Your food is speaking to you. It is telling you whether it is safe to eat. It is also telling you that it can deliver the calories, vitamins and minerals that your body needs to survive.
If you were offered a raw potato for lunch it is very likely you would find it unappetizing. Now cut up that same potato and fry it and your mouth will start watering. Those French fries are sending you signals that entice you to consume them. The fries look better. They smell better. And they taste better. (Spoiler alert: they are better. A raw potato can be hard on our evolved digestive systems).
Those signals are thanks to the Maillard reaction, a chemical reaction produced during cooking that creates new colours, flavours and aromas. As food is heated, amino acids (building blocks of proteins) and simple sugars engage in small reactions that form new molecules.
The Maillard Reaction is named after French chemist Louis-Camille Maillard, who first described it in 1912.
The most obvious indication that a Maillard reaction is occurring is the darkening or ‘browning’ of the food. During the reaction amino acids and sugars rearrange in rings and groups of rings forming pigment molecules called melanoidins that reflect light in such a way that the food appears browner or darker in colour.
While browning visually indicates food’s desirability to us, molecules formed during the reaction are also responsible for the aromas and flavours we associate with food being fried, roasted and baked. These smells and tastes differ from food to food and can even depend on how food is cooked. A fried egg, for example, tastes very different from a poached or scrambled egg.
A Maillard reaction will start given the right combination of temperature, moisture and time. As heat is applied water within food turns to steam and evaporates. As food dries out sugars and proteins become more concentrated and the rate of chemical reaction increases.
Too much water inhibits the reaction. Boiling water can only reach temperatures of 100 degrees Celsius so none of the pleasant sights, smells and tastes associated with Maillard can be produced. Just think of how appetizing a boiled steak appears and tastes.
Grilled steak, roasted coffee, and toasted marshmallows are all delicious examples of the Maillard Reaction in action. Can you think of one that makes your mouth water?
It is no coincidence that many recipes call for food to be cooked at 180 degrees Celsius or 350 degrees Fahrenheit. That is the temperature level most associated with the chemical reaction described by Maillard. It is also why most ovens feature it as a present cooking temperature.
Going above this temperature can result in a less desirable reaction, pyrolysis, more widely known as burning. At this point browning turns to charring and aromas and flavours become bitter and for most people, unpleasant.