How to Control Acidity in Pour-Over Geisha Coffee: Best Brewing Methods to Enhance Sweetness

Having a preference for sweetness over bitterness is a natural tendency for many of us. Many people who are just beginning to explore specialty coffee often fail to perceive the "sweetness" described by baristas, largely because their sensitivity to bitterness is higher than to sweetness.

The flavor potential of coffee beans is determined during their green bean stage, while the roasting process determines the flavor profile of the beans. Consumers have little opportunity to interact with or influence these two stages. However, consumers can make choices: those who dislike acidity can opt for dark roasts, those who dislike bitterness can choose light roasts, those who prefer clean, acidic profiles can select washed processed beans, and those who enjoy complex, sweet flavors can choose natural processed beans.

Although we cannot control the upstream aspects of coffee, we can still utilize certain techniques during the brewing stage to adjust the flavor expression of coffee. Here, FrontStreet Coffee would like to reiterate an old principle: brewing cannot change the fundamental flavor profile of coffee beans; it can only finitely control the acidity and sweetness of the coffee.

Brewing Techniques for Sweetness

When it comes to brewing coffee, brewing techniques are undoubtedly the most attention-grabbing aspect. Introductions to brewing methods such as "this technique can bring out the sweetness of coffee" or "that technique can highlight the bright acidity of coffee" typically attract many viewers. After all, when it comes to flavor, taste experiences like acidity and sweetness are more directly expressed. Those who prefer sweeter coffee will learn techniques that emphasize sweetness, while those who enjoy more acidity will study methods that highlight acidic notes.

These techniques generally involve several elements: the number of brewing stages, water distribution for each stage, water flow rate, and the size and speed of circular pouring motions.

What these techniques actually change is the extraction time and stage-by-stage extraction efficiency of the coffee. During the extraction process, acidic compounds are released most easily, followed by sweet compounds, and finally bitter compounds. Therefore, acidic compounds dissolve more prominently in the early stages, sweet compounds reach their peak release in the middle stages, while bitter compounds become significantly apparent only in the later stages.

Let's take the classic example of single-pour versus three-pour methods. The single-pour method has a shorter extraction time than the three-pour method. During pouring, the efficiency of wash extraction is higher than the steeping extraction that occurs when pouring stops. In single-pour brewing, wash extraction is concentrated in the first half, while in three-pour brewing, wash extraction is distributed throughout the early, middle, and late stages. Consequently, single-pour brewing yields a flavor profile that leans more acidic, while three-pour brewing produces a relatively sweeter taste.

The same principle applies to water distribution among stages. For example, with three-pour brewing, allocating more water in the early stage will result in a more acidic coffee; allocating more water in the later stage will produce a sweeter coffee.

High Temperature for Sweetness, Low Temperature for Acidity

Adjusting water temperature is the simplest method to balance acidity and sweetness. Higher water temperature increases the extraction efficiency of coffee, resulting in a more pronounced sweetness. Conversely, lower water temperature reduces extraction efficiency, leading to a coffee profile that expresses more acidity.

The typical brewing temperature range for pour-over coffee is 86-96°C. For light roast coffee, 90-93°C is a relatively safe temperature range (less likely to produce burnt bitterness, yet sufficient to extract coffee flavor).

Don't Change Grind Size Casually

When the coffee grind size is already appropriate, FrontStreet Coffee does not recommend adjusting the grind size to achieve a sweeter or more acidic flavor. For beginners, grind size is a highly uncertain factor, often resulting in either flavorless coffee when ground too coarsely or unpleasant flavors when ground too finely. Therefore, if your current grind setting produces good coffee, there's no need to change it simply to pursue more sweetness or acidity. There are other more controllable parameters that can be adjusted instead.

Add More Water

The purpose of continuing to pour water is to increase the coffee-to-water ratio. This can first extend the extraction time, allowing for more thorough extraction of sweet compounds from the middle and later stages, thereby relatively reducing acidity and enhancing sweetness. Additionally, adding more water continuously increases the overall extraction rate, which relatively diminishes acidity while making sweetness more pronounced. However, this approach has one side effect: it reduces concentration.

Considering that increased water will first reduce concentration, FrontStreet Coffee recommends adopting conservative adjustments. For example, if you're using a 1:15 or lower coffee-to-water ratio, you can first extend it to 1:16 to see if the coffee improves. If the concentration remains acceptable and sweetness has increased, then no further improvements are necessary.

Brewing Sweetness from "Bitter Coffee"

Friends with brewing experience should know that those who dislike acidity often prefer dark roast coffee because these typically express roasted aromas such as nuts, dark chocolate, almonds, and seeds, with minimal acidity and prominent sweet notes like cocoa, caramel, and maple syrup.

However, because medium-dark roast beans undergo longer and higher heat exposure, their texture is very loose, and they experience more caramelization reactions than light roast coffee. Therefore, under identical parameters, bitterness in the later extraction stages is more easily released. Once parameters are not properly controlled, the roasted bitterness can easily dominate, masking the sweetness and potentially resulting in unbearably bitter coffee with a lingering astringent sensation in the throat. Consequently, brewing dark roast coffee to achieve sweetness has become one of the main practices for many newcomers to improve their brewing skills.

To avoid extracting excessive undesirable flavors while preserving the rich sweetness, FrontStreet Coffee employs a slow-flow Kono dripper with coarse grinding and low water temperature, combined with gentle small circular pouring motions and a 1:15 coffee-to-water ratio to rinse the coffee grounds, with extraction time controlled around 2 minutes.

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