Yeast is a microscopic fungus which is used for leavening or raising agents in baking. When yeast is added to flour for making a dough fermentation occurs converting the starch into carbon dioxide and alcohol. Yeast requires warm temperature for fermentation to happen, but extremely high temperatures can also kill it. Carbon dioxide produced during the process creates air pockets hence rising the dough. On baking the yeast dies and the air pockets become stable, giving the baked product a light and airy texture. Yeast is also used in brewing various alcohols like beer.
There are two main types of yeast; fresh yeast and dried yeast. Fresh yeast, also known as bakers’ yeast, is sold in compressed cake blocks. This yeast does not last for very long and tends to get spoilt. It should always be stored refrigerated. This is a preferred choice of bakers and is used widely in all bakeries. Dried yeast looks like tiny round granules and are available in sachets or jars in the market. It is a great option for home bakers when fresh yeast is not available and only a small amount is required. In ancient times cakes were leavened using yeast until baking powdered was discovered. Ever since, it has been the leavening agent for making bread. I have also used yeast to make bread but a creative version of herbed bread.