Uncovering Hidden Sugar in Your Food

[deleted-264418]

Hi there,
I have done this science fair project experiment:
Sucrose & Glucose & Fructose, Oh my ! Uncovering Hidden Sugar in Your food
I tested Coca cola, Orange juice and Orange Gatorade and also tested the 1 % Glucose and Sucrose solutions. Now I am working on the results.
Glucose, Sucrose and the Orange juice tested according to my expectation.

Coca Cola puzzles me the most.
It is made with high fructose corn syrup. My research shows that this should consist of 55 % free fructose 41% free glucose and about 4 % other sugars.
Therefore I expected the 1,1 g of sugar my 1:10 dilution contained to show a glucose concentration of 0.451 so about 0.5 on the Diastix test strips before adding the Invertase. The result was about 0.5 -0.6, which means slightly above but probably close enough.
Given the fact that almost the intire sugar was already divided up in free Glucose and free fructose, I didn't expect a big change due to the invertase. But it turned out, that the glucose nearly doubled !!!

Where did that come from? I have no idea ! Is there any starch that wouldn't have been on the label sugar listing but would have been changed into glucose due to the enzym ?
Wouldn't that have been on the ingredient list?

I hope you can help me with that

[SciB]

Hi Sabeeka,

Interesting result! I don’t know why your test would show double the glucose after the coke was digested with invertase unless the coke contained sucrose. The invertase enzyme is specific for sucrose and does not produce glucose from starch or anything else that I know of. Maybe some of the other experts have more experience with this reaction and can provide an explanation.

I think you should test other soft drinks with invertase, measure the glucose levels and see if the results you get are in agreement with what the beverage label says. HFCS is cheaper than sucrose but I think sucrose is still sometimes mixed with it. Maybe the labels are wrong. Try Pepsi, a generic cola, a non-cola that has HFCS and your coke again and do let us know the results. I am very curious to find out what is going on here and I’m sure others would also like to know for future reference.

Thanks for your post.

Sybee

[deleted-264418]

Hi,
thank you for the answer. Trying another cola is exactly what I did because I didn't understand the result.

I bought a bottle of Pepsi, and tested it and it shows the same result.

I tested it twice so far and will test it three more times this weekend. ( I am supposed to do my experiment 5 times to be sure to have reliable data ) and I will go and get another Cola and probably another soda too.

I wish I could find an answer to this.

Thank you very much
Sabeeka

[SciB]

You're welcome Sabeeka! Let us know how your next experiment turns out.

There's one control I just thought of to ask you about and that is invertase with just water--no soda or juice. Did you do that one? That would rule out the possibility that the enzyme solution itself contains glucose. It is unlikely, but a good scientist tests everything.

The other thing you could try is varying the time of treatment of the soda with the invertase. If the enzyme is digesting something in the soda to produce glucose then you should see an increase in the glucose concentration with time. This would be good proof that it is an enzymatic reaction that is causing your result and not something else.

Do you think maybe these sodas do contain sucrose and they just are not listing it on the label?

Good luck and please post again with your new results.

Sybee

[deleted-264418]

Hi there
A long day of testing and some more surprising results.
I bought a bottle of Fanta, Dr. Peppers, and Mexican coca cola.
I tested these along with pure water, sucrose, and my previous choices Orange juice, Coca Cola and Gatorade and Pepsi.

The water tested as expected negative before and after adding Invertase.
Sucrose, Orange juice and Gatorade reacted according to my expectations.

Coca Cola and Pepsi both were again slightly above my expectations to begin with and a lot above it after reacting with the invertase.

Fanta and Dr. Peppers were a lot higher than expected to begin with but at least didn't change while reacting with the invertase. (Which makes sense, because they both contain High fructose corn syrup which contains free glucose to begin with and doesn't need an enzym to set it free.)

And then there was the Mexican Coca Cola:
In theory it should contain sugar ( labeled ) and not like the american one High fructose corn syrup. So I assumed that would mean sucrose. I expected a negative reading before adding the invertase and about a 0.5 reading after it doing his splitting up into glucose and fructose. That's not what I got.
I got a 0.8 reading before and a 1.0 reading after. Something is really wrong with that labeling !!!

This is scary, is nobody checking those labels ?

Thanks for your help, do you have another hint for me ?
Sabeeka

[deleted-264418]

Oh yes, and i tested as you recommended the developing of the glucose level of the Coca Cola over the time frame that the invertase needs to split up sugar. It clearly increased over the time.

[SciB]

Wow! You really have some eye-opening results, Sabeeka! I can't think of any explanation now except that the labels are not correct.

I tried searching 'are soft drink labels correct' and I found one report showing that labels on some Coke, Pepsi and Mexican cola were wrong--but their tests indicated more fructose, not sucrose, than stated on the label: http://www.consumeraffairs.com/soft-dri ... nd-obesity

But what that report tells me is that what is on the label may NOT be exactly what is in the can or bottle.

I looked through several more pages of Google search hits but found no other mention of inaccuracies on soft drink labels.

Did you try a different soda like Pepsi Throwback that is supposed to be made with sucrose? Since Mexican coke did not show much of a glucose increase, you should probably test another sucrose-containing soda which hopefully will show a large increase in glucose after invertase treatment. It would be nice to have this so you can show it as a comparison for those sodas that are not supposed to contain sucrose but do show an increase in glucose after invertase treatment.

You did the water control, so we know the invertase itself is not causing the increased glucose signal. You have a time-course experiment that shows the enzyme product, glucose, increasing with time. And we know that invertase cannot convert fructose into glucose. So, unless we are overlooking something, your data shows that sodas that contain HFCS also contain sucrose.

Can you calculate about how much sucrose was in the soda from the Diastix reading? Sucrose is a disaccharide of glucose and fructose so if you know the weight of one you should be able to calculate the weight of the other sugar. It would be very useful to be able to say exactly how much sucrose was in the drinks. I don't know if you could use a glucose meter to measure glucose in soda but it might be worth trying as a way to verify the concentration. I wish there was some way to specifically test for sucrose but the only tests I know of also give positive signals for fructose.

I'm hoping the other experts read this and see if they can think of another explanation for your results. Also, I am sure there have been other students who have done this project and I wonder if they found the same results.

Please let us know what else you find out about this puzzling outcome.

Good luck!

Sybee

[deleted-264418]

Hi there
Thank you for the article. I looked into it and into the research. It helped me to clear my mind.

They tested all the sugar contents, including Glucose and fructose with three different fancy machines. They tested most of the sodas I tested too, they had quite different results. Their outcome is that the drinks contain less glucose but more Fructose then estimated according to the labeling. Their guess is that the soft drink companies probably use a HFCS with a higher concentration of fructose in their drinks than we think.

I have been very accurate in my testings, but I have diastix and they have all these machines and their results make so much more sense than mine. My guess is they are right and I was about to give up.

But then I thought it through:
My results make sense as long as there are only natural sugars involved: glucose, fructose ( from fruit juice ). Only when I measure sodas containing HFCS the result is wrong. (Mexican Cola is most likely to contain HFCS according to their results).

My guess is that when the diastix are used with something containing HFCS the results show some of the fructose content as glucose as well. To me it's the only explanation that makes sense. Given the fact, that in the production of high fructose corn syrup the fructose content is increased by an enzyme reaction that changes glucose into fructose, that might even be a reason why. I know that the diastix doesn't react to natural fructose.

I am running out of time the project is due on February second.

Here is what I decided to do:
I bought an apple juice, coconut water and an iced tea, all of them without HFCS and will do the testing with those to finish my project.

What do you think about this?
Again: Thank you very much for your help and thoughts. I will write again after the new testing.
Sabeeka

[deleted-264418]

Hi,
I am done. I had to pick one because I was about to run out of diastix ( I have used 198 during the whole experiment ). I picked apple juice. The results were reasonable.

Now I have to put everything together.
Thanks
Sabeeka

[SciB]

Hi Sabeeka,

Congratulations on completing a very interesting project! You should get lots of questions about your results. In fact, I have some right now!

You said: “My guess is that when the diastix are used with something containing HFCS the results show some of the fructose content as glucose as well.” If this was true then you should have gotten the same readings before and after invertase, right?

You said: “Given the fact, that in the production of high fructose corn syrup the fructose content is increased by an enzyme reaction that changes glucose into fructose, that might even be a reason why. I know that the diastix doesn't react to natural fructose.” You seem to be saying that the process of making HFCS somehow results in an altered form of fructose that acts like glucose on the Diastix. Is that what you mean? But there again, I don’t understand how you are going to explain why the invertase-treated Coke has double the reading of Coke before invertase. Can you tell me how that happened?

Doesn’t the fact that invertase doubled the glucose reading of the Diastix prove that sucrose was present? I could find no evidence that invertase can convert any form of fructose to glucose. It is absolutely specific for the disaccharide, sucrose. So where would sucrose come from in the HFCS-sweetened drinks? I don’t know the answer to that one. Since fructose is sweeter than sucrose, I can’t see why a soft drink maker would add sucrose but it is possible.

I thought maybe the enzyme that converts glucose to fructose, glucose isomerase, might be able to link glucose and fructose to make sucrose, but I could find no evidence for that in a quick google search.

There is one other thing that you could try and that is to call the biochemistry department of a university and tell them you are a student with a puzzling question about carbohydrates. Ask to speak to someone who knows about carbohydrate synthesis. Tell them briefly and clearly what you found and I’m betting that you will get their attention and arouse their scientific curiosity! Try it! It would be very, very interesting to know what a professional biochemist (other than myself—I have a PhD in biochemistry) would say about your results.

Good luck!

Sybee

[deleted-264418]

Hi Sybee,
you are absolutely right, I have no idea how to explain the increase of glucose while the invertase was working and it very clearly did. I knew this was the weak spot in my explanation and was sure you would pinpoint it.
But after all I don't know what they really mix into those drinks.

The only thing I know is that they say the sugar it contains is HFCS and that I am quite sure if they would put sucrose in instead it would be in every commercial.
The testing of that institute showed clearly that in the coca-colas they tested was no sucrose, and the relation between Fructose and Glucose was 60:40 which can only be explained when they actually use a higher HFCS concentration than they make us believe( 60:40 and not 55:41 ).

Honestly I don't know what to think about this ! That's why I decided to concentrate on the part of my experiment that make sense to me. The juices, the gatorade and as control groups glucose, sucrose and water. With the the coca cola I will have to admit I have no clue what's going on.

I wish I had more time and better equipment to look into this. I would love to be to able to measure not only the glucose but also the fructose content.

I was thinking about sending an email to this research group telling them about that result and asking them if they have an explanation for me.

But right now I need to concentrate on wrapping it all up. I have only a few days left. All that testing took a lot longer than expected. There is still so much to do. Luckily we had a snow day today and will have another one tomorrow.
But I enjoyed the project and I learned a lot. Bottom line: to stay away from all of this, drink water, enjoy my fruits with their fiber and to rather take a bit of chocolate.

I really want to thank you again for all your help.
Sabeeka

[SciB]

You are certainly welcome, Sabeeka! I just wish we could have come up with an explanation of your HFCS results. But I must disagree with you on your choosing not to emphasize this finding. This is the part that everyone is going to find most interesting! In fact, you may have found something important that just has not been noticed before. This is exactly the sort of thing that makes science exciting. Yes, I know you don’t have the time or the equipment to do a proper study but I would still make this HFCS result center stage. Everyone loves a mystery story and you have one!

If you have a couple of days before the project is due I think you should really take the time to make some calls to people who might be able to give you some clues as to what happened. You may decide in the future that you want to do a science project with a mentor in a lab and talking to scientists is one way to find such a group. You may have to make several calls before you find someone who is willing to listen to you and able to offer some help. If you know or can get in touch with a biochemistry graduate student they would be an ideal contact.

I have enjoyed working with you, Sabeeka, and look forward to helping you again on your next science project.

Good luck,

Sybee

[deleted-264418]

Hi Sybee,
I wanted to ask if it would be ok, if I put a print out of our conversation in the documentation of my project. You were a big help I would like to mention.
.... and I send emails: one to my science teacher, one to the researchers that did the study at the University of Southern California and another one to Biochemistry Department of Yale.
Back to work now.
Thanks
Sabeeka

[SciB]

Of course, Sabeeka! If I can help you solve this mystery I will be very happy and you will have the satisfaction of accomplishing a first-rate project. I'm sure your teacher is just as excited as I am to find out the reason for your unexpected results.

If you are going to include the posts in your report just be sure to say that the source of the content is the Ask-the-Expert forum on Science Buddies.

Good luck,

Sybee

[deleted-264418]

You were right : ) I got a very nice answer from one of the researchers of the article. He came up with a few ideas and asked for more information. After I sent that to him, he wrote that he really doesn't have an explanation of why the glucose goes up in the coke after adding the invertase.

Ok, now I came up with a probably very far fetched idea.
I realized that it would be much easier to explain the results, if I had accidently switched the american and the mexican coca cola. That would mean, that the american coca cola would contain HFCS, still more than expected like with Fanta and Dr. Peppers but than there wouldn't be that big difference between before and after. The mexican cola would contain sucrose like they label but definately also HFCS what they don't label. It all would make so much more sense.

Only the thing is, I am sure I didn't switch the dilutions. Because I started the whole testing with the american coca cola and only when the results were off, I went and bought more sodas including the mexican one.

Now I did a little research. There isn't one big plant producing Coca cola products. On their internet page they state: "Our Company manufactures and sells concentrates, beverage bases and syrups to bottling operations, owns the brands and is responsible for consumer brand marketing initiatives. Our bottling partners manufacture, package, merchandise and distribute the final branded beverages to our customers and vending partners, who then sell our products to consumers."

What if one of these bottling partners accidently switched the syrups ?

To far fetched ?

You see I am still thinking and thinking......

[SciB]

Well, Sabeeka...I'm fresh out of ideas! You have done everything I suggested and we still do not have an explanation. Your data shows that there has to be sucrose in the sodas that you thought only contained HFCS. Maybe, as you suggest, the bottlers of soda are not as careful in mixing the ingredients as they should be.

If there are any experts or people with experience in doing this Scibuddies sugar project and you have any ideas how to explain this data, PLEASE post them!

Have you talked to your teachers about your results? Maybe one of them could suggest something we haven't thought of.

I asked you in one of the previous posts if you knew anyone who had a diabetic glucose meter. If you can do a test using that and the meter shows the same increase in glucose, then your data will be much stronger. As a last possibility, I would buy another brand of glucose test strips and repeat the invertase reaction with the same colas. I don't see how the test strips could cause these results, but researchers have to test almost every possibility.

This has been fun! I hope you come up with another great project for next time. If you have some ideas about potential projects, run them by us and we can help you decide.

Good luck!

Sybee