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The Science of... Slow Cookers

The Science of... Slow Cookers

How does a slow cooker work? And why meat is the perfect food to slow-cook? Discover all the scientific secrets behind cooking at a low temperature.

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Imagine the scene: you put some ingredients into a pan in the morning before going to work, then after an evening out you come home late. And you find a nice hot dinner waiting for you, ready to be served.

The secret lies in using a slow cooker, by which we mean a lidded cooking pot that is able to cook foods at a low temperature for a long time. Tough, stringy cuts of meat become tender melt-in-the-mouth morsels. It’s all down to science, based on a simple consideration: pressure being equal, temperature and time are the factors determining how food is cooked.

What to cook in a slow cooker

Now. the question is: what is the best food to slow-cook?

In order to grasp the sophisticated scientific theory behind a normal slow cooker, first of all it is necessary to remember a few notions regarding the composition of meat.

What we call meat is usually the muscle of an animal, in other words a mass of muscular fibres, traversed by other fibres of collagen. Collagen is the principal protein of so-called connective tissue and, as its name suggests, it “connects” to the other tissues of the animal. Because of this structural function, collagen is very tough and therefore, the cuts of meat containing more collagen, will consequently be stringier. Fillet steak, for example, is excellent when served as a tartar or “blue”, because it contains no connective tissue. Wherever connective tissue abounds, a lengthy cooking method is called for, such as boiling or braising.

This brings us to another mechanism: between 65 and 70 °C the collagen proteins “denature” and, wherever there is water, as in muscles for example, the formation of gelatine takes place, something we are all familiar with. Cut a delicious slice of boiled meat and you will recognize it immediately as it oozes out, tasty and velvety, from between the muscular fibres.

If you cook a cut of boiling meat at a very high temperature, you would end up with the outer surface cooked to such a point that it would shield the inner meat from much of the heat. Consequently, the meat would be raw inside.

Owing to the numerous collagenous fibres, it would not be a pleasant experience, I can assure you. That is why a very slow cooking process is able to radiate the heat evenly, right through to the centre.

What is a slow cooker

To enable the remotest parts of our meat to reach 70 °C, however, the temperature needs to be slightly higher, at least 80 °C. This, in fact, is the ideal “slow cooking” temperature. Then, in the course of time, slow cookers have started to offer a wider range of temperatures. As well as “Low” at about 80-87 °C, we are sure to find the “High” mode of approximately 120-130 °C. Some models also offer “Med” (medium), which is set at 100 °C.

To facilitate heat penetration, the slow cooker does not only become hot on the bottom but also on the sides. At the same time, in order to preserve the heat it has generated, it is fitted with a nice heavy lid. Obviously, the lid must NEVER be removed, otherwise the heat will be lost.

Cooking times vary a good deal according to the model you choose but, for one kilo of roast veal cooked at a “low” temperature, you can expect it to take at least seven-eight hours. Once the operation is complete, most slow cookers reduce the temperature automatically to about 40-50 °C, which suspends the cooking process but enables you to come home to some nice hot food.

Slow-Cooker Recipes

By the way: what about a quick and easy recipe for a superlative slow cooked dish?

Traditional pork ribs are always a good idea. Take a rack of ribs, without dividing them, and season with salt, pepper, powdered garlic and a smear of Dijon mustard. Put everything into the slow cooker, set it to low and just forget about it for eight hours.

When the time is up, take out the ribs which can be served just as they are or, alternatively, placed in a hot oven preheated to 200 °C, for 15 minutes, just long enough to make them deliciously crisp. Now enjoy all the flavour of slowly cooked food.


Have you ever dreamt to prepare a whole English breakfast with a slow cooker? Of course it's possible!

And - guess what - you can also follow the Michelin-starred chefs' tips for a perfect slow cooking.

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