Willem Koert

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23.07.2008

Martins captures the moment that chocolate turns brown

Portuguese PhD graduate Sara Martins built a model that shows how the brown colour in roasted and baked foods such as chocolate, bread, fried meat and beer develops. Martins studied in minute detail what happens to amino acids and sugars when heated, recording one of the most important reactions in the food industry.
In 1912 the French chemist Louis-Camille Maillard discovered that when they are heated together, amino acids and sugars form substances that are responsible for the brown colour found in many foods. Ever since then technologists have been studying the reaction, but there is still much they don't understand completely.
"The substances created in the Maillard reaction are important for the taste of products," explains Martins' supervisor Professor Tiny van Boekel. "They cause both good flavours, such as the taste of fried meat, but also tastes we'd rather not have, the off flavours as they are called. An example of this is the aftertaste of sterilised milk."
The Maillard reaction also produces substances which are good and bad for the health. Acrylamide, a carcinogenic substance about which little could be done until recently, is an example.
"The food industry is very interested in understanding more about the Maillard reaction so that it can be better managed,", continues Van Boekel. "Martins' research has increased our quantitative knowledge of the reaction. She studied reactions at the test tube level and used her observations to build a model which indicates how much of which substances are produced under varying conditions. Her work produced no great surprises, but she did come up with formulas which indicate when and how much 3-deoxysone is produced in a reaction. This compound is the building block of the melanoids that form the brown substances in roasted coffee and meat, and bread."
Martins'research focused on the brown colour, says Van Boekel. "But I think that 3-deoxysone will give us the key to understanding the healthy and unhealthy substances in the Maillard reaction."

Wb, 19 Juni 2003.