Preparation and consumption of raw vegetables
Fruits and vegetables provide the highest percentages of nutrients if properly cleaned and eaten raw, though there are many vegetables whose nutrition is improved by cooking, such as carrots for beta carotene, some leafy greens, and tomatoes which, when cooked, increase their level of usable lycopene (though they lose a bit of their vitamin C).
The majority of the nutrients are contained in the outside parts of the vegetables, so when removing the external parts of the vegetable, or damaged or withered sections, care must be taken to remove the least possible amount, for example when peeling celery and carrots or removing the outer leaves of spinach, lettuce, etc.
Cleaned vegetables eaten raw give the maximum amount of their nutrients and antioxidants, so 8 out of 10 portions consumed should be raw if possible.
Eating fruit with the peel, when this is edible, is a good habit because it increases the intake of fibre.
The peel protects the fruit and preserves the vitamins contained in the pulp from oxidation (air and light).
If eaten in pieces or peeled, fruit should be eaten immediately and the same goes for juices or smoothies that should be drunk as soon as you have made them.
Some vegetables are cooked to soften the cellulose and make them tastier and more edible.
The most frequent cooking methods are boiling, steaming, grilling and baking; during cooking, important parts of minerals, vitamins and nutrients that are soluble in water and subject to deterioration may be lost due to exposure to heat.
During boiling, water-soluble minerals and vitamins such as vitamin C and those of the vitamin B complex, which are also subject to deterioration due to heat, dissolve in water.
The minerals, though, can be recovered if the water the vegetables are cooked in is consumed as well.
Steaming vegetables and fruit prevents the nutrients from dissolving.
Some vitamins, however, deteriorate due to the heat of cooking, and should be steamed for as short a time as possible.
Using a pressure cooker, vegetables can be cooked much more quickly.
Baking or grilling causes the vegetables and fruit juices to be released during the cooking; as this liquid carries some of the minerals and vitamins, cooking time should be as short as possible.
In any case, lightly cooked vegetables and fruit preserve more nutrients.
Baking fruit with its peel preserves fibre in quantities similar to raw fruit.