Processing food

Preparing food

Why do we usually cook meat or fish, even though it is possible to eat both raw?

  • To reduce biological risk (germs, toxins)
  • To make food easier to digest
  • To make food more appetizing (taste, smell, texture)

How does cooking work?

  • Heat convection: immersion in a hot liquid or gas Examples: water (cooking), oil (frying), air (oven), steam (pressure cooker)
  • Heat conduction: contact with a hot surface (pan, hot stone, grill, casserole dish)
  • Electromagnetic radiation: radio waves (microwave oven), infra-red light (infra-red oven, embers, barbecue)

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Cooking techniques

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WHY DO WE COOK FOOD?

Cooking is a thermal technique enabling us to refine what we eat. Why do we eat cooked food, when much of our food can be eaten raw?

Keywords > To reduce biological risk

The main reason is to reduce biological risk. Cooking destroys germs and toxins that may be present in food. It is therefore less risky to eat cooked food in order to avoid food poisoning.

Keywords > To help us digest food

It is also easier to digest cooked food. Consequently, to aid digestion, it is preferable to eat cooked food rather than raw food.

Keywords > To make food more appetizing

Finally, cooking makes dishes more appetising. It enables us to create new textures, as well as new flavours and aromas.

KEY GUIDELINES FOR EFFECTIVE COOKING

In your opinion, what are the key guidelines for good cooking? There are two: First of all, the temperature distribution in food, then the exposure time. How does cooking work? That all depends on the way heat is transmitted to the food.

If food is submerged in a hot liquid or gas, this is called thermal convection.

Keywords > Thermal convection: water (cooking), oil (frying), air (oven), steam (pressure cooker)

A foodstuff can be submerged in water, oil, air or steam.

If food is in contact with a hot surface, this is thermal conduction.

Keywords > Thermal conduction: pan, hot stone, grill, casserole dish

This is true of a pan, hot stone or grill.

There is also electromagnetic irradiation.

Keywords> electromagnetic irradiation: radio waves (microwave oven), infrared light (infrared oven, embers, barbecue)

In a microwave oven, these are in the form radio waves. In the case of an infrared oven, embers and the barbecue, they are infrared beams.

Here are some details of these cooking techniques.

COOKING IN WATER

There are two different ways of cooking in water. You can put the ingredients into cold water and heat them slowly to dissolve their juices. With this method you can make a good stock or broth, or you can put the food into a ready-flavoured boiling liquid. This is a good method for cooking meat.

COOKING IN OIL

When we fry food, we submerge it in oil heated to 160°C to 180°C. The surface of the food cooks quickly and encloses the juices inside crispy and tasty food. Fried food is fatty. Too much heat transforms the fat which then burns, takes on a bad taste and develops toxic compounds. Therefore, it is important to use oil that is stable when heated, to filter it and to change it regularly.

COOKING WITH AIR

Food cooked in an oven bakes in hot air. Many recipes call for baking in an oven. Biscuits, cakes, terrines or gratins are placed on a tray or in tins and dishes. Bread is put directly into the baker’s oven. The method of cooking in hot air dates back to Antiquity.

COOKING WITH STEAM

The doctor Denis Papin was fascinated by steam pistons and invented the safety valve in 1679. He decided to fit it into his famous meat-cooking machine known as the digester. The machine uses steam placed under pressure in a closed container, allowing the boiling point of water to be raised to 140°C. This system means you can save energy, have a shorter cooking time and retain more of the vitamins and minerals.

COOKING IN CONTACT WITH A HOT SURFACE

In 1912, the biochemist Louis-Camille Maillard discovered that when carbohydrates and proteins are exposed to high heat, they react with each other. This reaction, called the Maillard reaction, creates compounds, which give a cooked dish colour and aroma. When a little fat is added to the pan, the heat is better transmitted to the food, and the food sticks less to the pan.

COOKING IN A CASSEROLE DISH

 Cooking in a casserole dish enables you to cook food slowly, evenly and at moderate temperatures. The thickness of the casserole dish also spreads out heat evenly. Because the vessel is lidded, juices remain in the dish, and the loss of steam and flavour is reduced. The dish cooks gently in its own juices, softening vegetable fibres and dissolving collagen. Collagen is a family of proteins surrounding muscle fibres, which is responsible for the firm texture of meat.

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