To keep coffee hot longer, add milk just before drinking
November 19, 2011
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You’ve poured yourself a cup of coffee and then there’s a knock on the door – the FedEx guy. You want your coffee to be as hot as possible when you come back in a few minutes. Should you add the milk now or wait until just before you drink it? Most people would say to wait, but that’s wrong – put the milk in now. Here’s why:
- Dark-colored objects radiate more heat than light-colored ones, so the light coffee will radiate less heat than the black.
- The heat loss is proportional to the temperature differential between the cup of coffee and the room air. By adding the milk now, you have slightly cooled the coffee, reducing the temperature differential and the heat loss.
- If you use cream or half-and-half, the fat may lessen the evaporation from the surface of the coffee and the resultant evaporative heat loss.