Bread Lab

Lab Roles:

Blog Writer: Rebecca 

Baker/Chemist: Samantha 

Photographer: Anna 

Recipe:

• 1 1/2 cups of flour
• 1/2 cup of water
• 1 1/8 tsp of yeast
• 1/8 cup of vegetable oil/cooking oil
• 1/2 tsp of salt
• 1 tbsp of sugar

Process:

1. We began by gathering our flour, water and yeast into a gallon plastic bag and closing it.

2. Then, we mixed the ingredients together in the bag and let them sit for 10 minutes to give the yeast time to ferment and activate.

3. After the 10 minutes, we removed the dough from the bag and gathered it into a ball. 

4. We then kneaded the dough for about a minute to mix in all the ingredients.

5. As we kneaded the dough, we slowly added in a mixture of vegetable oil, salt and sugar.

6. We continued kneading the dough for a few minutes to mix in all the ingredients. 

7. After kneading and mixing the ingredients into the dough, we placed the dough into the tray and put it under multiple lights to heat up and rise some.

8. Our bread dough was then placed in the oven to bake for a little under an hour.

9. The next day, we viewed the results of our recipe and reflected on what we could have done to improve the outcome. 

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Cellular Respiration:

Equation: Oxygen + Glucose ----> Carbon Dioxide + Water + ATP

Cellular respiration is a process that occurs in two forms, aerobic and anaerobic. Aerobic respiration occurs in the mitochondria, while anaerobic respiration occurs in the cytoplasm of the cell. 

Cellular respiration within the yeast is important in bread making because it is needed for bread to rise and form carbon dioxide bubbles in the bread. 

Plants, specifically wheat, are involved in this process because of the process photosynthesis which they performed when they were still alive. Photosynthesis allows for cellular respiration to occur because it creates glucose, a reactant in the equation for cellular respiration. The yeast needs the glucose to perform cellular respiration and produce carbon dioxide, making the bread rise. 

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Anaerobic vs Aerobic Respiration:

Yeast and humans undergo different forms of cellular respiration. Humans primarily perform aerobic respiration, which means they use oxygen to complete cellular respiration. They can also perform lactic acid fermentation, which is a form of anaerobic respiration and does not require oxygen. Yeast, on the other hand, perform alcoholic fermentation, which is another form of anaerobic respiration. 

Anaerobic respiration is important for bread making because it is the process that makes the yeast rise and form CO2 bubbles. 

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CO2 Cycle:

When the yeast are activated and undergo cellular respiration, they release CO2 as part of the process. This CO2 is released into the atmosphere and eventually taken in by plants in the process of photosynthesis. The plants then use this to perform cellular respiration and release it back into the atmosphere. 

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Design Rationale for Recipe:

To design our recipe, we took the base recipe given to us and combined it with information from multiple sources to decide what would work best. We also took what we knew about each ingredient involved in baking bread and used that knowledge to decide which were necessary. We then scaled the amount of each ingredient to match the base recipe and then began creating our dough. 

Each ingredient in baking bread has a purpose. Although our recipe was not very successful, it did have the basic ingredients needed to create a loaf of bread. 

The purpose of adding sugar to bread is to provide food for the yeast to activate. During this activation process, the yeast produces alcohol and carbon dioxide. Sugar also keeps moisture in the bread and keeps it from becoming dry. Artificial sweeteners do not provide food for the yeast as they don't have the same components. 

Fats, like vegetable oil, keep the bread from becoming stale quickly and keeps it tasting fresh for longer. it also keeps the bread from getting too elastic. 

Salts tighten the gluten structure in the dough and give it strength. They also make the yeast rise slower and slows down the fermentation of the yeast, keeping it from rising too quickly. 

Flour has many purposes in bread making. It is made of two proteins: Glutenin and Gliadin. When water combines with these two proteins, they form gluten. Another molecule, starch, can also be found in flour. Starch releases sugar for the yeast to feed on, but only when enzymes in the flour attack it. Starch supports the gluten by adorning water during baking. It also helps gluten contain the gas pockets the yeast produces. 

Yeast are responsible for creating CO2 and making the bread rise.

Lastly, warm water is necessary in baking bread because it activates the yeast and begins the process of cellular respiration. 

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Recipe Reflection:

Overall, our bread recipe was not the most successful. The finished product was burnt on the top, likely because when we put the dough in the pan it was still very oily on the top. After cutting into the bread, we found it was very soft and had good elasticity and texture. Eventually, we sampled the bread's taste and found that we had not mixed our ingredients well enough. Parts of the bread tasted normal, while other parts tasted very sweet and other parts very salty. It would have been better if we had taken more time to mix in our ingredients  or even found a different way to mix them together. In the end, although our recipe was not the most successful, we did successfully bake a loaf of bred which was the objective of our lab.