Water Temperature and Contact Time

The water temperature and contact time for brewing coffee

Water Temperature

Water of any temperature will extract coffee, but hot water extracts faster than cold. Never pour boiling water on coffee, even on instant, as it brings out a harsh flavor. The optimum temperature range for coffee preparation is between 92-96C/197-205F. Conversely, if cooler water is used, the brew will be under-extracted. When coffee is intentionally boiled, as with Turkish brewing, sweetening offsets any bitterness.

 

Contact Time
When ground coffee and water are combined, a certain amount of time is needed for the water to saturate the coffee grounds and extract the various soluble solids, some of which take longer than others to pass into the water. For the first few minutes of the brewing cycle, the "blend" of the flavor compounds in the liquid is changing continuously. If the contact time is to be limited, the particles must be finer for the water to penetrate them and extract the flavor compounds. If the contact time is very long, the grounds should be coarser so as to slow the rate of extraction. In certain methods of brewing, such as those in which cold water drips very slowly through coffee grounds for several hours, the resulting brew will be extremely bitter, which is to be expected with such over-extraction, but will be offset later by dilution and sweetening.

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