Why you're always left with a few popcorn kernels that haven't popped

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There are few things more disappointing than a bowl of un-popped popcorn kernels

It's happened again: some of your popcorn hasn't popped. You've got those hard, yellow things at the bottom of your bowl, waiting to destroy your teeth.

Popcorn didn't always come in fancy bags with ridiculous seasonings ( baked potato flavour , really?). Back in the day, you'd stick a bag of salted or salty sweet popcorn in the microwave and something wonderful would take place. Then you'd watch a film.

You probably still indulge in a microwaveable popcorn bag or box. And when you do, it remains an undeniable fact that not every kernel will burst into fluffy softness.

Why doesn't popcorn always pop?

First, you need to understand popcorn husks. Popcorn shells are waterproof, and inside each kernel is a small amount of water, moisture, along with lots of starch.

When you cook popcorn, you heat it up, which means pressure is applied to the inside of each piece. You're cooking the starch. In doing this, the water begins to evaporate.

Starch expansion

The kernels 'pop' when the pressure gets too much – as the heat expands each bit of popcorn , they become little ticking time bombs, and need to blow. Simply, the starch cooks and grows, just like rice or pasta, but to a much greater degree.

The kernels left behind have essentially suffered a 'leak'. If the moisture escapes, the popcorn can't heat up to the extent it needs to to burst. The starch might still cook inside, but not enough pressure occurs to break the shell/husk. It's upsetting.