Gluten in Ingredients

Bread ●
●
1 lbs flour
2 tsp of rapid-rise yeast
● 2 tsp of kosher salt
● 1 ½ cups warm water

Equipment Needed
● Oven
● Dutch oven
● Tool to scrape dough out of bowl
(optional but very helpful)
● Wooden spoon
● Bowl
● Hot pad
● Oven mitts

Preparation
1. Mix dry ingredients
2. Add yeast to water and leave for 5
minutes
3. Add to the dry ingredients and mix
Ready in 3 hours
4. Cover and let rise for 2 hours in a warm
Makes 1 large loaf place

Personal Commentary 5. Preheat oven to 450℉ with dutch oven

6. Place dough inside with parchment paper
On occasion, about every 2 months my dad
7. Bake for 30 minutes
would bake his bread. I would always eat it
hot with butter and smiles. It is a very simple 8. Remove lid of the dutch oven and cook
for another 15 minutes
thing to cook but for me that never took
9. Let cool for 15 minutes
anything away from the experience for me.
 Experimental Design Qualitative Results
In my experiment, I was testing the
relationship between the dough’s
deformation, the resulting bread, and the
time spent kneading. For my experiment, the
independent variable is kneading time. I
tested 4 different amounts of kneading:
none, 1 minute, 2 minutes, and 6 minutes. I
made 1 loaf of each. To quantitatively
measure the deformation of each batch of
dough, I held one half of the dough and
measured how fast the second half stretched. The qualitative data that I collected was the

I did this by taking a video of the process preferences of chewiness, texture, and crust

next to a ruler and looking at the time of the bread. Using the t-test with a t-value of

stamps. The second piece of quantitative 0.05 I found no significant difference

data that I collected was whether or not the between the data in the types of bread for

bread broke under its own weight when held. the qualitative data. The lowest t-value that

I then baked the bread and collected was found was 0.115, this was in the

qualitative data through a Google Form that comparison of the crust of the 2 minute

was filled out by my peers in which they rated knead time and the 6 minute knead time. This

the texture, crunchiness of the crust, was by no means an anticipated difference. If

chewiness, and overall preference on a scale a correlation did exist I would have thought

of 1-5. This was a blind test. I collected data that it would exist between the two

from 8 different participants. I anticipated to extremes. .However, the t-value is still not

see a correlation between the elasticity of large enough to be certain that there is in

the dough and the texture, I was curious to fact an impact. Because of the fact that there

see if that correlation was also present for was no distinguishable difference in the

other qualities of the bread such as the qualitative data, I will not try and outline a

crunchiness of the crust. correlation between the qualitative and

quantitative data because it will be equally
inconclusive.
Quantitative Results
The independent variable in the experiment was the times spent kneading. The dependent variables
are the deformation of the dough over time and when/if the dough broke under its own weight when
half of it is held and the rest fall. I recorded the data and from it was able to make the following graph.

In the second chart note that the 6

minute knead dough did not
deform. The first graph shows a
very even deformation. This means
that the dough deforms very
consistently, meaning that there
are minimal elastic forces within
the dough. There is also a very
distinct difference between the
data points. From this it is easy to
infer that the correlation between
kneading and the deformation of
dough is very strong. Because of
how distinct the difference in the
quantitative data is, it is expected
that there would also be a distinct
difference in the qualitative data,
assuming that the two are
connected. In this case that would
be the physical properties of the
dough and texture of the resulting

bread. At the beginning of the experiment I highly anticipated that there would be a strong correlation
between the two. The research that I did confirmed this. In theory, the more well structured the gluten
network is, the more easily it is able to stretch and adapt to the trapped gasses. I expected to see in the
more kneaded bread that it would have smaller bubbles because gas would be trapped more locally.
However, I did not see this correlation in the qualitative data. It is possible that this was due to the
error in the experiment but, due to the definitive results of the t-test, I doubt this.
Chemical Explanation
Gluten is the main component behind the structural properties of dough. Gluten is the network of
proteins found in flour (Glutenin and Gliadin). It is what allows the elasticity of dough, and helps in
forming the texture of bread in the way that it is able to trap gasses within its structure. Dough is a
non-linear viscoelastic material which is very interesting and I found it intriguing to research. However,
in this context it means that the properties of dough are both elastic and capable of permanent
deformation with relative ease. Gluten networks are the cause of this, because they are built up by the
proteins found in flour. When the dough is created the proteins in the flour are dissolved in water
which allows these proteins to unravel.

The two proteins in flour bond via intermolecular disulfide bonds to form long polymers. The process of
kneading, which causes shearing and stress forces, aligns and strengthens the disulfide bond and forces
them to re-arrange, which pushes the bread to a more ordered state. This causes the two proteins to be
further aligned, which causes a greater elasticity. In order to form the disulfide bond, cysteine is
necessary. Flour contains about 2-3% of cysteine. The bond of the two proteins accounts for the
majority of the elastic properties. Without this, the dough would still maintain the property of
stretching (due to the fact that the polymers are so large) but lose the ability to return to its original
shape. In addition to the disulfide bonds there are also intermolecular hydrogen bonds that contribute
to the elasticity of dough.

Salt is also an important component in the formation of

gluten. When salt is dissolved in water, the ions dissociate.
This leaves the negatively charged chlorine and the
positively charged sodium. The proteins in flour naturally
repel each other due to negatively charged portions of the
amino acids that they are built up from. This repulsion
doesn’t allow the proteins to pack tightly causing a reduction in the number of cross links for any given
area. However, we know that sodium is present. This sodium acts as a charge shield. That fits between
the proteins. Because of the inverse-square law, the positively charged sodium ion has a greater effect
than the negatively charged amino acids have less of an effect. The inverse square law is given by
𝑘·𝑐1·𝑐2
𝑓 = 2 because the distance between the two negative charges is greater, the force drops off very
𝑑

quickly. Because the distance between the sodium and the protein is shorter, the force of attraction
drops less. All of this adds up to a compact network for higher potential for elasticity.