Why Use Different Temperatures for Pour-Over Coffee? An Introduction to Variable Temperature Brewing Techniques

Recently, the world-class coffee brewing championship concluded successfully, and FrontStreet Coffee noticed that many competitors used variable temperature brewing methods. At this point, some might wonder: when using the same coffee beans with the same technique but only changing the water temperature, how does the coffee flavor change so dramatically? Today, FrontStreet Coffee will guide you through an exploration of variable temperature brewing.

Brewing Plan

15g coffee grounds, coffee-to-water ratio: 1:15, three-stage pouring with 30ml, 120ml, and 90ml respectively. First, we have a standard constant temperature three-stage brew, which serves as our baseline comparison. The next two brews will use variable temperature adjustments.

For the first variable temperature brew, FrontStreet Coffee wanted to highlight the coffee's fruity characteristics, so we increased the water temperature by 2 degrees to maintain the extraction rate in the early and middle stages. For the final stage, we used lower water temperature to reduce the extraction rate, avoiding the extraction of undesirable compounds, creating a stepped variable temperature extraction.

For the second variable temperature brew, FrontStreet Coffee wanted to create a softer coffee, which required lowering the water temperature during the bloom stage to reduce the acidity released during blooming. The second stage became the main extraction focus. Therefore, FrontStreet Coffee used high temperature for the second stage brewing, then returned to low temperature with immersion for the final stage, similar to Variable Temperature Brew #1, to prevent extracting undesirable compounds.

The high temperature should extract more than conventional brewing. When using 92°C for standard brewing, we increased it by 2°C. The low temperature used was 85°C (FrontStreet Coffee has tested that light to medium roast coffee beans experience under-extraction when brewed with water temperatures below 85°C).

Beginning the Experiment

Brewing preparation: several pour-over kettles, several thermometers (can be omitted if using temperature-controlled kettles), coffee beans, V60 dripper, and a less important coffee measuring instrument (TDS) to verify the extraction rate of variable temperature brewing.

Coffee beans used for brewing: We used light to medium roast Panama Elida Typica because of its rich floral and fruity notes, which helps with flavor identification in this experiment. The grind was medium-fine, with 80% passing through a Chinese #20 sieve. (FrontStreet Coffee uses the EK43s grinder from our shop, with a grind setting of 10.)

Experiment Begins

(This experiment aims to compare what kind of coffee can be brewed from the same beans using different variable temperatures, so FrontStreet Coffee won't showcase the detailed brewing process extensively.)

Measurement Results

After brewing, FrontStreet Coffee measured the concentration of each coffee group. The purpose of measuring concentration was to determine whether these three coffee groups achieved reasonable extraction, and the measurement results of all three groups showed no under-extraction, with little difference between them. (Formula: Concentration TDS (%) × Coffee liquid weight (g) ÷ Coffee grounds weight (g) = Extraction rate (%)). Now let's proceed with flavor tasting for comparison~

Flavor Tasting

First, let's describe the flavor profile of the standard constant temperature brew: delicate white floral notes, bright citrus acidity, honey-like texture, and tea-like aftertaste. Balanced and smooth!

The Variable Temperature Brew #1, with high temperature in the early stages and low temperature in the final stage, showed richer tropical fruit flavors compared to the constant temperature group, with slightly weaker floral notes. When the temperature dropped to medium-low, the tropical fruits combined with the honey-like texture, evolving into a fuller juice-like profile.

Variable Temperature Brew #2, with low temperatures during both bloom and final stages, reduced acidity. The floral notes were slightly higher than the standard constant temperature brew, with subtle sweetness of peach, soft citrus, and a very clean tea-like aftertaste. The overall experience was like an elegant English floral and fruit tea.

Some observant readers may have noticed that although the first brew used constant temperature, its concentration was actually lower than the second brew with variable temperature. What's the principle behind this?

First, even the baseline constant temperature brewing actually experiences a temperature variation process. The temperatures we mentioned earlier were all measured at the beginning of brewing. As time passes, the hot water in the kettle gradually loses heat. For example, with 92°C water temperature, from the 92°C during bloom to the moment of third-stage pouring (about 1 minute and 20 seconds), it had already dropped to around 89°C.

Second, water temperature is crucial for extraction, and the water temperature at each stage affects the corresponding extraction. For example, reducing the water temperature during the bloom stage significantly decreases the overall acidity of the coffee, while lowering the temperature in the final stage directly slows down the extraction speed, limiting the release of certain macromolecular substances, such as bitter compounds.

Understanding this framework allows everyone to better control their brewing process and achieve the delicious cup of coffee they desire.

- END -

FrontStreet Coffee

No. 10 Bao'an Front Street, Yandun Road, Dongshankou, Yuexiu District, Guangzhou, Guangdong Province

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473