The kitchen is able to make edible and tasty foods that would otherwise be inedible due to their composition and flavor, preserves their nutritional qualities, gives them new colors, different aromas and flavors and stimulates our visual, olfactory and digestive systems.
What changes during cooking?
- Weight: changes during cooking, for example, 100 g of uncooked glossy rice after boiling becomes about 260 g, 100 g of raw semolina pasta becomes about 240 g, 100 g of peeled raw potatoes becomes about 90 g, 100 g of raw chicken breast after frying and grilling becomes about 80 g and 100 g of adult lean meat after boiling becomes 60/70 g and after grilling 50/60 g
- Proteins: proteins coagulate with heat (better digestibility, as long as the cooking of the food is not too long). Boiling determines the reduction of the protein content of the meat that passes into the cooking liquid, especially if the meat is immersed in cold water and then brought to a boil.
- Carbohydrates: with heat, the starch granules pass into the cooking water, which acquires a sticky appearance. Dry heating at high temperature transforms starch into dextrins (better digestibility).
- Lipids: cooking meat causes the loss of lipids. The triglycerides subjected to heat, especially if cooked by frying, give rise to free fats and glycerol, which is partially transformed into acrolein, irritating and toxic to the liver.
- Vitamins: heat can reduce the content of many vitamins in food: the most stable vitamins once cooked are vitamins B12, K, B3, B5, B8; Vitamin A and carotenoids are quite stable when cooked, on the contrary cooking increases the availability of lycopene; the most labile vitamins once cooked are vitamins C, B1, B9; quite labile are vitamins B2, B6, D, E.
The loss of vitamins during cooking is valid depending on the food and also depends on the cooking method.
Cooking is done using the WET, DRY or MIX methods. In wet cooking (boiling, steaming, pressure cooking, bain marie) heat is transmitted to the food through water or steam.
When cooking in a dry medium (roasting, frying) the heat is transmitted to the food through the air or fat; the temperature is 150-200 degrees; During cooking, a crust forms on the surface of the food which limits the loss of nutrients. Mixed cooking: stew, stew, casserole cooking.
- Boil: there are two possibilities. In the first, the food (meat, dried legumes, potatoes with skin) is immersed in cold water and then brought to a boil. This modality implies a high loss of proteins, lipids, vitamins and minerals. In the second possibility, the food (rice, pasta, vegetables, meat) is immersed in boiling water; this implies a modest loss of nutrients, especially if the boiling is short in little water. Even a prolonged boiling does not sterilize the food, as it only kills a part of the pathogenic microorganisms and molds present in them and is not sufficient to kill the spores.
- Steam cooking: it is an excellent cooking system, which keeps the flavors and colors of food unaltered and avoids the dispersion of nutrients in the cooking liquid.
- Cooking in a pressure cooker: the loss of nutrients is less than boiling thanks to the cooking speed and the small amount of cooking liquid.
- Cooking in a bain marie: it is a delicate cooking method, which preserves most of the nutrients, suitable for cooking foods that would be damaged by high temperatures, such as panna cotta and caramel cream.
- Roast: in roasting (on the grill, on the fire, in the oven, on the grill) cooking starts from the surface of the food and proceeds inwards: the formation of a crust on the surface of a food limits the loss of nutrients. Avoid charring the external parts of the meat and eliminate the charred parts as charring is accompanied by the formation of toxic and carcinogenic substances.
- Frying: cooking a food completely immersed in a fatty substance at high temperatures (150, 190 degrees). Fried foods are good, but they are high in calories and poorly digestible because part of the fat is absorbed from the food; In addition, it causes the formation of harmful substances, especially for the stomach and liver, such as acrolein, and perhaps promotes the appearance of tumors.