Pour-over Coffee Beginner's Guide: Three-Stage Segmented Extraction Principle & Coffee Flavor Characteristics

Introduction

The joy of pour-over coffee lies in using different brewing techniques to give coffee a unique character. Among these techniques, three-stage extraction is one of the most commonly used methods. When brewing coffee, have you ever wondered about the significance of three-stage water pouring?

What is Three-Stage Extraction?

Simply put, three-stage extraction divides the entire water pouring process into three parts, including the first stage of blooming. The advantage of three-stage pouring is that it can more fully extract the flavor compounds from coffee, enhancing the coffee's layered complexity. Why is this so?

Temperature Changes in Segmented Extraction

Let's first consider a question. If you're using 90°C water for brewing, is the water still 90°C when it hits the coffee grounds? FrontStreet Coffee conducted a test on segmented brewing water temperature. When using 90°C water for segmented brewing, the first stage bloom water temperature is approximately 86°C, the second stage water temperature is about 85.3°C, and the third stage water temperature is around 84.5°C.

After water at different stages and temperatures is poured onto the grounds, the temperature changes of the grounds are as follows: After the first water pour, the room-temperature grounds rapidly heat up (to about 86.2°C). After 30 seconds of blooming, the grounds cool down significantly (to about 78°C). After the second water pour, they heat up again substantially (to about 84.5°C), then cool down slightly (to about 84°C). After the third water pour, they heat up slightly again (to about 84.3°C).

From this, we can observe that although the brewing water temperature continuously decreases with each stage, the grounds experience stepwise heating. This means the grounds heat up when water is poured, cool down when pouring stops, and heat up again when water is poured again. Different soluble flavor compounds in coffee are extracted at different water temperatures.

What Flavor Compounds are Extracted at Different Temperature Stages?

The purpose of the first stage blooming, besides allowing the coffee grounds to be evenly soaked in hot water and release most of the carbon dioxide, is also the most crucial step for extracting coffee's acidity. For example, acidic aromatic substances like citrus and berry notes are released during the first stage.

The second stage is primarily responsible for extracting coffee's sweetness. Fewer flavor compounds are extracted during this stage, and the remaining acidic substances from the first stage complete their extraction. For example, sweet substances like sucrose sweetness, fruit sweetness and tartness, and tea-like sweetness are released during the second stage.

The third stage mainly extracts the rich, body-enhancing compounds from coffee. Since the water temperature by the third stage is no longer as high as in the first stage, it effectively reduces the appearance of some unpleasant flavors, such as woody notes. The third stage extraction primarily enhances the overall richness of the coffee, with roasted flavor compounds like nuts and cocoa being released during this stage.

How to Segment the Three-Stage Pouring Technique?

Using FrontStreet Coffee's daily production standard of 15g coffee grounds with a brewing ratio of 1:15 as an example: First, use 30g of water for a 30-second bloom, pouring at an average rate of 4g/s in a circular pattern from center to outer edge and back to center at 4 seconds per circle. Pour to 125g and stop. Wait until the grounds have dropped to half their height, then begin pouring in the same manner to 225g and stop. After all the coffee liquid from the filter cup has flowed into the lower pot, remove the filter cup and finish the extraction.

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