9 Difference between Reducing and Non-Reducing Sugar (With Table)

Mar 13, 2022 · 3 min read ·

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Sugar is a type of carbohydrate that occurs abundantly in sugarcane and sugar beet plants. It comprises hydrogen, oxygen, and carbon in its structure.

These components help to tell if sugar is simple or complex. Some sugars have simple structures such as monosaccharides and others have complex structures like disaccharides.

The chemical behavior of these sugar structures helps to classify sugar into reducing sugar and non-reducing sugars. This is the best option of telling the differences between reducing and non-reducing sugars.

So, what is the main difference between reducing and non-reducing sugar? The former has free aldehyde or ketone groups while the latter does not have free aldehyde or ketone groups.

This article provides further differences between reducing and non-reducing sugars in tabular form. Take the time to read through the function of reducing sugar and examples of non-reducing sugar.

Comparison Table (Reducing vs Non-Reducing Sugar)

Basic Terms	Reducing Sugars	Non-Reducing Sugars
Meaning	It is a sugar that can act as a reducing agent due to the presence of free aldehyde or ketone groups	It is a type of carbohydrate that cannot act as a reducing agent due to the absence of free aldehyde or ketone group
Reducing Agents	A good reducing agent	Not a reducing agent
Chemical Properties	Have free aldehyde or ketone group	Do not have free aldehyde or ketone group
Fehling’s Test	Tend to give positive reaction towards Fehling’s test	Tend to give a negative reaction towards Fehling’s test
Sweet Test	Tend to have a sweet-tasting	Tend to have a little sweet taste
Sugar Class	Monosaccharide	Disaccharide
Benedict’s Solution Test	Tend to give a dark red color after the reaction	Benedict’s solution tends to retain its color
Molecular Weight	Comparatively low	Comparatively high
Examples	Monosaccharide examples are glucose, fructose, and galactose Disaccharide examples are lactose and maltose	Sucrose and trehalose

What Are Reducing Sugars?

Reducing sugars refers to any sugar that can act as a reducing agent due to the presence of a free aldehyde group or a free ketone group.

Most examples of reducing sugars have a sweet taste. Reducing sugars tend to play a vital role during baking.

All monosaccharides and some disaccharides are examples of reducing sugars. Monosaccharide examples are glucose, fructose, and maltose while disaccharide examples are lactose and maltose.

Both Benedict’s test and Fehling’s test can help to identify the presence of reducing sugar. It tends to reduce Cu+2 ions to Cu2O precipitate after a reaction.

What Are Non-Reducing Sugars?

Non-reducing sugars are typically carbohydrates that cannot act as reducing sugar since they tend to lack free aldehyde or ketone groups.

Besides that, non-reducing sugars tend to have a little sweet taste. The compound also does not generate an aldehyde group in an aqueous state.

Sucrose is a disaccharide which is the only example of non-reducing sugar readily available. The compound tends to have a negative test in benedict’s and Fehling’s solution.

Main Difference between Reducing and Non-Reducing Sugar

Reducing sugars tend to act as reducing agents whereas non-reducing sugars cannot act as a reducing agent.

Reducing sugars tend to contain aldehyde or ketone groups whereas non-reducing sugars do not contain either aldehyde or ketone groups.

Reducing sugars have more sweet tastings while non-reducing sugars have less sweet-tasting sugars

Reducing sugars tend to have a positive result in Fehling’s test while non-reducing sugars tend to have a negative result in Fehling’s test or Benedict’s test.

Examples of reducing sugars are fructose, glucose, and maltose whereas a non-reducing sugar example is sucrose.

Summary

The core difference between reducing sugar and non-reducing sugar is that reducing sugars are typically used as reducing agents whereas non-reducing sugar is not.

Examples of reducing sugars are all monosaccharides and some disaccharides, some oligosaccharides, and some polysaccharides. Sucrose is the only example of non-reducing sugar readily available.

More Sources and References

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