Fruits are a particularly good source of vitamin C and is why they are essential to our diet, but juices are not as good a source of vitamin C as fresh fruits due to the processes they undergo before being sold and to solely have your intake from these is not satisfactory, and is only made worse by producers lying about the amount of nutrients in the product and might possibly lead to people suffering a malnutrition of vitamin C.
Aims of this practical:
The aim of this investigation is to investigate the vitamin c contents, in different fruit juices. The juices I decided to use in this investigation were apple juice and orange juice. From these two juices I wanted to see which one had the highest vitamin c contents. Before I started I made a hypothesis: I believe that the highest concentration of vitamin C will be found in the orange juice.
Apparatus:
Our apparatus will include; several beakers and test tubes to hold and measure the liquids, a variety of fruit juices we will be testing, DCPIP as an indicator, syringes for the measuring and accurate transport of the liquids, as well as pipettes for the same purpose. We will also have pen and paper to record our results.
Method:
- With each different liquid containing vitamin C we will do the following; We will begin by measuring 1cm3 of DCPIP and putting it into a test tube.
- We then filled a syringe with the liquid and began allowing one drop at a time to fall into the test tube.
- After each drop we would lightly shake the test tube to ensure the solution was fully mixed, and continued this until the solution was satisfactorily clear at which point we wrote down the number of drops that had been administered into the solution and proceeded to redo the test with another juice.
- We began the investigation by testing a control of 1% vitamin C solution that we knew had 10mg of vitamin C in 1cm3.
- Once we had tested this we continued to test the fruit juices and compared the results against the control and attempted to estimate the amount of vitamin C actually in the juices.
- The independent variable would be the fruit juices and their different vitamin C levels, and the dependant variable would be the amount of DCPIP.
Risk Assessment:
There is not a lot of risk involved in this investigation, it is vital to follow the standard lab procedures. Obviously, in this investigation I indicated that I would be using glassware as part of my apparatus, there is always a possibility that glass can break, broken glass can lead to cuts and gashes, so when using the glassware there must be precaution and handled with care. As we are using DCPIP and it is a redox dye, if spilt it will stain surfaces and clothes, if participants in the investigation wear lab coats it will minimize the risk of staining clothes. Another risk is that DCPIP is a mild irritant, so if there is any skin contact with the chemical, hands should be washed, even though it is a very mild irritant.
Results:
We have already been given the 0.6cm3 of 1% vitamin C will decolorize 1cm3 of 0.1% DCPIP, we also know that 1cm3 of 1% vitamin C contains 10mg of vitamin C so therefore it takes 6mg of vitamin C to decolorize 1cm3 of DCPIP. We have also found that one drop is equivalent to 0.1cm3 however there is bound to be some differentiation between drops. When we ourselves tested the volume of a drop we found it to be 0.6cm3, and therefore to use the average of these two results we will make our average drop size 0.35, or 0.4cm3 rounded to 1d.p. (6 + 1 divided by 2).
The results we collected can be seen below.
Conclusion:
From this investigation it is very notable was orange juice, followed closely by apple, so my hypothesis I created was supported by my results. To make my results both more comparable and reliable, I should investigate further into categories i.e. freshly squeezed, diluted and different concentrations for all the juices and see whether this makes any difference. In a real life case this would mean, people with scurvy would gain more benefit in terms of vitamin c level, if they drunk orange juice compared to apple juice.
Evaluation:
I think this investigation, from my results showed that the most vitamin C in fruit juices in contained in orange juice. The only problem with my results was, I had to re start the investigation half way through, due to a contamination in the DCPIP, and this meant all my results where no longer accurate, this then took a long time to re clean my pipettes, and start again with a new mixture if DCPIP, as the other one was contaminated and was partially oxidized already. This pro longed the process as a whole, but in the end meant the results were more reliable. However, I do feel more background research should have been received on the juices for example if they were pre packed or diluted etc.
