How to Extract Sweetness in Pour-Over Coffee? Understanding the Flavors from Early, Middle, and Late Extraction Stages

To brew a flavorful cup of coffee, the goal is to capture more of the coffee's sweet and sour notes while reducing the extraction of bitter compounds. FrontStreet Coffee attempted to "break down" each extraction stage of pour-over coffee for tasting, to identify which stage releases the most sweetness.

The Purpose of Multi-Stage Extraction

During the multi-stage extraction process of pour-over coffee, different flavor components extract at different rates. The order of flavor release when exposed to hot water is: sour, sweet, then bitter.

With segmented water injection extraction, besides the blooming stage, maintaining the same coffee-to-water ratio but dividing it into more segments reduces the water volume per segment. This increases the number of times the coffee grounds are flushed and stirred, resulting in higher extraction rates. Additionally, increasing the number of segments extends the total extraction time, allowing more coffee compounds to be released in each stage, creating richer flavor layers.

Three-Stage Water Injection: Coffee Flavors from Each Segment

FrontStreet Coffee selected a medium-roasted Papua Paradise Bird coffee bean, which has distinct cane sugar flavors and high sweetness, making it easier to identify the corresponding extraction stages. Parameters: Coffee amount: 15g, Grind size: EK43 setting 10.5 (75% retention on #20 sieve), Water temperature: 89°C, Total water volume: 225ml, Water injection method: Three-stage pour-over, with pre-wetted filter paper and dripper, using a pre-warmed serving carafe for each stage.

First Stage: 30ml circular pour for 30-second bloom. Early coffee flavors: Hazelnut, dark cocoa, caramel, with high concentration, noticeable acidity and salinity.

Second Stage: After 30 seconds, pour 95ml of water from inside to outside in circular motion while raising the coffee bed. Mid-stage coffee flavors: Sugarcane, nuts, citrus, fruity notes, tea-like sensation, with slightly high concentration. As temperature decreases, sweet and sour notes become prominent.

Third Stage: After the coffee liquid level finishes dripping, transfer to the final serving carafe and pour 100ml in small circles. Total extraction time: 2'16". Late-stage coffee flavors: Almond, citrus, light white tea sweetness, with relatively light flavor but clean mouthfeel.

The purpose of the first stage is to wet the coffee grounds and release gases from the coffee. With minimal water volume, the overall concentration is high, with high concentrations of both acidic and bitter compounds, creating a more complex mouthfeel. The second stage increases water volume, resulting in slightly lower concentration than the first stage, with accelerated release of sweet and sour flavor compounds, creating a relatively lighter mouthfeel. The final stage uses the most water volume, aiming to extract the rich body components of coffee, which in this particular coffee manifests as almond aftertaste and tea sweetness, with the lowest overall concentration and milder flavors.

Flavor Comparison with Four-Stage Extraction

To more clearly identify the extraction stage of sweetness, FrontStreet Coffee used the same coffee-to-water ratio and grind parameters but employed four-stage water injection, divided into four pours of 30ml, 65ml, 65ml, and 65ml, with a total time of 2'31''.

After comparison, the early-stage flavors were the same as in three-stage extraction, dominated by high concentrations of acidity and salinity. The second stage wasn't as concentrated, with clear sweetness of roasted hazelnuts and sugarcane, and low acidity. The third stage was primarily nut and sugarcane sweetness with some tea-like aftertaste, but overall weaker flavor. The final stage had the lowest concentration, with only slight tea flavors, almond bitterness, and woody notes.

When FrontStreet Coffee mixed and tasted the four carafes of coffee liquid, the overall mouthfeel was balanced and moderate, with the sweetness of roasted hazelnuts and sugarcane, the gentle acidity of citrus, but the aftertaste carried a slight over-extraction bitterness.

Since more segmentation means longer operation time, it increases the risk of over-extraction. Large molecular compounds in the later stages of coffee are more easily released, potentially masking the sweetness. This shows that more water injection segments are not necessarily better.

Which Stage Contains Sweetness?

Returning to our comparison, whether using three-stage or four-stage water injection, sweetness was higher in the middle and later extraction stages, with the final stage being most obvious.

Sweetness mainly originates from the 6-9% sugar compounds in coffee. Therefore, to fully extract the sweetness from coffee, it's necessary to increase the extraction rate while controlling to avoid over-extraction. This can be achieved by raising water temperature, using a finer grind, or extending extraction time.

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