, extending the extraction time can effectively help us brew a sweeter coffee, as extraction time refers to the duration that water contacts the coffee grounds. When extraction time is extended, substances like sweetness and bitterness can naturally be extracted in sufficient quantities.

There are many ways to extend extraction time—for example, adjusting the grind finer, as mentioned earlier, is one method. Additionally, you can extend extraction time by changing the dripper or altering brewing techniques. Typically, drippers without ribs or with short ribs and smaller water outlet holes will have slower flow rates because gases released from coffee beans during brewing have fewer channels to escape, forming resistance that impedes hot water penetration. Therefore, drippers without ribs or with short ribs usually have slower flow rates. By switching to these types of drippers, we can effectively extend the coffee's extraction time.

Changing brewing methods is quite simple—we just need to divide the hot water into multiple pours to extend extraction time. Due to water pressure and waiting time, pouring small amounts multiple times always results in longer extraction time than pouring a large amount all at once. This is also why the three-pour method takes longer than the single-pour method. Generally, controlling brewing time between 2 to 2.5 minutes is most reliable. Of course, FrontStreet Coffee isn't saying that good coffee cannot be brewed outside this range—it mainly depends on how other parameters are paired with time. However, controlling brewing time within this range makes it less likely to produce over-extracted coffee while avoiding under-extraction, offering relatively high fault tolerance.

3. Increasing Brewing Water Temperature

Water temperature determines the rate of substance dissolution—the higher the water temperature, the faster substances dissolve, and vice versa. Through conversations, FrontStreet Coffee has found that many friends fail to brew light-roasted coffee well mainly because they don't use the correct water temperature. For example, some friends use hot water from office water dispensers for brewing. Except for some high-end models, the hot water temperature from most dispensers typically ranges between 85°C to 88°C. For dark-roasted coffee, this water temperature is acceptable, but for light-roasted coffee, it's somewhat low. Unless you significantly extend brewing time and adjust the grind finer, it will be difficult for the coffee to achieve full extraction.

FrontStreet Coffee generally recommends brewing light-roasted coffee at water temperatures between 90°C to 94°C, depending on how other parameters complement each other. For instance, FrontStreet Coffee typically uses around 92°C. When the grind is coarser and extraction time is shorter, use higher water temperatures, and vice versa. After discussing all this, you might be feeling a bit overwhelmed, so next, FrontStreet Coffee will share its specific parameters and methods through practical demonstration, which should provide valuable reference for all friends~

Brewing Demonstration

This time, FrontStreet Coffee will use FrontStreet Coffee's Yirgacheffe·Gedeb from the bean list because it not only has excellent flavor expression but also possesses higher density due to being grown at high altitudes and light-roasted, making it perfect for this demonstration. The extraction parameters are as follows:

Coffee dose: 15g
Coffee-to-water ratio: 1:15
Grind level: 10 on the Ek43, 75% pass-through rate on #20 sieve, fine sugar grind
Brewing water temperature: 92°C
Brewing method: Three-pour method
Dripper used: V60

First, we use twice the amount of water in grams for blooming, i.e., 30ml of hot water for 30 seconds.

After blooming, use a moderate water flow (pouring rate approximately 4-5ml/s) to pour the second segment of 120ml of hot water from the center outward in a circular motion. Because this bean has higher density, to prevent hot water from submerging the coffee bed and creating channeling, we need to use a slightly smaller water flow, which also effectively extends extraction time. If you cannot control water flow well, don't worry—we can divide the post-bloom water flow into three equal segments, which can achieve the same purpose. The pouring takes about 30 seconds (for 120ml of water). After pouring is complete, we just need to wait for the liquid in the dripper to permeate until we can see the coffee grounds at the bottom, then we can begin pouring the third segment of hot water.

Similarly, the third segment continues to use a moderate water flow, with this segment injecting 75ml of hot water in small circles from the center of the coffee bed. After injection is complete, we just need to wait for the coffee to finish dripping, then we can remove the dripper and end the extraction~

Total time: 2 minutes and 17 seconds. Compared to conventional brewing, this time is somewhat longer, but that's okay—light-roasted coffee beans are known for their extraction tolerance!

Through tasting, we first notice the delicate fragrance of lemon and jasmine—gentle and elegant. This is followed by the vibrant acidity of red berries and honey-like sweetness, creating a pleasant sweet and sour balance. After swallowing, we can clearly perceive the aroma of oolong tea—long-lasting and distinct~ In summary, when brewing light-roasted coffee beans, we can be bolder, without worrying that certain extreme parameters will produce bitterness. Most light-roasted coffees are truly extraction-tolerant. Even with longer times and finer grinds, it's difficult to produce unpleasant negative flavors~

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