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I read that when the oranges are kept in the cold, (that probably means in a refrigerator), the content of Vitamin C increases in the beginning, but afterwards it decreases. Is this true and if it is, why is this happening? Also, taking the case of damaged orange in the same conditions, I am making the conclusion that this kind of orange will not change its Vitamin C content in the beginning, because ascorbic acid oxidase will reduce the concentration of vitamin C, but on the contrary the orange itself will increase the Vitamin C content. Is this true? And if it is, is it going to make the shortage of the Vitamin C or excess if I damage 1 cm3 of the orange in the beginning. Thank you!
Igloo writes ...
I cannot think of a valid reason why keeping an orange in a refrigerator will cause the concentration of vitamin C to rise at first, and then fall later. However, if you wish to carry out experiments to see whether or not this is the case, you could take several oranges of the same variety, size and age and place them all in a refrigerator.
Each day you could remove one of them, use a knife and liquidiser to extract the vitamin C, and then carry out titrations to find its concentration. If your theory is correct then you should find the concentration of vitamin C rises and falls as you have predicted.
If you wish you could then carry out a set of extension experiments to study the effect of damaging the fruit before they are placed in the refrigerator. To do this you could squeeze several oranges between your hands for several minutes, without cutting into them, and then repeat the experiments I have described above to see whether the bruising changes your results in any way.
Always carry out a risk assessment and check with your teacher before starting any practical work.
Risk assessment
Before attempting any practical work based on the advice and suggestions on this website, you must do the following. Identify any hazards, assess the risks from these hazards, and then decide appropriate control measures to reduce the risks. You must have these approved by those in authority in your school or college laboratory. Do not rely on what is said on this website.
For further guidance see our tutorial on Risk Assessment.
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updated: 26 September 2007
