Cooking with CO2
If it wasn't for the gas called carbon dioxide cooking would be dull and boring, especially when baking cakes. It is a very important gas in the process of bread and cake making and also in the soft-drink industry.

Fermentation is a process that a fungus, called yeast, performs. This process involves the chemical conversion of glucose (sugar) into ethanol, commonly referred to as alcohol, carbon dioxide and heat energy. We can write this process in the form of a word chemical equation, shown below.

Glucose --> carbon dioxide + ethanol + heat.

This reaction (fermentation) is why bread makers all over the world use yeast to make the dough rise, as shown in the video on the right.

After the yeast is mixed in with the dough the mixture is placed in a warm place for a few hours.
Explain what is happening during this period of time?
Why is it necessary to keep the mixture warm?


Now the gas that is trapped inside the dough must rise even more when baked to form soft bread. It does this through the creation of many bubbles throughout the dough, as shown on the right.

 

Once in the oven, our gas is heated and expands to make the dough rise again as shown on the right.

 

Now refresh yourself with the particle theory of matter.

 


Sourced from youtube/DsImShazEFs?list=TLPQMDEwNzIwMjB55tGBVyWP2A on 1/07/20 4.23 pm.

View the video on the right. It shows a balloon on top of a bottle with air. As the bottle is placed in warm water, on the left, the balloon expands in volume, while it decreases in volume when placed in cold water. Explain why this happens and how it relates to dough rising when placed in the oven.

Use the particle theory of matter to explain how the bread rises when placed in the oven.

 

 

 
The image on the right showsnthe air particles in the balloon. For simplicity only 4 particles are shown. Notice how they move about at random colliding with the sides of the container, in this case the bottle. Click to see what happens when the air is heated.

View the video on the right. It shows some of the chemistry of bread making.

1) Yeast undergo a process called where the three following substances are produced , and .

2) Sugar is placed in the dough mixture. Apart from giving the bread a sweet taste its other function is to

3) From what you know of how water dissolves substances, explain why warm water activates the yeast and starts the chemical process of fermentation.

Solutions

 

sourced from https://www.youtube.com/watch?v=-H9pyNHxIO8
on 2/07/20 3.37 pm