How Does Water Temperature Affect Pour-Over Coffee Flavor? What's the Ideal Temperature? What Happens When the Water Temperature Is Too Low?

The Impact of Cold Weather on Coffee Brewing

Whether it's because FrontStreet Coffee has been teasing about it for too long, the temperature in Guangdong actually dropped dramatically overnight. Excellent! Finally feels like winter! However, precisely because of this, I'm sure everyone has noticed a problem today - the brewed coffee doesn't taste as good as before!

Even when using the same parameters and methods as before, the flavor expression and texture of the coffee are somewhat inferior to what was brewed before the temperature dropped. The reason is simple: our extraction efficiency during brewing is relatively lower than before. This is affected by many factors, but the main culprit can actually be attributed to cold air!

When we brew coffee, there's a difference between the water temperature we set and the actual temperature that contacts the coffee grounds for extraction. This is because hot water comes into contact with air before reaching the coffee grounds. Since the air temperature is relatively lower than the hot water, it will absorb some of the heat from the hot water. (The principle is explained below)

For example, if the hot water in our kettle was originally 92°C, by the time it passes through the air and contacts the coffee grounds, it might have already dropped to around 90°C. The specific temperature drop depends on the pouring height and ambient temperature. The higher the pouring height and the lower the ambient temperature, the more heat will be absorbed from the hot water. Therefore, what we consider consistent parameters only exist on the surface. In the cold winter, cold air causes more significant heat loss from hot water. With reduced extraction rate, naturally we can't brew coffee as delicious as before.

Solutions for Brewing in Cold Weather

The solution is actually quite simple - just increase the brewing water temperature by 1-2°C! This can balance out the excessive temperature taken away by cold air.

However! The impact of cold air isn't limited to the poured hot water. If you're like FrontStreet Coffee, using a non-temperature-controlled kettle that requires a thermometer to measure water temperature, you'll find that the water temperature in the kettle drops faster than usual! Because non-temperature-controlled pouring kettles have no insulation effect, water continuously cools down. Under the influence of cold air, the temperature will drop even faster. In such situations, this will also affect overall extraction. Therefore, FrontStreet Coffee recommends improving this by increasing the amount of hot water in the kettle. When there's more hot water in the kettle, the rate of temperature loss naturally slows down, and this can also help improve the stability of the poured water flow - killing two birds with one stone.

Equipment Impact on Coffee Temperature

Besides these two points, we also need to pay attention to the impact of equipment on coffee temperature. This is a point mentioned by FrontStreet Coffee in the article "The Impact of Filter Cup Materials" - "heat transfer," a common physical phenomenon. Heat transfer refers to the phenomenon of heat energy transfer caused by temperature differences. As long as there's a temperature difference within or between objects, heat energy will transfer from high temperature to low temperature through one or more of these three methods: heat conduction, heat radiation, and heat convection. In fact, the principle mentioned above where cold air absorbs heat from water temperature also comes from this principle - two objects in contact will eventually reach the same temperature. So it's not just cold air that affects water temperature and extraction. During our brewing process from start to finish, the gooseneck spout, filter cup, serving pot, and serving cup will all affect the liquid temperature if not preheated.

FrontStreet Coffee once conducted an experimental comparison in summer, using an unheated serving pot versus a preheated serving pot to collect coffee dripping from the filter cup. The final coffee temperatures were 65°C and 70°C respectively (approximately), a full 5°C difference. In winter, this gap will be even larger. If we also need to pour into serving cups, the temperature will drop further.

Pre-Wetting Filter Paper for Better Brewing

Therefore, during the filter paper wetting step before brewing coffee, FrontStreet Coffee suggests using hot water for wetting. This way, while wetting the filter paper, you can also preheat the spout, filter cup, and serving pot. The temperatures of hot water and coffee won't be excessively drained. Not only can we more easily brew a delicious cup of coffee, but we can also keep the coffee warm longer in this cold winter~

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