eli5: What exactly happens when you burn food (I.e Toast)?

Question

eli5: What exactly happens when you burn food (I.e Toast)?

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Answer 1

Chemically speaking, all food is just an assortment of certain organic compounds. All organic compounds are essentially chains of carbon and other atoms attached in unique ways. When you burn food, you heat up those organic compounds so that the other atoms begin to break off and form other bonds. All that’s left are rings of carbon aka “ash”

Answer 2

Everything organic on our planet is based on carbon. Deep down everything is carbon. When you heat up toast you make a lot of molecules disconnect from carbon and fly away, because big heat does that to many things. What remains is pure carbon, which isn’t that much bothered by heat.

Answer 3

Look up “Maillard Reactions” and you’ll get a great little snippet of chemistry education.

Specifically *burning* is a chemical reactions adding oxygen to molecules and releasing energy in doing so.

But toasting bread *isn’t* burning (unless your toast is literally on fire) it’s a maillard reaction.

Maillard reactions are a whole class of chemistry that involved heat, low moisture, carbohydrates, proteins, and fats. When you apply heat to a substance that is like this, it starts to “cook” and turn brown in color (we call this “non-enzymatic browning” by the way, so it’s different from say a cut apple turning brown in the air).

It turns out that this browning and the creation of these new maillard reaction compounds ARE FUCKING DELICIOUS to humans. Think about some delicious smells – freshly baked bread, grilled steak, frying bacon, Porter or Stout beer, whiskey, cookies rising in the oven. These are all examples of malliard reaction chemistry reaching our noses, and we *love them*.

So there is a line between a maillard reaction (toast) and *burning* (black bread) if you take it too far.

Finally this is the reason why bread forms crusts, the outside of the bread dries out allows for the low moisture condition for maillard reactions, the inside of the bread (the crumb) is still very moisture rich so it doesn’t brown or get all crispy and tasty.