Melts in your mouth, not your hand! But, why?

chocolate candy-mms

Halloween is right around the corner and what better way to get prepared than with a little candy science! M&M’s have always been one of my favorite candies. Let’s take a look into the magic behind the chocolate. 

Why do M&M’s melt in your mouth but not your hand?

The answer is actually a lot simpler than you may expect and lies in the crispy sugar coating (CSC). This component of the candy is made up of just sugar and water and coats the outside of the chocolate like a shell.

A close-up of the crispy sugar coating shell

Because the CSC is made of sugar and water, that means it’s soluble (dissolvable) in water (like dissolves like). So, when you pop an M&M in your mouth the sugar coating immediately begins to dissolve thanks to your saliva. 

Take a look at this experiment below. I placed M&M’s next to one another other in a plate of water. Immediately the coating began to dissolve and the color moved into the water. You can begin to see the chocolate underneath. This is exactly what’s happening in your mouth!


Now we know part of why the M&M melts in your mouth. But why not your hand?

First, think a little about the physical properties of sugar versus chocolate. We know that if we leave a chocolate bar in the sun, it will melt. However, if you’ve ever made candies at home or worked with the caramelization process, you know it takes much more heat to melt sugar.

This means the melting point of milk chocolate is significantly lower than that of sugar. In fact, the melting point of chocolate is just below body temperature, meaning it is perfectly suited to melt in your mouth. The crispy coating on the outside can withstand the warm temperatures of your hand and acts as a barrier to the chocolate on the inside.

Putting it all together


Once you place the candy in your mouth, the sugar coating dissolves, as we saw in our experiment with water. The chocolate then begins to melt on your tongue due to its low melting temperature. Try holding an M&M in your mouth for about a minute, rather than chewing, and you’ll see exactly what I mean!

Did you know? M&M’s were first sold as a product for soldiers in WWII because the candy could withstand hotter climates and could be easily transported. The idea originated from the British candy Smarties.

Now that you’ve learned a little chocolate science, you are fully prepared to indulge in your favorite Halloween candy!

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