How and Why is Yeast Used in Food
I remember my mother baking bread. She always started with a small bowl of warm water and sugar, over which a little package of yeast was sprinkled. I was told that it would come alive in the water. As a little kid, I was fascinated.
Last weekend, as I was baking bread, I began to wonder about the yeast. So, okay I knew that it was a living organism and that it produced gases that would eventually rise the dough. I also knew that it was somehow used to create the alcohol in beer. But, I wanted to know the details. What is it exactly? Where does it come from? How is it made? Is it good for you? Etc…
After some research, this is what I’ve found out. Yeast is sort of a plant composed of only one cell. Actually, it is in the same family as mushrooms and other fungi. It been used for thousands of years, dating back to ancient Egypt. In fact, it was one of the first cultivated/domesticated organisms. It can be found everywhere, and is common on plants leaves and flowers, in the soil, and in salt water. One species, Saccharomyces cerevisiae, started to be sold commercially by the Dutch around 1780. It is still sold today and is used in baking and fermenting alcoholic beverages. However, baking and brewing varieties are generally different strains, cultivated for specific requirements.
Alcoholic beverages are created when carbohydrate containing plant materials are converted by the yeast into ethanol (C2H5OH).
Similarly, when baking, it converts the sugars found in the dough into ethanol and carbon dioxide (CO2). The CO2 gas is trapped in the dough and causes it to rise. As the dough is baked, the yeast dies, leaving a soft spongy texture.
These days there are basically two types of yeast you can buy for baking: Active Dry Yeast, and Instant Yeast. The instant variety might also be called Bread Machine or Rapid Rise Yeast. You can also buy Fresh Active Yeast, sold in cake form, but I don’t see it often.
The main difference between the two types is that instant yeast can be added directly to dry ingredients and does not need to be “proofed”. Recipes using active dry yeast generally need two risings.
Yeast needs to be stored in a cool, dry place.
Many times yeast is sold in 1/4 oz. packets. If you’ve buy it in bulk, then when the recipe calls for a 1/4 oz. packet, use 2 1/2 tsp.
Generally you can substitute the different types in you recipes but there are limitations. If you’re using a bread machine, it is probably better to stick with instant yeast. See the bread world link below for more information.
Is It Good For You?
De-activated yeast is often included in vitamin supplements because it is high in protein, and a rich source of B vitamins such as niacin, folic acid, riboflavin, and biotin. Some pro-biotic supplements also include it.
However, some people can develop yeast allergies and so need to avoid foods like bread and beer.