Does anyone have information on how to test the Vitamin C content of different fruits?
We do a simple practical using 5 different juices: freshly squeezed orange juice, bottled 100 percent cordial, lemon juice and boiled orange juice as comparisons. You could also use grapefruit but note that if you were using, for example, strawberry then you would not be able to see the colour change of the DIP solution easily.
Make up a 0.1 percent solution of DIP (2,6-DICHLOROINDOPHENOL SODIUM SALT), which can be obtained from Southern Biological Services Pty Ltd. It is expensive and comes in very small quantities. It must be a fresh solution.
In the prac:
(1) Add 20 drops of DIP to a clean, dry test tube.
(2) Add the juice to be tested to the DIP. ONE DROP AT A TIME and gently shake the tube to mix the contents after each drop. Count the number of drops of juice it takes to turn the DIP colourless.