In-Class Experiment: Dough!

The baking experiments we performed in class involved tasting three different loaves of bread and trying to see the what variable changed between all of them.  The other was making pizza dough and varying when the oil was incorporated into the dough. Let’s start with the pizza dough experiment!

Pizza: Two batches of pizza dough were prepared.

1)      The first step to making the dough was to take 2 tablespoons (19 g) of active dry yeast and put it in 1.5 cups of water with a temperature of about  112o F. 2 teaspoons of brown sugar were also stirred into the water to feed the yeast. Almost immediately a slight foam began forming on top of the mixture. Over time the foam grew, and at about 9.5 minutes the foam nearly reached  the brim of the cup. This represented the yeast activating. The yeast was feeding on the brown sugar and releasing CO2 and ethanol.

2)       4.5 cups (657 g) of bread flour (4 g protein/quarter cup) and 1 teaspoon (8 g) of salt were mixed together.

3)      A well was formed in the center of the flour-salt, and the water-yeast mixture was poured into it.  At this point the procedure for the two doughs branched.  Therefore, a procedure for “Dough A” and “Dough B” will be followed.

Dough A

4)      5 tablespoons of olive oil was added into the well along with the yeast-water mixture.  The dough was then mixed. After the ingredients were incorporated, the countertop was floured, and the dough was kneaded. This dough appeared moist, smooth, and soft, and it did not take very long for all ingredients to become incorporated.

5)      Dough A was kneaded for a total of approximately 13 minutes, and then allowed to rise in a bowl covered by a tea towel for an hour and a half.

Dough B

6)      The flour mixture and yeast were immediately mixed (illustrated in picture below) after the addition of the water-yeast mixture into the well. After most of the ingredients were incorporation, the dough was kneaded on a floured countertop.

7)      After 7 minutes of kneading, Dough B had a tablespoon of olive oil added to it. Incorporating the oil was very difficult. The dough seemed to repel it. This was because a very tight, elastic gluten layer had been formed, making it difficult for any other substances to get into the dough. This was different from Dough A that had the oil added immediately to it, which inhibited a small portion of the gluten formation by blocking some of the proteins.

8)      An additional tablespoon of olive oil was incorporated into Dough B, which was kneaded for a total of 13 minutes.  Dough B was then allowed to rise in a bowl covered with a tea towel for an hour and a half.

9)      After rising, both doughs were punched down in their center to deflate them.

10)   Dough A was flatted by hand to create a thin, circular pizza dough.  Dough B was flattened using a rolling pin to create a thin, circular pizza dough.  The doughs were covered in pizza sauce and cheese and put into the oven at 450o F for approximately 25 minutes.

The Results

The pizza made from Dough B had a very firm structure: a slice held stiff when cut and put in the air. It also tasted very “doughy” or dense.  The dough had big, flat bubbles and was very tender, but it was too filling. 

The pizza made from Dough A had a more weakened structure, so the slices gave a little when held. Overall, dough A was softer, the pizza appeared larger, and it had a great flavor.

The difference in structure between the two pizzas could be attributed to the flattening methods (a rolling pin vs. hands), or kneading methods.  However the most probable cause of the differences in texture and structure can be attributed to the time at which the oil was added. It became clear that if oil is first put into a mixture before the incorporation of all ingredients, gluten formation is somewhat inhibited. This gives for a much weaker, softer structure (dough A). The addition of oil after ingredient incorporation does not work very well, as sheets of gluten have already formed during the kneading process, creating a much tougher and chewier structure (dough B).

Breads: The second experiment, as mentioned, involved tasting, making visual observations, and feeling several different kinds of bread in an attempt to figure out the altered ingredient. To figure this out, several characteristics were noted.

Loaf A:  The bread was white in color, had risen the most, appeared to have small air pockets throughout its structure,was not very dense, and had a very neutral smell and taste.

Loaf B: The bread was almost gray in color, raised the least, was extremely moist and dense, had a vinegar-like smell to it, and tasted somewhat sour.

Loaf C: The bread appeared yellow in color, was very dense, and seemed to have a buttery taste to it.

After coming up with different ideas of what ingredient could have been changed and how it would affect the structure of the overall bread, it was eventually concluded that the changed variable was the type of flour. In fact, the ingredients used to make each loaf of bread were 685 g of flour, 348 g water, 12 g salt, and 9 g yeast. The first bread was made with cake flour, the second with all purpose flour, and the third with bread flour. All three have different protein contents, allowing for different amounts of water absorption and final molecular structures, ultimately resulting in three very different loaves of bread.


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