How does coffee brewing change a bean's flavor?

Brewing accounts for roughly ten percent of a cup's final flavor, but it is the part a drinker can control. Water temperature, pouring strategy, and grind size cannot turn a light roast into dark chocolate, yet they can shift a coffee from sharp acidity toward sweeter, rounder results without changing its basic character.

Front Street Kenya Asalia and Ethiopia COE#22 show how it works. Changing the three-stage pouring ratio, the blooming water volume, and the pouring technique moves flavor from bright acidity to prominent sweetness, or from intense fermentation to a light berry tone. Upstream factors such as variety and roasting set the ceiling.

In the composition of coffee flavor, variety cultivation, roasting, and brewing each carry different weights. Among them, brewing, though accounting for only ten percent, is the only part that enthusiasts can actively control. Starting from this industry consensus, this article systematically explains how to adjust water temperature, pouring strategy, and grinding parameters to bring out a bean's performance more in line with personal preference without changing the flavor direction of the coffee beans themselves. Using Front Street Kenya Asalia and Front Street Ethiopia COE#22 as examples, the article specifically demonstrates how to shift flavor from bright acidity to prominent sweetness, and from intense fermentation to a light berry tone, by changing the three-stage pouring ratio, blooming water volume, and pouring technique, helping readers understand the extraction logic behind brewing adjustments.

There is a saying in coffee circles: among the factors that determine whether a cup of coffee tastes good, variety and cultivation processing account for about forty percent, roasting quality for thirty percent, brewing equipment and water quality for twenty percent, and the remaining ten percent goes to the brewer's understanding and skill level.

What this is trying to convey is that from seed selection, cultivation, and processing to roasting and brewing, the closer a step is to the upstream, the more significant its influence on the final flavor, while at the brewing end, the room to influence flavor is relatively limited.

However, this does not mean that brewing understanding and technique, which account for only ten percent, are negligible. From the perspective of seed selection and cultivation, they directly set the flavor floor of a cup of coffee—excellent varieties, growing environments, and processing methods can raise the flavor floor very high. Roasting determines the flavor direction, such as light roasts leaning toward citrus and floral notes, medium roasts with prominent sweetness and good balance, and dark roasts with full body and notes of nuts and dark chocolate. These directional flavor frameworks cannot be changed through brewing technique.

So what can brewing do? It cannot defy fate and turn a light-roasted bean with citrus and floral notes into something with the heaviness of nuts and dark chocolate, nor can it make a Catimor taste like a Geisha. But with sufficient brewing understanding and technique, it can fully release the potential endowed by the preceding ninety percent of factors and present a bean at its best. At the same time, by adjusting brewing parameters and techniques, one can find the version within the delicious flavor range that best suits one's own taste.

Take Front Street Kenya Asalia for example. Front Street's standard brewing method is 15 grams of coffee, a coffee-to-water ratio of 1:15, a grind size with 80% passing through a No. 20 sieve, a water temperature of 90°C, and a three-stage pour (30g/95g/100g), ultimately presenting bright acidity with notes of dark plum, lemon, and cherry tomato.

Some customers want this bean to have more prominent sweetness. The approach of Front Street baristas is to raise the water temperature to 91°C and change the three-stage water distribution to 30g/120g/75g. Raising the water temperature can increase the extraction rate, bringing out more sweetness and bitterness in the mid-to-late stages of extraction; increasing the middle-stage pour can concentrate more sweet components. After this adjustment, the cherry tomato and honey sweetness of Front Street Kenya Asalia becomes noticeably more prominent.

Here is another example: Front Street Ethiopia COE#22, which Front Street won at auction last year. This bean is known for its intense tropical fruit flavor and prominent sweetness. Front Street's standard brewing plan is 15 grams of coffee, a coffee-to-water ratio of 1:15, a grind size with 80% passing through a No. 20 sieve (note: the same 80% passing rate corresponds to different grind settings for different coffee beans), a water temperature of 91°C, and a three-stage pour (30g/95g/100g).

Some customers are not very accepting of fermented notes and want a crisper taste. Front Street baristas start with the brewing water distribution: during the blooming stage, pour 40g of water directly. A water volume exceeding twice the coffee dose achieves saturated wetting, and the excess water falls into the server before fully extracting coffee compounds, so the overall cup leans toward acidity. In the second stage, pour 185g of water in a steady circular motion with a small stream. Coffee treated this way is lighter overall, with more prominent berry notes and diminished fermented notes.

Front Street shares these brewing adjustment plans not in the hope that everyone will simply memorize the numbers, but rather that they understand the principles behind them. Just as in a good cup of coffee, brewing understanding and technical ability account for only ten percent, yet it is precisely this ten percent that brewing enthusiasts can adjust on their own. Whether a cup of coffee determined by the "90%" of factors ultimately performs at 92% or 98% depends on the remaining ten percent in your hands.

The above content is compiled by CoffeeHunters, a coffee news website.