Scientists have been researching why tepid coffee tastes so bad, focusing on how temperature affects the taste of food and beverages.

The first of the three theories they have come up with is related to cavemen and the fact that our ancestors only ever ate food at room temperature, according to LiveScience. 

Karel Talavera of the Laboratory of Ion Channel Research in Cuba has found that certain taste receptors inside our taste buds are most sensitive to food molecules that are in the 20-35 degrees Celsius (68-95 degree Fahrenheit) range, or at room temperature.

This means that taste receptors are less likely to register, or taste, food that is hotter or colder than this range. Therefore, hot coffee may seem less bitter, and tastier, than room-temperature because our taste buds are not so sensitive to it.

“This is still an obscure phenomenon that we cannot explain, but that could fit to the fact that taste perception does decrease above a certain temperature,” Talavera said, adding, “Our ancestors did not eat food at extreme temperatures.”

Because our biological processes such as our sensory systems have evolved from “our ancestors,” we too, are more sensitive to food at room temperature.

Other researchers think tepid coffee's bitterness has more to do with smell than taste. “Odors influence coffee flavor very strongly, and it is easy to go from sublime to horrible,” Paul Breslin, an experimental psychologist who studies taste perception at Rutgers University, explained.

So, even bitter coffee tastes good when it is piping hot because of its pleasant aroma.

Barry Green, a taste perception scientist at Yale University, added that hot coffee releases more aromatic compounds than room-temperature coffee, so it has a greater chance of impacting taste.

One last theory says that hot coffee's heat could be distracting us from its strong flavor.

Breslin added, “It is possible that an attentional mechanism is at work. You do not think about how bitter or sweet [coffee] is when it is hot or cold. Hot coffee may force you to think about temperature, which is a bit of a distraction from its bitterness.”

From the March 28, 2012, Prepared Foods’ Daily Update