“…the choice of cooking method is far from trivial…” Not only does proper nutrition mean choosing a good variety of food to eat. It means that the processing and cooking of foods should be designed for maximizing the preservation of beneficial chemicals which they contain.
Cooking prolongs the storage time of foods, kills bacteria, improves digestibility, improves flavor and aroma, and deactivates anti-nutrients*. The negative results of cooking include destroying vitamins (especially vitamins B and C), destruction of amino acids, and loss of minerals and vitamins into cooking water. Also, cooking can inactivate proteins in meat, and causes the formation of toxic substances.
Microwave and pressure cooking preserve phenolic** chemicals in vegetables compared to boiling. Some vegetables are eaten raw, but legumes require cooking to destroy natural anti-nutrients which block digestion and may cause health problems. Boiling and steaming of vegetables is done at around 100 degrees centigrade, which may destroy nutritional substances.
Sous-vide*** (pronounced ‘soo veed’) cooking is offered as an alternative method to maintain nutrients, minerals, and vitamins. Vitamin C, anthocyanins, and polyphenols were shown to be better preserved after this manner of cooking. The result is food with the anti-oxidant value of foods cooked at lower temperatures and freedom from oxygen species.
Sous-vide cooking is putting foods in heat-stable pouches and cooking them slowly around 90 degrees C. In addition to producing more nutritious foods, it is more tasty and aromatic than boiled food. The pouch reduces the oxidation damage to chemicals such as carotenoids and chlorophyll by reducing the exposure to oxygen. Also, such food can be stored longer.
The study reviewed was to compare sous-vide prepared food with boiled food in regard to total mineral content and amounts of specific minerals in cereals and legumes. Magnesium, potassium, iron, zinc, and copper were tested in 50 samples of legumes (red lentils, peas, Borlotti beans), as well as grains (pearl barley and cereals soup). These were tested after cooking with sous-vide and compared with traditionally cooked (boiled) foods.
All tests after sous-vide cooking resulted in increased mineral levels except the following: Potassium in cereal soup, iron in Borlotti beans, and magnesium in pearl barley. The total ash**** content was increased in sous-vide cooked foods compared to traditionally cooked foods. Boiled foods tend to lose 20 to 40% of mineral content; sous-vide food has not been tested before in the same manner.
CONCLUSION: Sous-vide cooking is a new method with nutrition and health benefits. Mineral contents of foods prepared this way are, in general, preserved. Legumes and cereals were tested.
NOTES: *Anti-nutrients interfere with absorption of certain chemicals or block digestion. They include phytic acid, tannins, and lectins.
**Natural phenolics play a role in cancer prevention and have other medicinal health impacts.
***Sous-vide means under vacuum.
****Ash content is the total amount of a specific mineral in a food.
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