Foods which enable the body to work are termed energy-giving or fuel foods.
There are a number of energy-giving or fuel foods: sugar is the first one to be considered.
EXPERIMENT 10: THE SOLUBILITY OF GRANULATED SUGAR IN COLD WATER--Place half a teaspoonful of granulated sugar in a test tube, add a little cold water, shake. Is the mixture clear? Set it aside for a few minutes. Does the sugar separate from the water?
EXPERIMENT 11: THE SOLUBILITY OF GRANULATED SUGAR IN HOT WATER.--Dissolve half a teaspoonful of granulated sugar in hot water. Compare with Experiment 10. Which dissolves sugar more readily,--cold or hot water? If you desired to dissolve some sugar quickly, at what temperature would you have the water?
EXPERIMENT 12: THE SOLUBILITY OF POWDERED SUGAR.--Dissolve half a teaspoonful of powdered sugar in the same quantity of hot water used in Experiment 11. Does it dissolve more readily than granulated sugar? Explain this difference. If you desired to dissolve some lumpy sugar quickly, how would you prepare it?
THE DIGESTION OF SUGAR.--Since sugar is so readily dissolved, and since dissolving is an important step in the process of digestion (see Solution and Digestion), it would seem that the digestion of sugar would be easy. Some sugars, such as glucose, need no digestion in a chemical sense, and are wholesome provided their solution is not too concentrated. The digestion of other sugar, such as granulated sugar, is slightly more complex.
Because the digesting of some sugar is simple, one should not conclude that this food should be used in large quantities or in preference to other fuel foods. If sugar is eaten in large quantities there is so much dissolved sugar for the organs of digestion to take care of that the stomach and small intestines become irritated. This is especially true when candy is eaten between meals,--at a time when the stomach is empty. Then, too, it may ferment in the stomach or intestines and produce digestive disturbances. All sweets should be eaten only in moderation and either during a meal or at its close. When sugar is mixed with other foods, it is diluted, and is not so apt to cause distress.
SUGARS AND SIRUPS.--In various plants and in milk, the chemist finds a number of different kinds of sugar. These may be classified into two groups:--(1) single sugars and (2) double sugars. Dextrose or glucose is one of the single sugars, while sucrose or cane sugar is an example of a double sugar.
The solid sugars and sirups found at market and having different trade names consist of one or more of the different kinds of sugars. A discussion of these follows:
(a) Granulated sugar is made either from the sugar cane or sugar beet. The juice is pressed or soaked out of these plants, then purified, refined, and crystallized. Powdered sugar is prepared by crushing granulated sugar. Confectioners' sugar is a very finely ground form of cane or beet sugar. Granulated sugar is 100 per cent sugar. Crushed sugars sometimes contain flour or other materials.
Brown sugar is made from the cane or beet, but is not refined as much as is granulated sugar. It contains some ash and moisture.
(b) Corn sirup is made by boiling corn-starch with an acid and then refining the product. This sirup contains no cane sugar. Its sweet flavor and sirupy consistency are due to the presence of 38.5 per cent glucose and 42 per cent dextrin. Glucose is not as sweet as granulated sugar. Hence, in depending upon corn sirup alone, the tendency is to use more sugar than is advisable so as to satisfy our taste for sweets. At least 1 1/2 times as much corn sirup as granulated sugar is needed to produce the sweetness of the solid sugar. A mixture of corn sirup and granulated sugar is often used for sweetening foods.
(c) Molasses and Sorghum.--Molasses is a by-product of cane sugar. In addition to sugar, it contains certain mineral materials such as lime. Since it is especially necessary that foods given children contain lime, the use of molasses in place of sugar may be recommended for children.