Data Analysis Of Our Pizza

DATA ANALYSIS

Our experiment consisted pointing the differences of two types of yeast in a pizza: the dry and the fresh yeast. Letting the dough grow in a closed environment proved our hypothesis of anaerobic respiration, and also we could notice that the warm water and the sugar played an important part on the experiment.

Yeast is activated by warm water. If we use cold water, the dough will never grow and we would never see the difference between the fresh and the dry yeast. Sugar is going to be also the fuel of the yeast (in order for fermentation to take place, the yeast needed glucose), because the hot water may activate it, but the sugar is the one that is going to regulate how much the dough grow and how long is the yeast going to be active.

Respiration is important because it releases energy from glucose. It occurs in the mitochondria. Respiration is not necessarily of oxygen use, not in every case. When there is use of oxygen, we call it aerobic; and when there is no use of oxygen is called anaerobic which can lead to fermentation (bacteria) or lactic acid (eukaryotic).  Without respiration we wouldn't have any energy to perform necessary day to day functions. On the pizza dough when the dough grows, is the yeast doing anaerobic respiration.

If you leave the dough with the yeast in a closed environment (in this case we covered it with vinipel), it would make an anaerobic respiration which would lead to fermentation. The yeast would do oxygen-less respiration.

People take advantage of yeast in many different ways. Two of the most important or relevant uses are in the production of alcoholic beverages and baked products. Both of these take advantage of the products released by the yeast during fermentation. The ethanol released (C2H5OH) is what makes an alcoholic drink, well, alcoholic. And the carbon dioxide (CO2) is the gas that makes bread “bloom”. So yeah, yeast is a pretty good chef.

Some species of yeast are opportunistic pathogens that can cause infection in people with compromised immune systems. Cryptococcus neoformans and Cryptococcus gattii are significant pathogens of immunocompromised people. Yeasts of the Candida genus, another group of opportunistic pathogens, cause oral and vaginal infections in humans, known as candidiasis. Nonetheless, not all microorganisms cause us harm. As we have seen before, certain bacteria such as Lactobacillus Bulgaricus and Streptococcus Thermophilus are essential in the process of making yogurt. If we take advantage of our knowledge of microorganism and the life process that take place within them, we use these small organisms for our own purposes. Instead of considering yeast a nasty bacteria that could cause an infection, we should considerate as a small friend that will help us bake all types of bread, if the conditions are right.

In our experience, we could see that the dry yeast was softer than the fresh yeast. The dry yeast grew more and at the moment of tasting it, it was better than the fresh yeast. At the beginning even with the color and the texture of both pieces of dough, we could see a remarkable difference. The dry yeast was less hard and we were able to make the pizza shape easier, at the moment of cooking, it grew a lot more than the fresh yeast pizza. The fresh yeast was harder to shape and it grew less than the dry yeast.

The dry yeast is in a ‘sleepy´ mode before cooking; the fresh yeast is ´activated´ but its reaction lasts less than the dry yeast. If the dry yeast has a longer duration, the dough is going to grow more that the fresh yeast. Or also we could see more factors: like the amount of water and sugar, if it was enough or unequal.

From this experiment we proved how an anaerobic respiration works and how the biochemistry affects more that we can imagine in the kitchen. All processes have an explanation so we had to infer why the yeast on a pizza grows and how the types of yeast can make be different when cooking a pizza. Now we can really understand the fermentation processes, the goal was accomplished. 

SOURCES:

http://www.gourmettraveller.com.au/recipes/how-to/2008/2/can-i-swap-dried-yeast-for-fresh/
Amy Oliver, Can I swap dried yeast for fresh? (cited, march 2014)
http://www.genetics.org/site/misc/yeastbook.xhtml
Alan G. Hinnebusch, National Institutes of Health, Nov 2011, Yeastbook. (cited, march 2014)
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3785618/
World J Gastroenterol. Sep 28, 2013 (cited, march 2014)
http://www.ars.usda.gov/research/publications/publications.htm?SEQ_NO_115=176765
Kurtzman Fell, Cletus Jack, Yeast Systematics and Phylogeny - Implications of Molecular Identification Methods for Studies in Ecology, Publication #176765, 2014 (cited, march 2014)

By: Valeria Arias, Laura Ibañez, Carolina Lopez, Juan Felipe Vasquez.