3.1.2.3 Reducing and Non-Reducing Sugar Tests Flashcards Preview

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Flashcards in 3.1.2.3 Reducing and Non-Reducing Sugar Tests Deck (20)
1

What does it mean if a food sample turns benedicts solution this colour?

Low concentraiton of reducing sugar is present

1

What is a reducing sugar?

A sugar that can give an electron to the Copper (II) Sulphate found in Benedict's reagent to make it form a red Copper (I) Oxide precipitate. 

1

How would you carry out a Benedict's rest for a reducing sugar

  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

2

What do the followign instructions describe a test for?

  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

Non-Reducing Sugars

3

Which two reducing sugars are released when sucrose is hydrolysed?

Glucose

Fructose

3

What do we mean when we say that the Benedict's Test for Reducing Sugars is 'semi-quantitative'?

That the colour of the result can be used to estimate the approximate amount of reducing sugar in a sample

4

What does it mean if a food sample turns benedicts solution this colour?

No reducing sugar is present

5

Name a disaccharide that is a non-reducing sugar

sucrose

7

What does it mean if a food sample turns benedicts solution this colour?

Medium concentration of reducing sugar is present

8

What does it mean if a food sample turns benedicts solution this colour?

High concentration of reducing sugar is present

9

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

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

10


What do the following instructions describe a test for?

  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

A Benedict's Test for a Reducing Sugar

12

What does it mean if a food sample turns benedicts solution this colour?

Very low concentraiton of reducing sugar is present

13

What does this picture show?

The results of Benedict's test according to the concentration of reducing sugar present

14

What is a Non-Reducing Sugar?

A sugar that is unable to give an electron to the Copper (II) Sulphate in Benedict's Reagent so it is unable to form a red Copper (I) Oxide precipitate

15

Which types of sugars are all reducing sugars?

Monosaccharides

17

How would you test for a Non-Reducing Sugar?

  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

18

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

Hydrolysis

19

Name 2 common disaccharides that are reducing sugars

Maltose

Lactose

20

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

serial dilution

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