Cooking can be
both detrimental and beneficial to the nutrient content of food.
effects of cooking
Cooking is important
in food processing. Although cooking results in the loss of some nutrients,
it can also convert other nutrients into a form that would otherwise
not be used by our bodies. Cooking also produces the desired texture,
flavour and palatability we want in our food.
such as potatoes, corn, beans, and lentils are made more digestible
by cooking. The nutritive value of the protein in legumes such as
soya beans, lima beans, lentils and chick peas is also improved by
cooking. Heating these foods destroys substances that would otherwise
interfere with the digestibility of the protein. Adequate cooking
of the foods is particularly important when they comprise the main
source of protein. Other substances in soya beans, kidney beans and
lentils can produce toxic effects unless cooked prior to eating. Egg
whites and some fish, unless cooked, are not an effective source of
the vitamins biotin and vitamin B-1 respectively. Heating flour during
baking increases the amount of niacin that can be utilized by the
Cooking is also
necessary to ensure that food is free from harmful levels of micro-organisms.
As well as causing undesirable flavours and odours in food these organisms
can sometimes lead to illness.
loss during cooking
Losses of protein
and carbohydrate during cooking are generally small. The amount of
fat in food may be either reduced or increased depending on the method
of cooking. Generally, grilling will lower the fat content and frying
will increase it. The smaller the size of the pieces being fried,
the greater the amount of fat that will be absorbed per 100 grams.
The largest vitamin loss during cooking is usually due to destruction
of vitamin C, and to a lesser extent vitamin B-1 and the other water-soluble
vitamins. A few simple guidelines for maximizing vitamin retention
during cooking are listed in Figure
involves cooking at higher temperatures for shorter times compared
with normal boiling. Because the vegetables are in contact with steam
rather than boiling water, less of the water-soluble vitamins dissolve
in the cooking water. Generally, pressure cooking will retain more
nutrients than normal boiling. However, food steamed or boiled in
a small amount of water in a tightly covered saucepan is likely to
be as nutritious as food cooked in a pressure cooker.
is much quicker than conventional cooking. The microwaves preferentially
heat the water in food so that the cooking process is essentially
similar to that of steam cooking. With meat, the differences in vitamin
B-l and vitamin B-2 retention between microwave cooking and conventional
grilling or roasting are small. With vegetables, the vitamin C in
microwave-cooked food is similar to that achieved by cooking with
steam or using a small amount of water in a tightly covered saucepan.
Generally, microwave cooking retains nutrients as well as conventional