Scrumptious Science: Great Globs of Gluten!
Do you have a favorite Thanksgiving dinner dish? Maybe it’s an aunt’s special cranberry sauce, or mashed potatoes combined with perfectly-seasoned gravy. Or perhaps you enjoy sinking your teeth into a succulent roasted turkey the most. Dinner rolls, biscuits, corn breads, muffins, pastries and pies may also be baked for this special meal; the foods in this group typically all contain a substance called gluten. In this science activity, you’ll explore why some foods, all made from wheat flour, have such different levels of tenderness and toughness based on their gluten content. Then, while enjoying the bready sides on Thanksgiving, you could impress your family with your gluten knowledge!
This activity is not appropriate for use as a science fair project. Good science fair projects have a stronger focus on controlling variables, taking accurate measurements, and analyzing data. To find a science fair project that is just right for you, browse our library of over 1,200 Science Fair Project Ideas or use the Topic Selection Wizard to get a personalized project recommendation.
Breads, bagels, pastas, cakes, cookies, crackers, muffins, pastries, pies and pizza crusts. Are you hungry yet? What do all these foods have in common? Traditionally, they are all made from wheat flour, the fine powder made from grinding and sifting kernels of wheat, the edible part of the wheat. Wheat belongs to the grass family, which contains 8,000 species. Wheat was likely first cultivated in the Middle East about 10,000 to 12,000 years ago. Today, it is the third most produced cereal grain in the world (corn is first and rice is second).
Why is wheat flour used in so many foods? When water is mixed with most other flours (like those made from corn or rice), you get a ball of paste that sort of sits there. Mix wheat flour with water, though, and it can make a ball that is both plastic (it can change shape) and elastic (it can return to its original shape)! Gluten, a composite of proteins within the wheat kernel, makes these unique qualities possible. Because of these qualities, wheat dough can trap gas (carbon dioxide made by yeast) and expand, which helps breads and other baked goods rise to become light and fluffy!
Extra: If you want, you can bake your gluten balls by putting them in the oven at 450 degrees Fahrenheit for 15 to 30 minutes. How do the gluten balls look, feel, and taste after they’ve been baked?
Extra: Repeat this using a wider variety of flours made from wheat and use a ruler to quantify your size comparisons between the gluten balls. Which flours make the largest gluten balls (the ones with the greatest diameters), and which make the smallest? How big are the differences?
Extra: You could investigate how kneading affects the size of the gluten ball made. To do this, choose one type of flour and create three equally-sized balls of dough from it with different degrees of kneading: no kneading, 5 minutes of kneading and 10 minutes of kneading. Rinse the dough balls and evaluate the gluten balls that are created, either by measuring their diameter or weighing them. How does the amount of kneading affect the gluten ball’s size?
Extra: Select one type of flour and make dough with different additives, such as salt, sugar or oil. How do the additives affect the amount of gluten that develops?
Observations and Results
Were the gluten balls made using bread flour or gluten flour the largest, while ones made using cake flour or pastry flour were the smallest and all-purpose flour gluten balls were intermediate in size?
Typically, bread and gluten flours have a relatively high amount of gluten (around 12% to 14%), while cake and pastry flours have the lowest amounts (around 7% to 10%) and all-purpose flour has an intermediate amount (around 9% to 11%). The more gluten a flour has, the larger the resultant gluten ball should be. “Hard wheat” flours, like bread flour, are high in gluten and are good for baking things that need toughness and strength, like yeasty breads, bagels and puff pastries. “Soft wheat” flours, like cake and pastry flours, are low in gluten and are better for baked goods that need to be tender, like pancakes, cookies, and pastries.
Why is kneading important for measuring the gluten content in the flour? As the dough is kneaded, the chain-like molecules that make up gluten (glutenins and gliadins) get linked together, end to end, to form super-long, spring-like chains. This makes the tight, coiled mesh that is gluten, and this gives the dough its elasticity. All of those springs want to “spring back” when they’re stretched!
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Teisha Rowland, PhD, Science Buddies
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