The stability
of nutrients in food depends on their environment.
Nutrients can
be lost to varying degrees depending on whether the food is exposed
to light or air, acid or alkali, the temperature and their ability
to dissolve in water. Generally the losses of carbohydrate, fat, protein,
vitamin K, niacin, biotin and elements are small during processing
and storage. Greatest losses are usually seen with vitamins B-l and
C, with intermediate losses shown by vitamin A, provitamin A and vitamins
D, E, B-2, B-6, B-12, pantothenic acid and folacin.
Losses may be
due to destruction of the nutrient or by dissolving in water that
is later thrown away. The presence of acid (from other foods or addition
of vinegar) or alkali (from other foods or added sodium bicarbonate
(baking soda)) can cause destruction of some vitamins.
The stability
characteristics of nutrients are shown in Figure
32.
