Strength of DCPIP X Volume = Volume of Vit. C x Strength
Results
Juice 1 = Ascorbic Acid. (Pure Vitamin C)
Juice 2 = Orange Juice. (Smooth)
Juice 3 = Pure Orange with Mango Pure.
Juice 4 = Orange and Grapefruit.
Ascorbic Acid (J1)
Strength of DCPIP x volume = Strength of Vit. C x Volume
0.06 x 10ml = )( x 8ml
)( = 0.06 X 10ml
8ml
Strength of Vitamin C = 0.075
Orange Juice Smooth (J2)
Strength of DCPIP X Volume = Strength of Vit. C x Volume
0.06 x 10ml = )( x 13ml
)( = 0.06 x 10ml
13ml
Strength of Vitamin C = 0.046
Pure Orange with Mango Pure (J3)
Strength of DCPIP x Volume = Strength of Vit. C x Volume
0.06 x 10ml = )( x 14ml
)( = 0.06 x 10ml
14ml
Strength of Vitamin C = 0.042
Orange and Grapefruit (J4)
Strength of DCPIP x Volume = Strength of Vit C x Volume
0.06 x 10ml = )( x 13ml
)( = 0.06 x 10ml
13ml
Strength of Vit C = 0.046
Results
The graph shows that the Orange and Grapefruit Juice had the highest concentration of Vitamin C. Compared with the other Juices (excluding juice one as it is pure Vitamin C) it takes less of this Juice to turn the DCPIP straw coloured (an average of 13ml). In comparison to the others there was not much difference between them all. The Pure Orange Juice with Pure Mango took an average of 14ml to turn the DCPIP straw coloured.
After doing some research on the Vitamin content on different fruits, it was seen that both mangos and grapefruits, Mangos and Oranges are excellent vitamin C sources.
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The values are for one whole fruit, however not many would eat a whole medium sized watermelon at a sitting, so for these larger fruit the value is for a slice, a 'slice' being, very generally, about an eighth of a medium sized fruit, or a quarter of a 'smaller' fruit.
In the particular case of lemon and lime, the 'slice' value is juice of one wedge.
For a few small fruit, such as Kei apple, the ranking is adjusted upward where the fruit mg/100 gram analysis shows it has large amounts of vitamin C, but the small size of the fruit gives it a lower per fruit vitamin C content. You are likely to eat more than one at a serving. In the case of tiny fruit, like red or black currants, a lot more, but probably still only 20-30 raw fruit, especially if they are a bit acid..
The chart states that Mangos have a higher Vitamin C level than Grapefruits implying that the results should have been the other way around with the Orange and Mango Juice having more Vitamin C present. However it could be due to the preparation process that has taken an effect on the amount of Vitamin C present.
Vitamin C is a particularly fragile vitamin and is easily destroyed when in contact with oxygen in the air or if it is exposed to light. The vitamin C content of sliced, cut or bruised fruit and vegetables diminish rapidly when such foods are left standing. Freshly squeezed orange juice will lose half of its vitamin C content by the next morning.
Vitamin C is one of the least stable vitamins, and cooking can destroy much of this water-soluble vitamin from foods. Vitamin C is a weak acid and is stable in weak acids. Alkalis, such as baking soda, however, destroy ascorbic acid. It is also easily oxidized in air and sensitive to heat and light. Since it is contained in the watery part of fruits and vegetables, it is easily lost during cooking in water.
Evaluation
The experiment went very well in that that the investigation was carried out in a safe and efficient way. The investigation was planned to produce an out come showing the strength of Vitamin C concentrations in different Juice types. This was done and a conclusion was gathered showing what was being looked for.
In hindsight it was seen that the calculation could have caused problems in the reliability of the results. All the calculation were done with one main equation. However if there was any point were the calculations were not dome properly it would mean that the given numbers would not have been correct. Also, the calculator did not round up decimals; therefore figures given would have been dependant on if the numbers were rounded up or not. Making sure that the same method was used at all stages could have rectified this. This would have ensured that all the figures were reliable.
Another problem that could have caused results to be unreliable is the readings that were taken. The syringes that were used had markings that went up in 5’s. It’s possible that the reading were not done very accurate and not made at their actual point. If this problem were consistent all of the readings would have been inaccurate. By having the same person doing the readings and also having used a syringe that has more reading points would have made them more accurate in that the individual points would have been easier to read.
Another possible problem that was seen was the fact that the aim was to look for colour changes. It would not have been able to come to a sure conclusion of what was straw colour and what was not. It would have not been able to come to a sure mark of straw coloured. There would not no real solution to this problem as it would be dependant on the person. The only solution that could minimise this problem would be to have the same person making the judgments, as their perception of Straw coloured would be the same.
Apart from the above points the investigation was went well and was carried out smoothly. The team were able to conclude the investigation with the use of gained figures and reactions.