Maillard reaction (/maɪˈjɑːr/ my-YAR; French
pronunciation: [majaʁ]) is a chemical reaction between amino
acids and reducing sugars that gives browned food its distinctive
flavor. Seared steaks, pan-fried dumplings, cookies and other kinds of
biscuits, breads, toasted marshmallows, as well as many other foods,
undergo this reaction. 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 non-enzymatic browning which typically
proceeds rapidly from around 140 to 165 °C (280 to
330 °F). Many recipes will call for an oven temperature high
enough to ensure that a
Maillard reaction occurs. At higher
temperatures, caramelization and subsequently pyrolysis become more
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 aromas and flavors.
This process is accelerated in an alkaline environment (e.g., lye
applied to darken pretzels; see
Lye roll), as the amino groups (RNH3+
→ RNH2) are deprotonated and, hence, have an increased
nucleophilicity. The type of the amino acid determines the resulting
flavor. This reaction is the basis for many of the flavoring
industry's recipes. At high temperatures, a potential carcinogen
called 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 that flavor scientists have used over the years
to make artificial flavors.
2 Foods and products with Maillard reactions
3 Chemical mechanism
5 See also
7 Further reading
In 1912 Maillard published a paper 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.
Foods and products with Maillard reactions
Maillard reaction is responsible for many colors and flavors in
The browning of various meats like steak, when seared and grilled
The browning and umami taste in fried onions
The darkened crust of baked goods like pretzels, bagels, and toast
The golden-brown color of
French fries and other crisps
Malted barley, found in malt whiskey or beer
Dried or condensed milk
Dulce de leche
Lightly roasted peanuts
6-Acetyl-2,3,4,5-tetrahydropyridine is responsible for the biscuit or
cracker-like flavor present in baked goods like bread, popcorn, and
tortilla products. The structurally related compound
2-acetyl-1-pyrroline has a similar smell, and occurs also naturally
without heating and gives varieties of cooked rice and the herb pandan
(Pandanus amaryllifolius) their typical smells. Both compounds have
odor thresholds below 0.06 ng/l.
Roast pork, browned using the Maillard reaction
The preparation of
French fries at high temperature can lead to the
formation of acrylamide.
The browning reactions that occur when meat is roasted or seared are
complex, and occur mostly by Maillard browning with contributions
from other chemical reactions, including the breakdown of the
tetrapyrrole rings of the muscle protein myoglobin.
Caramelization is an entirely different process from Maillard
browning, though the results of the two processes are sometimes
similar to the naked eye (and taste buds).
sometimes cause browning in the same foods in which the Maillard
reaction occurs, but the two processes are distinct. They are both
promoted by heating, but the
Maillard reaction involves amino acids,
as discussed above, whereas caramelization is simply the pyrolysis of
In making silage, excess heat causes the
Maillard reaction to occur,
which reduces the amount of energy and protein available to the
animals who feed on it.
The carbonyl group of the sugar reacts with the amino group of the
amino acid, producing N-substituted glycosylamine and water
The unstable glycosylamine undergoes Amadori rearrangement, forming
There are several ways for the ketosamines to react further:
Produce 2 water and reductones
Diacetyl, aspirin, pyruvaldehyde and other short-chain hydrolytic
fission products can be formed
Produce brown nitrogenous polymers and melanoidins
The open-chain Amadori product undergo further dehydration and
de-amination to produce dicarbonyls. This is a crucial
Dicarbonyls react with amine to produce Strecker aldehyde through
Acrylamide, a possible human carcinogen, can be generated as a
Maillard reaction between reducing sugars and amino
acids, especially asparagine, both of which are present in most food
Maillard reaction also occurs in the human body. It is a step in
the formation of advanced glycation endproducts (AGEs). It is
tracked by measuring pentosidine.
Maillard reaction has been studied most extensively in
foods, it has also shown a correlation in numerous different diseases
in the human body, in particular degenerative eye diseases. In
general, these diseases are due to the accumulation of AGEs on nucleic
acids, proteins, and lipids. Though AGEs have numerous origins, they
can form from the oxidation and dehydration of Amadori adducts, which
themselves are products of nonenzymatic Maillard reactions. Apart from
ocular diseases, whose correlation with Maillard chemistry has been
more recently studied, the formation of AGEs has also proven to
contribute to a wide range of human diseases that include diabetic
complications, pulmonary fibrosis, and neurodegeneration. The
positron emission tomography imaging agent fluorodeoxyglucose has been
shown to undergo the
Maillard reaction to form
Receptor systems in the body have been suggested to have evolved to
remove glycation-modified molecules, such as AGEs, to eliminate their
effects. The adverse effects of AGE accumulation appear to be mediated
by numerous different AGE receptors. Examples include AGE-R1,
galectin-3, CD36, and, most noted, RAGE, the receptor for AGEs.
Advanced glycation in numerous different locations within the eye can
prove detrimental. In the cornea, whose endothelial cells have been
known to express RAGE and galectin-3, the accumulation of AGEs is
associated with thickened corneal stroma, corneal edema, and
morphological changes within patients with diabetes. Within the lens,
Maillard chemistry has been studied extensively in the context of
cataract formation. Advanced glycation is known to alter fiber
membrane integrity in the lens, and dicarbonyl compounds are known to
cause increased aggregate formation within the lens. This effect is
exacerbated by both diabetes and aging. Furthermore, it is thought
that AGE-inhibiting compounds are effective in preventing cataract
formation in diabetics.
Glycation in Maillard reactions may lead to destabilization of the
vitreous gel structure within the eye via unnecessary cross-linking
between collagen fibrils. Again, this process is more strongly
observed within diabetic patients.
Within the retina, the accumulation of AGEs in the drusen and Bruch's
membrane has been associated with age, and has also been observed at a
higher level among patients with age-related macular degeneration
(AMD). This is manifested by the thickening of the Bruch's membrane.
Furthermore, it has been observed that AGE levels increase with age
within the lamina cribrosa, and the products of the Maillard reaction
have been observed there, as well.
A wide range of ocular diseases, particularly diabetic retinopathy,
may be prevented by the inhibition of the Maillard reaction. This may
be achieved in numerous ways: preventing the formation of AGEs,
reducing the effectiveness of the AGE signaling pathway and the
receptor-ligand interactions, or breaking the AGE crosslinks. This
latter method has already been achieved to some extent by the breaker
alagebrium, though its effectiveness against retinopathy is unknown.
Another method is by the use of amadorins, which are able to prevent
the reaction of Amadori intermediates, which form into AGEs, by
scavenging the reactive carbonyls.
Acrylaway is an enzyme that cannot be seen or tasted in the food. It
can only be measured through advanced laboratory equipment. During the
Maillard reaction, the asparaginase Acrylaway can reduce the
mitigation of acrylamide by up to 90 per cent, and can be used in a
broad range of foods such as biscuits, cookies, crackers, French
fries, crisp and toasted bread, fried and baked snacks, and breakfast
cereals – without changing the taste or appearance of the
The Maillard delycases are a set of enzymes of the DJ-1/Park7 family,
that can degrade Maillard adducts and prevent the formation of
advanced glycation endproducts in proteins and DNA. They act on the
early glycation adducts between glyoxals (methylglyoxal and glyoxals)
and cysteine, arginine and lysine in proteins and guanine in DNA and
RNA (18, 19). Their ability to prevent the glycation of proteins and
nucleic acids suggests that they are involved in the fight against
aging, and against many diseases including cancer, neurodegenerative
diseases, diabetic and post-diabetic diseases.
Akabori amino-acid reaction
Advanced glycation end-product
^ a b Maillard, L. C. (1912). "Action des acides amines sur les
sucres; formation de melanoidines par voie méthodique (Action of
Amino Acids on Sugars. Formation of Melanoidins in a Methodical Way)".
Compt. Rend. 154: 66.
^ Chichester, C. O., ed. (1986). Advances in Food Research. Advances
in Food and Nutrition Research. 30. Boston: Academic Press.
p. 79. ISBN 0-12-016430-2.
^ Bui, Andrew. "Why So Many Recipes Call for a 350-Degree Oven".
Tasting Table. Retrieved 6 November 2017.
^ a b Tareke, E.; Rydberg, P.; Karlsson, Patrik; Eriksson, Sune;
Törnqvist, Margareta (2002). "Analysis of acrylamide, a carcinogen
formed in heated foodstuffs". J. Agric. Food Chem. 50 (17):
4998–5006. doi:10.1021/jf020302f. PMID 12166997.
^ Hodge, J. E. (1953). "Dehydrated Foods, Chemistry of Browning
Reactions in Model Systems". Journal of Agricultural and Food
Chemistry. 1 (15): 928–43. doi:10.1021/jf60015a004.
^ Everts, Sarah (October 1, 2012). "The Maillard Reaction Turns 100".
Chemical & Engineering News. 90 (40): 58–60.
^ Harrison, T. J.; v, G. R. (2005). "An expeditious, high-yielding
construction of the food aroma compounds
6-acetyl-1,2,3,4-tetrahydropyridine and 2-acetyl-1-pyrroline". J. Org.
Chem. 70 (26): 10872–4. doi:10.1021/jo051940a.
^ McGee, Harold (2004). On Food and Cooking: The Science and Lore of
the Kitchen. New York: Scribner. pp. 778–9.
^ Nursten, H. E. The Maillard Reaction: Chemistry, Biochemistry, and
Implications. Royal Society of Chemistry. doi:10.1039/9781847552570.
^ Stadler RH, Robert F, Riediker S, Varga N, Davidek T, Devaud S,
Goldmann T, Hau J, Blank I (2004). "In-depth mechanistic study on the
formation of acrylamide and other vinylogous compounds by the Maillard
reaction". Journal of Agricultural and Food Chemistry. 52 (17):
5550–8. doi:10.1021/jf0495486. PMID 15315399.
^ Acrylamide. Cancer.org. Retrieved on 2016-07-24.
^ Virk-Baker MK, Nagy TR, Barnes S, Groopman J (2014). "Dietary
Acrylamide and Human Cancer: A Systematic Review of Literature".
Nutrition and Cancer. 66 (5): 774–90.
doi:10.1080/01635581.2014.916323. PMC 4164905 .
^ Mottram DS, Wedzicha BL, Dodson AT (2002). "
Acrylamide is formed in
the Maillard reaction". Nature. 419 (6906): 448–9.
^ Grandhee, SK; Monnier, VM (June 25, 1991). "Mechanism of formation
of the Maillard protein cross-link pentosidine. Glucose, fructose, and
ascorbate as pentosidine precursors". J. Biol. Chem. 266 (18):
11649–53. PMID 1904866.
^ "Advanced Glycation End Products (AGEs): A Complete Overview".
^ Stitt, Alan W. (2005). "The Maillard Reaction in Eye Diseases".
Annals of the New York Academy of Sciences. 1043: 582–97.
^ "Food Browning by Maillard Reaction". WorldOfChemicals. Oct 25,
2017. Retrieved October 26, 2017.
Van Soest, Peter J. (1982). Nutritional Ecology of the Ruminant (2nd
ed.). Ithaca, NY: Cornell University Press. ISBN 9780801427725.
Wikimedia Commons has media related to Maillard reaction.
Flour treatment agent
Chorleywood bread process
Sponge and dough
Bread in Europe
History of bread
Brand name breads