Gluten Lab: for high school sophomores

            Gluten is a protein in wheat; it is what makes dough elastic and bagels chewy.  Gluten is a complex of glutenin and gliadin, which make up eighty five to ninety percent of all protein in wheat.   These complexes are responsible for structural support in yeast-leavened baked products.  The gluten complex can be described as a unified and flexible extensive fibrillar network surrounded in a protein membrane.  These complexes are not just found in wheat, gluten like protein associations can be found in a variety of other grains, most notably: rye, barley, kamut, spelt and oats (although recent testing has called oats into question).  There is a viscoelastic (having viscous as well as elastic properties) difference between the gluten in wheat and the “gluten” in these other grains.  The “gluten” in rye and barley is less flexible and cohesive.  The functionality of gluten is derived from its protein components.    “ Glutelin is responsible for strength and cohesion or the wheat gluten complex … Gliadin is necessary to provide elasticity, allowing the gluten film to stretch” (Christen 2000).  Gluten is so important because it holds the gas produced by yeasts and makes bread rise. “Think of gluten as the rubber of a balloon: The stronger it is, the more gas it can hold” (The Science of Cooking).  Stronger is desirable for some products like hearty yeast breads but for other bakery products gluten development is avoided.
            Gluten has gained some notoriety lately due to celiac disease.   Celiac disease, also called celiac sprue or celiac enteropathy, is intolerance to gluten.  In people with celiac, “the protein causes an immunological reaction in the small intestine, resulting in the disintegration of the finger-like villi that facilitate the absorption of nutrients”(Allen, 2005).   Recent studies suggest that as many as one in 133 people or a total of 2,131,019 Americans are afflicted with celiac disease (Adams, 2005).  Symptoms include "mild weakness, bone pain, and aphthous stomatitis to chronic diarrhea, abdominal bloating, and progressive weight loss" (Halsted, 1996).  The wide range of symptoms can make the diagnostic process rather difficult although the actual test for the disease is relatively simple. Testing involves “screening the patient's blood for antigliadin (AGA) and endomysium antibodies (EmA), and/or doing a biopsy on the areas of the intestines …” (Adams, 2005).  Currently the only method of treatment is a strict adherence to a gluten free diet.  Since long-term effects of the condition can be anemia, malnutrition, osteoporosis and an increased risk of gastrointestinal cancer strict adherence is absolutely necessary (Allen, 2005).  This can be extremely difficult because, “according to Dr. Chaitan Kholsa of Stanford University,  ‘After sugar, gluten is the second-most prevalent food substance in Western civilization’” (Allen, 2005).   This is because gluten is used in so many things that many people may not normally think of: as a thickener and binder in things like soups, sauces, and candies, it may also be present in pharmaceuticals and even envelope glue.  However, Dr. Chaitan Kholsa is currently trying to determine a pharmacological ways of treating celiac disease so those affected can consume gluten painlessly and safely.  People with celiac are not the only ones who should try and avoid gluten it has been found that, people with autism and disorders in the autistic spectrum (like Asperger's) may also be sensitive to gluten as well as casein (a protein in milk ).

            In this lab we will conduct an experiment to compare two breads one using traditionally flour and one made using a gluten free flour (gluten free flour is a mixture of different flours including corn, rice and tapioca).  The purpose is to compare these two products and hopefully gain first hand knowledge of what gluten actually does.
For this lab the class may split into 2 groups.  One group will make the traditional white bread and one will make gluten free white bread.  The recipes come from The Betty Crocker Cook Book; but I have modified the gluten free recipe.  Make sure that during the lab you get a chance to observe the other groups dough so that you can compare them.

Regular White Bread

Materials

2-package active dry yeast

2-cups luke warm water

3-tablespoons sugar

3- tablespoons shortening

1-tablespoon salt

7 to 8-cups all- purpose flour

margarine or butter softened

2-loaf pans

an oven

rolling pin

mixing bowl

large bowl ( to grease and allow dough to rise in)

wire cooling rack

Gluten Free White Bread

Materials

2-package active dry yeast

2-cups luke warm water

3-tablespoons sugar

3- tablespoons shortening

1-tablespoon salt

7 to 8-cups all- purpose flour

margarine or butter softened

2-loaf pans

an oven

rolling pin

mixing bowl

large bowl ( to grease and allow dough to rise in)

wire cooling rack

 

Procedure (same for both)

1. Dissolve the yeast in the luke warm water in a mixing bowl

2. Stir in milk, sugar, shortening and salt

3. Add 4 cups of flour

4. Beat until smooth

5. Mix in as much of the remaining flour as needed to make dough easy to handle

6. Place dough on a surface that has been lightly dusted with flour

7. Knead until smooth and elastic(about 10 minutes)

8.  While some students are kneading others should be greasing a bowl

9.  Place kneaded dough in greased bowl; turn dough in bowl so bottom gets greased

10. Cover, and let rise until its doubled (about 1 hour)

11. Punch down dough, divide into halves

12. Roll each ½ into rectangles 18x9 in

13. Fold 9-inch side into thirds, overlapping ends (see picture at bottom or ask teacher for further clarifications)

14. Roll up tightly and pinch end of dough to seal tightly; fold ends under

15. Once again while part of the group is rolling another part should be greasing loaf pans

16. Place loaves seam side down into greased pans

17. Brush lightly with margerine

 *I realize that many class periods might be over at this point so the teacher may finish these steps for you

18. Let dough rise until doubled (about 1 hour)

19.  Heat oven to 425 and place pans in center of lower rack

20. Bake until golden brown (25-30 min)

21. Remove immediately from pan, brush top of loaves with margerine and place on cooling racks

 

 

 

Questions

  1. What differences did you observe in the dough’s?
  2. What differences did you observe in the final products?
  3. What accounts for these differences?
  4. Suggest ways to eliminate these differences?
  5. Which bread did you prefer?

 

Links: (for your own personal enjoyment)

Check out this link for another simple gluten experiment

For more information on celiac or other gluten free recipes check out these links

Celiac.com, Clan Thompsons Celiac Site, & Gluten Free Recipes

Check out Webster’s online dictionary for a definition and other facts about gluten

Some more good gluten information

Works Cited

Adams, Scott. 2005. Prevalence of Celiac Disease in the United States is Found to be 1 in

133. Celiac.com. <http://www.celiac.com/st_prod.html?p_prodid=789&p_catid

=&p_print=y&sid=91hH9H1Eo2jr3GX-13105269428.4c>19 Apr. 2005

 

 

Allen, Kimberly Jordan. 2005. Gluten-Free Cuisine. E Magazine: The Environmental

Magazine 16(1);42-3 <http://triton3.galib.uga.edu/cgibin/homepage.

cgi?style=&_id=80c0bdf2-1136600102-6302&_cc=1>23 Apr. 2005

 

1981. Betty Crocker's Cookbook. Wisconsin: Western Publishing Company, Inc. 209

 

Christen, Genevieve L. and Smith, J. Scott. 2000. Food Chemistry: Principals and

Applications. California: Science Technology System. 317-318

 

Halsted, Charles H. 1996.The many faces of celiac disease. New England Journal of

Medicine 334(18);1190-1

 

The Science of Bread: Great Balls of Gluten Activity. Exploratorium.

<http://www.exploratorium.edu/cooking/bread/activity-gluten.html>23 Apr. 2005