Water temperature

Water temperature in coffee brewing

The temperature at which you brew your coffee plays a significant role in flavor extraction. Extraction refers to the flavors and compounds that dissolve from the coffee into your cup. Coffee consists of soluble compounds – flavors, oils, and acids – that dissolve at different rates when exposed to water.

The hotter the water, the faster it extracts compounds like oils, acids, and caffeine. Each of these substances impacts the coffee’s flavor differently. At higher temperatures, controlling the extraction rate becomes more difficult. If the water is too hot, it may over-extract the coffee, leading to undesirable flavors and excessive bitterness. On the other hand, if the water is too cold, the extraction will be incomplete, resulting in weak or acidic coffee with a flat taste. An exception to this is cold-brewed coffee, where coffee is intentionally extracted slowly in cold water. However, trying to brew coffee quickly with cold water results in a flat flavor profile because the coffee oils don’t extract, leaving the coffee lacking body, sweetness, and balance between bitterness and acidity.

The science of brewing

When hot water comes into contact with coffee grounds, it extracts soluble compounds in phases:

First phase – Acids and aromas: At lower temperatures, acids (such as citric or malic acid) dissolve first. These create bright, fruity flavors, often associated with lighter roasts. If the water is too cold, only these compounds will dissolve, leading to overly acidic coffee.

Second phase – Sugars and body: As the temperature reaches the optimal range, sugars and other pleasant compounds dissolve. These add sweetness and body to the coffee, balancing the initial acidity.

Final phase – Bitterness and over-extraction: At very high temperatures, bitter compounds like chlorogenic acids and tannins dissolve last. If the water is too hot, these compounds dominate, making the coffee taste harsh and overly bitter.

Ideal coffee brewing temperatures range between 92°C and 96°C.

This range ensures balanced extraction, harmonizing flavors such as sweetness, acidity, and bitterness. While this temperature range is a good general guideline, you can experiment with both roast levels and water temperatures. For lighter roasts, brew at a slightly higher temperature to speed up the extraction process. For darker roasts, use a lower temperature to avoid over-extraction and minimize bitterness.

When using a kettle or manual method, it’s a good idea to preheat the brewing vessel since water temperature starts to drop immediately, and it’s nearly impossible to achieve an overly hot result. For drip coffee machines like Moccamaster, you could preheat the machine by running some hot water through it before brewing to ensure the best extraction but, this might be a bit of a gimmick.

Summary

• According to SCA standards, the water temperature for cupping should be between 92.2–94.4°C when poured over the grounds.
• If you don’t have a temperature-regulating kettle, boil water to 100°C and let it cool for 20-30 seconds.
• Most common drip coffee machines brew between 92-96°C, and the warming plate keeps coffee at 80-85°C.
• Too hot water combined with too long brewing time can lead to over-extraction, creating undesirable flavors and unpleasant bitterness.
• By experimenting with brewing temperatures, you can find your preferred flavour profile, but if you’re not interested in experimenting, trust your coffee machine, as it’s designed to extract the best flavours from any coffee!

Finding the temperature for different brewing methods