The Maillard reaction is something you will most likely enjoy at least once a day. So what is it?
Wikipedia: is a chemical reaction between amino acids and reducing sugars that gives browned food its desirable flavor. Seared steaks, pan-fried dumplings, cookies, breads, toasted marshmallows, and many other foods undergo this reaction. It is named after French chemist Louis-Camille Maillard, who first described it in 1912 while attempting to reproduce biological protein synthesis
In the process, hundreds of different flavor compounds are created. These compounds, in turn, break down to form yet more new flavor compounds, and so on. Each type of food has a very distinctive set of flavor compounds that are formed during the Maillard reaction. It is these same compounds that flavor scientists have used over the years to make reaction flavors.