I have not been able to find any answers to this. Does anybody know?
When I originally heat the brewing coffee from ground beans, the temperature is the boiling point of water as recommended but if I reheat to the boiling point of water again I have a feeling, the coffee will become dry and gray, but I have not tried it as of yet.
The brewing temperature should be between 90 °C and 95 °C. If the temperature is too low, the aroma will be constrained, and if it is too high, the coffee will have a bitter and burnt flavor.
After the initial brewing, you shouldn't reheat coffee at all. This will destroy much of the aroma and introduce a burnt taste.
It is much better to maintain the coffee at a nice temperature, eg. by keeping it in a thermos.
