Behind the golden crust that forms on meat as it cooks or the aroma that a slice of freshly toasted bread releases lies a chemical reaction that is fundamental to cooking, known as the Maillard reaction. This reaction (actually there are many reactions) is responsible for the formation of the colors and aromas that characterize many of our favorite dishes. But how exactly does it happen? What does it take for this to happen? We fuck it in this article.
What is the Maillard reaction and when does it happen?
The Maillard reaction is most famous for its role in the cooking processes of meat, fish, baked goods, vegetables and many other foods.
In reality, the Maillard reaction is not a single chemical reaction, but a complex set of chemical reactions involving sugars and proteins. Specifically, the starting reagents are reducing sugars (such as glucose) and amino acids (protein building blocks).
These “ingredients” react with each other, giving rise to a series of compounds that give color and aroma to foods and therefore influence the flavour.
There are two fundamental conditions for this reaction to occur quickly enough to see its effects:
- Temperature above 140°C. At this temperature, the reaction occurs quickly enough to be compatible with food cooking times. If the temperature rises too much, above 200°C, there is a risk that the food will burn, leading to a charring process. On the other hand, if the temperature is too low, the reaction becomes too slow and is not sufficient to produce the desired change in the food.
- Moisture: The amount of water in the food is also important. If the food is too dry (therefore with too low a water concentration) the reaction struggles to start, since water is necessary to move the sugar and amino acid molecules together. On the contrary, if there is too much water, the temperature would not be able to exceed 100 °C and therefore the reaction could be too slow.
Speed and temperature: what happens
The rate at which the Maillard reaction occurs depends on the temperature. At higher temperatures, the reaction is faster, allowing the aromatic and colored compounds to form in the time it takes us to cook a dish. This is why when we grill meat or toast bread, the cooking times are quite fast and we can see and hear the reaction taking place.
If the temperature is too low, the reaction will be much slower and may not be noticeable. Furthermore, the reaction can also occur at room temperature, but at such a slow rate that we don’t even notice it
The products of the Maillard reaction and undesirable effects
Specifically, the main compounds generated by the Maillard reaction are:
- Melanoidins: these compounds are responsible for the color ranging from yellow to dark brown, passing through light brown (depending on the cooking time and temperature) that we see on the surface of foods.
- Aromatic molecules: among these we find aldehydes, ketones, pyrroles, furans and many other compounds. These molecules are volatile, meaning they evaporate easily at room temperature, allowing us to perceive their scent.
The difference between Maillard and caramelization
Be careful though! The Maillard reaction should not be confused with caramelization. While the Maillard reaction involves sugars and proteins, caramelization concerns exclusively sugars, which at temperatures above 160 °C react with each other, producing colored and aromatic compounds. Although both reactions can occur simultaneously during cooking, they are two very different chemical processes.
