| Cooking with CO2 Solutions |
| 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? The fermentation process is taking place where carbon dioxide, alcohol as well as heat are produced. The carbon dioxide gas is trapped in the dough and forms bubbles which increase in size as the amount of gas increases. The small amount of heat produced also contributes to the speed at which the gas particles are moving about in the bubbles. This causes the gas particles to collide with the walls of the bubbles thus pushing them further out increasing the volume of the bubble. Why is it necessary to keep the mixture warm? So the chemical reactions involved with fermentation can take place at a more rapid rate. Heat speeds up the movement of particles so they can react faster than when the temperature is low. |
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 Water dissolves the sugar and salt and makes it accessible to the yeast. In this soluble form sugar and salt are so small that they can pass into the yeast where they are used in the fermentation process. Warm water has water molecules that move faster than water molecules in cold water and so dissolve the sugar and salt quickly.
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