Food Science: The Maillard Reaction
One of this processes is called CARAMELIZATION. It is simply the chemical decomposition of the ingredients in the sugar cristals or sugars contained in foods, into other kinds of sugars like fructose and glucose as well as other substances that give nutty and buttery flavor as well as brown color as temperature increases. The highest heat, the browner. Caramelization is a non enzymatic browning.
This process is also accompanied by another process ocuring in the foods when heat is present. It is a process that occurs when the denatured proteins/aminoacids combine with the sugars present.
Maillard reaction is a type of non-enzymatic browning which involves
the reaction of simple sugars (carbonyl groups) and amino acids (free amino
groups). They begin to occur at lower temperatures and at higher dilutions
For this reason it is also called browning reaction.
The Maillard reaction is not a single reaction, but a
complex series of reactions between amino acids and reducing sugars,
usually at increased temperatures
The Maillard reaction occurs most readily at around 300º F to 500º F. When a product is cooked, the outside reaches a higher temp than the inside, triggering the Maillard reaction and creating strongest odors and flavors on the surface. This reaction was discovered by Lous Camille Maillard in the early part of the 20th century. He was trying to find out how aminoacids linked up from proteins. He discovered that when he heated sugars and aminoacids together, the mixture slowly turned brown.
Further studies showed later that there was also a connection between aminoacids and development of new flavors. This process is accelerated in an alkaline environment. Each type of food has a very distinctive set of flavor compounds that are formed during the Maillard reaction. The Maillard reaction is also promoted by both high temperature and low moisture levels and as said before, increased by alkaline factors. It starts at a temperature range higher than the temperature needed for evaporating water which is 212F or 100C. So by the time browning starts some of the water will have evaporated already.
As temperature or
time of heating increases, the results are increases in colour development, the carbon-to-nitrogen
ratio and the degree of unsaturation and the chemical aromaticity.
Maillard reactions are important in baking, frying or otherwise heating
of nearly all foods. Maillard reactions are (partly) responsible for
the flavour of bread, cookies, cakes, meat, beer, chocolate, popcorn,
cooked rice. In many cases, such as in coffee, the flavour is a
combination of Maillard reactions and caramelization. However,
caramelization only takes place above 120-150 °C