What is the best temperature for brewing cold brew?

In the world of coffee science, cold brew is defined less by a specific degree and more by the absence of high heat. While hot brewing relies on thermal energy to rapidly dissolve acids, oils, and aromatics, cold brewing uses time as a substitute for temperature. Because extraction rates follow Arrhenius’s law—roughly doubling with every 10°C increase—the temperature you choose dictates how long your coffee must steep to reach the desired strength.

Brewing at refrigerator temperatures (4–8°C) is the most common method for home and commercial setups. This slow, steady approach minimizes the risk of over-extraction and bacterial growth, resulting in a very clean, mellow cup. However, because the solubility of coffee compounds is significantly lower at these temperatures, you must compensate with a much longer steep time, typically ranging from 12 to 24 hours.

Alternatively, brewing at ambient room temperature (20–25°C) accelerates the process, often yielding a finished concentrate in as little as 4 to 8 hours. While this is efficient, it requires more vigilance. Higher temperatures can draw out more bitterness if the coffee is left to steep too long, and the risk of spoilage increases if the environment is not strictly controlled. Many professional shops opt for a 'cool room' temperature around 15–20°C to find a middle ground between speed and flavor clarity.

In practice, the 'best' temperature is the one that fits your schedule and flavor preference. If you enjoy a sweeter, more chocolatey profile, a longer, colder steep is often superior. If you prefer a slightly more complex acidity, a shorter, room-temperature steep may be more effective. Regardless of the temperature, ensure your vessel is scrupulously clean, as the long contact time makes cold brew particularly susceptible to contamination if hygiene is neglected.