Carbohydrates or Saccharides make up 50 % of the dry biomass of the earth and are therefore the most frequent class of biomolecules. Besides at least two hydroxy groups, they also have an aldehyde or a ketone group and can be subdivided according to the number of monomeric components in mono-, di-, oligo and polysaccharides.
Whereas mono-, di- and oligosaccharides are soluble in water, taste sweet and are therefore called as sugar, polysaccharides are hardly, or not at all, soluble in water and have a neutral taste.
Carbohydrates, together with fats and proteins make up a large percentage of nutrition. In addition to their central role as an energy source, they are also an important structural component especially in plants (e.g. Cellulose). Ribose, a monosaccaride with five carbons (C5H10O5) is an essential element of coenzymes (such as ATP, FAD and NAD) and a structural component of RNA. Desoxyribose (a ribose derivative) is a structural component of DNA.
Disaccharides
Disaccharides consist of two monosaccharide units. These are interlinked covalently via a glycocide bond. The most familiar representatives are saccharose, lactose and maltose.
Appearance | white to almost white powder |
Heavy metals | ≤0.0005 % |
Specific rotation [α]20D | +54.4° to +55.9° |
Loss on drying | ≤0.5 % |
Sulphated ash | ≤0.1 % |
Water | 4.5-5.5 % |
Absorbance | |
400 nm | ≤0.04 |
210-220 nm | ≤0.25 |
270-300 nm | ≤0.07 |