Science focus: Yeast

In our house my husband bakes the bread and oh does that trigger the interest of our kids, especially my son. He is a science nut at this stage, yes at 5 year old that does happen.

One of the main lessons my husband has taught my son is:

"The magic behind the rising bread is sugar and yeast, but mainly yeast."

But...

What is yeast?

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Yeast is single-celled fungi that are egg-shaped and can only be seen with a microscope. Its scientific name is Saccharomyces Cerevisiae (Sugar-eating fungus). This type of yeast is very strong and capable of fermentation. In other words, the process that causes bread dough to rise. When sugar is added to yeast the process of alcoholic fermentation begins. During bread baking, the yeast ferments the sugars that are available from the flour and/or the added sugar. The carbon dioxide gas the cannot escape because the dough is elastic and stretchable. As a result the dough begins to inflates/rises.

Let's experiment

Experiment 1: The Science of yeast

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You will need the following:

1. Active dry yeast
2. Two bottles (Bottles with narrow openings like water bottles works the best.)
3. Two balloons
4. Sugar
5. Warm water

Instructions:

1. Pour a 1/4 cup of very warm water in each bottle.
2. Add 1/2 a teaspoon of table sugar to each jar.
3. Add the packet of active dry yeast to one of the containers.
4. Place a balloon over each jar.
5. Let the learners predict what is going to happen.
6. The bottle with yeast will begin bubbling. If the learners put their ear to the bottle they will hear the bubbles from the yeast.

Experiment 2: Let's blow up balloons with four different kitchen ingredients.

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You will need the following:

1. 2 clean bottles
2. Yeast
3. A teaspoon of sugar
4. Vinegar
5. Baking soda
6. A Packet of Pop rocks candy
7. Roll of mint mentos
8. Couple bottles of soda
9. Funnel
10. Big regular sized balloons.

Instructions:

Bottle 1

1. Pour an inch of warm water in the bottle and dump the entire packet of yeast in.
2. Swirl the yeast around and then add the teaspoon of sugar. Swirl again.
3. Put the balloon over the mouth of the bottle and let it sit in the sun.
4. Let the child observe and tell what they are seeing.

Bottle 2

1. Pour a couple of inches of vinegar.
2. Prep the balloon by using the funnel to fill half of it with baking soda.
3. Put the balloon over the mouth of the bottle and press to dump the baking soda in the bottle.
4. Let the child observe and tell what they are seeing.

Bottle 3

1. Half fill the bottle with Diet Coke or any soda. It is best to use a freshly opened bottle and pour out the soda you don't want to use.
2. To prep the balloon, dump a pack of Pop Rocks into it.
3. Put the balloon over the mouth of the bottle and dump the Pop Rocks into the bottle.
4. Let the child observe and tell what they are seeing.

Bottle 4

1. Half fill this bottle with the rest of the soda from the previous bottle.
2. Put two Mentos in the balloon.
3. Put the balloon over the bottle and dump the mentos into the bottle.
4. Let the child observe and tell what they are seeing.

Line up the bottles next to each other to see what is happening to all of them.

Ask the following questions:

1. Which bottle blew up the balloon the best?
2. Which reaction made the most carbon dioxide.

Hope you have learned something new!!!

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