Joel Gil GómezRoger Alifa ArandaAida López LacallePol Admella Clanchet

RESEARCH PROJECT 2011 COMENIUS BREAD

PROJECT YEAST

INDEX- Introduction

- What is yeast?

- Types of yeast

- Experiment

- Hypothesis

- Explanation

- Results

- Conclusions

- Statistics part

- Conclusions of this project

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…

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

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.

Types of yeast IChemical 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.

Types of yeast IIBiological 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)

ExperimentHypothesis:

Our starting hypothesis was that chemical yeast produces more CO2

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 CO2 being released and inflating the balloon.

Inconvenience: Not quantitative, only qualitative test

The gas that swells the balloon is the carbon dioxide.

We thought that using a syringe connected to a test tube with the mixture could provide an easy way to measure the amount of CO2 released.

Finally, we decided to use a program called Multilab. This program increases the accuracy of our measures of CO2 released by each yeast.

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 CO2 sensor to the erlenmeyer and we could see on the screen of the computer how the CO2 was increasing.

Then, we did the same with the other types of yeast.

Results:

Chemical Yeast

We have smoothed the graph

Conclusions: Our starting hypothesis was wrong because looking at these two graphics we can see that the CO2 levels in the fresh yeast is higher than the chemical.

Fresh Yeast

Here, we have also smoothed the graph

Statistics part

FRESH YEAST

y = 26,374x + 2371,8

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,,

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

CHEMICAL YEAST WITH THE MODIFICATE LINE

y = 42,851x + 274,15

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

Graphs about emissions of Co2

Median305,39999Standard deviation213,187891

Median374,089972Standard deviation126,404864

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.