Science Buddies: "Ask an Expert"

I am working on the Maple Syrup: For Pancakes, Waffles, and...Crystal Candy? idea posted on the website. I have tried several times with different boiling times for the syrup, but do not seem to see crystals in the syrup form. Can I see them without a magnifying glass? All I see is air bubbles. My project is due 3/20 and I am running out of time. Can you give me some advice? Thank you.


Kameron

You have chosen a very good topic to demonstrate some aspects of chemistry and phsical chemistry.

I have a few questions for you -
What was your procedure - briefly describe the steps taken in the experiment
When boiling the syrup did it become thick (slow to run or spread)
How was the cooling done - with or without ice?

Your answers will help us advise you.

Matt Mulanax

When boiling it did get thicker, but looked foamy. It had a lot of air bubbles when put on the pans to cool. Used one pan with ice, one at room temperature, and one at refidgerator temperature. Have tried steps a few times. twice same results as just described, and once it turned almost solid in the pans while cooking. Thanks for the help.

Hi Kameron,

I had not looked at this project idea before, but it's a really great way to learn about saturated solutions. Maple syrup contains a very high concentration of sugar, and if water is removed by boiling, the sugar will be too concentrated to stay in solution. If the supersaturated sugar solution is cooled rapidly, you should get lots of small crystals, and if it is cooled slowly, then the crystals will be larger. In looking at the experiment, I would have thought it could not fail, but you have shown repeatedly that there is something in your syrup that is inhibiting the crystallization process. I know this has been frustrating, but you can turn this into an advantage at the science fair. You will actually have a better project because you can find out what happened. Crystals form when the individual sugar molecules bump into each other. If there's something else in the sample, it may get in between the sugar molecules and prevent the formation of the crystals. Here's what might be causing the problem:

1. Fats and oils could coat the sugar molecules. Try cleaning your pan with lots of hot soapy water and rinse it thoroughly. Don't even let a fingerprint get on the pan and try the experiment again.
2. Acid in the sample. Acids like lemon juice are sometimes added to syrup to keep it from forming crystals, and sometimes maple syrup contains natural acids. Look at the product label to see if anything was added. Add a small amount of baking soda to some of your maple syrup. If acids are present, you will see bubbles of carbon dioxide form. If the maple syrup doesn't bubble when you add baking soda, then this is probably not the reason for no crystals.
3. Wrong sugar in the sample. Maple syrup crystallizes because it contains mostly sucrose, which is the same as table sugar. Sometimes natural maple syrup will contain sucrose that has been broken down into two other sugars called glucose and fructose. Crystallization occurs best when there is only one type of sugar in solution. You could get good crystals with pure glucose, pure fructose, or pure sucrose, but not when you mix the 3 types of sugars. Did you use pure maple syrup? This is important for this experiment.
4. Cooking temperature too high. If you cook the maple syrup too long, it will get so thick that the sucrose molecules will not be able to move and line up with each other to form the crystals. I think that’s what happened when your sample solidified in the pan. Try cooking the syrup for less time and see if that makes a difference.

I suggest that you try this experiment with some table sugar to see if your technique is good for making crystals. Use just sugar and water. This will tell you if it’s you or your syrup that is causing no crystals. Then, do a scientific approach. Try changing one detail in your experiment at a time until you get crystals. You may have to find a different brand of maple syrup to try to get crystals.

This is a very interesting project, especially now that you have to find out what happened. Please let us know what you discover!

Donna Hardy

I'm posting the link to the Science Buddies project:

Maple Syrup: For Pancakes, Waffles, and...Crystal Candy?
https://www.sciencebuddies.org/science- ... p044.shtml

Amy
Science Buddies

My 7th grader is doing this same project and he is having the same trouble getting crystals. He is following the procedure as outlined in this experiment (https://www.sciencebuddies.org/science-f ... p044.shtml); he as tried three different brands of pure maple syrup; he has heated the syrup for as little as 2 minutes. All to no avail. He was able to create crystals following the same steps but substituting simple syrup (just sugar & water). Based on the comments above, he's not sure what to extrapolate from this in order to move forward with the maple syrup-crystal growing.
Please help!

Hi,

Projects that don't work as expected make the most interesting science fair projects. This is a mystery that your son can investigate using a scientific approach to find out why the maple sugar did not crystallize. A careful analysis of the problem will make an outstanding project.

Since your son has been able to make crystals using a simple water and sugar, his technique in boiling the syrup has been eliminated as the source of the problem, and the pan used for the experiment is obviously not coated with oil. This means that he has isolated the problem to the maple syrup; there is something in the sample itself that is interfering with crystallization. The two primary possibilities are that the syrup could have too much acid in it (low pH) or it may not contain enough pure sucrose.

First check the label of the maple syrups you purchased, and check to make sure it is pure maple syrup with no additives. If anything (acid, enzymes, or corn syrup) has been added, then the syrup will not be suitable for crystallization. If the product has a lot number on it, you could try checking with the manufacturer to see if they have a record of the analysis of the lot, including the pH and the Brix (sugar content). This information would be helpful in solving the problem.

To verify a pH problem, you can test the pH with a pH meter or pH paper, if you have these available. Or try adding a small amount of baking soda to neutralize the sample. See if this will solve the problem. Pure maple syrup will have a pH of 6.8.

Sucrose, the main sugar in maple syrup, can be converted to its individual sugars, glucose and fructose. If too much sucrose is converted, then the syrup will not crystallize. Maple sugar that has a Brix of 66 degrees or greater is best for crystallization. A lower Brix product would not crystallize well. The Brix of the syrup can be measured using a refractometer:

http://www.eckraus.com/RF110.html

At $79, I would not recommend getting one of these for this project, but you may know someone who has one you could borrow for an experiment.

Please let me know what your son discovers. And let me know if you need more explanation on the science or the analysis of the syrup. I'm very curious to know what you find out.

Donna Hardy

Help!
We have tried over 6 bottles of 100% Pure Maple syrup and can not get any crystals to form!?!
Please advise if this experiment has ever been sucessfully completed.
We are very frustrated and this is getting expensive.
Thanks!

Hi Eleanor,

Don't buy any more maple syrup! Maple syrup candy is made by the process described in this experiment, so it works all the time for other people. However, the experiment will be successful, but only if all conditions are perfect. Even commercial candy makers have problems if the composition of the syrup is not right. Crystallization projects always sound easy when you read about them, but there are certain things that will interfere with the process, and you have had non-ideal conditions six times in a row now.

This is a science project, so you need to investigate and find out what is going wrong. And you should not worry about the results; you can have a complete science project even if the results don't turn out as expected. It's the process of doing your investigation that's important. You just need to understand the science behind your project and explain your results.

First, you need to understand how sucrose can crystallize. Here is a website that describes the how sucrose crystallizes and what interferes with this process:

http://www.exploratorium.edu/cooking/candy/sugar.html

I recommend that you isolate the problem by making a simple syrup of sucrose(sugar) in water; boil it to make a supersaturated solution and when it cools, you should see crystals form. If this is successful, then you know that the chemical composition of your 6 maple syrup samples is interfering with the crystallization process. If it doesn't work, then you will know that you will need to change your experimental technique. Please try this and let me know what happens. You have until December 3rd, so there's time to make this a great science project, even if you never see a sugar crystal.

I hope this helps!


Donna Hardy

Hi,

Any organic chemist can tell you that sugars are notoriously hard to crystalize, and form rather stable supersaturated solutions. Chemists in training are taught tricks to get solutions to crystalize. The best trick is to add a few very small crystals of the substance you want to crystalize to the solution. Another trick is to scratch the inside of the container holding the solution with something sharp. It helps if the solution is not too supersaturated. Here is a paper about the crystalization of supersaturated mixed sugar solutions. Note that it took up to 84 days for some to crystalize.

http://www.nt.ntnu.no/users/skoge/prost ... d/4066.pdf

http://www.newton.dep.anl.gov/askasci/c ... m03421.htm

Good luck with the project!

Best regards,

Barrett L. Tomlinson