January 17 - Bread - pre-class

What is yeast? What are the different types of yeast available?

Yeast are single-cell fungi.  It is very strong and capable of fermentation, which causes the bread to rise. Yeast cells digest food to obtain energy for growth. There are 3 types of yeast: baker’s yeast, Nutritional yeast, Brewer’s yeast.

What is the function of yeast in bread?

The process of fermentation produces useful end products, carbon dioxide and ethyl alcohol. When yeast ferments the sugars available from the flour and sugar, the carbon dioxide gas cannot escape the dough, so the dough inflates.

Why do you have to add sugar to the yeast?

When yeast ferments the sugars available, the carbon dioxide gas cannot escape because the dough is elastic and stretchable. 

Why do you knead bread dough?

As you knead the dough, the gluten becomes more and more stretchy. This substance fills with thousands of gas bubbles as the yeast goes to work during rising. 

What chemical reaction causes the elastic bread dough to form?

The chemical reaction between acidic and alkaline compounds produces the carbon dioxide necessary to inflate dough.

What is gluten? What happens if your body can't digest gluten?

Gluten is made when you add water to wheat flour.  The water molecules combine with two proteins, gliadin and glutenin, to form gluten.  Celiac disease is a disease where people are sensitive to gluten.

What is sourdough bread? What is a sourdough starter, and why is it necessary?

Sourdough is s dough containing a lactobacillus culture.  It is one principal mean of leavening in bread baking.  It produces a tangy or sour taste, because of the lactic acid produced by the lactobacilli.  A starter is an essential form of pre-ferment.  A starter is made with a small amount of old dough saved from a prior batch, which contains the culture.  You then add the new dough and knead it together.  You can then save a small part from this dough to make another starter.  The starter needs to be fed flour and water weekly. 

What is responsible for the flavor, texture, and leavening differences in: injera, pita, nan, etc. (or your favorite type of bread)?

It all depends on what you add to your bread.  The texture is dependant on whether you put nuts or raisins or other things in your bread. I love nuts in my bread so that adds texture. The flavor is dependant on what you like. I like banana bread, poppy seed bread, and French baguettes.  The leavening of the bread is dependant on what you use.  Not all bread requires yeast in it.