What's the Ideal Water Temperature for Pour-Over Coffee? How Brewing Temperature Affects Coffee Flavor and Taste

If you ask whether water temperature is important for extraction, FrontStreet Coffee believes it's important but not critically so. As a tool for adjusting extraction speed, higher temperatures more easily extract soluble substances. However, because too high a temperature causes coffee to quickly release bitter flavors, it's necessary to choose a conservative range. Generally, most coffee beans on the market are suitable for brewing with water at 86-93°C.

Based on FrontStreet Coffee's pour-over experience, high-altitude, light-to-medium roast coffee beans can use 91-93°C, such as Ethiopia's Guji, Panama's Geisha, and Kenya's AA. Darker roasted beans are recommended to use water temperatures of 86-88°C, like Golden Mandheling, Blue Mountain No. 1, and Brazil Queen Estate, among others. Coffee with both acidity and bitterness can be brewed directly at 90°C, making it neither over-extracted nor under-extracted.

But precisely because water temperature is an easy parameter to control and its impact on flavor is better understood, many people fall into a misconception: that a 1°C difference is significant. For example, one customer purchased a bag of Sidra coffee beans and brewed them at home according to FrontStreet Coffee's recommendation (91°C), finding the aroma weak and bitterness prominent. They subconsciously attributed this to too high a water temperature, but when they lowered it by 2°C, the taste remained the same. After some discussion, they discovered the real culprit was grinding too fine.

FrontStreet Coffee has conducted experiments showing that coffee brewed at 91°C and 93°C has very similar flavor profiles. Although there are subtle differences in mouthfeel, without direct comparison, it's difficult to discern significant distinctions. Therefore, as long as you don't use temperatures that greatly deviate from FrontStreet Coffee's aforementioned recommendations, when coffee shows obvious abnormalities, we can determine it's not the water temperature's fault—the problem likely lies with other parameters.

The Rise of Variable Temperature Brewing

In recent years, we've frequently seen coffee competition competitors using variable temperature brewing methods—using higher water temperatures in the first half and lower temperatures in the second half. What's the secret behind this temperature-changing brewing approach?

FrontStreet Coffee recalls that variable temperature brewing isn't a recent concept. Earlier on, Mr. Wu Zelin invented the "Three-Temperature" brewing method, which belongs to one of the variable temperature brewing methods. This is how he did it:

Using 16 grams of coffee grounds as a standard, he divided the pour into four sections totaling 240 milliliters of water, with each section being 40, 80, 80, and 40 milliliters respectively. The first two sections used water at 94°C, the third section used 90°C, and the final section used 80°C. This creates a stepped variable temperature extraction.

In the 2021 WBrC finals, champion Matt Winton also used a variable temperature extraction method. Using 20 grams of coffee grounds as a standard, he divided the pour into five sections totaling 300 milliliters of water, with each section being 60, 80, 60, 60, and 40 milliliters respectively. The first three sections used water at 93°C, while the last two sections used 88°C.

From both extraction concepts, they use higher temperatures for the first approximately 2/3 of the water volume and lower temperatures for the remaining 1/3. Therefore, FrontStreet Coffee also used similar methods to compare the differences between variable temperature and constant temperature brewing.

FrontStreet Coffee's Variable Temperature Experiment

FrontStreet Coffee used 15 grams of coffee grounds as a standard, divided into three sections totaling 240 milliliters of water, with each section being 30, 120, and 90 milliliters respectively. The coffee was ground to a medium-fine consistency (80% pass-through rate on a #20 sieve).

The variable temperature group used water at 94°C for the first two sections and 88°C for the final section. The constant temperature group used an initial water temperature of 91°C. Friends who carefully read FrontStreet Coffee's articles will notice at this point that the constant temperature group's parameters are exactly what FrontStreet Coffee typically uses! That's right—FrontStreet Coffee conducted this comparison not to prove whether variable temperature or constant temperature is better, but to identify what differences variable temperature makes to flavor. Therefore, the variable temperature settings were based on ±3°C from 91°C, so everyone can focus on observing the results of these changes.

The coffee beans used were Panama's Maracatã. After brewing, FrontStreet Coffee first measured the concentration of both groups. Measuring concentration ensures that the extraction rates of both groups are similar. If they differed significantly, the variable temperature group would need temperature adjustments. Fortunately, the variable temperature group measured 1.34% concentration while the constant temperature group measured 1.31%—not a significant difference, allowing for comparison.

First, let's describe the flavor profile of the constant temperature group: gentle berry and honey flavors with an oolong tea aftertaste, overall smooth and very pleasant.

In comparison, the variable temperature group's flavor profile was more intense. At the first sip, the berry's sweet and sour sensations were more pronounced, with brighter acidity and relatively weaker honey sweetness. The aftertaste was more like green tea.

Understanding Variable Temperature Flavor Changes

How to understand the flavor changes produced by variable temperature? FrontStreet Coffee will provide two key points of knowledge, believing everyone will then understand easily.

First point: actually, even the constant temperature group in the comparison experiences temperature variation. When we talk about temperature in coffee brewing, we're referring to the initial temperature when we first start pouring water. The water temperature in the kettle gradually decreases over time. If we also calculate the initial 91°C temperature by dividing it into the first two sections and the final section, the temperature when starting to pour the final section would be approximately 89.5-90°C (temperature at 1 minute 20 seconds).

Second point: using higher water temperatures can extract more coffee substances. However, there's a risk—it can easily lead to over-extraction and bitter flavors. But when we understand the extraction of flavor compounds, acidic substances extract first, followed by sweet substances, and finally bitter substances. Therefore, we can split the water temperature into the first half and second half.

The first half uses higher temperatures to extract more of the coffee's sweet and sour flavor compounds, while the second half reduces temperature to decrease the release of flavor compounds. This achieves a more intense flavor expression.

To put it another way, variable temperature extraction is essentially artificially widening the temperature difference during coffee extraction. Although everyone understands the principle, finding the actual high and low temperatures to use for brewing, and how to distribute water amounts, is challenging and requires extensive testing. Admittedly, the high and low temperatures and other brewing parameters used in FrontStreet Coffee's comparison today weren't perfectly matched, and in overall sensory evaluation, the constant temperature group still performed better.

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