The Science of Food 'Rest'

It is a well known fact that time is the smart chef’s best ally: the more he or she has, the better the results. This is particularly true of dishes that need to be left to rest. It may come as a surprise to learn that food needs rest. Just as sleep is restorative for human beings, rest can make a good dish taste even better.

Have you ever wondered why some recipes are better “the day after”? Or why others, once cooked, need to be left to rest before being consumed? Here's the scientific reasons why certain dishes should be left to "rest."

Why some recipes are better "the day after"

All dishes that are “better the day after” have one thing in common: they are rich in fats and spices. In the case of spices, the problem is that when they have just finished cooking they tend to have strong and very distinguishable flavours. With time, and left to rest sufficiently, their aromatic substances mellow and blend, creating a well-balanced and uniform result, offering the best possible flavours.

Another reason is that these ingredients, similarly to onion, garlic and herbs, tend to trigger many chemical reactions during cooking, particularly when in contact with proteins and starchy foods. When the cooking process is over, these reactions are suspended, only to resume when the food is reheated.

This is why certain flavours are more evident, and more enjoyable, when the dish is reheated time after time: it is no coincidence that the famous Tuscan soup known as ribollita is largely made up of bread and beans rich in starch combined with onions and kale, which are in fact very reactive.

Tuscan Ribollita

You will now understand that the secret behind reheated food derives from many different chemical and physical processes. Now, with regards to stews and casseroles we are going to learn something else. These dishes are made from cheaper cuts of meat that are rich in collagen and suitable for long slow cooking methods.

Collagen, when cooked, takes on a jelly-like consistency and incorporates the flavours of the casserole sauce. When it cools, the gelatine “captures” the flavours and for this reason, a lukewarm stew tends to be tastier.

The same principle also applies to boiled meat dishes made from similar collagen-rich cuts, which are most enjoyable when eaten slightly warm rather than piping hot. The reason why it is preferable to leave a good beef steak to rest after cooking is somewhat different.

It's a matter of proteins

Hang on a minute: were you thinking of serving it straight from the grill? That would be a mistake and I shall tell you why. Meat is muscle tissue packed with rod-like bundles of muscular fibres, which in their turn are crammed with finer filaments called myofibrils. The latter are made up of two proteins called myosin and actin.

When heated, these proteins unite, causing the myofibrils to come together and contract. In this way, all the juices contained in the meat are forced out: we can see this happening on the grill when our steak releases a considerable amount of liquid.

Just think, heat can reduce a myofibril to half its volume. However, this process is partially reversible: once the meat has been removed from the heat source, the myofibrils relax and, at this point, tend to reabsorb external moisture.

So this is why, after grilling your meat, it is not only advisable to leave it to rest for five minutes, but also to dress it with plenty of oil and its own cooking juices. This creates a moist environment enabling some of the juices to be absorbed by the myofibrils, making the meat more tender and succulent than ever. In brief, leave your dishes to rest, when appropriate: you will be rewarded with lots of extra flavour.

By FDL