Sugar

Sugar, another important form of carbohydrate, is mainly of vegetable origin, except that which is found in milk and called lactose. This, together with the fat found in milk, supplies the child with energy before it is able to digest a variety of foods. The sap of various plants contains such large quantities of sugar that it can be crystalized out and secured in dry form. The liquid that remains is valuable as food, for, by boiling it down, it forms molasses. Sugar is also present in considerable amounts in all fruits, and much of it is in a form that can be assimilated, or taken up by the body, quickly. A sugar very similar to this natural fruit sugar is made from the starch of corn and is called glucose. Much of the carbohydrate found in vegetables, especially young, tender vegetables, is in the form of sugar, which, as the vegetables grow older, changes to starch.

Sugar melts upon the application of heat or, if it is in a melted condition, as sirup or molasses, it boils down and gives off water. When all the water has boiled away, the sugar begins to caramelize or become brown, and develops a characteristic flavor. If the cooking is continued too long, a dark-brown color and a bitter taste are developed. Because the sugar in fruits and vegetables is in solution, some of it is lost when they are boiled, unless, of course, the water in which they are cooked is utilized.