Sugar

SUGAR. This name applies to over i oo substances, having distinctive properties and scientific names; for example, sucrose, glucose, fructose, lactose, maltose.

Of the numerous sugars which occur in plants, sucrose (q.v.) is the most abundant and has been extracted commercially from sugar cane, sugar beet, maple tree, Indian maize, sorghum grass, and several species of palm. As it occurs in solution in the sap or juice, man's task is to extract the juice, and to convert the dissolved sucrose into the marketable crystals we call sugar. Therefore, cane sugar, beet sugar, maple sugar, etc., consist essentially of sucrose, admixed with small percentages of impur ities derived from the plant-juices. These impurities account for differences in col our, odour, and flavour of raw cane and beet sugars. When refined these sugars are colourless and odourless, have equal sweetening power, contain about 99.8% of sucrose, and cannot be distinguished by chemical analysis. After further purifica tion in the laboratory, they both contain 00% of sucrose.

The Sugar Cane.

This plant is a gi gantic grass, sometimes attaining, under favourable conditions of growth, a height of 20 ft. (See Plate, fig. I.) The average length of stalk is about 12 ft. The plant belongs to the natural order Gramineae, genus Saccharum, and is a perennial. It requires a moist and warm climate. Some varieties can only thrive in the tropics, others can be grown successfully in sub-tropical countries. The time re quired to reach maturity varies with climate and averages 13 months. The stems of different varieties vary in diameter from one half to nearly three inches, and are divided transversely by nodes (fig. I).

The stem has a hard, very thin skin or rind, varying in colour from pale yellow or green to deep purple and sometimes striped with two colours. The interior of the stem is solid, consisting of colourless fibrous tissue in which the juice is stored. The leaves are from 3 to 4 ft. in length and from 2 to 3 in. in width, a single leaf springing from each node, and on alternate sides of the stem.

Although the plant usually bears flowers and seed, it has always been propagated from cuttings of the stem, the attached "eyes" or buds (fig. I) then forming a clus ter or stool of canes.

When harvested, the canes are cut at the ground-level, the leafy upper joints (tops) cut off and reserved for planting mate rial, and the long stems transported to the sugar factory. They contain from II to 16% of sucrose, with a general average of 13%. The root-stock, left in the ground, remains alive and sends up new stems in successive years. On reaching maturity, most varieties produce an immense num ber of flowers, of microscopic size, forming a feathery plume called the arrow. This is borne on a stalk which grows erect from the top of the stem, to a height of 2 or 3 ft.

Since 1890, great efforts have been made to produce improved varieties of cane, following the example set in the beet sugar industry. For this purpose, the cane was raised from seed, and hybrid varieties obtained with greater resistance to disease.

The Sugar Beet.

This plant belongs to the natural order Chenopodiaceae, genus Beta, and belongs to the same family as the red garden beet and mangel-wurzel. The modern sugar beet (fig. 2) was evolved from a white beet (Beta Alba) formerly grown as a forage crop in Silesia. By systematic seed-selection, extending over many years, the sucrose content was gradu ally increased from about 5% in the Silesian root, to 20%, or even more. At the same time, the tap-root was much reduced in size, and the purity of the sap increased by a reduction in the saline impurities. The plant is a biennial, developing root and foliage and storing up sucrose during the first year's growth. During the second year, it sends up tall, branched shoots which flower and bear seed, after which the plant dies.

The tap-root consists of colourless parenchyma tissue, in which the juice is stored, and alternate layers of fibrous tissue. The ex ternal skin is usually white, but, in some varieties, pink. Fine root-threads extend from the sides and apex of the tap-root, to supply the plant with water and mineral plant-foods. The large leaves spring from the top, or crown of the tap-root, and spread laterally just above the ground. The flowers are very small, greenish in colour, and finally develop into the fruit or seed-ball. This is commonly called the seed, but contains from one to seven embryos (true seeds), and is used for propagating the plant.