Reducing Sugars and Non-Reducing Sugars

The monomers of sugars are monosaccharides.
The polymers of sugars are polysaccharides.
Multiple polysaccharides create carbohydrates.
Sugars can be classified into two categories: Reducing and Non-Reducing.
The categories are dependent on whether or not the sugar is able to donate electrons.
This relates to whether the sugar can be oxidised.

The carbonyl group in reducing sugars can be oxidised.
Reducing sugars are able to donate electrons.#
This means that they can act as a reducing agent.
They can be detached using the Benedict test as they reduce the soluble copper sulphate to an insoluble brick red copper oxide.
To identify whether a substance is a reducing sugar, you can use the Benedicts Test.
Examples of Reducing sugars: Galactose, Glucose, Fructose, Maltose

Non-Reducing sugars cannot be oxidised.
Non-Reducing sugars cannot donate electrons.
This means that they cannot act as reducing agent.
To be detached they need to be hydrolysed to break the disaccharides into two monosaccharides before a Benedict test can be carried out.
To identify whether a substance is a non-reducing sugar you can do the following.
- Add the substance to dilute hydrochloric acid.
- Then heat it in a water bath that has been brought to a boil.
- Add an alkali, such as sodium hydrogencarbonate, to the solution to neutralise it.
Examples of Non-reducing sugars: Sucrose