Drinking hot coffee: Why doesn't it burn the mouth?

Coffee served at temperatures recommended by the hospitality and food literatures for brewing and holding are above thermal pain and damage thresholds. Yet, consumers do not report pain or damage on drinking coffee at such temperatures. To investigate this discrepancy, the temperature of hot coffee before and during sipping was investigated for 18 subjects. Coffee temperature was continuously monitored by thermocouples in the cup, in the coffee bolus in the oral cavity and on the surface of the tongue. There was minimal cooling as the coffee entered the mouth from the cup, yet the coffee temperature was still above threshold for inducing burn damage. It is hypothesized that during drinking, the bolus of hot coffee is not held in the mouth long enough to heat the epithelial surfaces sufficiently to cause pain or tissue damage.