Maillard Reaction

The Maillard reaction is not a single chemical event but a cascade of parallel and sequential reactions first described by French physician Louis-Camille Maillard in 1912. It begins when a free amino acid — from protein breakdown — reacts with the carbonyl group of a reducing sugar (glucose, fructose, lactose, maltose, etc.) to form an unstable glycosylamine, which rapidly rearranges into an Amadori compound. From there, multiple reaction pathways diverge depending on temperature, pH, water activity, and the specific amino acids and sugars present, producing an enormously diverse set of products: melanoidins (brown, high-molecular-weight pigments), pyrazines (nutty, roasted), furans (caramel, nutty), oxazoles (green, herbaceous), and hundreds of other volatile aroma molecules. Cooking implications are vast. Virtually every dry-heat technique that produces browning relies on Maillard chemistry: searing meat, baking bread crust, roasting coffee and cacao, frying potatoes, grilling fish. The reaction accelerates exponentially with temperature and proceeds fastest above about 140–150 °C (285–302 °F) in a pan-sear; it slows dramatically in the presence of excess water (steam suppresses surface temperature at 100 °C). Alkaline pH promotes faster browning — which is why a baking-soda wash on pretzels or Peking duck skin produces deep mahogany color before the inside overcooks, and why adding a pinch of baking soda accelerates onion browning. Low water activity (dry surfaces, dry-aged or dehydrated foods) also favors the reaction by concentrating reactants. The reaction is distinct from caramelization in requiring both amino acids and sugars — caramelization is sugar-only pyrolysis. However, the two often occur simultaneously, particularly in baked goods and roasted meats. Maillard products also differ: they tend toward meaty, roasty, savory, nutty, and bready notes rather than the sweet, bitter-toffee register of caramelization. A further dimension is the slow, low-temperature Maillard pathway operating during fermentation, aging, and anaerobic processes — see the related entry on Maillard at Low Temperature.

“Getting a true sear on the duck breast demanded a bone-dry surface and a smoking-hot pan — moisture is the enemy of the Maillard reaction, and a steamed breast is a pale, flavorless breast.”

• ConceptCaramelization
• ConceptMaillard at Low Temperature
• TechniqueSearing

1. 1.On Food and Cooking: The Science and Lore of the Kitchen — Harold McGee (Scribner, 2004)
2. 2.Modernist Cuisine: The Art and Science of Cooking — Nathan Myhrvold et al. (The Cooking Lab, 2011)
3. 3.The Maillard Reaction in Food and Medicine — Royal Society of Chemistry (1994)
4. 4.Flavor Chemistry and Technology — Gary Reineccius (CRC Press, 2nd ed., 2006)
5. 5.The Food Lab — J. Kenji López-Alt (W. W. Norton, 2015)

Confidence: high