Chemistry of Cooking: The Maillard Reaction

Cooking is very much a study in chemistry, you have to deal with acids, bases, heat, air pressure. Knowing the science behind the food will help to make you a better cook and further your understanding of why recipes go a certain way.

Today, I wish to talk about cooking methods and why they can affect your food.

Stews and boils are cooking food submerged in water, steaming is of course cooking food surrounded by water vapor, and braising is cooking food sitting in water (not fully submerged). All of those cooking methods have one drastic limitation, namely that water cannot exceed 212 degrees. Boiling water is going to be 212 degrees no matter how hard it is boiling. This means, anything cooked in water or water vapor will not be able to exceed ~212 degrees.

This is good in many ways. You can cook something for a long time and if there is adequate moisture you know it will not overcook or burn. It is really hard to burn things that are in boiling water, and that water helps moderate the temperature of your food, preventing drastic swings.

However, there is a major downside to cooking in water, and that is that it inhibits the Maillard Reaction.

For instance, any dish that requires a browned topping will always tell you to either cook uncovered, or uncovered for a period of time to brown the top. This is because covering a cover traps steam, which then keeps the temperature moderated at around 212, way too low for the Maillard Reaction.

So what is the Maillard Reaction? It is the reaction which caramelizes sugars in food to turn it brown. The most straightforward example is the creation of actual caramel from sugar. The sugar is denatured into over a hundred different compounds, creating a very sweet and complex taste.

But nearly everything has sugars (starches) in it, and so the Maillard Reaction is also responsible for making toast taste so much better than bread, for making skin crispy on turkey, for making grill marks on meat, and for making pretty much every golden brown and delicious food, golden brown and delicious. This all doesn’t really start to happen until around 230 degrees and continues on up past 300.

So, you can’t get browning, in any food, in the presence of water. So, if you want crisp, you need dry heat. This is also why you can’t really brown things in the microwave (microwaves just heat water, water can’t go higher than 212) and why non-stick pans can’t really brown food either (They also just don’t get hot enough… nor are they supposed to, high heat ruins their nonstick surface).

But in addition to browning the outside of food, the Maillard Reaction will work on the interior as well. This is why roasted vegetables taste so much better than boiled vegetables.

So, now you know. This is why certain foods taste better when cooked with dry heat, and this is why you are sometimes asked to brown and or roast something before introducing it to liquid.