_Water._--All fluids and tissues of the body contain large quantities of
water, therefore water is regarded as one of the most important
food-stuffs required by the body. Practically all foods contain some
water. Fresh vegetables and fruits provide the body with a high
percentage of water.
Water is a valuable medium for cooking. As it heats, small bubbles are
formed, which continually increase in number and size, but gradually
disappear. Some time before the boiling-point is reached, an occasional
large bubble will rise to the surface and disappear. The water has then
reached the simmering-point, 185°, a temperature frequently made use of
in cooking. When many bubbles form and break, causing a commotion on the
surface of the water, the boiling-point, 212°, has been reached.
_Mineral matter._--Mineral matter is a second food-stuff that is needed
by the body, but the amount required is very small. If a variety of food
is used, there is generally sufficient mineral matter in the diet.
Fruits and vegetables, especially fresh green vegetables, are
comparatively rich in mineral matter. Mineral matter builds up the bones
and certain tissues, such as the hair, teeth, and nails, and regulates
the body processes by keeping the blood and digestive fluids in proper
condition.
_Green vegetables._--Green vegetables hold an important place in the
diet, because they contain valuable mineral matter. They also contain a
high percentage of water and considerable cellulose. With few exceptions
they should be eaten raw, because the mineral salts, being soluble, are
lost in the water in which they are cooked and because the cellulose
serves its purpose best in the crisp form. Cabbage is rendered much more
difficult of digestion by cooking. Spinach, beet tops, etc., are more
palatable when cooked. The delicately flavoured vegetables should be
boiled in a very small amount of water, so that they need not be
drained. Thus the mineral matter will be retained when the vegetables
are served.