Want to know why that glossy-skinned, brown-roasted duck tastes so darn good? Brace yourself for a chemistry lesson then.
TO understand how a lot of good food is produced, one can start by understanding something called the Maillard reaction.
You may have heard of the Maillard (pronounced my-YAR) reaction in association with the browning of food during cooking. It also happens to be the most common group of chemical reactions in the world.
Maillard reactions are happening in our own bodies all the time – so it’s a bit odd that many people, cooks or otherwise, do not seem to know much about the reactions.
One of the main Maillard reactions occurs when food is dry-cooked – that is, fried, grilled or baked – in temperatures around 140°C or higher. So Maillard reaction is at work when meats and other ingredients turn brown during cooking. This happens because amino acids are reacting with a reducing sugar under the heat.
Meat as you know, is made up of strings of proteins, and proteins are made up of amino acids – rather long strands of amino acids, in fact.
Even though there are only 20 primary kinds of amino acids, the amino acid strands can combine in many different and complex ways – which is why different meats don’t taste the same. The proteins are different because the mix of amino acids are distinct for each animal.
You might like to think of amino acids as the alphabet and proteins are words and sentences; you can imagine the number of words and sentences that can be constructed by just combining the 26 letters of the alphabet.
A reducing sugar is just a simple sugar compound which can “reduce” other compounds by reacting with them and it does this by donating electrons to another chemical compound capable of accepting them, like amino acids under the right conditions.
Sugars are present in some degree or other in practically all food – but this is not necessarily the same sugar that you spoon into a cup of tea.
In meats and vegetables, the sugars present in the cells tend to be glucose, fructose and ribose. All three are reducing sugars (or monosaccharides), which explain why they work particularly well with the Maillard reaction.
The crystalline sugar for your tea is sucrose as it comes from sugar cane – and sucrose actually isn’t a reducing sugar. However, dry-cooking sucrose causes it to break down into the simpler sugars, fructose and glucose, which can contribute to the Maillard reaction.
Why is it always brown?
As mentioned, one of the most obvious manifestations of the Maillard reaction is when food turns brown in dry heat when cooked (optimally between 140°C to around 180°C) for selected periods of time.
Leaving food a little too long at these or higher temperatures produces another effect called caramelisation – and if food is cooked at even higher levels of heat, then the effect is called pyrolysis (or carbonisation or more accurately, charring and burning).
Both caramelisation or pyrolysis are not Maillard reactions – caramelisation is simply sugars darkening in heat and pyrolysis is your food burning and that will happen with or without sugars or amino acids.
So if your fire alarm goes off in the kitchen, you’ve basically gone past the Maillard reaction stage and it’s time to use a fire extinguisher, turn the cooker off or evacuate the place.