Maillard Reaction Explained: What Is the Maillard Reaction?

The Maillard reaction is a non-enzymatic browning reaction that occurs between amino acids and reducing sugars. First described by French chemist Louis-Camille Maillard in 1912, it has been put to great use in the field of food science. Chefs exploit this quirk of food chemistry to create delicious flavors.

The Maillard reaction occurs when the appropriate foods are cooked at relatively high temperatures ranging from 140 to 165 degrees Celcius (280 to 330 degrees Fahrenheit). At higher temperatures, the Maillard browning reaction gives way to caramelization, which is a different process that involves the browning of simple sugars. When taken too far, the heating process ends in pyrolysis (burning) that denatures enzymes and leaves your food charred and flavorless. By heating slowly at lower temperatures, you can avoid this burning and produce a delicate Maillard reaction.

At a high level, the Maillard reaction comes down to a reaction between carbohydrates and proteins submitted to high heat.

1. 1. Heat prompts a chemical reaction. When you heat certain foods by baking or grilling, simple sugars like glucose, lactose, and fructose activate. So, too, do complex pentose and hexose sugars.
2. 2. Sugars react with amino acids. The carbonyl group within sugars (most notably pentoses) will react with the amino group of an amino acid. This reaction nets two products: N-substituted glycosylamine and water. Because water is a product of the Maillard reaction—and not a reactant—the reaction will not work when water is already present. Thus you cannot produce a Maillard reaction by boiling food.
3. 3. The glycosylamine rearranges. N-substituted glycosylamine is inherently unstable. Almost immediately, it undergoes Amadori rearrangement, which in turn produces intermediates known as ketosamines.
4. 4. Ketosamines perform their own reactions. As the Maillard reaction progresses, the ketosamines undergo their own transformation, typically via short-chain hydrolytic fission. Depending on the specific reaction, ketosamines can end up producing diacetyl, pyruvaldehyde, brown nitrogenous polymers, melanoidins, reductones, or more water.
5. 5. New flavor compounds are formed. By the end of a Maillard reaction, new flavor compounds exist. These Maillard reaction products give roasted food a savory aroma. However, when you grill or sear food with excessively high heat, the Maillard reaction can also produce a possible carcinogen called acrylamide. Cooking at lower temperatures can prevent this chemical from appearing.

The Maillard reaction produces the flavors, colors, and aromas behind some of the most beloved food products.

1. 1. Toast: When you lightly sear a piece of bread, it turns a pleasing brown color and becomes crispy. This owes to the Maillard reaction.
2. 2. French fries: The golden-brown color of French fries comes from the Maillard reaction.
3. 3. Roasted coffee: Roasting coffee at the right temperature unlocks aroma compounds and flavor compounds that make coffee the beloved drink that it is.
4. 4. Toasted marshmallows: When you carefully roast marshmallows over an open fire, you can produce a delicious golden-brown crust.
5. 5. Malted beverages: Before malt can be turned into beer or malt whiskey, it gets gently roasted, which activates flavors, aromas, and color pigments.

Become a better chef with the MasterClass Annual Membership. Gain access to exclusive video lessons taught by the world’s best, including Gordon Ramsay, Gabriela Cámara, Chef Thomas Keller, Dominique Ansel, Yotam Ottolenghi, Alice Waters, and more.