3.1.2.3 Reducing and Non-Reducing Sugar Tests

Question 1

What is a reducing sugar?

Answer 1

A sugar that can give an electron to the Copper (ll) Sulphate found in Benedict’s reagent to make it form a red Copper (l) Oxide precipitate

Question 2

How would you carry out a Benedict’s test for a reducing sugar?

Answer 2

1. Add 2cm3 of the food sample to a test tube
2. Add an equal volume of Benedict’s reagent
3. Heat the mixture in a boiling water bath for 5 minutes
4. Observe colour change

Question 3

Which two reducing sugars are released when sucrose is hydrolysed

Answer 3

Glucose

Fructose

Question 4

Name a disaccharide that is a non-reducing sugar

Answer 4

Sucrose

Question 5

During a Non-reducing sugar test, why do we need to neutralise the food sample after heating it in acid?

Answer 5

Because Benedict’s reagent will not work in acidic conditions (ideally alkaline)

Question 6

What is a non-reducing sugar

Answer 6

A sugar that is unable to give an electron to the copper (ll) sulphate in Benedict’s reagent so it is unable to form a red copper (l) Oxide precipitate

Question 7

Which types of sugars are all reducing sugars?

Answer 7

Monosaccharides

Question 8

How would you test or a Non-reducing sugar?

Answer 8

1. Boil the sample with hydrochloric acid
2. This will hydrolyse any disaccharide into 2 monosaccharides
3. Cool solution and neutralise with sodium hydrogen carbonate
4. Add Benedict’s reagent and heat
5. Observe colour change

Question 9

The process of breaking a disaccharide up into 2 monosaccharides is called…

Answer 9

Hydrolysis

Question 10

Name 2 common disaccharides that are reducing sugars

Answer 10

Maltose

Lactose

Question 11

What method would you use to produce different concentrations of sucrose from a concentrated sucrose solution?

Answer 11

Serial dilution