yeast is incorrectly written and it should be written as "leavening" being its meaning:
The yeasts are microscopic fungi that serve to break down organic elements, especially carbohydrates, thus obtaining other products that we are very useful, such as wine, beer, bread or antibiotics. All of these processes involve the yeast called " sacharomices sereviciae 34. This yeast than in my country, (Ready, province of Zamora ) have traditionally used to knead flour and bake the bread in the oven called it " hurmiento "
