Food Testing

Question 1

What is a reducing sugar ?

Answer 1

A reducing sugar is able to lose (oxidation) and give it to another compound.

Question 2

What is reduction?

Answer 2

Reduction is the gain of molecules

Question 3

How do we test for reducing sugars?

Answer 3

By adding Benedict’s Reagant.

Question 4

What does Benedict’s contain and the colour?

Answer 4

It’s blue and contains Cu2+ ions in the form of copper 2 sulfate.

Question 5

Why does the Benedict’s reagant turn red?

Answer 5

This is because the molecule contains a reducing sugar so when the Cu2+ ion gains an electron from a reducing sugar they become Cu+ in the form of red copper 1 oxide.

Question 6

How to test for a reducing sugar?

Answer 6

1. Add Benedict’s
2. Heat it up
   3.Look for a colour change.
3. should turn from blue to Red

Question 7

What are some of the possible results?

Answer 7

B - neg
G- v. Low
Y- low
O- mod
R- high

Question 8

What is the meaning of semi quantitative results?

Answer 8

This gives an idea of concentration not fully quantitatively

Question 9

How to test for non- reducing sugars?

Answer 9

1. get a negative Benedict’s test
   2.Boil with HCL to hydrolyse non-reducing sugars
   3.Neutralise HCL using NaOH
   4.Add Benedict’s
   5.Heat
   6.Colour change from Blue to Red.

Question 10

How to test for starch?

Answer 10

Use iodine solution.
Should go from orange to black.

Question 11

On a colorimeter what is the number called?

Answer 11

It’s called an absorbance reading. The higher the value, the more light being absorbed/blacked. 1= max conc, 0 =dilute.

Question 12

What is the number also called on a colorimeter

Answer 12

It is called a transmission value. The higher the number, the more light that can pass through. 0 = max conc, 1 = dilute conc.