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Bread hardens as it goes stale because of starch retrogradation — its amylose and amylopectin molecules slowly recrystallize and lock water away, making the loaf feel dry even though almost no water has actually left it. Chips do the opposite: their fried, virtually water-free structure is hygroscopic, so it pulls in moisture from the surrounding air and goes soft. Counter-intuitively, bread stales fastest in a refrigerator (around 0–4 °C), where retrogradation is at its peak — freezing it (or sealing it airtight) is what actually keeps it fresh.
Bread and chips are two of the most beloved food items of the 21st century. Humans use bread as an ingredient in so many mouthwatering dishes (can you imagine a world without sandwiches!), not to mention our fascination with chips! Despite knowing that devouring a single packet of potato chips can add countless calories to our body (a 100-gram packet of potato chips adds almost 540 calories to our body), we just can’t get enough of them.
What’s the worst thing about them, apart from the ‘calorie aspect’?
Both bread and chips become stale over a period of time. While chips get stale much faster than bread, they both face the same fate if left in open air conditions. Despite being very similar, chemically and structurally, the way they go stale is different; in fact, they are totally opposite of each other. Chips soften when they become stale, whereas bread hardens.
Why is that?
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Why Does Bread Harden?
There’s a common misconception that bread hardens when it gets stale because it rapidly loses moisture over a period of time. If that were the case, then you could control the staling process to a great extent by putting bread in a fridge, or better still, in a freezer, which has ample moisture and practically no heat (which could make bread lose moisture). However, as it turns out, bread stales almost six times faster when kept in a refrigerator than it does in normal conditions. Therefore, loss of moisture is clearly not the culprit here.
In fact, it’s just the opposite. Bread is made up of starch molecules and wheat flour protein (gluten) molecules. Mixed in amidst the dense network of these molecules are tiny packets of carbon dioxide, which are produced during fermentation.
When bread is baked, its starch granules absorb water and swell (gelatinization). Once the loaf cools and sits, the amylose and amylopectin chains slowly realign and re-form crystals — a process called starch retrogradation. The water doesn’t actually leave the loaf (it gets bound up in those new crystals and migrates from the crumb to the crust), but the bread feels dry and firm because the starch has rearranged into a more rigid structure. That’s why bread stales fastest in the fridge: retrogradation peaks at temperatures between 0 °C and 8 °C, exactly the range a refrigerator sits in. Freezing the loaf (below about −8 °C) actually freezes the process in place.
Why Do Chips Soften When They Go Stale?
Just like bread, chips also consist of starch molecules, but the way they interact with moisture in their surroundings is very different. When chips are first fried (during their preparation), all the water present inside them evaporates due to the presence of heat. In other words, there’s practically no water content in chips that have just been removed from their packet.
However, once the packaging is undone, chips come in direct contact with air, which contains moisture. The water molecules begin to bind with starch molecules in the chips and make them lose their crunch and go stale.
How To Reverse The Staling Process In Chips And Bread?
Since water is the main culprit in staling both of these things, all you have to do is take moisture out of the equation. Literally.
Chips
To make chips return to their original form, or in other words, make them crispy again, lay them out in a single layer on a microwave-safe plate lined with a paper towel (it soaks up the escaping moisture) and zap them in 20–30 second bursts until they’re dry and crunchy again. For larger quantities, an oven at about 120–150 °C (250–300 °F) for 5–10 minutes — or an air fryer for 2–3 minutes — gives even better results. Voila!
Bread
‘Unstaling’ bread takes a bit more effort. You should start by taking a damp towel and wrapping it around the stale bread. Place it on a dish and microwave it at a high temperature for 10 seconds. Keep an observant eye on it, lest the bread overcook or the cloth catch fire (if not dampened properly).
You should be aware that the softness and texture of such ‘unstaled’ bread obviously wouldn’t match that of freshly baked bread, or bread that hadn’t gone stale in the first place. Also, this type of ‘unstaled’ bread would turn hard even faster if left in the open for a second time.
The best thing you can do to avoid staling in both cases is to keep your chips and bread in closed, air-tight containers. After all, prevention is always better than treatment!
