You will need
  • - yeast;
  • - warm water or milk;
  • - sugar;
  • - timer.
If you have fresh compressed yeast in blocks, then, first of all, pay attention to their appearance and smell. Live yeast pale cream-colored, with obvious delicious yeasty smell. If you press on them with your finger, they left a hole, and they are, in any case, will not crumble. If live yeast is "smeared" their activity is also under question, it is possible that they have absorbed too much moisture.
Active dry yeast needs to be a tiny little pellets, like small balls of different diameter. They should not adhere to each other and, as the name suggests, should be dry and crumbly if you RUB them between your fingers.
Yeast is a living organism that "eats" sugar and produces alcohol and carbon dioxide, so in order to test yeast activity to them definitely need to add some sugar. One tea spoons of live yeast, you need to put one teaspoon of sugar.
After you've added in a container of yeast is sugar, there pour ¼ Cup warm water or milk. The temperature of the liquid that you add to the yeast, very important. The fact that live yeast can "brew" too hot water and milk. The optimum medium temperature is 42 degrees Celsius. If you poured the yeast with boiling water or just hot water with a temperature of over 50 degrees Celsius, do not expect them to activity. Even if they were "live" before the start of your experiment, too hot liquid killed these whimsical microorganisms.
Set the timer for 10 minutes and go do other things. When the timer goes off, look at what happened with the yeast. Ideally, on the "experimental" capacity should appear smelling delicious thick, creamy foam, similar to the one that you can watch over svejenatertogo a glass of good dark beer.
If you have dry yeast, first mix ¼ Cup warm water or milk with one teaspoonful of sugar and then scatter the contents of one small bag (11 grams) of dry yeast on the surface of the liquid. Try to pour evenly, make sure all the yeast is scattered in a thin layer, if necessary, gently rotate the jar to distribute them.
Set a timer for the same 10 minutes. When the timer works, look at the yeast. They should make beautiful foam "cap".