Is There a Big Difference Between Coffee Brewed at 91℃ and 93℃?

A friend once privately messaged FrontStreet Coffee: "Should your recommended brewing water temperature be 91°C or 93°C? Would there be a significant difference in taste between these two or three degrees?"

Regular customers might know that when FrontStreet Coffee shares coffee extraction parameters, the water temperature is often a range rather than a precise number. For example, when brewing light to medium roast coffee beans, this range is 91°C to 93°C; while for dark roast coffee beans, it's 86°C to 88°C.

Does this mean any temperature within this range can be used? There's a difference of two to three degrees between the highest and lowest temperatures in this range—would there be a significant difference in the brewed coffee? Without further ado, let's conduct an experiment to compare.

Experiment Setup

This experiment will be conducted in two comparative groups, selecting the minimum and maximum values of generally recommended water temperatures to brew a light roast bean (91°C and 93°C) and a dark roast bean (86°C and 88°C), totaling four pots of coffee. For light roast, we selected Yirgacheffe from the Ethiopia Gedeb processing plant, while for dark roast, we used Brazil Queen Estate.

Gedeb (Light Roast) Brewing Parameters:

Coffee Dose: 15g; Water-to-coffee ratio: 1:15; Grind size: 80% pass-through rate on 20-mesh sieve (EK43s setting 10); V60 filter cup; Three-stage pouring technique.

Brazil Queen Estate (Dark Roast) Brewing Parameters:

Coffee Dose: 15g; Water-to-coffee ratio: 1:15; Grind size: 75% pass-through rate on 20-mesh sieve (EK43s setting 10.5); Kono filter cup; Three-stage pouring technique.

Extraction Analysis

We sampled and tested the concentration and calculated extraction rates for all four cups of coffee:

Light Roast (Gedeb):
91°C: 1.32% concentration, 18.13% extraction rate
93°C: 1.36% concentration, 18.69% extraction rate

Dark Roast (Queen Estate):
86°C: 1.39% concentration, 19.11% extraction rate
88°C: 1.44% concentration, 19.81% extraction rate

From the data, the maximum water temperature showed concentrations 0.04% higher (light roast) and 0.05% higher (dark roast) than the minimum water temperature, with extraction rates increased by 0.56% (light roast) and 0.7% (dark roast) respectively. After reviewing the data, let's taste and compare the flavor characteristics of both groups.

Tasting Results

First, for the light roast (Gedeb) group, both 91°C and 93°C cups showed similar citrus notes with soft lemon acidity. The difference was that the 93°C cup had slightly more prominent sweetness, better layering, and a more tea-like character.

For the dark roast (Queen Estate) group, both cups displayed nutty and creamy flavors. The 86°C cup had some subtle acidity at high temperatures, making it comparatively fresher than the 88°C version. The 88°C cup had a richer mouthfeel and more sweetness, but exhibited slight smokiness at higher temperatures.

Scientific Explanation

This is because higher water temperatures more easily extract flavor compounds from coffee. The higher the water flow temperature, the faster soluble substances dissolve (using sugar at different water temperatures is a good example). Additionally, increased temperature activates flavor compounds, thereby improving extraction efficiency.

Therefore, FrontStreet Coffee typically uses 91°C water temperature when brewing most light to medium roast coffee beans. With the same parameters, this significantly reduces the likelihood of accidents and ensures consistency in output. However, this isn't absolute. In daily production, we've found that with the same extraction parameters, using 93°C water temperature for Kenyan coffee beans can express richer layering of flavors and solid acidity.

For dark roast coffee beans like Indonesian Mandheling, Blue Mountain, or Brazil Queen that focus on expressing rich mouthfeel and charming aftertaste, FrontStreet Coffee doesn't recommend using overly "aggressive" temperatures. Water temperatures of 86°C to 88°C can make the coffee milder, with bitterness less easily extracted, preventing you from wearing a "pain mask."

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

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