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.