Quality control checking of Vitamin
C concentration in fruit juice
1) To understand how to complete a
titration experiment
2) To complete a quality control
practical.
What you will be marked on:
Vocational context
Any food or drinks organisation will need to
identify the level of different nutrients
(ingredients) in their product (for quality
control and packaging information).
This test will allow you to identify the
concentration of vitamin C in Sunny Delight.
Background information
1) DCPIP is a chemical which changes from
blue to clear (pink) when you add vitamin C to
it.
2) Titration is a method to accurately measure
how much of a chemical you have added.
3) By using known concentrations of vitamin
C we can work out the concentration of
vitamin C in a drink.
Titration
demonstration
Risk Assessment
Hazard
Risk level
Action
(Low, Med,
High)
Method
1) Use a pipette to add 2 ml of DCPIP
solution to the conical flask.
2)
Add 0.001% vitamin C solution to the
burette.
3)
Add the vitamin C to the conical flask
until the solution becomes clear.
4)
Record how much vitamin C was
added.
5)
Repeat with other solutions.
6)
Repeat this method with the unknown
Sunny Delight sample.
Results table
Vitamin C
solutions
0.001%
0.002%
0.003%
Titration 1
Titration 2
Titration 3
(Volume of vit (Volume of vit (Volume of vit
C solution cm3) C solution cm3) C solution cm3)
Mean Average
(cm3)
Calibration Graph
Volume of
Vitamin C
required
(cm3)
Vitamin C solution (%)
The Sunny Delight solution
Repeat the experiment sunny delight solution
(3 times and take an average).
Checking against the label
What is the concentration from the graph?
_____________ %
What is this in mg per 100 cm3
______________ mg / 100cm3
The sample was diluted by 10, so what was the original sample:
______________ mg / 100cm3
Evaluation
1) How did your result compare against the value
stated on the bottle?
2) What were the limitations of your practical?
3) How would you improve your result given
more time and extra money.
Demonstrating advanced calculations
The mean average calculation will get you the
basic marks (3/5).
Doing a standard deviation calculation
correctly will get you further marks:
Your calculation
√ (titration1 – mean)2 + (titration2 – mean) 2 + (titration3 – mean) 2
3-1
What you will be marked on: