At 154C bread undergoes the Maillard reaction (named after the French chemist who first described it in 1910). This happens when heat breaks down the structure of proteins and sugars on the bread’s surface to form new flavour compounds and a brown colour.QI: Quite Interesting, of course, specializes in things you wouldn't know. If you like this blog, their website should be among your bookmarks.
The same process occurs when roasting meat and coffee or when frying onions. The word “toast” comes from the ancient root ters – meaning “dry” (from which we also get terra, “earth”). The past tense of Latin torrere “to parch” was tostus, which became a new verb, tostare “to toast”.
30 January 2011
"Things you wouldn't know," courtesy of the QI column at The Telegraph: