Any natural food cooking or warming affected the nutritional content of food.
Nutritional Losses occurs for different reasons. Minerals are not destroyed but leached in boiling water. Vitamins are destroyed and leached but different amounts depending on the vitamin. When cooking a previously frozen product is slightly higher since the leach some degradation of the cell walls has already occurred. The energizing nutrients fat, protein and carbohydrates destroyed a negligible extent in normal cooking but rather may "increase" the water content of the food falls during natural food cooking.
The water soluble vitamins (B and C) are susceptible to oxidation by the action of oxygen, heat, light, and acidity. Food, comminution also play. The water-soluble vitamins are washed and dissolved in the boiling water. To take advantage of the leached nutrients, you can use the broth for sauce or soup or similar.
Leaching into the natural food cooking water makes you should cook food in as little water as possible, so that it barely covers. Other factors for an optimal treatment involves such a short time and temperature as low as possible. This applies regardless of cooking method such as boiling, microwaving, roasting or frying.
The estimated food in the "Search the nutritional content of food", factors used for loss of vitamins during cold and hot cooking. These figures are general and losses are dependent on the type of food. See Table Retentionsfaktorer.
The fat-soluble vitamins (A, D and E), these are mainly for degradation by oxidation. In industrial food production is often added an antioxidant such as vitamin C (E 300), or vitamin E to prevent oxidation. Antioxidants are substances which themselves easily oxidized and therefore protects for example, polyunsaturated fatty acids and vitamin A from oxidation. Antioxidants are found naturally in foods such as these are bioflavonoids, carotenoids and selenium. Antioxidants are often interact so that the total effect is greater than the effect of each of them. Especially in antioxidant-rich foods like fruits and vegetables, this synergistic effect particularly important and prominent. This is one of the reasons that it is better to eat fruits and vegetables than supplements.
When keeping warm is a further gradual reduction of the particular content of water-soluble vitamins. Keeping warm should be for as short a time as possible. Also the appearance, taste, smell and even affected by warming. For professional management Food Administration recommends a maximum of one hour Keep Warm potato and a maximum of two hours for other foods. For hygiene reasons, a minimum temperature of 60 degrees celsius held.
In some cases the natural food cooking and preparation to be positive for vitamins due to increased bioavailability. For example, plant-based foods with beta carotene, a precursor of vitamin A, making cooking that cell wall proteins relaxed and carotene in the cells can be released. Thus, it is positive to boil carrots. In the fermentation of vegetables is an increase of particular B vitamins according to the microbial synthesis.
The largest losses of minerals occurs through leaching and leaching into the extracellular fluid and cooking water if not boiling and freezing performed optimally. Potassium which are mostly found in the cell walls, is the most loss-sensitive.
Positive effects of natural food cooking can be that oxalic acid in spinach and rhubarb is released during cooking and blanching and thus prevented from insoluble calcium compounds formed. This increases the availability of calcium. Phytic acid present in many cereals and can bind including zinc, iron and calcium may be affected and degraded by the enzyme phytase on the foodstuff is subjected to processing such as germination, fermentation and fermentation.
When preparing and cooking affected the absorption of fat, protein and carbohydrates usually in a positive way in that cell walls relaxed and the food increases bioavailability. For example, potatoes are in the uncooked state contains very little of the human absorbable energy. Only after natural food cooking or gelatinized starch granules gelatinise and may be broken down in the digestive tract.
When the fat in the food in contact with oxygen starts a form of oxidative rancidity. Fat oxidation taking place during transport, storage, cooking and even during freezing. The process is slow but eventually gets the food inedible, namely when the polyunsaturated fatty acids have härsknat and formed free radicals. Subjecting the oil to high temperatures for a long time, e.g. in frying härskningen can be faster. Nutrient losses in this case means a loss of essential fatty acids, taste and smell occurs, however, much earlier. Antioxidants are used to fat oxidation will be reduced and the durability is improved. Loss of fat can also arise from rendering frying and boiling.
Factors affecting protein foods include boiling, frying, low pH (pickled herring) and high salt and sugar levels (burial). This effect leads to denaturation, which increases the availability of protein, namely amino acids become free. If denauteringen progress at too high a temperature and for a long time, or for heavy mechanical processing, the protein loses its water storage capacity. The fluid then leaks following minerals and vitamins and also water-soluble proteins, and the food is dry and hard. Some of the essential amino acids lysine and cysteine ??becomes disabled or unavailable for absorption. In bread baking destroyed 70 percent of the lysine in the surface layer, while only 10 percent of the giblets.
Carbohydrates absorption depends on the distribution of starch, amylose and amylopectin in different foods. Generally, natural food cooking or other effects of the starch increases availability. Other carbohydrates such as sugars and degraded starch is digestible directly and additionally soluble in cold water. Any loss may occur by leaching.
At fermentation temperatures greater than 100 degrees (bakery) is some degradation and loss of sugars. In the latter case arises caramelization and the formation of Maillardprodukter on the surface of the bread, but the bread crumb is not affected.
When cooking starch has a tendency to form resistant starch. This occurs, for example starch during cooking and subsequent cooling of the rice. Resistant starch is formed even when the bread aging. Resistant starch is not broken down until the colon which makes it can be considered as dietary fiber.