Natural yeast, in comparison to the chemical sort, is of biological origin and is commonly found on sale in the form of dried yeast and fresh yeast. Natural yeast determines the rising of the dough to make bread and works best when there is heat, humidity and sufficient oxygen. Fresh yeast is perishable and, therefore, best kept in a cool, dry place. Dried yeast, on the other hand, can be preserved for a long time and can be directly mixed with the flour. Fresh yeast, on the other hand, should be disintegrated in luke-warm water or milk. Natural yeast begins to work before cooking and, therefore, the dough should be left to stand before being placed in the oven. Natural yeast, which is bred on molasses is generally gluten-free and, therefore, it is necessary to take care with yeast from other types of cultivation such as, for example, from barley (brewery yeast). Such types of yeast are to be avoided by those affected by the coeliac condition.
As opposed to natural yeast, the chemical sort (chemical yeast/baking powder) is used for rich and sugary doughs, often containing a lot of fat. Natural yeast, in comparison to the chemical sort, is of biological origin and is commonly found on sale in the form of dried yeast and fresh yeast. Chemical yeast should be sieved together with the last part of the flour and added to the dough. On the contrary to what happens with natural yeast, chemical yeast begins to work during cooking.