Sugar Definition

Sugars are carbohydrates which are soluble, have a more or less sweet taste and many minor qualities which distinguish them from the starches. The disaccharides yield monosaccharides under the influence of enzymes or on boiling with dilute acids. When heated to a high temperature sugars form caramel. In dietetics we are especially concerned with grape sugar (dextrose), milk sugar (lactose) and cane sugar (sucrose).

Substitute For Sugars

Since sugar is used not only as a fuel food but as a condiment, attempts have been made to secure a substitute for use in cases where carbohydrate is limited or denied. The best known of these is "saccharin" or "sweetina," a crystalline coal-tar product. It is many times sweeter than sugar, but it has no food value.

Use Of Sugar In Practical Dietetics

Sugar taken in small quantities will replace starch weight for weight, and be more easily and quickly absorbed. The amount of sugar which can be taken in place of other fuel food depends on the amount of exercise and the peculiarities of the individual. An excess of sweets may cause nausea and always blunts the appetite, thus cutting down the consumption of other foods. If a very large amount be taken, sugar will appear in the urine. The maximum advisable daily allowance of sugar is considered to be about four ounces.

Sugar should be avoided in gastric disorders, such disturbances of nutrition as gout, rheumatism, and especially diabetes. Being a highly concentrated food, it should be avoided in obesity.

Uses Of Sugar In Cookery

Glucose is not so sweet as cane sugar, so that when used for sweetening other foods a larger amount must be taken. In cooking fruits, sugar should be added when the process is nearly complete, as it tends to harden the fruit tissues. By boiling for a long time or in the presence of acids (whether naturally in the fruit or added to it) cane sugar is changed to invert sugar, which is a mixture of equal parts of dextrose and levulose. While dextrose is not so sweet as cane sugar, levulose is very much sweeter, so that the resulting product has a peculiar, penetrating sweetness that is not so well liked as the cane sugar flavor. This is another reason for reserving the sugar till the end of the cooking process.

Test For Sugar

A simple test for sugar, irrespective of whether it is glucose or cane sugar, consists in adding a little 33 per cent. solution of caustic soda to the suspected solution, and boiling. If sugar is present the solution turns brown.

The chief test for glucose or grape sugar alone is Fehling's. A test solution should be on hand, and may be obtained at any apothecaries. It should be obtained fresh. The test is based on the fact that glucose "reduces" salts of copper, i. e., by depriving them of some of their oxygen, an insoluble oxide of copper is precipitated. The test solution contains sulphate of copper, caustic potash and tartrate of sodium and potassium. To make the test, add to a portion of the test solution a few drops of the suspected solution in a test tube and boil. If a red substance precipitates, glucose is present. The sole use of this test for the nurse will probably be in connection with diabetes, when the nurse makes the test at the request of the medical attendant. In all other tests for sugar, the first test mentioned above will suffice, and would also suffice for diabetic urine were it not for the fact that a shamming patient could deceive the nurse by placing common sugar in her urine.