Sugars are of common occurrence in the vegetable world in the fruits and juices of many plants. Pure grape juice may contain as high as 25 per cent of glucose though usually it is not so concentrated. Glucose is also found in considerable amount in sweet corn and onions. It is not so sweet as
Fig. 48. - Composition of sugars cane sugar (sucrose). Fructose is one of the sweetest of sugars, and helps to give honey its great sweetness.
Lactose or milk sugar is found chiefly in milk. It is the least sweet of all the sugars. If there were as much cane sugar in milk, we should soon grow tired of it because it would be too sweet. It is sometimes added to milk to make its fuel value higher, especially in case the milk has been diluted, as in the diet of babies and invalids.
Maltose or malt sugar is formed from starch in germinating seeds.
Sucrose or cane sugar is most commonly manufactured from sugar cane and sugar beets. To a much smaller extent it is made commercially from the sugar maple, sorghum cane, and sugar palm, and it is found in considerable amount in some common fruits and vegetables.
Its manufacture forms a great industry, and its consumption is enormous, some ten million tons coming into commerce annually, and this does not represent the total consumption.
Figure 48 shows the composition of several common sugars. Notice that the granulated sugar is a pure foodstuff, being 100 per cent carbohydrate, while all the others contain traces of protein, ash, and water. Sugar is a fuel food, exclusively, like olive oil and other pure fats.
Sugar is a valuable food material, but should not be used in excess; the tendency in the United States is rather toward an excessive use of sugar. It is liable to cause an acid fermentation in digestion, when taken in large amounts, and is sure to irritate the stomach. It should be well diluted by other foods. The amount that may be eaten daily varies for most people from two ounces for young children to four ounces for adults, but many people cannot eat these amounts without more or less irritation of the stomach. It is a common practice to oversweeten cakes and desserts, the sweetness of the sugar often disguising other agreeable flavors. The liking for sweets should be well under control, for the eating of too much sugar is a habit easy to form, and one which crowds out other valuable foods.
Cane Sugar is sold both brown and white, and is manufactured in powdered, granulated, and solid form, the latter usually cut in cubes or dominoes.
The canes are first crushed, the juices passing from the machine being of a rather dark greenish color. This juice is first clarified and filtered, and then boiled down in order to crystallize the sugar, the liquid sirup forming molasses. In the older methods the sirup was boiled in open pans, and the crystals filtered from the molasses by a slow process. In the modern process the sirup is boiled at a low temperature in vacuum pans, and the sugar is separated from the molasses by a centrifugal machine, built on the same principle as a cream separator. The principles of beet sugar manufacture are essentially the same, with some differences in detail.
The molasses manufactured in the older method is richer in cane sugar and is a better table molasses than the new process molasses, the latter being used chiefly for the manufacture of alcohol. Molasses is either dark or light, the darker having a stronger flavor especially suited to gingerbread and Indian meal pudding. Molasses comes in the bulk, and may be slightly acid; or in cans, in which case no acid fermentation should have taken place. Where canned molasses is used in a batter, it is sometimes necessary to use baking powder instead of soda. "New Orleans" is a light-colored molasses, "Porto Rico" dark.
Brown sugar has not passed through the refining processes necessary to the whitening of the sugar. It is softer than the granulated white, has a decided brownish color and a rich flavor.
In buying sugar it is economy to purchase granulated in large quantities, a fraction of a cent per pound being saved in this way. The cut sugar comes in convenient boxes, which keep the product clean. Powdered sugar may be bought in small quantities, three or five pounds, since it is not used so much in cooking as the granulated.