Warm Food Stimulates Taste More Than Cold

The temperature of food in the mouth influences the strength of the signal to the brain sent by taste buds, find researchers. Foods at higher temperatures stimulate a stronger signal. The effect is down to the TRPM5 channels in the cell membranes of the taste buds which open more as temperature increases. Researchers from the Physiology section of the Katholieke Universiteit Leuven (K.U.Leuven, Belgium) made this discovery together with their Japanese and American colleagues. The findings are published in Nature.

The researcher have discovered that the Trpm5-channel is highly sensitive to changes in temperature. At 15 ºC the channel scarcely opens, whereas at 37 ºC its sensitivity is more than 100 times higher. The warmer the food or fluid in the mouth, the more TRPM5 reacts and thus the stronger the electrical signal sent to the brain. For example, the sweet taste of ice cream will only be perceived when it melts and heats up in the mouth.

Based on these findings, K.U.Leuven’s researchers now conclude in Nature that TRPM5 lies at the basis of our taste’s sensitivity to temperature. This was also confirmed in experiments on mice: taste responses increased dramatically when the temperature of sweet drinks was increased from 15 °C to 37 °C. This temperature sensitivity of sweet taste was entirely lacking in genetically altered mice that no longer produced the Trpm5 channel.

This research opens the way to the development of chemical substances influencing the functioning of the Trpm5-channels so as to suppress unpleasant tastes, for example, or to explore completely unprecedented and new taste experiences.

Finally, these results provide an explanation for a well known psychophysical experiment, whereby test persons experience taste sensations just by heating specific parts of the tongue. Leuven’s researchers attribute this phenomenon to a direct activation of TRPM5 in the taste buds. Indeed, at higher temperatures the sensitivity of TRPM5 increases to such a degree that it becomes activated in the absence of taste molecules, leading to a "thermal taste" signal to the brains.

Abstract

Source: Katholieke Universiteit Leuven, Belgium