Cool Science

Why does warm ice cream taste sweeter than cold?

Phil Sheard

You must have noticed how warm ice cream tastes much sweeter than cold, you notice this even when you lick the runny bits on a hot day. If you haven't noticed this, design a simple experiment to test it for yourself. How sweet a food or drink tastes is often a function of how much sugar it contains, but warm ice cream has the same amount of sugar as cold so why does it taste sweeter?

Our basic taste sensations (like sweet and sour) derive from the activity of taste cells that live in the taste buds in our mouth. Sweet-sensing taste cells have a temperature-dependent response, this means that the warmer the taste substance is, the more it excites them. In this case, sweet stimulates the taste cell to allow calcium into the cell, and this in turn initiates a process whereby a signal is sent to the brain and the taste is perceived. The presence of a temperature-sensitive calcium channel (called (TRPM5) in our sweet-sensitive taste cells means that a given sweetness will result in a bigger response when the substance is warm than when it is cold. You can think of it as a little biological signal amplifier that gets turned up by warm, and turned down by cold. How cool is that?

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