What is sugar, Non sugar, Reducing sugar, Non reducing sugar?

Sugar:

• Substances which are water soluble, crystalline and sweet in taste are called sugar. 
• All monosaccharides and disaccharides are sugar.

Non sugar:

• Substances which are water insoluble and amorphous.
• Polysaccharides are non sugar.

Reducing sugar:

• They act as reducing agent in alkaline media.
• Presence of free aldehyde and or ketone functional group is responsible for this property of carbohydrate.
• All monosaccharides maltose and lactose are reducing sugars.
• Reducing property of sugar is tested by their ability to 
• Reduce alkaline CuSO4 solution (Positive Benedict's test)
• From osazone crystal with phenyl hydrazine
• Show maturation

Non reducing sugar:

• They do not contain free aldehyde or ketone as functional group.
• Their functional groups are usually engaged in glycosidic bond formation
• Sucrose is non reducing sugar.

What is carbohydrate? Classify Carbohydrate.

Carbohydrate:
The compound which on hydrolysis produces the substances having aldehyde or ketone functional group.

Classification:
1. Monosaccharide or simple sugar.

• The simplest form of carbohydrate which cannot be hydrolyzed further into further simple form of carbohydrate.
• These are of 3 to 9 carbons and serve as building blocks of all carbohydrate.
• Pentoses and Hexoses are the monosaccharides of greatest biological importance.
• Example: Glucose, Fructose, Galactose, Mannose, Ribose, Ribulose etc.

2. Disaccharide

• Carbohydrate produced by condensation of two monosaccharide units by glycosidic bond.
• Sugars that produce two molecules of same or different monosaccharide on hydrolysis.
• Example: Maltose (Consists of two glucose molecules)

                        Lactose (Consists of one glucose and one galactose)
                       Sucrose (Consists of one glucose and one Fructose)
3. Oligosaccharide

• Carbohydrate produced by condensation of 3 to 10 monosaccharide units by glycosidic bond.
• Example: Maltotriose, Raffinose, Blood group substances.

4. Polysaccharide:

• Polymer of monosaccharide composed of more than 10 monosaccharide units connected by glycosidic bond.
• Example: Starch, Glycogen, Cellulose, Mucopolysaccharide, Glycoprotein.