The chemical name of vitamin C is
Ascorbic Acid, C6H8O6.
Figure 1: Part of the molecular structure of vitamin C.
Ascorbic Acid is one of the thirteen vitamins that are solvable in water.
The advantage of this vitamins is that it is very hard to take an overdoses. Your body does not use all the vitamin C you have eaten, this excess of vitamin C just ‘flushes’ away. That is why it is better to eat food which contains vitamin C instead of eating vitamin C pills. Eating your vitamin C with food results in a better absorption of the vitamin.
Vitamin C is an important vitamin, it has a lot of positive effects. Meanly sportsman need vitamin C. Because during the performance a lot of vitamin C is used by the convert from carbohydrate to energy. Vitamin C is also concerned with other things.
It keeps your bones, teeth and gum healthy. It keeps your joints smooth and it is a hardly involved with the production of collagen. Collagen plays an important role in the growth and recovery of connective tissue (your skin). Studies have proved that one gram vitamin C per day can lower your cholesterol percentage. When you have a cold, extra vitamin C will decrease your ‘cycle’ ( from five days) with one day. Natural vitamin C (kiwis, oranges..) is chosen above vitamin C pills. The most important ‘task’ of vitamin C is the role of antioxidant, and the help the vitamin gives to the vitamins A and E with fulfilling their antioxidant tasks. Antioxidants are also very important. They prevent oxidation reactions in your body.
Humans, human apes, bats and guinea-pigs are the only creatures that cannot make their own vitamin C. Because of a gene defect we cannot make the enzyme L-gulonolactione oxidase. Without this enzyme we cannot complete the last step of the synthesis of vitamin C. We cannot make the vitamin ourselves, that means we have to eat food which contains vitamin C. A lot of food contains vitamin C, the most important are vegetables, fruit and potatoes. Much food has added vitamin C, the vitamin is a preservative. The E-number is E300.
Figure 2: Vitamin C under the microscope
Juices mostly have added vitamin C, but some juices contain only real fruit juice. Which of them contains more vitamin C? This is the research question; Which juice contains more vitamin C, homemade orange juice, Appelsientje, fanta or Surango?
Our hypothesis is that the homemade orange juice will contain the most vitamin C and that the Fanta contains the least. The Appelsientje costs more and has a better reputation, that is why we think that this juice contains more vitamin C than the Surango.
Experimental procedure and approach
For a perfect measurement a buret is used. 90mL distilled water and 10mL acetic acid are used to make a diluted acetic acid solution. For the inquire 2mL diluted acetic acid is mixed with 2mL juice. This solution is used for the inquire.
The DCPIP-solution was poured into the buret. Then a beaker is filled with 2 mL orange juice and 2 mL acetic acid. Carefully the DCPIP-solution is dripped into the beaker. The dripping is stopped when the colour of the concoction changes into red. After that the used amount of DCPIP-solution is read from the buret.
This was repeated four times with different juices. The first time with homemade orange juice, then with Surango, next Appelsientje and the last time with Sinas. Homemade orange juice is made from fresh oranges, Surango is a cheap juice, Appelsientje has a good reputation and Sinas is a soft drink. The juices were tested two times for the reliability.
Figure 3: The experimental set-up
All four juices changed colour from yellow to red. When the DCPIP-solution reacted with vitamins C the colour changed. This is the equivalence-point. The used DCPIP-solution in mL is reported in table 1.
The proportion between DCPIP and vitamin C is 1:1.
To calculate the percentage vitamin C in grams in the juices, known fact are needed.
The molecular mass of DCPIP is 326,11 gram and the molecular mass of vitamin C is 176,13 gram. 185 mg/L DCPIP-solution is used.
Used DCPIP (mL)
Used DCPIP (mL)
Table 1: Used DCPIP-solution in mL.
185 mg/L : 1000 = 0,185 g/L
9,61e10-3 L x 0,185 g/L 1,78e10-3 g.
This gives the used amount of DCPIP-solution in grams.
1,8e10-3 : 326,11 5,45e-6 mol
This shows the used amount of DCPIP-solution in mol.
5,45e-6 mol x 176,13 9,60e-4 g
When the amount of used DCPIP-solution in mol is duplicated with the molecular mass of vitamin C, the amount of vitamin C in grams in the juices is calculated.
This calculation is done with all the juices, the results are given in table 2.
Vitamins C (grams)
Vitamins C (grams)
Table 2: Percentage vitamin C in grams.
Figure 4 shows the measured amounts of vitamins C in grams versus the different juices.
Figure 4: Measured amount of vitamin C (gram) vs different juices.
Figure 5 shows the average amounts of vitamins C in grams versus the different juices.
Figure 5: Average amount of vitamin C (gram) vs different juices.
Discussion and conclusion
The results (table 1) of the titrations show that the homemade orange juice used the most DCPIP-solution. That means this juice contains the most vitamin C. The vitamin C percentage of the Surango comes next. The Appelsientje contains less vitamin C than the Surango. The Fanta contains the least vitamin C.
These results do not entirely support the hypothesis that the Surango contains less vitamin C than the Appelsientje.
The hypothesis does support the fact that the orange juice contains the most and the Fanta contains the least percentage of vitamin C.
The hypothesis is based on the reputation and price of the juices. The results show the opposite. The Surango does not show the ingredients on the package and it was very cheap. The Appelsientje did show their ingredients on the package, and also placed an announcement on it that the juice contains pure orange juice and extra vitamin C, it is also more expensive than the Surango. The Fanta does not have the reputation of a healthy orange drink, it is a soft drink.
The expectation that the Fanta contains the least vitamin C was therefore right.
The titrations were done twice for each juice. The difference between the first and the second time with the Fanta, the Appelsientje and the Surango was very close. However, the difference between the first and the second time with the homemade orange juice did deviate. The difference might be because of the fact that two different oranges were used, and those two oranges contained different amounts of vitamin C. For an as accurate as possible measurement, only one orange must be used.