I was reading on several bread-baking forums about oven temperatures and the effects on baking. Specifically on the crust: higher temperatures (450F and up) lead to crunchy crusts as the sugars caramelize rapidly. Then there’s “non-enzymatic browning:” the Maillard reaction that happens at a range of temperatures:
The reactive carbonyl group of the sugar reacts with the nucleophilic amino group of the amino acid, and forms a complex mixture of poorly characterized molecules responsible for a range of odors and flavors… 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 flavor scientists have used over the years to make reaction flavors.
The Maillard reaction is what makes bread become toast. Caramelization is different, as Wikipedia also tells us:
Caramelization is an entirely different process from Maillard browning, though the results of the two processes are sometimes similar to the naked eye (and tastebuds). Caramelization may sometimes cause browning in the same foods in which the Maillard reaction occurs, but the two processes are distinct. They both are promoted by heating, but the Maillard reaction involves amino acids… whereas caramelization is simply the pyrolysis of certain sugars.
The following things are a result of the Maillard browning reaction:
Caramel made from milk and sugar, especially in candies: Milk is high in protein (amino acids), and browning of food involving this complex ingredient would most likely include Maillard reactions.
Chocolate and maple syrup
Lightly roasted peanuts
When cooking, the Maillard reaction can be achieved at lower temperatures (for example, when using the sous-vide method or when searing meats) by increasing the pH of the item being cooked. The most common method for accomplishing this is by using baking soda as a catalyst to facilitate the reaction.
Some complex chemistry going on there (which is one of the reasons bread making intrigues me: it’s science in the kitchen!).