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Get Saucy with the Thickening Power of Starches

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Areas of Science
Time Required
Long (2-4 weeks)
Material Availability
Readily available
Very Low (under $20)
Adult supervision is recommended when using the stove.
*Note: For this science project you will need to develop your own experimental procedure. Use the information in the summary tab as a starting place. If you would like to discuss your ideas or need help troubleshooting, use the Ask An Expert forum. Our Experts won't do the work for you, but they will make suggestions and offer guidance if you come to them with specific questions.

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Who doesn't love soaking up the last bit of gravy on Thanksgiving? Or dipping a crusty cube of bread into a cheese fondue? Or scooping up the thick juices from a fruit pie? Sauces make eating a joy! They provide concentrated flavor in a thickened liquid form, with a pleasing texture and consistency that carries or compliments the flavor of the rest of the food. No matter if they're salty, spicy, savory, or sweet, sauces make foods richer and more special.

There are many ways to thicken sauces, but one of the most common ways is to use starches. Cooks have two choices in deciding how to thicken sauces with starches: they can use the starches from grains, or the starches from tubers and roots. Starch is the complex carbohydrate part of a seed or tuber. It contains two kinds of molecules: amylose and amylopectin. The starch in grains like wheat, corn, and rice is different from the starch in roots and tubers like potatoes, tapioca, and arrowroot. To do this science fair project, you will need to read about the differences, and then select at least three plants to test, and a liquid to test them in, such as, broth, water, fruit juice, or milk. In setting up your experiment, you should use the same amount of test starch for each trial; for example, 1 tablespoon of starch, and the same amount of test liquid for each trial, such as, 1 cup of broth. You will also need to warm and whisk them gradually in the same way, and in the same size saucepan.

To test your three starches, you will need to get the starch into the test liquid. It sounds like a simple task. You just put it in, right? Actually, it can be a tricky process! There are several methods to incorporate the two together, including mixing the starch first with a small amount of cold water, mixing the starch first with a bit or fat, or making a roux. However you decide to get your starch into the test liquid, you will need to use the same method each time you do a trial.

Finally, you will need some way to measure the thickening power of your starches and compare one sauce to another. One way is described in the Science Buddies project, Egg Substitutes. Once you have your measurements, think about whether your results make sense. Do you expect a starch from a tuber or root to have more thickening power than a starch from a grain? If so, what starch molecule is responsible for this increased thickening power?

So put some starchy plants to the test and see which one has the supreme thickening power!


This source gives an overview of thickeners:

  • McGee, Harold. On Food and Cooking: The Science and Lore of the Kitchen. New York: Scribner, 2004. pp. 610-620.
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General citation information is provided here. Be sure to check the formatting, including capitalization, for the method you are using and update your citation, as needed.

MLA Style

Science Buddies Staff. "Get Saucy with the Thickening Power of Starches." Science Buddies, 3 Mar. 2022, https://www.sciencebuddies.org/science-fair-projects/project-ideas/FoodSci_p028/cooking-food-science/thicken-sauces-starches. Accessed 22 Sep. 2023.

APA Style

Science Buddies Staff. (2022, March 3). Get Saucy with the Thickening Power of Starches. Retrieved from https://www.sciencebuddies.org/science-fair-projects/project-ideas/FoodSci_p028/cooking-food-science/thicken-sauces-starches

Last edit date: 2022-03-03
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