Carbohydrates Classification

Carbohydrates are classified into simple carbohydrates (monosaccharides, oligosaccharides)
and complex carbohydrates (polysaccharides).

1. Monosaccharides

From Greek, mono = one, and sakkron=sugar. Monosaccharides are often called simple sugars. They are the simplest sugars and cannot be hydrolyzed.
The general formula is Cn(H2O)n. The monosaccharides are subdivided into trioses, tetrose, pentoses, hexoses,
heptoses, etc., Examples of monosaccharides are glucose, fructose, erythrulose, ribulose, etc.

• Glucose: The immediate source of energy for cellular respiration and “blood sugar”.
• Galactose: A sugar in milk and yogurt.
• Fructose: A sugar found in honey.

However, glucose is considered the fundamental unit of carbohydrates.

2. Oligosaccharides or Oligosaccharoses

In Greek, Oligo means few. Oligosaccharides are compound sugars that yield 2 to 10 molecules of the same or different monosaccharides on hydrolysis.

Oligosaccharide yielding 2 molecules of monosaccharides on hydrolysis is known as a disaccharide,
and the ones yielding 3 or 4 monosaccharides are trisaccharides and tetrasaccharides, respectively, and so on.

The general formula of disaccharides is Cn (H2O) n-1 and that of trisaccharides is Cn(H2O)n-2 and SO on.
Two monosaccharides can be linked to form a “double” sugar or disaccharide. Three common disaccharides are:

• Sucrose-common table sugar=glucose + fructose.
• Lactose-major sugar in milk=glucose +galactose.
• Maltose – product of starch digestion = glucose + glucose.

3. Polysaccharides

In Greek, poly means many. Polysaccharides are compound sugars and yield more than 10 molecules of monosaccharides on hydrolysis. They are further classified depending on the type of molecules produced as a result of hydrolysis.

They may be homo polysaccharides, i.e. monosaccharides of the same type, or hetero polysaccharides, i.e. monosaccharides of different types. The general formula is (C6H10O5)n. Examples of homo polysaccharides are starch, glycogen, cellulose, and pectin. Hetero polysaccharides are Hyaluronic acid and Chondroitin.