Cane Sugar is the clarified and crystallised juice of the sugar cane, but may be made also from beetroot. To the ordinary consumer the source of the sugar, whether from cane or beet, is indistinguishable, but for the manufacture of fruit syrups and British wines sugar from cane is said to be less liable to fermentation. Commercial sugar is extracted from sugar cane and the juice of the compressed beetroot by a process of refining which produces commercial white sugar of various grades. The principal steps in this process are as follows: - (1) Melting of the sugar; (2) straining through filters; (3) filtering through charcoal; (4) boiling or evaporating the decolorised liquid in vacuum pans; (5) separation of crystallised sugar by centrifuge.
Coarse brown sugar is somewhat impure and has a slightly laxative action; it is not cheaper than the more refined varieties.
Maple sugar is derived from the sap of the sugar maple of North America. The bark is tapped in early spring, and allows the sap to escape as it flows upwards. The sap is evaporated, the sugar crystallises out, and the residue is used as maple syrup.
There is no chemical difference between maple sugar and the other two described above, but it contains certain ethereal substances which give it its peculiar flavour. Maple sugar is chiefly used as a confection.
Molasses, treacle, and syrup are by-products formed during the process of refining the above sugar. The first two, owing to impurities, are more laxative than golden syrup, but all contain besides sugar - acids, extractives, salts, and mere or less impurities.
Heat applied to sugar makes it change its crystalline form. When strongly heated it melts into a yellowish liquid, and on cooling it does not crystallise, but forms a transparent, brittle mass - familiar as barley sugar. Sugar candy is made by extremely slow crystallisation. Caramel is made by heating refined cane sugar to about 400° F., when it is melted, browned, and converted into a non-crystallisable fluid with a distinctive "caramel" flavour. Caramel may be added to insipid invalid foods such as milk, custard, farina, arrowroot, and the like.
Confectionery and sweets are made from cane sugar or glucose (grape sugar), with the addition of butter or other fats, nuts, fruits, starch, and flavouring extracts. Sweets in moderation are good for growing children. There is no proof that sugar is harmful to the healthy, although doubtless sweets which adhere to the teeth undergo fermentation with the production of acids which attack the teeth.
Though one of the same group of sugars as cane, etc., it varies very considerably in chemical and physical properties. When taken in the form of malt extract the sugar is less apt to irritate the stomach, and although not capable of direct absorption as such, maltose may yet be regarded as a partially digested form of carbohydrate. Malt sugar is formed in the process of malting. The grain is roasted in a kiln till it shows signs of sprouting, when the temperature is raised to arrest further growth. The grain is now called malt, and is brownish, some of the starch having been changed into dextrin and part of it into sugar. The object of the malting is to convert the insoluble starch into the soluble sugar and dextrin (see Malt Extracts, p. 178).
Lactose, Or Milk Sugar, is the carbohydrate of milk. It differs from cane sugar in its flavour, being almost tasteless. It is hardly possible to ferment it by yeasts. It is therefore very useful in cases of stomach derangement with fermentation. It is readily split up by micro-organisms to form lactic acid.
Mannite is obtained from the sweet juice of the stems of the ash tree; it is found also in beetroots and some other vegetables. Like sucrose, it crystallises and is white. It does not ferment with yeast. It is laxative, and may be used in diabetes, not being excreted in the urine as glucose.