Ever wondered why an ice-cold glass of water seems so much more thirst-quenching than a room-temperature one, or why an ice cream cone always hits the spot on a warm day?
Researchers at Unilever Discover and the Common Cold Centre and Healthcare Clinical Trials at the Cardiff School of Biosciences, Cardiff, United Kingdom, sought to find out why cold stimuli (in this case, ice cream, cold drinks and popsicles), are perceived as pleasant in the mouth, despite that cold stimuli to the skin often cause discomfort and reflexes that defend body temperature.
For the paper, titled “Cold pleasure. Why we like cold drinks, ice-lollies and ice cream,” the researchers compiled data from a number of studies exploring body temperature control and its origins, as well as cold receptors in the mouth versus on the skin, and drew some conclusions as to why consuming cold food and drink is often viewed as pleasant.
“Cold water is preferred to warm water as a thirst quencher and cold products such as ice cream may also be perceived as pleasant because oral cooling satiates thirst,” they wrote. “The case is made that cold stimuli may be perceived differently in the skin and oral mucosa, leading to different effects on temperature regulation, and perception of pleasure or displeasure, depending on the body temperature and the temperature of the external environment.”
Cold stimuli perceived differently by skin and mouth
Cold receptors are more numerous than warm receptors on the skin, which suggests that man originated in a tropical environment, the report found. Cold stimuli may cause reflex responses such as skin vasoconstriction, tensing of muscles and shivering that will help to conserve body heat as an anticipatory response to any body cooling (and is why the sensation is usually unpleasant).
“The skin cold receptors are involved in temperature regulation as exteroreceptors, whereas the cold receptors in the mouth are involved in the appreciation of food and drink rather than temperature regulation,” according to the report.
Cold = refreshment
Ice cream and popsicles are by definition consumed “ice cold” because it’s the cold part that makes them so pleasurable, even though cooling tends to reduce the sensory effect of food and drink on taste and smell. They’re most popular during warm months, when the body tends to overheat.
In the same way cooling the skin on a warm day helps defend body temperature against rising above normal, a cold drink on a warm day will also “tend to defend body water against depletion.”
Cooling sensations are also strongly related to a refreshing perception, and the most important characteristic that makes a food or drink refreshing has been reported to be cold, cool or icy temperatures (rather than color, for example). Indeed, the most common foods and drinks reported as refreshing are water (first) and ice cream (second).
Moreover, researchers found that cold water is also generally preferred rather than warm water as a thirst quencher, despite the fact that equal volumes of cold and warm water will have exactly the same effects on plasma osmolarity, or concentration of substances in the blood.
“In a series of experiments on humans who had abstained from drinking for at least two hours the results clearly showed that cold water reduced thirst ratings significantly more than warm water,” they wrote.
“Cold pleasure. Why we like ice drinks, ice-lollies and ice cream,” Appetite (2013)
Authors: Eccles, R., Du-Plessis, L., Dommels, Y., Wilkinson, J.E.,