When to Stop Pouring Pour-Over Coffee? What is Flow Termination? Is it Related to Brewing Techniques?

The Art of Pour-Over Coffee: Understanding "Cutting Off" Technique

There are countless methods for pour-over coffee brewing. In many pour-over scenarios, many people prefer to remove the filter cone when the timer reaches the designated time, calling this action "cutting off." So, under what circumstances would we adopt this technique?

As shown in the image below, typically, substances extracted from coffee by water follow the sequence of sour, sweet, then bitter. The purpose of pour-over, simply put, is to extract as much of the good flavors as possible while minimizing the undesirable ones.

When it comes to "bitter" compounds, most people tend to dislike them. So, wouldn't cutting off the bitter compounds from the later stages be beneficial? This might be why some friends prefer cutting off – to reduce bitterness and improve balance. This is precisely why FrontStreet Coffee recommends that the brewing time for a single coffee bean should not be too long, as exceeding the brewing time excessively may result in over-extraction.

Of course, this time recommendation allows for some flexibility. It doesn't mean that if the suggested pour-over time ends at 2:00, over-extraction will definitely occur at 2:10 in actual brewing. Sometimes, a slightly longer time might be necessary for the coffee to reach its optimal flavor profile, as with drip bag coffee. From the image above, we can see that compounds in coffee don't dissolve at the same rate. Due to molecular weight, small molecule "acidity" is extracted first, followed by medium molecule "sweetness," and finally large molecule "bitterness" and "astringency." Only when "excess" goes beyond the "limit" does bitterness become increasingly prominent until it becomes unacceptable.

Conversely, when extraction time is insufficient, it directly leads to a lack of body. What is coffee body? Body refers to the tactile sensation in the mouth, perceiving the weight or fullness of the beverage. It's the feeling of richness and coating in the mouth, rather than a "watery" sensation. During coffee extraction, substances in the coffee grounds can be either soluble or insoluble. Soluble compounds manifest in taste, while insoluble ones manifest in mouthfeel – the former affects the cleanliness of the coffee, while the latter influences its body.

Additionally, another characteristic of body is its relatively "silky" mouthfeel. When body is reduced, the taste can easily become "dry" and "astringent." The sensation that contributes to body typically manifests during the middle to late stages of extraction. "Bitter" compounds, when tasted alone, might seem bitter. However, throughout the entire extraction process, they play a role in enhancing body, aftertaste, and finish. When body is reduced, the mouthfeel becomes lighter, and the finish diminishes. Losing the flavor compounds from the middle to late stages can easily lead to under-extraction. The original intention of cutting off is to manually stop the extraction when the time is appropriate. On the other hand, what many people overlook is that cutting off also changes the water-to-coffee ratio. The original 1:15 coffee-to-water ratio will differ after cutting off. You don't know how much water you've cut off, and therefore, you don't know the actual coffee-to-water ratio of the cup you've made.

Under certain influences, pour-over brewers might solely pursue time accuracy, removing the filter cone while there's still a significant amount of coffee liquid. In such cases, the brewing ratio will inevitably differ significantly from the originally intended ratio. This might result in an inability to replicate the same delicious cup of coffee despite its good taste, due to inaccurate data, rendering it without reference value. Cutting off is not for stable production but rather a necessary technique to correct brewing mistakes. Common situations where cutting off is needed include clogged filter paper, coffee ground too fine, or inability to control water flow timing. During the brewing process, if you can observe from the flow rate and coffee bed condition that the recommended time has arrived, then adopt the cutting off method as a temporary measure and adjust your pouring speed for the next time. If you're simply cutting off because the extraction time is reached, and there's little water left on the filter cone, the impact on flavor might be less than imagined. However, if there's still a lot of water remaining on the filter cone, the impact on flavor could be greater than expected.

Similarly, since we're pursuing the right time and the right ratio, then from the very beginning, pay attention to the grind size of the coffee, ensure stable water flow, roughly know that pouring completes by 1:45, and by 2:00 or a few seconds more, the last drop of coffee liquid falls into the lower pot. With such a simple method, there's no need to consider the fact that the water-to-coffee ratio has changed, because this means pouring as much water as intended, and after the coffee grounds absorb about 20 grams, all becomes coffee in the cup.

The above viewpoint focuses on adjusting the brewing rhythm while pursuing the right time and the right water-to-coffee ratio, with the ideal being that when the time is up, all the water has filtered through. Some believe that brewing actions take priority – as long as the time is right, or if they have different views on the flavors in the final stage, they adjust according to the actual situation and cut off as needed. In this case, whether to cut off, how much to cut off, and what ratio to use depends on personal preference.

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FrontStreet Coffee

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