Sweet as Sugar: Comparing the Sweetness of Sugar & Sugar Substitutes
AbstractCake, cookies, pie, ice cream, hot chocolate, lemonade... Yum! What do all these delicious treats have in common? Sugar. In addition to providing sweetness, sugar adds bulk, flavor, and structure to foods. But is it necessary to add sugar to achieve sweetness? Can the same sweetness be achieved using sugar substitutes like artificial or natural sweeteners? In this project, you will test sugar and sugar substitutes and compare the sweetness of each in relation to sugar. In the end, your day will be just a little bit sweeter!
To determine how the sweetness of sugar substitutes compares to the sweetness of sugar.
A trip to the bakery can be magical. Picture it: counters filled with every kind of sweet treat you can imagine, and something for everyone. Cakes, cookies, pastries, cupcakes, and a variety of sugary food wherever you look. We may not all like the same kind of baked treat, but one thing we all agree on is that baked treats should be sweet. Usually, sugar is used to lend sweetness to foods. But would cake taste just as good if the baker used a sugar substitute instead of sugar? Many people prefer not to use sugar, often due to health reasons, and instead depend on sugar substitutes to sweeten their foods (see examples of sugar and other sweeteners in Figure 1 below). But are sugar substitutes the same as sugar? And what exactly are the differences between sugar and sugar substitutes?
Figure 1. This image shows, from left to right, sugar, sucralose (Splenda®), and erythritol. Can you tell the difference? Can you taste the difference?
Sugar, also known as sucrose, comes from plants like sugar cane and sugar beets and is a carbohydrate. Sugar adds flavor and bulk to cakes, cookies, and all kinds of treats. Sugar also causes browning and caramelizing in foods when it is heated, as when cookies turn golden brown in the oven. Sugar is a natural substance, something that our bodies can use for energy.
Sugar substitutes come in three categories: artificial sweeteners, sugar alcohols, and natural sweeteners. Artificial sweeteners are synthetic (meaning created by humans); these sugar substitutes may be derived from naturally occurring substances like herbs and sugar itself. Artificial sweeteners are attractive because they add almost no calories to foods and are sometimes a part of weight-loss programs. Also, they do not increase blood sugar levels, which means that diabetics can use them. An example of an artificial sweetener is sucralose, which is derived from sugar. (Splenda® is a commercial product that uses sucralose as one of the ingredients.) Many artificial sweeteners, like sucralose, were discovered by accident in the laboratory. In 1976, a scientist in England was studying different compounds made from sugar. The scientist asked a student to test the compounds, but instead the student tasted them!
Another category of sugar substitutes is sugar alcohols. But don't be confused. Sugar alcohols are not like alcoholic beverages. They do not contain ethanol, which is found in alcoholic beverages. Sugar alcohols, like sugar, have calories and energy, but not as much as sugar. Sugar alcohols, like artificial sweeteners, do not contribute to tooth decay and affect blood sugar levels slowly, so diabetics can use them. Although sugar alcohols like xylitol, sorbitol, and erythritol, are manufactured products, the sources are often natural. For example, xylitol is made from corncobs and birchwood waste. Sugar alcohols are used to sweeten processed foods, chewing gums, candies, frozen desserts, and baked goods, rather than in home cooking.
The last category of sugar substitutes is called natural substitutes. This category includes maple syrup, agave nectar, and honey. These substances are absorbed by our digestive system and contain calories and nutrients that our bodies can use.
How sweet are sugar substitutes compared to sugar? If you wanted to substitute one for sugar in a recipe, should you use the same amount? Do recipes have to be modified to use sugar substitutes like sucralose (or Splenda®) or honey? This food science project will help you start answering some of these questions. You will test a group of volunteers to determine the taste threshold for sweetness for various sweeteners. You will start with a 10% solution (by weight), and use the process of serial dilution to make a series of solutions, each diluted ten times more than the preceding one with distilled water (10%, 1%, 0.1%, and 0.01%). At what dilution will testers be able to detect a change in taste? The earlier you can detect a "taste" in the dilution series, the "sweeter" the substance is. Is one of the substitutes sweeter than the others?
Terms and Concepts
- Artificial sweeteners
- Blood sugar
- Sugar alcohol
- Digestive system
- Taste threshold
- Serial dilution
- Weight/weight solution
- Volume/volume solution
- What are other examples of artificial sweeteners?
- Which category does the sweetener neotame fall into?
- How is the sugar alcohol erythritol manufactured? What are its sources?
- What are some products that contain artificial sweeteners? Why do these products not use sugar?
- Mayo Clinic: Nutrition and Healthy Eating . (2010, October 9). Artificial sweeteners: Understanding these and other sugar substitutes. Retrieved April 25, 2012.
- Selim, J. (2005, August 6). The chemistry of ... artificial sweeteners. Discover Magazine. Retrieved April 25, 2012.
- Yale-New Haven Hospital Nutrition Advisor. (n.d.). Eat any sugar alcohol lately?. Retrieved April 25, 2012.
- Tsai, M. (2007, May 14). How sweet it is?: Measuring the intensity of sugar substitutes. Slate. Retrieved April 25, 2012.
For help creating graphs, try this website:
- National Center for Education Statistics. (n.d.). Create a Graph. Retrieved June 2, 2009.
Materials and Equipment
- Plastic cups, clear, 12-ounce, disposable (30)
- Permanent marker
- Graduated cylinder, 100 milliliters (mL). Available online from Amazon.com.
- Graduated cylinder, 10 mL. Available online from Amazon.com.
- Paper, 8½ x 11 inches (3 sheets). Cut each sheet into four equivalent pieces, each 4¼ x 5½ inches, for a total of 12 pieces
- Digital kitchen scale. You can purchase a digital scale online from Amazon.com.
- Wood or plastic stirring sticks (20)
- Distilled water (1 gallon)
- Sugar (10 grams [g])
Sugar substitutes; the Experimental Procedure uses one artificial sweetener, one sugar alcohol, and one natural sweetener, but you can make other choices. To follow the Experimental Procedure exactly, you will need:
- Splenda® (10 g)
- Erythritol (10 g). You can purchase erythritol online from Amazon.com or at some grocery stores.
Honey (10 mL)
- Note: If you plan to conduct taste tests over more than one day, you will need more sugar and the sugar substitutes than listed here.
- Microwave and microwave safe container for heating up water
- Cotton swabs (package of 300). You can find cotton swabs at a pharmacy.
- Volunteers (10)
- Paper towels (1 roll)
- Lab notebook
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Working with Human Test Subjects
There are special considerations when designing an experiment involving human subjects. Fairs affiliated with Intel International Science and Engineering Fair (ISEF) often require an Informed Consent Form (permission sheet) for every participant who is questioned. Consult the rules and regulations of the science fair that you are entering, prior to performing experiments or surveys. Please refer to the Science Buddies documents Projects Involving Human Subjects and Scientific Review Committee for additional important requirements. If you are working with minors, you must get advance permission from the children's parents or guardians (and teachers if you are performing the test while they are in school) to make sure that it is all right for the children to participate in the science fair project. Here are suggested guidelines for obtaining permission for working with minors:
- Write a clear description of your science fair project, what you are studying, and what you hope to learn. Include how the child will be tested. Include a paragraph where you get a parent's or guardian's and/or teacher's signature.
- Print out as many copies as you need for each child you will be surveying.
- Pass out the permission sheet to the children or to the teachers of the children to give to the parents. You must have permission for all the children in order to be able to use them as test subjects.
Mixing the Sweetener Solutions
In this science project you will make 10%, 1%, 0.1%, and 0.01% solutions from sugar and each of the sugar substitutes. You will use the solutions to find out the threshold of taste (sweetness) for each substance.
- When you taste-test the solutions, you will be looking for a change in taste and not necessarily a change in sweetness.
- Label four plastic cups according to the solutions you will put in them. Label the first cup "Sugar 10%," the second cup "Sugar 1%," the third cup "Sugar 0.1%," and the fourth cup "Sugar 0.01%."
Measure 90 mL of distilled water into the 100 mL graduated cylinder, and pour it into the cup labeled "Sugar 10%."
- Place one of the pieces of paper on the digital scale, zero the scale, and weigh 10 g of sugar. Carefully pick up the paper and pour the sugar into the cup labeled "Sugar, 10%."
- Use a stirring stick to stir the solution until the sugar is completely dissolved and you can no longer see any sugar granules in the bottom of the cup.
- This gives you a 10% by weight (weight/weight, or w/w) sugar solution.
Make the 1% sugar solution. Measure 90 mL of distilled water into the 100 mL cylinder and pour it into the cup labeled "Sugar 1%."
- Use the 10 mL graduated cylinder to carefully measure 10 mL of the 10% sugar solution. Pour the 10 mL of 10% sugar solution into the cup labeled "Sugar 1%" and stir the solution with a new stirring stick until the two liquids are completely mixed, about 1 minute.
- This gives you a 1% w/w solution.
- Thoroughly clean and dry the 10 mL graduated cylinder. Cleaning the graduated cylinder (and using new stirring sticks every time) will prevent cross-contamination between the solutions.
Now make the 0.1% sugar solution. Measure 90 mL of distilled water in the 100 mL cylinder and pour it into the cup labeled "Sugar 0.1%."
- Use the 10 mL graduated cylinder to carefully measure 10 mL of the 1% sugar solution. Pour the 10 mL of 1% sugar solution into the cup labeled "Sugar 0.1%" and stir the solution with a new stirring stick until the two liquids are completely mixed.
- The result is a 0.1% w/w solution.
- Thoroughly clean and dry the 10 mL graduated cylinder.
Finally, make the 0.01% sugar solution. Measure 90 mL of distilled water in the 100 mL cylinder and pour it into the cup labeled "Sugar 0.01%."
- Carefully measure 10 mL of the 0.1% sugar solution in the 10 mL graduated cylinder. Pour the 10 mL of 0.1% sugar solution into the cup labeled "Sugar 0.01%" and stir the solution with a new stirring stick until the two liquids are completely mixed.
- The result is a 0.01% w/w solution.
- Thoroughly clean and dry the 10 mL graduated cylinder.
- Repeat steps 2-6 using Splenda® and erythritol. Make sure to label the cups properly (for example, "Splenda® 10%," "Splenda® 1%," and so on; "Erythritol 10%", "Erythritol 1%", etc.), with the dilution and the substance you are mixing into the water.
- Now you will make serial dilutions using honey. However, honey is a liquid, so the procedure to make the 10% solution is slightly different, because you will measure in milliliters and not in grams. You will also need to warm the water slightly in order to easily dissolve the honey.
- First, label four plastic cups. Label the first cup "Honey 10%," the second "Honey 1%," the third "Honey 0.1%," and the fourth "Honey 0.01%."
- Measure 90 mL of warmed (microwaving a cup of water for 30 seconds will be enough to warm the water) distilled water in the 100 mL graduated cylinder and pour it into the cup marked "Honey 10%."
Measure 10 mL of honey in the 10 mL graduated cylinder. Pour the honey into the cup labeled "Honey 10%" and stir the solution with a new stirring stick until the two liquids (warm water and honey) are completely mixed and the solution is a uniform light brown color.
- The result is a 10% by volume (volume/volume, or v/v) honey solution.
- Thoroughly clean and dry the 10 mL graduated cylinder.
- Now follow steps 4-6 to make up the rest of the honey solutions. Carefully prepare the solutions in properly marked plastic cups. Remember to use a new stirring stick each time you stir a solution and thoroughly clean the 10 mL graduated cylinder between solutions to prevent cross-contamination.
Testing the Solutions
- Find a place at school or at home where you can do your testing. The location must have water (a faucet or fountain) and a sink.
Gather ten volunteers. Make sure that each volunteer has written permission from a parent or guardian (if they are younger than 18 years old) to participate in the test.
- Remember, if you need to conduct your taste tests over more than one day, you will need to make new solutions each time you conduct tests.
- Prepare tables in your lab notebook, like the one shown below, to record your data. Make a table for each of your volunteers. For 10 volunteers, you will have 10 data tables.
|Substance||10% solution||1% solution||0.1% solution||0.01% solution|
- Each volunteer should rinse his or her mouth out with plain tap water and then gently dry his or her tongue with a paper towel.
- Fill a plastic cup with distilled water.
- Dip a clean cotton swab into the distilled water and smear it all over the first volunteer's tongue. This gives the volunteer a baseline for comparing the different solutions.
Dip another clean cotton swab into the 0.01% sugar solution and smear it all over the volunteer's tongue. Ask the volunteer if he or she can detect a change in taste compared with the distilled water. Make sure to tell the volunteer there is no right or wrong answer, and that each person tastes differently. If the volunteer can detect a change in taste, then write "yes" in the data table in the 0.01% solution box for sugar. If the volunteer cannot detect a change, then write "no" in that box.
- Reassuring the volunteers that their answers cannot be wrong will help you get their most accurate answer, instead of the answer they think you are looking for.
- Remember, you are asking for a change in taste. The change does not have to be in terms of sweetness.
- Repeat steps 6 and 7 for the 0.1%, 1%, and 10% sugar solutions. Be sure to test the solutions in that order, for least concentrated to most concentrated. Volunteers should rinse their mouths out with tap water and gently dry their tongues with a paper towel in between tasting after tasting each solution.
- Repeat steps 6-8 with each volunteer until all volunteers have tested the sugar solution. Follow the same steps for the Splenda®, erythritol, and honey solutions. Remember to record your volunteers' "yes" or "no" taste responses in your data table.
Analyzing the Data
- Review the data that you collected from your volunteers.
- For each combination of sugar, sugar substitute, and dilution percentage, count the number of volunteers who detected a change in taste. Record this data in a table like the one shown below.
|Substance & Dilution||Number of People Who Detected a Change|
Plot the data from Table 2 on a bar chart. Label the x-axis Dilution Percentage, and the y-axis Count of Volunteers Who Tasted a Difference. This kind of plot is called a histogram.
- Plot all of the data for each substance (sugar, Splenda®, etc.) on one chart to make comparisons easier.
- You can make your own plot by hand on graph paper.
- If you would like more information on plotting or would like to make your plot online, check out this website: Create A Graph.
- Let us assume that the detection threshold (when the volunteer notices a change in taste) and sweetness go hand-in-hand. So, the earlier a change in taste is detected, the sweeter the substance. Based on your data and plots, which substance did the volunteers find sweetest? At what dilution percentage did most people notice a change? How does this match your background research?
For troubleshooting tips, please read our FAQ: Sweet as Sugar: Comparing the Sweetness of Sugar & Sugar Substitutes.
Ask an Expert
- Instead of using water as a diluting medium to test the taste threshold of sugar and sugar substitutes, use unsweetened lemonade. This mimics a real-life use of sweeteners.
- Use Splenda® instead of sugar to make your favorite sweet treat, keeping in mind that you need to find out how much Splenda® to substitute for a given amount of sugar and that you might also have to add other ingredients to do the bulking and browning that sugar normally provides. As a final precaution, using Splenda® usually decreases baking time, so make sure you don't leave your treat in the oven too long.
- In this project, you used Splenda® as the source for sucralose. Repeat the experiment with pure sucralose. You can purchase pure sucralose online from Amazon.com.
Frequently Asked Questions (FAQ)
Also note that if your solutions were not mixed completely so that all of the sweetener dissolved, then the bottom of the solution may be sweeter than the upper parts of the solution. Be sure to mix your solutions until all of the crystals are dissolved.
Ask an Expert
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