Why is toast crunchy?

I asked my sister this question, and her response was “because you cooked it.” While cooking things can result in crunchiness, my question was not posed to understand what I had done to make my toast, toast but what chemical changes had happened inside the bread for this to happen? We cook lots of things which don’t get crunchy (we hope the opposite happens if we’re cooking rice or beans), so what’s different about bread?

The answer is the Maillard Reaction.

Why so crunchy?

The Maillard Reaction occurs at high temperatures (around 310 degrees Fahrenheit) and occurs when sugars react with amino acids. This makes an unstable glycosylamine in the first step which later converts into up to hundreds of different products, depending on the starting materials, through a series of subsequent steps. The product that we are smelling when we know our toast is done and which gives toast its texture is known as 2-acetyl-1-pyrroline. Mmmm, nothing like 2-acetyl-1-pyrroline for breakfast. Question answered.

The chemical reaction taking place inside our bread (who knew all this happened inside our toaster?)

The chemical reaction taking place inside our bread (who knew all this happened inside our toaster?)

Scientists are supposed to ask questions. Right? When I’m not asking questions about ants or cacti, I’m wondering why my breakfast is making so much noise. Have a question you’d like explained? The best thing to do is ask.

“Judge a man by his questions rather than by his answers.” ― Voltaire

Photos courtesy of Wikimedia Commons.

Information on the Maillard reaction was found in the October, 2012 issue of Chemical & Engineering News, available online at http://cen.acs.org/articles/90/i40/Maillard-Reaction-Turns-100.html.


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