FermentationFermentation is an anaerobic energy producing chemical reaction involving yeast, sugar, warm water, carbon dioxide and ethanol. It can also occur with bacteria in place of yeast. The definition of fermentation is: the conversion of sugar molecules into ethanol and carbon dioxide by yeast or bacteria. The scientific name for fermentation is zymurgy, and the study of zymurgy is known as zymology.
The pictures to the right are examples of fermented foods. |
In this recipe... |
When making pizza using this recipe, three ingredients are involved in fermentation. Warm water is used to "awaken" the yeast. This means the water cannot be too cool because the yeast needs be active for fermentation to occur. Water that is too hot may kill the yeast, resulting in little or no fermentation. The ideal temperature range is between 25°C and 40°C. The sugar provides the yeast with food. Yeast breaks down sugar to produce ethanol and carbon dioxide. The amount of these are dependent on time. The more time, the more ethanol and carbon dioxide.
Analysis of chemical reaction in the method: In the pizza dough recipe, the yeast is awakened with warm water and sugar during step 1. Ensuring the water is at the correct temperature is important, as well as adding the right amount of sugar for the yeast to have enough for fermentation. In step 2, the yeast is allowed to commence fermentation in a suitable environment (warm for best results). The yeast should be frothing after this step. (CO2 bubbles released to surface). In step 4 and 5, the yeast and dough are combined and mixed together. It is important to make sure that it is combined well so that the dough rises evenly. Kneading the dough for a sufficient amount of time lets the gluten develop, making the dough stronger and less easy to tear. In step 6, the dough is placed in a warm place and allowed to proof (rise/ferment). This is when the CO2 released by the yeast is trapped in the dough, causing it to expand. |
Physical changes |
Fermentation is an essential chemical reaction in the making of a pizza base. Aside from ensuring the success of the recipe, there are a number of physical changes that occur with fermentation.
The colour of the dough is changed when yeast is added, instead of a whitish colour, the dough turns into a yeasty colour (yellowish light brown). This is not so much because of fermentation, but because of the yeast itself. The aroma of the dough acquires a yeasty smell when yeast is added to it. Again, this is not because of fermentation but because of the yeast. The taste of the finished product is also altered by fermentation. The pizza is given a slight taste of alcohol, because ethanol is one of the products of fermentation. Pizza dough that has undergone fermentation is larger in volume because it would have expanded due to the CO2 released from the yeast in the dough. The viscosity of the dough is affected also. This is because fermentation aids gluten in its development. When CO2 is released during fermentation, the gluten and water move around, giving it more chances to connect and form more gluten. The gluten bonds the dough together, making it stronger, therefore higher in viscosity. Without fermentation, the dough would be very dense in texture. When CO2 is released in the pizza dough, it creates air pockets and allows the pizza dough to be of a fluffier texture. |
Evaluation of recipe
The chemical reaction fermentation is very significant in producing the final product. Without it, the above physical changes would not occur, resulting in a flat, dense and weak dough that would be easily broken apart. Fermentation also helps add to the taste of the final product, making it very important to the recipe.
The impacts of this chemical reaction on the recipe's physical properties are also described above, and aside from the change in colour and aroma, are important in ensuring the success and optimal quality of the final product.
Two factors that can determine the success or failure of the chemical reaction and thus the recipe are the temperature of the water added to the yeast and the amount of time it is allowed to ferment for. It is usually easy to know if water is the right temperature for yeast. As long as the water doesn't feel too cool or scalding, it is probably okay to combine it with the yeast. As mentioned before, the water should not be above 40°C or below 25° or the yeast will die or remain dormant, therefore stopping fermentation from happening. If unsure, a thermometer can always be used to check. The second factor, the time allowed for fermentation determines how much ethanol and CO2 is released. If it isn't left for enough time, there would not be enough CO2 released, therefore it would not have risen adequately for the dough to be large in volume and airy in texture. The ideal times allowed for fermentation to take place are stated in the recipe. It is a good idea to use a clock or timer to ensure that enough time is given for fermentation to happen.
The impacts of this chemical reaction on the recipe's physical properties are also described above, and aside from the change in colour and aroma, are important in ensuring the success and optimal quality of the final product.
Two factors that can determine the success or failure of the chemical reaction and thus the recipe are the temperature of the water added to the yeast and the amount of time it is allowed to ferment for. It is usually easy to know if water is the right temperature for yeast. As long as the water doesn't feel too cool or scalding, it is probably okay to combine it with the yeast. As mentioned before, the water should not be above 40°C or below 25° or the yeast will die or remain dormant, therefore stopping fermentation from happening. If unsure, a thermometer can always be used to check. The second factor, the time allowed for fermentation determines how much ethanol and CO2 is released. If it isn't left for enough time, there would not be enough CO2 released, therefore it would not have risen adequately for the dough to be large in volume and airy in texture. The ideal times allowed for fermentation to take place are stated in the recipe. It is a good idea to use a clock or timer to ensure that enough time is given for fermentation to happen.