Sunday, November 06, 2022

Maillard reaction

The Maillard reaction refers to a complex group of reactions, beginning with the covalent bond between the amine groups and carbonyl compounds.

The Maillard reaction is a very important flavor-producing reaction, as illustrated when sugar forms brown nutty-flavored caramel, in a process called non-enzymatic browning. Browning, or the Maillard reaction, creates flavor and changes the color of food. Maillard reactions generally only begin to occur above 140°C.

Following on from the work of Hugo Schiff, in the 1910s, the chemist Louis Camille Maillard (1878-1936) worked on the reactions between amino acids and sugars. He described that upon gently heating sugars and amino acids in water, a yellow-brown color developed. He recorded his observations and results in his paper Action de la glycérine et des sucres sur les acides amines (The effects of glycerine and sugars on amino acids), published in 1913.

The Maillard reaction is very significant for the dairy industries because it strongly affects the end quality.

The Maillard reaction, for purposes of simplicity, can be divided into three stages: early, advanced and final. The early stage of the Maillard reaction is characterized by the initial glycosylation reaction.

The advanced stage begins with the degradation of the ARP, or Heyns product, which may be altered by oxidation, fragmentation, enolization, dehydration, acid hydrolysis, and free radical reactions, resulting in multiple poorly characterized compounds.

A final phase of Maillard reaction consists of the condensation of amino compounds and sugar fragments into polymerized protein and brown pigments, called melanoidins (brown compound).

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.

The Maillard reaction occurs naturally and may have beneficial or harmful effects on the physical, chemical, biological, and organoleptic characteristics of food products in which it occurs. The development of the Maillard reaction is desired in products where a brown color and a special aroma are expected, such as coffee, bread, and meat. Before coffee beans are roasted, they lack the aroma of roasted coffee beans, and the Maillard reaction is very important in providing the characteristic flavor of a brew.

In addition to this, the Maillard reaction is well known to cause degradation of amino acids and an overall decrease in the nutritional value of foods that have been subjected to heat in processing.
Maillard reaction

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