NADH is then taken from the acetaldehyde and ethanol is left. (Starr, Evers & Starr, 2011) Bread making is an example of alcoholic fermentation, the yeast being the reason that the bread rising. As explained before the carbon dioxide molecules that are given off during the second stage of fermentation caused the dough to rise and the ethanol that was left bakes out of the bread. Methods and Materials In order to start this experiment we first needed to get two bowls and two spoons in order to have a control bowl and an experimental bowl.
We then put the one cup of flour in the control bowl followed by all the other dry ingredients; three quarters of a tablespoon of sugar, one quarter of a tablespoon of salt, one and one quarter tablespoon of dehydrated milk, and one tablespoon of yeast. We then mixed that together and added one half tablespoon of margarine we mixed that while gradually mixing the one half cup of warm tap water. As we did before we then put one cup of flour in the experimental bowl followed by all the other dry ingredients; three quarters of a tablespoon of sugar, one quarter of a tablespoon of salt, and one tablespoon of yeast.
We mixed that together and added one half tablespoon of margarine we mixed that while slowly mixing in the one half cup of warm tap water. In order to expedite the process of rising we took out a hot plate and heated it to one hundred and ninety degrees Celsius. We then put both the control and the experimental dough into two two-hundred milliliter beakers, labeled them, recorded how full they were when we started and covered the tops with plastic wrap. We then put the two beakers on the hot plate and watched them rise.
The lab group decided that we would not test it for any certain amount of time; we would heat it until one of the beakers had two hundred milliliters of dough in it. Finally we recorded the end results and cleaned up our lab station. Results In this experiment while both of the experimental and control dough rose, the experimental dough rose faster and had more than the control dough, the difference is illustrated in that data section with table one and graph one. The plastic wrap rose while on both the beakers while the dough was rising. The dough at the bottom of the beakers turned a toasty brown color. Summary
The experiment this week was meant to show fermentations and all the factors that could influence it. While the dough did rise on both the doughs, it proved my hypothesis wrong; I thought that reducing the milk in the dough would reduce the rate at which the bread would rise and reduce how much it did rise. We watched the dough until it reached the two-hundred milliliter mark and that took about twenty-five minutes. Looking back on what we did I do realize that there were some mistakes that could affect the outcome, while fermentation did happen it could have an effect at what rate and how much the dough rose.
First of all we probably had that hot plates set to a temperature that was too high, this conclusion came due to the fact that that dough at the bottom of the beakers was toasty looking. This could mean that we were actually killing off the yeast instead of quickening the process of fermentation. Milk contains bacteria normally and that is why we used dry milk to cut down on the bacteria and enzymes. The water also could have been too warm for the control dough causing it not to rise as much. Though the dough did rise more without the milk, I am unsure of the cause.
It could be a number of reasons why the dough without milk rose more than the dough with milk rose more though it appeared when they had the plastic wrap on them they had the same amount of carbon dioxide. In all it shows that while not using the milk in dough did effect fermentation.
References Starr, C. , Evers, C. A. , Starr, L. , (2011) Biology: Concepts and Applications. Belmont: Brooks/Cole Cengage Learning. Data Table 1 Started Stopped Difference Control dough 125 mL 177 mL 52 mL Experimental dough 140 mL 202 mL 62 mL