Sweet as Sugar: Comparing the Sweetness of Sugar & Sugar Substitutes

http://www.sciencebuddies.org/science-fair-projects/project_ideas/FoodSci_p016.shtml

• 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

1. 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.
   1. When you taste-test the solutions, you will be looking for a change in taste and not necessarily a change in sweetness.
2. 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%."
3. Measure 90 mL of distilled water into the 100 mL graduated cylinder, and pour it into the cup labeled "Sugar 10%."
   1. 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%."
   2. 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.
   3. This gives you a 10% by weight (weight/weight, or w/w) sugar solution.
4. 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%."
   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.
   2. This gives you a 1% w/w solution.
   3. 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.
5. 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%."
   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.
   2. The result is a 0.1% w/w solution.
   3. Thoroughly clean and dry the 10 mL graduated cylinder.
6. 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%."
   1. 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.
   2. The result is a 0.01% w/w solution.
   3. Thoroughly clean and dry the 10 mL graduated cylinder.
7. 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.
8. 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.
9. 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%."
10. 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%."
11. 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.
    1. The result is a 10% by volume (volume/volume, or v/v) honey solution.
    2. Thoroughly clean and dry the 10 mL graduated cylinder.
12. 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

1. 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.
2. 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.
   1. 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.
3. 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
Sugar
Splenda® (sucralose)
Erythritol
Honey

Table 1. Collect a volunteer's taste-threshold data in this table.

4. 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.
5. Fill a plastic cup with distilled water.
6. 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.
7. 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 changein 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.
   1. 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.
   2. Remember, you are asking for a change in taste. The change does not have to be in terms of sweetness.
8. 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.
9. 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

1. Review the data that you collected from your volunteers.
2. 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
Sugar 0.01%
Sugar 0.1%
Sugar 1%
Sugar 10%

Table 2. Use a table like this to tally the total number of volunteers who detected a change for sugar and/or sugar substitutes. The rows for sugar at all the tested dilutions are shown here as an example; you will need additional rows for the sugar substitutes you tested.

3. 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.
   1. Plot all of the data for each substance (sugar, Splenda®, etc.) on one chart to make comparisons easier.
   2. You can make your own plot by hand on graph paper.
   3. If you would like more information on plotting or would like to make your plot online, check out this website: Create A Graph.
4. 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?