- a Monosaccharids
- b Disaccharids
- c Polysaccharids
The principal subdivisions found in these classes of carbohydrate foods are given in the following table, arranged in the order of their importance:
| Monosaccharids | Disaccharids | Polysaccharids |
|---|---|---|
| 1 Glucose or grape-sugar | 1 Cane-sugar | 1 Starch |
| (formerly called dextrose) | ||
| 2 Pentoses | 2 Maltose | 2 Glycogen |
| (of which there are several) | 3 Lactose | 3 Cellulose |
| 3 Levulose | 4 Gums | |
| 4 Galactose | 5 Inulin |
a MONOSACCHARIDS
1 GLUCOSE OR GRAPE-SUGAR (C6H12O6)
Glucose or grape-sugar is the most important sugar known from the standpoint of the physiological chemist. This sugar is normally found in considerable quantities in human blood, and is absolutely essential to the life-process, a fact which forms an amusing contrast with the popular conception of the term glucose as something injurious or poisonous.
Sources of glucose
Glucose is found in honey, and in nearly all fruits, grains, and sweets. (For "Sweets" see Lesson VIII, Vol. II, p. 324). It may be taken into the human body directly from such fruits, or it may originate by the digestion of other carbohydrates.
Pure glucose crystallizes and resembles cane-sugar, but is not so sweet. The glucose of commerce, sold as sirup, is a product manufactured from corn, or other starches, and will be considered more in detail under the heading starch. (See "Polysaccharids," p. [114]).