Also Known As: Browning.
What is the Maillard Reaction?
The Maillard reaction, often referred to as browning or caramelization, occurs when proteins undergo a chemical reaction with reducing sugars upon applied heat. More specifically, proteins, peptides and the free amino groups of amino acids react with free reducing sugars to produce desirable flavors, aroma, and crust coloring in many baked goods such as bread, rolls, crackers, cakes, biscuits and any other baked item possible of producing a crust.
Lactose, Maltose, Fructose, and Glucose are the common reducing sugars found in breads. Flour contains most of the free amino acids such as lysine, alanine, cystine and proline. The reducing sugars and amino acids react together in three distinct stages to complete the Maillard reaction. The initial stage is undetectably colorless on crust and enables the sugars as well as the amino acids to condensate. Moving into the intermediate stage which ranges from colorless to light yellow crust, the sugars dehydrate and become fragments, at the meantime the amino acids begin to degrade as well. The final stage is where the most color is produced and exhibited as golden brown on the crust of the baked item. Polymerization of Aldehyde-amine compounds and formation of heterocyclic nitrogen compounds occur in the last stage. Once each stage has passed, the Maillard reaction is complete and many aromatic and flavor compounds are produced yielding a high quality baked good that exhibits positive final product attributes such as crust color, crumb grain, volume, and mouth feel.
The Maillard reaction can occur at room temperature around 20-25 ℃ (68-77 ℉) in the presence of oxygen. When the temperature is over 30℃ (80 ℉), the reaction rate starts to increase. With every 10 ℃ (50 ℉) difference, the reaction rate would increase at least 3 times. Over the temperature of 80 ℃ (176 ℉), the reaction rate will be consistent and unaffected by temperature or oxygen level.