How Significant is the Impact of Temperature on a Cup of Coffee? How Should You Be Mindful of These Effects

FrontStreet Coffee: The Impact of Temperature on Coffee and How to Manage It

In a cup of coffee, 98% is water, and the temperature of that water ultimately determines the final taste of the coffee.

During brewing, water and coffee undergo complex chemical reactions, and water temperature directly affects the extraction rate of different compounds. Water extracts quinic acid, amino acids, tannins, caffeine, oils and other substances contained in coffee. Different stages produce different reactions: caffeine is extracted in the early stages of brewing, for example, while fruit acids are extracted first, sweetness follows, and bitterness is extracted in the final stage.

Water temperature is crucial for coffee, not only when setting it before brewing but also in maintaining consistency throughout the brew if no specific brewing plan has been established. We want consistency in water temperature, in water flow rate and speed, and so on.

Unlike cold brew, hot water brewing makes it difficult to compensate for low temperatures through brewing time or grind size. That is because the compounds extracted first are mainly acids; if the temperature is insufficient, it becomes difficult to extract the oils and the sweetness and bitterness that balance the coffee's flavor.

Anyone who has tried cold brew, however, knows it is famous for its smooth, sweet taste and lower acidity. Although an extended extraction time is used to compensate for the low water temperature, certain compounds simply will not be extracted at specific temperatures.

Controlling water temperature is therefore crucial. Paying attention to water temperature can make coffee taste better.

FrontStreet Coffee Recommendation

Cold brew is where temperature control matters most, and the beans you choose matter just as much. FrontStreet Strawberry Sugar is a natural fit for cold brew: it pairs a Panamanian Geisha, with its fine rose and orange notes, with a Costa Rican honey-processed coffee that brings grape, raisin and strawberry fruit-candy sweetness. Cold brewed, it turns bright and lively, and if you let it settle and ferment gently it even takes on a fruit-wine character. If you prefer florals, FrontStreet Huakui, a naturally processed Ethiopian coffee, releases magnolia, cream strawberry, dried mango, guava and black tea in cold brew, because the natural process lets the beans soak up sweetness from the fruit pulp. For a fuller juice-like cup, FrontStreet Kenya Small Tomato shows cherry tomato, snow pear, black plum and smoked plum, and its bright acidity stays refreshing over ice.

To make cold brew at home, FrontStreet Coffee suggests 30g of beans ground to a fine-sugar size, about setting 9 on an EK43s or 24 clicks on a C40 hand grinder. Add 360g of room-temperature water at a 1:12 ratio, stir, cover and refrigerate for 8 hours, then filter out all the grounds and let the liquid age sealed in the fridge for another 3 hours. The result is grape juice, rose, sweet orange and fruit-wine flavors served cold and smooth.