UCSB Science Line
Sponge Spicules Nerve Cells Galaxy Abalone Shell Nickel Succinate X-ray Lens Lupine
UCSB Science Line
Home
How it Works
Ask a Question
Search Topics
Webcasts
Our Scientists
Science Links
Contact Information
Hello, I am currently doing my science fair project and I need your help. Just to give you a little understanding of my project, here is my hypothesis: If I boil citrus fruit juice then, it will have less vitamin C compared to citrus fruit juice that has not been cooked. I would highly appreciate if you could help me out. Here is a list of questions that I have:
What is the temperature at which vitamin C begins to be lost? 78F -90F? 110F?
Question Date: 2012-01-07
Answer 1:

I think you have a nice hypothesis, but a slight change of wording would be more correct. Boiled juice would have less active vitamin C but not less because it does not leave the juice when you cook it. Here is why.
Vitamin C or ascorbic acid is a type of molecule called an antioxidant. Antioxidant molecules (there are many different types vitamin E and many of the molecules that make berries red or blue) in the body are very useful because they prevent damage to cells, proteins and your DNA by reacting with other molecules that would oxidize (or take away electrons) from these important structures. When an antioxidant encounters an oxidant, the two react and the antioxidant gives up some of its electrons to the oxidant molecule. This reaction can change structure of the antioxidant molecule and effectively shutting it off to react with the next oxidant it runs into. This type of reaction is a redox reaction where one molecule is oxidized (the antioxidant or vitamin C) and the other is reduced (chemistry talk for gained electrons). Oxidants in the body can be metal ions like copper ions or free radicals. Free radicals can be created by UV light and breaks a bond in a molecule that leaves a free electron. Electrons like to stay in pairs, and that molecule with the unpaired electron looks for an electron it can to make a pair. If the electron it finds to make its pair is in your DNA it can cause damage to your DNA and possible lead to in the worst cases to cancer.

In general, a chemical reaction happens more quickly at higher temperature, since the molecules are moving around faster and are more likely to bump into one another and cause a reaction. Even in cold juice vitamin C can react with oxidants in the juice and be oxidized or "switched off" but far more reaction will take place at higher temperature. It would be a good experiment to see the temptress when the difference becomes noticeable.

I like your question about the syrup. I do not know for sure what would happen but here is my hypothesis: the syrup is made of a molecule (sucrose) that is not an oxidant in acidic conditions like in juice and should not react with the vitamin C. But the syrup will make the juice mixture thicker (more viscosity) and will keep the molecules from moving around as fast as when there wasn't syrup in the juice. This may act to keep more of the "active" vitamin C around for longer periods at higher temperature. Again this sounds like a good experiment.If you don't have enough vitamin C in your body for long periods you can develop a condition called Scurvy. This was found often in sailors when they would be at sea for many months without access to fruit or vegetables. Scurvy causes the collagen in your skin (the stuff that makes your skin stretchy) to break down, damaging your skin and gums.Different vitamins have different structures, perform different functions and not all of them are antioxidants. For those that are antioxidants, boiling would speed up the rate at which they react with oxidants and "switch off".

Answer 2:

Here's how you could test it: vitamin C is ascorbic acid. It makes the fluid it's in more acidic. Red cabbage juice is a pH indicator; it changes color depending on how acid a solution is. So, buy some red cabbage, extract juice out of it (by cooking it), and keep that juice aside. Then, subject your vitamin C treatments to a range of temperatures, including one that you did not cook at all. Finally, add some cabbage juice to each of your boiled/heated/not heated citrus juice treatments, and see which one(s) have different colors.


Answer 3:

I think you have a nice hypothesis, but a slight change of wording would be more correct. Boiled juice would have less active vitamin C but not less because it does not leave the juice when you cook it. Here is why.
Vitamin C or ascorbic acid is a type of molecule called an antioxidant. Antioxidant molecules (there are many different types vitamin E and many of the molecules that make berries red or blue) in the body are very useful because they prevent damage to cells, proteins and your DNA by reacting with other molecules that would oxidize (or take away electrons) from these important structures. When an antioxidant encounters an oxidant, the two react and the antioxidant gives up some of its electrons to the oxidant molecule. This reaction can change structure of the antioxidant molecule and effectively shutting it off to react with the next oxidant it runs into. This type of reaction is a redox reaction where one molecule is oxidized (the antioxidant or vitamin C) and the other is reduced (chemistry talk for gained electrons). Oxidants in the body can be metal ions like copper ions or free radicals. Free radicals can be created by UV light and breaks a bond in a molecule that leaves a free electron. Electrons like to stay in pairs, and that molecule with the unpaired electron looks for an electron it can to make a pair. If the electron it finds to make its pair is in your DNA it can cause damage to your DNA and possible lead to in the worst cases to cancer.

In general, a chemical reaction happens more quickly at higher temperature, since the molecules are moving around faster and are more likely to bump into one another and cause a reaction. Even in cold juice vitamin C can react with oxidants in the juice and be oxidized or "switched off" but far more reaction will take place at higher temperature. It would be a good experiment to see the temptress when the difference becomes noticeable.

I like your question about the syrup. I do not know for sure what would happen but here is my hypothesis: the syrup is made of a molecule (sucrose) that is not an oxidant in acidic conditions like in juice and should not react with the vitamin C. But the syrup will make the juice mixture thicker (more viscosity) and will keep the molecules from moving around as fast as when there wasn't syrup in the juice. This may act to keep more of the "active" vitamin C around for longer periods at higher temperature. Again this sounds like a good experiment.If you don't have enough vitamin C in your body for long periods you can develop a condition called Scurvy. This was found often in sailors when they would be at sea for many months without access to fruit or vegetables. Scurvy causes the collagen in your skin (the stuff that makes your skin stretchy) to break down, damaging your skin and gums.Different vitamins have different structures, perform different functions and not all of them are antioxidants. For those that are antioxidants, boiling would speed up the rate at which they react with oxidants and "switch off".

Answer 4:

of your questions about Vitamin C sound like good Science Fair projects. You can start at the highest temperature, and see how much Vitamin C is lost. Then you can test lower temperatures. The questions about sugar and freezing are also questions you can answer in your science fair project.

If you don't have enough Vitamin C in you, you get a disease called Scurvy. You can find the details on the internet, but I think your gums start to bleed a lot.

Different vitamins will break down different amounts when you heat them or boil them. That is because they have different chemical structures that are more or less damaged by heating.

Do you have a good way to measure Vitamin C for your science project?



Click Here to return to the search form.

University of California, Santa Barbara Materials Research Laboratory National Science Foundation
This program is co-sponsored by the National Science Foundation and UCSB School-University Partnerships
Copyright © 2017 The Regents of the University of California,
All Rights Reserved.
UCSB Terms of Use