The Maillard reaction is a chemical reaction between an amino acid and a reducing sugar, usually requiring heat. A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this A reducing sugar is any sugar that in basic solution forms some Aldehyde or Ketone. In Physics, heat, symbolized by Q, is Energy transferred from one body or system to another due to a difference in Temperature Like caramelization, it is a form of non-enzymatic browning. Caramelization or caramelisation is the Oxidation of Sugar, a process used extensively in cooking for the resulting nutty flavor and brown color Browning is the process of becoming Brown, especially referring to Food. The reactive carbonyl group of the sugar reacts with the nucleophilic amino group of the amino acid, and forms a variety of interesting but poorly characterized molecules responsible for a range of odors and flavors. In Organic chemistry, a carbonyl group is a Functional group composed of a Carbon Atom double-bonded to an Oxygen In Chemistry, a nucleophile (literally nucleus lover as in nucleus and phile) is a Reagent that forms a Chemical bond to Amines are Organic compounds and Functional groups that contain a basic Nitrogen Atom with a Lone pair. In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this This process is accelerated in an alkaline environment as the amino groups are deprotonated and hence have an increased nucleophilicity. Amines are Organic compounds and Functional groups that contain a basic Nitrogen Atom with a Lone pair. This reaction is the basis of the flavoring industry, since the type of amino acid determines the resulting flavor. Alternate meanings Seasoning (cast iron; Seasoning (wood; Seasoning (slave Seasoning is the process of imparting or improving In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this

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 create artificial flavors. A flavorist, also known as flavor chemist is someone who uses both Chemistry and art to engineer artificial and natural Flavors The tools and materials used by flavorists

Although used since ancient times, the reaction is named after the chemist Louis-Camille Maillard who investigated it in the 1910s. Louis Camille Maillard ( February 4, 1878 - May 12, 1936) was a French Physician and Chemist. The 1910s decade ran from January 1 1910 through December 31 1919

Contents 1 Foods and products with Maillard reactions 2 The process 3 Factors 4 Physiology 5 See also 6 External links 7 References

Foods and products with Maillard reactions

The Maillard reaction is responsible for many colors and flavors in foods:

• Toasted bread
• Malted barley as in malt whiskey or beer
• Roasted or seared meat
• Dried or condensed milk
• Roasted coffee
• Dulce de Leche

6-Acetyl-2,3,4,5-tetrahydropyridine is responsible for the biscuit or cracker-like flavor present in baked goods like bread, popcorn, tortilla products. Toast is sliced Bread which has been browned by exposure to dry Heat ("toasted" Malting is a process applied to Cereal grains in which the grains are made to Germinate by soaking in water and are then quickly halted from germinating further Malting is a process applied to Cereal grains in which the grains are made to Germinate by soaking in water and are then quickly halted from germinating further Whisky (uisge-beatha or whiskey (uisce beatha or fuisce) refers to a broad category of Alcoholic beverages that are distilled from fermented Beer is the world's oldest and most widely consumed Alcoholic beverage and the third most popular drink overall after water and tea Searing (or pan searing) is a technique used in Grilling, Roasting, Braising, Sautéing, etc Powdered milk is a manufactured dairy product made by evaporating Milk to dryness. Condensed milk, also known as sweetened condensed milk, is cow's milk from which Water has been removed and to which Sugar has been added yielding CoFFEE is an Open source Software for computer supported collaborative learning (CSCL in a digital classroom Dulce de leche in Spanish or doce de leite in Portuguese ("milk candy" is a milk-based syrup 6-Acetyl-2345-tetrahydropyridine, with the IUPAC name 1-(3456-tetrahydropyridin-2-ylethanone is an Aroma compound and Flavor that gives Bread is a Staple food prepared by Baking a Dough of Flour and Water. Popcorn or popping corn is a type of corn which explodes from the kernel and puffs up when heated In Mexico, Central America, the Caribbean, the United States, and Canada, a tortilla is a type of thin unleavened 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 spice pandan (Pandanus amaryllifolius) their typical smell. 2-Acetyl-1-pyrroline, abbreviated 2AP, with the IUPAC name 1-(34-dihydro-2 H -pyrrol-5-ylethanone is an Aroma compound and Flavor Rice is a Cereal foodstuff which forms an important part of the diet of many people worldwide and as such it is a staple food for many A spice is a dried Seed, Fruit, Root, Bark or vegetative substance used in Nutritionally insignificant quantities as a Food additive Pandanus amaryllifolius is a tropical plant in the screwpine genus which is known commonly as pandan and used widely in Southeast Asian cooking Both compounds have odor thresholds below 0. The odor detection threshold is the lowest concentration of a certain Odor compound that is perceivable by the human sense of smell. 06 ng/l. The litre or liter (see spelling differences) is a unit of Volume. ^[1]

The browning reactions which occur when meat is roasted or seared have often been referred to as Maillard reaction browning. However, lean meat contains very little, if any, reducing sugars. Furthermore, red meat undergoes more extensive browning than does white meat. The browning reactions in lean meat are most likely due to the breakdown of the tetrapyrrole rings of the muscle protein, myoglobin. Thus, the browning of meat is technically not a Maillard browning since it does not involve the reaction with a reducing sugar.

Caramelization is an entirely different process from Maillard browning, though the results of the two processes are sometimes similar to the naked eye (and tastebuds). Caramelization or caramelisation is the Oxidation of Sugar, a process used extensively in cooking for the resulting nutty flavor and brown color Caramelization may sometimes cause browning in the same foods in which the Maillard reaction occurs, but the two processes are distinct. They both are promoted by heating, but the Maillard reaction involves amino acids, as discussed above, while caramelization is simply the pyrolysis of certain sugars. Pyrolysis is the Chemical decomposition of organic materials by heating in the absence of Oxygen or any other reagents except possibly Steam The following things are a result of the Maillard browning reaction:

• Caramel made from milk and sugar, especially in candies; NB: milk is high in protein (amino acids) and browning of food involving this complex ingredient would most likely include Maillard reactions. Caramel (pronounced /ˈkærəmɛl/ or /ˈkɑrməl/ refers to a range of confections that are Beige to dark brown in Color, derived from the Milk is an opaque white liquid produced by the Mammary glands of female Mammals (including Monotremes. Sugar is a class of edible Crystalline substances mainly Sucrose, Lactose, and Fructose. See references below.
• Chocolate and maple syrup
• lightly roasted peanuts

In making silage, excess heat causes the Maillard reaction to occur, which reduces the amount of energy and protein available to the animals that feed on it. Chocolate ( pronounced or /-ˈələt/ comprises a number of raw and processed foods that are produced from the seed of the tropical Cacao tree Maple syrup is a sweetener made from the sap of Maple trees In Canada and the United States it is most often eaten with waffles and pancakes The peanut, or Groundnut ( Arachis hypogaea) is a species in the Legume family Fabaceae native to South America, Mexico

The process

1. The carbonyl group of the sugar reacts with the amino group of the amino acid, producing N-substituted glycosylamine and water
2. The unstable glycosylamine undergoes Amadori rearrangement, forming ketosamines
3. 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

Factors

High temperature, low moisture levels (low moisture levels are mainly necessary because water boils into steam at 212 Fahrenheit (100 Celsius), whereas the Maillard reaction happens noticeably around 310 Fahrenheit (155 Celsius): by the time something is in fact browning, all the water is vaporized), and alkaline conditions all promote the Maillard reaction. In Organic chemistry, a carbonyl group is a Functional group composed of a Carbon Atom double-bonded to an Oxygen Amines are Organic compounds and Functional groups that contain a basic Nitrogen Atom with a Lone pair. In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this Glycosylamine is a biochemical compound consisting of an Amine with a β-N-glycosidic bond to a Carbohydrate. The Amadori rearrangement is an Organic reaction describing the acid or base catalyzed Isomerization or Rearrangement reaction of the N- A ketosamine is a compound word used to describe the combination of two Organic chemistry Functional groups, derived from Ketose and Amine. Diacetyl ( IUPAC Systematic name: butanedione or 23-butanedione) is a natural byproduct of fermentation. Aspirin, or acetylsalicylic acid (ASA (əˌsɛtɨlsælɨˌsɪlɨk ˈæsɨd is a Salicylate drug, often used as an Analgesic to relieve Methylglyoxal, also called pyruvaldehyde or 2-oxo-propanal (CH3-CO-CH=O or C3H4O2 is the Aldehyde form of Hydrolysis is a Chemical reaction during which one or more water molecules are split into hydrogen and hydroxide ions which may go on to participate in further reactions Melanoidins are brown high molecular weight heterogeneous polymers that are formed when Sugars and Amino acids combine (through the Maillard reaction) at ^[2]

The rate of Maillard reactions increases as the water activity increases, reaching a maximum at water activities in the range of 0. Water activity or aw is a measurement of the energy status of the water in a system 6 to 0. 7. However, as the Maillard reaction produces water, further increases in water activity may inhibit Maillard reactions. ^[3]

Pentose sugars react more than hexoses, which react more than disaccharides. A pentose is a Monosaccharide with five Carbon Atoms They either have an Aldehyde Functional group in position 1 ( aldopentoses In Organic chemistry, a hexose is a Monosaccharide with six Carbon atoms having the Chemical formula C6H12O6 A disaccharide is a Sugar (a Carbohydrate) composed of two Monosaccharides 'Disaccharide' is one of the four chemical groupings of carbohydrates ( Different amino acids produce different amounts of browning.

Physiology

The Maillard reaction also occurs in the human body. It is a step in the formation of advanced glycation endproducts. ^[4] It is tracked by measuring pentosidine. Pentosidine is a Biomarker for Advanced glycation endproducts or AGEs

See also

• Baking
• Advanced glycation endproduct
• Wok hei

External links

• Course website on Maillard reaction (archived copy)
• Diagram of the Maillard Reaction
• Food-Info.net
• The Thermochemical Joy of Cooking

References

• Peter J. Van Soest, 1982. Nutritional Ecology of the Ruminant published by Cornell University Press

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