Science & TechFact
Bread crust, steak and coffee owe their flavour to the same reaction.
From roughly 140 to 165 °C, amino acids react with sugars into hundreds of new flavour and colour compounds: the Maillard reaction, described in 1912 by chemist Louis Camille Maillard. It browns toast, fries, roasted nuts and coffee beans. Caramelisation is different: there sugar breaks down on its own, without protein.
Useful: Pat meat dry before searing: while water evaporates, the surface stays below 100 °C and won't brown.
Source: en.wikipedia.org