Research Question: How the amount of vitamin C in fruit juices affects its freshness and till what extent is the information provided on the pack by manufacturers is reliable? Background Information:
-fresh juices have more vitamin C than long-life
-juice that is ‘not from concentrate’ is best in terms of vitamin content -if heat destroys vitamin C then heat-treated long-life juices will have lower concentrations -if heat destroys vitamin C then boiled fruit juice will have lower concentrations than unboiled -manufacturers generally provide reliable information about their products -the amount of vitamin C content in given fruits is:
So the amount of vitamin C and its percentage in fruit juice must go with the given ratio which means that guava and apple juice should have the highest and lowest concentration respectively. Variables:
6 test tubes,
50 cm3 burette,
3 small beakers,
0.1% ascorbic acid,
4 varieties of fruit juice, for example mango, grape, apple, guava etc. Preparation
Take a properly washed beaker and make 0.1% solution of vitamin C or ascorbic acid with 0.1 g of vitamin C in 100 cm3; this is 10 mg cm-3 or one may also use a readily prepared 0.1%ascorbic acid. Take a 0.1% solution of DCPIP.
Take 6 test tubes and label them as A, B, C, D, E and F. Now slowly pipette out 1cm3 of DCPIP solution into each test tube using a 1 cm3 pipette. Take 5cm3 of the 0.1%ascorbic acid using a 10cm3 pipette. Using a graduated pipette or a burette, add 0.1% ascorbic acid drop by drop to the DCPIP solution. Shake the tube gently after adding each drop. Add the acid solution until the blue colour of the...
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