Question

What are reducing and non-reducing sugars? Give examples. What are their sources? How are they distinguished from each other?

Short answer

Answer: Reducing sugars are carbohydrates with a free aldehyde or ketone group, allowing them to reduce other compounds, while non-reducing sugars do not have this group and cannot reduce other compounds. Examples of reducing sugars are glucose, fructose, and lactose, while non-reducing sugars include sucrose and trehalose. They can be found in various sources like fruits, vegetables, grains, milk, and honey. To distinguish between them, chemical tests like Benedict's test or Fehling's test can be used, where reducing sugars react and form a precipitate, and non-reducing sugars show no reaction or precipitate.

Step-by-step solution

Definition of Reducing and Non-Reducing Sugars

Reducing sugars are carbohydrates that have a free aldehyde or ketone group, which allows them to reduce other compounds. In contrast, non-reducing sugars are carbohydrates that do not have a free aldehyde or ketone group, which means they cannot reduce other compounds.

Examples of Reducing and Non-Reducing Sugars

Examples of reducing sugars include glucose, fructose, and lactose. Examples of non-reducing sugars include sucrose and trehalose.

Sources of Reducing and Non-Reducing Sugars

Reducing sugars can be found in various sources, such as fruits, vegetables, grains, milk, and honey. Non-reducing sugars, such as sucrose, can be found in sources such as table sugar, fruits, vegetables, and some grains.

Distinguishing Between Reducing and Non-Reducing Sugars

One way to distinguish between reducing and non-reducing sugars is by using chemical tests such as the Benedict's test or Fehling's test. In these tests, the reducing sugars react with the test reagents, forming a precipitate, while non-reducing sugars do not react or form any precipitate.