How to Use a Coffee Pot Temperature Reading for Pour-Over

The number on the kettle is not the temperature in the coffee bed. Measured tests found that pouring with water at 90°C puts the actual slurry at roughly 84.5-86°C, so the common 86-93°C guideline refers to the water, not the grounds.

Lighter roasts tolerate the higher end of that range, darker roasts the lower end. Because extraction rises with heat, and near-boiling water pulls out bitterness, a practical lever is pour height: a taller, thinner stream loses more heat before it lands on the bed.

What temperature range should be used for pour-over coffee? The mainstream recommendation is 86°C to 93°C—use higher temperatures for light roasts and lower temperatures for dark roasts. But did you know that the initial water temperature in the pour-over kettle is not the same as the actual extraction temperature when the water contacts the coffee grounds? Through a series of temperature measurement experiments, Front Street Coffee found that when brewing with an initial temperature of 90°C, the actual extraction temperature in the coffee bed is only between 84.5-86°C. This article will use actual test data to analyze the relationship between water temperature and extraction, and share a practical technique for changing extraction temperature by adjusting the pouring height, helping you control the brewing flavor more precisely.

For more specialty coffee knowledge, please follow: Front Street Coffee (Frontsteet Coffee)

What temperature should be set for pour-over coffee? The currently common recommended range is 86°C to 93°C. Lighter-roasted beans are suitable for higher water temperatures, while darker-roasted beans are better with lower water temperatures.

Once, while sharing pour-over coffee with a customer in the shop, the customer quickly identified the name of that bean, so we took the opportunity to chat a bit. During the conversation, we learned that this customer also often brews coffee at home. He had previously bought this same bean from Front Street to brew at home, so when we shared the same coffee, he tasted exactly the same flavor and blurted out the answer.

When talking about brewing experience, the customer said: "I've tried water temperatures from 90 to 94°C, and only 93°C brews the best-tasting cup—just like this one." However, the pot of coffee used for sharing was actually brewed at 90°C!

When Front Street sets brewing parameters, it always bases them on the characteristics of the coffee beans themselves, the roast level, and the flavor direction. The higher the water temperature, the stronger the extraction efficiency, the more fully the substances are released, and the higher the concentration becomes. If water close to boiling is used for brewing, it easily brings out unpleasant bitterness. Therefore, for medium-dark roasted beans, Front Street uses a different approach from that for light-roasted beans. Medium-dark roasted beans have undergone a more complete caramelization reaction and more easily release bitter large-molecule substances. In order to suppress the emergence of off-flavors, Front Street appropriately lowers the water temperature: light-roasted beans are recommended at 91–93°C, while medium-dark roasted beans are recommended at 87–88°C.

Of course, the same bean paired with different parameters (reasonable adjustments and combinations of grind size, water temperature, etc.) can indeed brew similar flavors—after all, there are countless delicious brewing recipes. But if only the water temperature differs, can this still happen?

Brewing water temperature in the parameters vs. the actual extraction water temperature

What we usually call brewing water temperature actually refers to the initial temperature in the pour-over kettle. That is, if you want to brew coffee with 91°C water, you only need to control the initial water temperature in the kettle at 91°C, put on the lid, and start brewing. But the water temperature when it actually contacts the coffee grounds definitely cannot reach 91°C. For this reason, Front Street conducted a simple temperature measurement experiment.

Insert a wire probe thermometer into the coffee bed and record the temperature changes within the grounds during brewing. When the coffee grounds are dry, they are about 32°C. When we brew with 90°C water, at the very beginning of blooming the bed temperature rises to 85°C; after the first pour ends and the blooming stage begins, the internal temperature drops to 78°C; then the second pour begins, the temperature rises back to 85°C, and afterward the extraction temperature stabilizes between 84.5-86°C, reaching a maximum of 86.2°C.

From this it can be seen that when brewing with 90°C water, the water temperature actually involved in extraction is between 84.5-86°C.

Then the same brewing was done again with water at an initial temperature of 93°C: at the beginning of blooming, the bed temperature reached 86.3°C; after the first pour ended and blooming began, the internal temperature dropped to 83°C; after the second pour began, the temperature rose to 87°C, and afterward the extraction temperature stabilized between 85-88°C, with a maximum of 88°C.

Comparing the two sets of data, it can be found that the initial water temperatures differ by 3°C, but the difference in actual extraction temperature is less than 3°C. Although the gap has been narrowed, the difference can still be clearly distinguished by taste.

It seems that when other parameters remain unchanged, different water temperatures will only produce different flavors. However, let Front Street sort out the earlier information again: when brewing with 90°C, the actual extraction temperature is 84.5-86°C, so how are those 4-5.5°C lost? The reasons include heat absorption by the coffee grounds, heat absorption by the dripper, and heat loss from water exposed to the air. Therefore, it is enough to accelerate heat loss during the time from when the water leaves the kettle to when it contacts the coffee grounds.

Seeing this, you may think some "advanced technique" is needed to achieve it, but actually you only need to raise the pouring height. Front Street usually pours at a height of about 3-4 cm during pour-over; this time we raised it to 7-8 cm and used 93°C water for the experiment;

During the blooming pour, the bed temperature rose to 87°C; after the first pour ended and blooming began, the internal temperature dropped to 83°C; after the second pour began, the temperature rose to 86.2°C, and afterward the extraction temperature stabilized between 84-86.7°C, with a maximum temperature of 87°C.

In both the data and the flavor tasting, this brew was closer to the effect of brewing with an initial temperature of 90°C. I believe that by this point, everyone roughly understands the key to brewing water temperature, and also understands why some people like to pour close to the liquid surface while others like to raise the stream and pour in a straight line.

When brewing coffee in daily life, we will not go to great lengths to measure the temperature of the coffee bed, so we can only take an easier parameter to control—the water temperature in the pour-over kettle. But at least you now clearly understand the relationship between the water temperature in the parameters and the actual extraction temperature, so you can be more skillful in actual brewing!!!

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