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Vincenzo Fogliano » 8.Maillard Reaction


Maillard reaction

Many info at   IMARS
Web site of the International Maillard Reaction Society

Many info at IMARS Web site of the International Maillard Reaction Society


Keypoints of Maillard Reaction (MR)

  • MR occurs in all foods where reducing carbohydrates and free amino groups are present.
  • MR causes browning. In fact it is called non enzymatic browning reaction.
  • MR depends of many factors, the main ones are:
    • Type of reagents.
    • Water activity.
    • Time and temperature of the treatment.

Maillard Reaction Products (MRP)

  • MR is important because its product MRP are colored and flavoured.
  • In many foods MRP is essential to give desired color and flavour, in others they should be avoided.
  • Some MRP are potent antioxidant.
  • Some MRPs are potentially toxic.

Louis-Camille Maillard

Louis-Camille Maillard(1878 – 1936)
Photographed in his laboratoryca 1915.

Louis-Camille Maillard (1878 - 1936) Photographed in his laboratory ca 1915.


Maillard-Hodge Reaction?

John Hodge: 1914 -1996
Chemist at USDA in Illinois (1941 – 1980)
His proposed mechanism for the chemistry of non-enzymatic browning is largely unchanged after 60 years.

Maillard-Hodge Reaction?

Maillard-Hodge Reaction?

John Hodge

John Hodge


Hodge Scheme

Hodge J E. Dehydrated foods: chemistry of browning reactions in model systems. J. Agric. Food Chem. 1:928-43, 1953.

Hodge J E. Dehydrated foods: chemistry of browning reactions in model systems. J. Agric. Food Chem. 1:928-43, 1953.


Hodge Scheme


Chemistry of MR

At high temperature reducing carbonyl react with free amino groups.

Reducing carbonyl usually belongs to glucose or fructose group, but can also be an oxydised fat.

Free amino group is usually on lateral chain of proteins (Lys or Arg) In a few cases free amino acids or ammonia.

The first step is the formation of a Shiff base followed by a complex sequence of dehydratation and rearrangments leading to the formation of colored and flavoured MRPs.

Amadori products is the first stable intermediate


Final MRP: the melanoidins

Melanoproteins, melanoidins different Maillard polymers in different products

Melanoidins are present in coffee (soluble) bread (crust) and many other products.

In some cases they are made up mainly of polysaccharides in others by proteins.

Loss of free lysine: nutritional implications.

Role in texture, taste and antioxidant activity.

Behave as dietary fibre.

Norwegian brown cheese


Melanoproteins


Dangerous MRPs: Acrylamide

Acrylamide is formed through MR only from free asparagine.

Potato, cereal (particularly bran), cocoa, coffee.

Correlation between acrylamide biomarkers and incidence of cancer.


Dangerous MRPs: Heterocyclic amines

In roasted meat heterocyclic amines can be formed from creatine amino acid and sugar.

Only in the burned region.

Heterocyclic amines are potent carcinogenic agents.


Mutagenic activity of extracts obtained from meat cooked at different time/temperature


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