Food Science – The Maillard Reactions

Cooking improves with practice and experience, that’s a given. Experimenting with ingredients and flavours is part of what makes cooking so interesting and enjoyable. As with everything, a little knowledge can work in your favour here – knowing why you are frying, or roasting or boiling a food can really help.

With cooking, the “why” more often than not, comes down to chemistry, which to many, is a very unappetising subject, but it doesn’t have to be. You don’t need to have a degree in chemistry to understand that certain flavours are developed at higher temperatures, but it certainly helps to know why they are, so that you can make use of your knowledge and produce them during your cooking.

A very important set of chemical reactions called The Maillard Reactions are at the core of a large number of foods and dishes’ flavours – amongst others, they are the reason why toasted bread tastes better to many than the bread itself, why the roasting of coffee beans is so important, why dark beers have deeper flavours than lighter ones, why the curing of a good ham cannot be rushed, and why a quality crust on a bread is so sought-after by bakers.

So you see – The Maillard reactions are important!

Louis-Camille Maillard (1878-1936)
Louis Maillard studied Medicine and Chemistry at the University of Nancy, where he studied the metabolism of urea in relation to kidney illnesses. He went on to study the reactions between amino acids and sugars, which let to the naming of these types of reactions as “Maillard Reactions”. He also had quite an impressive moustache.

So what are they and why should I care?
Concisely, the Maillard Reactions are the reactions between carbohydrates and amino acids. Carbohydrates are compounds containing sugars, starch and cellulose, and amino acids are organic molecules, the free part of a protein chain. This reaction produces hundreds of by-products, and more intense flavours in the food.

We use water a lot when cooking, but water has a limitation – it cannot get hotter than 100 Deg C, or 212 F (unless a pressure cooker is used). Although some Maillard reactions occur at room-temperature, they really start to take-off at temperatures higher than 120 C, which of course under normal circumstances, water can never reach. This also explains why you can’t brown foods in a microwave – the microwaves excite water molecules to heat up the food, and as we have established, water can’t go above 100C.

So if we are to brown foods (and brown=flavour), we cannot do that in the presence of water, since the brown colour comes from both the caramelisation of sugars, and the Maillard reactions between amino-acids and sugars. Both of these occur at higher temperatures.

While similar to caramelisation, the Maillard Reactions produce more complex, meaty flavours. This is due to the presence of the amino acids and the sulphur and nitrogen that they contain.

Contrary to popular belief, the browning or searing of a meat does not seal in the juices and flavours of the meat, it kicks off Maillard reactions, adding deep and complex flavours to the meat. It’s important to do this quickly and at relatively high temperatures to brown the surface without drying out the meat itself.

Harold McGee (On Food and Cooking) states:

So it is that foods cooked by “moist” techniques – boiling, steaming, braising – are generally pale and mild compared to the same foods cooked by “dry” methods – grilling, baking, frying. This is a useful rule to keep in mind. For example, one key to a rich -tasting stew is to brown the meat, vegetables, and flour quite well by frying them before adding any liquid. On the other hand, if you want to enhance the intrinsic flavours of the foods, avoid the high temperatures that create the less individualised browning flavours.

So to sum up:
1) Brown = Flavour
2) You can’t brown in the presence of water
3) Brown meat and vegetables prior to adding liquid if you want a stew to be rich and deep
4) Avoid browning if you want to emphasise individual flavours

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