Bread Blog: Alexandria, Ashley, and Lauren

Background: Cellular Respiration & CO2 Cycle

When making bread you can see cellular respiration in action, but what is cellular respiration? Cellular respiration is the process of the cell turing glucose into a usable energy.  It can be expressed in the chemical equation below:

image credit;study.com

There are two types of cellular respiration: aerobic and anaerobic. Aerobic respiration is the kind that is pictured above; broken down glucose combined with oxygen creates CO2, H2O, and most importantly ATP. ATP, or adenosine triphosphate, is the kind of energy your body uses. Aerobic respiration produces 34 molecules of  ATP.

When you look at bread you see the other kind of respiration: anaerobic. Anaerobic is respiration without oxygen. There are two types of anaerobic respiration, lactic acid fermentation and alcohol fermentation. For the purpose of this lab we’re going to focus on the later, although most organisms go through both processes.

Animals use aerobic respiration and lactic acid fermentation. Plants use aerobic respiration and alcoholic fermentation. The process for aerobic respiration is pretty similar in all organisms; the glucose (whether created by photosynthesis or consumed in food) in broken down in a process called glycolysis which takes place in the cell’s cytoplasm. Then in the mitochondria the glucose combined with oxygen as depicted in the equation above.

Anaerobic respiration in humans happens with lactic acid fermentation, while it produces no ATP it is still very important.. When the cells in your muscles run out of oxygen they anaerobically produce lactic acid so that your body can continue working. If you muscles start to hurt while exercising, that’s lactic acid fermentation

In plants and yeast however they use alcohol fermentation. When they don’t have access to oxygen they produce CO2 and ethanol. This is important in bread making because the CO2 produced by the yeast is what makes the bread fluffy.

The CO2 cycle is the way that carbon dioxide cycles through the atmosphere. There is tons of CO2 in the atmosphere and there are many ways that it gets there.We can see the cycle operating in plants and animals.  Animals when they respirate take in oxygen and release CO2, this CO2 is then taken in plants in order to photosynthesize (turn CO2 and water into glucose and O2). CO2 is also released by animal waste, released in matter broken down by decomposers and emitted whenever fossil fuels are burned.

The carbon cycle is one of the most important environmental processes in our world today which is why it’s dangerous to tamper with it. Scientists believe that the excessive burning of fossil fuels releases too much CO2 in the air, trapping heat in the atmosphere which can cause global climate change.   

Overall you can see the importance of CO2 and respiration within the process of bread making and other places in your everyday life.

Original Recipe and Why We Changed it

When we first started this process we did some research and created a recipe. It consisted of flour, water, sugar, yeast, and salt. In class we were able to test and see how it would work. We started with adding ¼ cup of flour into the bag and combining it with ½ teaspoon salt, ¼ teaspoon yeast and ¼ teaspoon of sugar. Then we added 4 tablespoons of water that was about 128 degrees. Then we let the yeast sit for 10 minutes. After that we added the final ¼ cup of flour and let it rise. In comparison to some of our other peers our bread was not rising as much, why was this? We were able to conclude that we had too much salt in our recipe, while salt can add flavor to the bread it also can stop the yeast from feeding on the sugars making it harder for it to rise. Another issue we ran across was in our process. We definitely could’ve been more careful in how we measured and combined our ingredients. We determined that the next day when we made our final bread using less salt, being more careful with our measurements, and being more careful in the way we combined our ingredients.

Why We Used the Ingredients We Did

Flour: Flour is most commonly made from wheat and serves one main purpose in bread. Raw flour contains gludian and gliadin. When these two ingredients are combined with water they create gluten. Gluten is what makes the bread dough stretchy. Gluten helps trap the CO2 produced by the yeast in the bread. Flour also contains starch which is stored glucose in plants, this is one of the main sources of food for the yeast.

Water: Water is used to create gluten with the flour and to activate the yeast. The water has to be in the 120-130 degree range in order for it to work properly. If the water is too hot the yeast will die, if the water is too cool the yeast won’t activate.  

Yeast; Yeast is probably the most important and complex part of the bread making process. The yeast once activated by the water feeds off the sugar in flour (the addition of cane sugar or honey can give the yeast more food) and begins the anaerobic respiration process of alcohol fermentation. The yeast takes in the glucose and turns it into ethanol and most importantly, carbon dioxide. The carbon dioxide produced by the yeast is released and trapped. This gives bread it’s fluffy and airy qualities.

Sugar: The addition of sugar (or any natural sweetener) can provide additional food for your yeast which can cause it to rise more giving you a fluffier bread. Although, too much sugar can kill your yeast and if you use artificial sweeteners it won’t provide food for your yeast so it’s not recommended.  

Salt; Salt provides a better flavor in and out of your bread, if you put some salt on the bread before you bake it can create a nicer crust. But, if you add too much it can prevent the yeast form feeding.

Oil: Oil helps to keep the bread from growing stale after a short period of time and like the salt it can enhance the flavor.

Recipe Reflection

We as a group would like to think that our bread was overall quite successful. It was fluffy with air bubbles and rose a fair bit. Looking back on the changes we made I think that made our bread a lot better than if we had gone with our original recipe. We also have no doubt that there are certainly more improvements we could’ve made. Our bread certainly had potential to be fluffier and maybe with more of a crust to it. With unpredictable and for the most part unchangeable factors such as the environment, the brands we used, the exact temperature of the water, etc there is no true way to tell how successful our recipe would be on another day. It could work even better or it could end up worse. But, looking at the time we had and after thoroughly examining our results we can proudly say we did a pretty good job.

RECIPE

Ingredients:

• ½ cup of all purpose flour

• ¼ tsp yeast

• ¼ tsp sugar

• ¼ tsp kosher salt

• ⅛  tsp olive oil

• 4 tbsp of water

• Additional pinch of salt  

Procedure

1. In your plastic bag combine ¼ cup of flour ¼ tsp of yeast, ¼ tsp of sugar, and the ¼ tsp of salt.

2. Heat up 4 tbsp of water until it’s 120-130 degrees and gradually add to dry ingredients while stirring.

3. Wait about 10 minutes for the yeast to activate (you will see bubbles forming)

4. Then add the additional ¼ cup of flour to bag.

5. On a lightly floured surface knead your dough for about 1 minute.

6. Take your ball of dough and allow it to rise for about 30 minutes on a warm surface. (We used heat lamps but if you heat your oven and place the dough on top it will work just as well.)

7. When your dough has risen lightly coat it in the olive oil and add the final pinch of salt.

8. Bake for 30-40 minutes.