1. Joel Gil Gómez Roger Alifa Aranda Aida López Lacalle Pol Admella Clanchet COMENIUS BREAD PROJECT YEAST YEAST

2. INDEX - Introduction - What is yeast? - Types of yeast - Experiment - Hypothesis - Explanation - Results - Conclusions - Statistics part - Conclusions of this project

3. Introduction Research Project: Comenius: -In 4th of ESO there is a research project. -It’s about statistics and the entire course has to do it. -This year, the Comenius, it’s about bread and there are sub-groups like disorders linked to bread, the bread’s history, flour, yeasts…

4. What is yeast? Yeast is an unicellular fungus and one of the first organisms to have their genome sequenced. The main of yeast is to serve as a catalyst in the process of fermentation, which is essential in the making of bread. Ancient Egyptians used yeast and fermentation to produce alcohol and leaven bread

5. What is yeast? The purpose of any leavener is to produce the gas that makes bread rise. Yeast does this by feeding on the sugars in flour, and expelling carbon dioxide in the process. This carbon dioxide fills thousands of balloon-like bubbles in the dough. Once the bread is baked, this is what gives the bread its airy texture.

6. Types of yeast I Chemical yeast: It is a white powder that comes in packets (15 g). The most popular brand is Royal. It is used in cakes and muffins but it is not suitable for breads, pies, pizzas and some pastries. It is a mixture of baking soda with some other salts that will release carbon dioxide (CO2), which is the gas that fills the cells.

7. Types of yeast II Biological or baker yeast: These organisms are alive and die above 50 degrees. Their essential action must be done before baking, at a temperature between 35-40 degrees. Baker's yeast is used to make bread, pizza dough, pies and some pastries. Baker yeast is sold in two ways: 1) Fresh or pressed. 2) In powder (also called dry yeast)

8. Experiment Hypothesis: Our starting hypothesis was that chemical yeast produces more CO 2 than the other types of yeast (fresh yeast). Explanation: First, the English team suggested to use a balloon connected to a test tube with yeast, flour and warm water in it so that we could easily “see” the CO 2 being released and inflating the balloon. Inconvenience: Not quantitative, only qualitative test The gas that swells the balloon is the carbon dioxide.

9. We thought that using a syringe connected to a test tube with the mixture could provide an easy way to measure the amount of CO 2 released. Finally, we decided to use a program called Multilab. This program increases the accuracy of our measures of CO 2 released by each yeast.

10. First of all, we prepared the solution with: Chemical yeast + flour + warm water. We put it into an erlenmeyer and we shacked it. We connected the Multilab CO 2 sensor to the erlenmeyer and we could see on the screen of the computer how the CO 2 was increasing.

11. Then, we did the same with the other types of yeast. Results: Chemical Yeast We have smoothed the graph

12. Conclusions: Our starting hypothesis was wrong because looking at these two graphics we can see that the CO 2 levels in the fresh yeast is higher than the chemical. Fresh Yeast Here, we have also smoothed the graph

13. Statistics part This graph has slope less than baking powder but ferments faster and reaches a higher CO2 expelling the baking powder.

14. This last graph is 1.624 times faster than the other (the first one) in the fermentation.

15. Graphs about emissions of Co2 Median 305,39999 Standard deviation 213,187891

16. Median 374,089972 Standard deviation 126,404864

17. Conclusions We got more knowledge about yeast. We are aware now of its importance not only for making bread. We’ve learnt about how to design an experiment. We’ve improved our abilities working with sensors. We’ve also learnt that the previous ideas are not always the right ones.