Another classification concerns the thermoleability or thermostability of food vitamins; some of them boast a more or less heat-resistant structure and as such are called thermoSTABLE vitamins; on the other hand, others inevitably undergo inactivation by cooking, consequently they are cataloged as thermoLABLE vitamins.
With cooking, ALL foods suffer a certain nutritional loss, a phenomenon that varies according to the nature of the food processed, the processing itself, the cooking method, the cooking temperature, the type of vitamins and minerals they contain, etc.
(or vit.B1) appears to be one of the most heat sensitive molecules; it follows that, with cooking, foods suffer a considerable overall loss, regardless of the technique or system used; on the contrary, riboflavin (vit. B2) is distinguished by an "excellent resistance even at sterilization temperatures. Niacin (vit. PP) and" pantothenic acid (vit. B5), despite being thermostable vitamins, are however lost due to of their remarkable solubility in aqueous cooking liquids. Ascorbic acid (vitamin C) is extremely unstable; it is affected by both cooking and exposure to light and some enzymes (ascorbic acid oxidase), and contact with copper containers, which is why vegetables belonging to the 7th food group should be consumed mainly raw.
The fat-soluble vitamins seem on average not very sensitive to heat.
Below we will list the cooking methods in DECREASING order and on the basis of the criterion of GREATER loss of mineral salts, therefore from the most harmful to the most advisable:
- Boiling in LOTS of water (maximum loss)
- Boiling with little water (average loss)
- Steam cooking (medium-low loss)
- Pressure cooker boiling (minimal loss)
- Microwave cooking (minimal loss)
- Steaming in a pressure cooker (minimal loss)
The most useful technique to limit the loss of mineral salts (and also vitamins) is steam cooking in a PRESSURE COOKER; with it it is possible to reduce cooking times to a minimum (preserving the thermolabile vitamins) but without soaking the food (which would facilitate the dispersion of water-soluble ions and molecules).
and fat (see articles: cooking proteins, cooking sugars and cooking fats). On the other hand, in the case of vegetables, the oxidation of carotenoids is the only vitamin alteration attributable to cooking that determines a chromatic modification of the food (lightening), while the typical browning it is attributable to the degradation of the chlorophyll contained in them.Cooking also determines a change in the consistency of the vegetables which, after treatment, are softer and more chewable; this is not attributable to any nutritional curtailment but to the fragmentation of the cellulose possibly facilitated by the addition of sodium bicarbonate in the cooking water.
