bread, askflipscience

Welcome to #AskFlipScience, where we answer even the strangest, silliest questions with science!

This week’s question: Why does bread go stale?

Piping hot pan de sal. Glorious slices of white bread. Deliciously sweet Spanish bread. There’s no doubt about it: Filipinos have a soft heart for baked goods. We’ve integrated them into our breakfasts, made them into snacks, and packed them in baon boxes all over the country.

As a result, we’re quite familiar with how bread works, including the fact that if you leave it exposed to air, it hardens over time. (The jury’s still out, though, as to whether this creates a psychological need for you to eat all the bread as soon as it’s served, thus perpetuating the endless cycle of person-bread addiction.)

But how does this process happen? (The hardening, we mean, not the addiction.)

It’s in the air

The answer is quite simple. Since bread contains starch, prolonged exposure to air will cause it to take in moisture and eventually harden.

Starch crystalizes on exposure to air, as the water in the atmosphere binds to the starch molecules.

Of course, there are other things that can happen to bread once it’s exposed, like mold.

This is a more noticeable side effect for anyone who’s ever bought a loaf from the grocery store. Since the package is often very tightly sealed from the factory to the shelves, very little air can get into the packaging and do funny things to the loaf.

But since the loaf itself has been sitting for a while (unlike fresh pan de sal), moisture would already be leaking out in tiny amounts. This is one of the reasons they come with a “Best Before” tag.

How can I avoid this?

Fortunately, you don’t have to do anything too complicated to stop your breakfast bun from becoming a glorified paperweight.

Simply limit the access of air and moisture to the bread, and it should retain its spongy, delicious form for a while.

Tossing it in the fridge won’t work, though. The air itself contains even more moisture there, causing it to harden even faster.

Either way, more incentive to eat all the pan de sal while you can, right?–MF

Cover photo: Pexels



Author: Kyle Edralin

A writer, creative, and craftsman – Kyle (or as his friends call him, Phenex) trawls the internet for interesting science stories to share to the aforementioned friends. He has since decided to bring this pursuit to a much wider audience, and is working delivering this kind of information in a way that makes much more sense than his usual ramblings. He is also very fond of penguins.