The Maillard reaction is a chemical reaction between amino acids and reducing sugars that gives browned foods their desirable flavor. It is named after French chemist Louis-Camille Maillard, who first described it in 1912 while attempting to reproduce biological protein synthesis.
The reaction is a form of nonenzymatic browning which typically proceeds rapidly from around 140 °C (284 °F) to 165 °C (329 °F). At higher temperatures, caramelization and subsequently pyrolysis become more pronounced.
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. This process is accelerated in an alkaline environment (e.g., lye applied to darken pretzels), as the amino groups (RNH3+) are deprotonated and, hence, have an increasednucleophilicity. The type of the amino acid determines the resulting flavor. This reaction is the basis of the flavoring industry. At high temperatures, acrylamide can be formed.
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 flavour scientists have used over the years to make reaction flavors.
In 1912 Maillard published a paper trying to explain what happens when amino acids react with sugars at elevated temperatures. However, it was chemist John E. Hodge, working at the U.S. Department of Agriculture in Peoria, Illinois, who published a paper in 1953 that established a mechanism for the Maillard reaction.
- Maillard reaction
- alters flavour
- makes firmer
- makes stale bread more palatable
- people on diets rather eat toast than bread because they think it helps (actually makes no difference, see http://www.tescodiets.com/px/NewsAndTools/healthyrecipes/does-toast-have-fewer-calories-than-bread)
- sick people rather eat toast because it’s easier to digest (Bread is doughy and harder to digest, it takes longer to work it’s way through. Toast is crumbly and dry, therefore easier to digest, and helps the stomach faster.)
- contains high levels of acrylamide (It is a white odourless crystalline solid, soluble in water, ethanol, ether, and chloroform. Acrylamide decomposes in the presence of acids, bases, oxidizing agents, iron, and iron salts. It decomposes non-thermally to form ammonia, and thermal decomposition produces carbon monoxide, carbon dioxide, and oxides of nitrogen. From this, they concluded acrylamide levels in food were safe in terms of neuropathy, but raised concerns over human carcinogenicity based on known carcinogenicity in laboratory animals. Acrylamide is a known lethal neurotoxin (median lethal dose in rabbit = 150 mg/kg) and animal carcinogen. Its discovery in some cooked starchy foods in 2002 prompted concerns about the carcinogenicity of those foods.)
- contains carcinogen (A carcinogen is any substance, radionuclide, or radiation that is an agent directly involved in causing cancer)
- Buttered toast phenomenon-buttered bread always lands on the buttered side.