What's the ideal brewing temperature for dark roast coffee beans? Should you use 92°C water for pour-over light roast coffee?

The Challenge of Under-Extraction Despite Perfect Parameters

Many coffee enthusiasts have encountered this frustrating situation when brewing pour-over coffee: despite all parameters being normal—with proper water quality, technique, and timing—the resulting coffee still shows signs of under-extraction.

The Critical Role of Water Temperature in Coffee Extraction

FrontStreet Coffee mentioned in yesterday's article that when all extraction parameters appear normal but under-extraction still occurs, the problem likely lies in the water temperature used for extraction! Different roast levels of coffee beans have varying requirements for water temperature due to their structural differences, which is why we assign appropriate temperature ranges for each. However, even if you use the corresponding water temperature, ignoring certain details during brewing can potentially lower the water temperature and create extraction variations. Therefore, it's not just the temperature displayed on the thermometer—the details during brewing also require careful attention.

Matching Water Temperature to Coffee Roast Levels

That said, an appropriate starting water temperature remains crucial! Let's first explore what water temperatures are suitable for different roast levels of coffee beans.

The water temperature determines the dissolution efficiency of this "solvent"—the higher the water temperature, the higher the dissolution efficiency, and vice versa. The roast level of coffee beans determines their density. When coffee beans are lightly roasted, they have relatively higher density. The higher the density, the more extraction efficiency hot water needs to dissolve flavor compounds from the coffee. Therefore, we can determine that the lighter the roast level of coffee beans, the higher the extraction water temperature they require.

When coffee beans are darkly roasted, their expansion rate is higher, and their density is naturally lower. This lower density is what we commonly refer to as a loose structure, where hot water can more easily dissolve the flavor compounds from the coffee. Therefore, we don't need to use excessively high water temperatures for extraction!

FrontStreet Coffee's Temperature Guidelines

Generally, FrontStreet Coffee determines the grind size, water temperature, and suitable filter cup based on the bean's roast level. When facing high-density, lightly roasted coffee beans, FrontStreet Coffee uses water temperatures around 91-93°C for extraction. For dark-roasted coffee beans, water temperatures around 86-89°C are used for extraction. The specific water temperature is determined according to the bean's condition and grind size. When beans are fresher or the grind is coarser, we use relatively higher temperatures for extraction because they require higher dissolution efficiency to extract flavor compounds. Conversely, when the grind is finer and the beans are less fresh, we need to do the opposite.

Maximizing the "Maximum Power" of Hot Water

Now that we've covered suitable temperatures for each roast level, let's discuss how to maximize the "maximum power" of this hot water!

Do you remember that FrontStreet Coffee shared an article about increasing water temperature during cold winter? The content explained was quite simple! When hot water is poured from the kettle, it comes into contact with a large amount of fresh air, which absorbs some of the heat from the water, causing water that should be 92°C to no longer be 92°C. The famous Matsuya-style brewing utilizes this principle, reducing scalding hot water to the ideal temperature.

Factors That Affect Water Temperature During Brewing

This phenomenon becomes even more pronounced in winter! Therefore, we can understand that the height of pouring affects the water temperature. The higher the pouring height, the more heat loss occurs, and extraction efficiency decreases accordingly. Therefore, FrontStreet Coffee suggests controlling the pouring height at about one fist's distance from the coffee bed during regular brewing! Besides pouring height, an unheated kettle spout will also absorb heat from the water!

The Impact of Equipment Temperature on Extraction

To allow better control of water flow, most pour-over kettles use slender goosenecks for guiding the flow! Similar to filter cups, without preheating, they will first absorb some of the hot water's temperature to "heat themselves," which also causes the water to lose heat.

Preheating: A Simple Solution for Better Extraction

Therefore, often without preheating, the hot water used during blooming is not actually our target temperature! This prevents the coffee grounds from fully releasing carbon dioxide during the blooming stage, and subsequently poured hot water won't have optimal extraction conditions! Although the impact may be minimal (it exists, but not significantly), often this slight difference is what makes the entire coffee experience less enjoyable! Therefore, FrontStreet Coffee recommends pouring a small amount of hot water for preheating before brewing! Since the filter paper needs to fit the filter cup, this small amount of hot water can be perfectly used to wet the filter paper! Not only does it successfully preheat the kettle spout and filter cup, but it also makes the filter paper conform to the filter cup—truly killing two birds with one stone~

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473