How to ferment old yeast quickly?

Prepare a basin, put about a catty of flour into it, and then add the prepared warm water, the water temperature is about 40 degrees. When adding warm water to the flour, stir the flour with chopsticks until the flour looks like cotton wool, so don't add water. Then knead the dough by hand and knead the flour into dough. After kneading the dough, you need to prepare a clean towel to cover it tightly, and then ferment the dough at a temperature of about 30 degrees. The fermentation time is preferably greater than 10 hour. When the dough has obvious expansion and a large number of beehives appear, it proves that the dough has been fermented, so the fermented dough is old yeast.

Method 2: Fermentation of cooked steamed bread.

Using the method of cooked steamed bread fermentation, it is necessary to prepare three steamed buns steamed with old yeast in advance, and then break them into small pieces for later use. At the same time, prepare a washbasin, add the required flour into it, add warm water and stir it into cotton wool. Then, add the prepared steamed bread slices into these flour, knead them into dough, and knead the flour into dough. Finally, cover it with a clean towel (it is best to cover it with plastic wrap in winter). When the dough is placed at a temperature above 30 degrees and fermented to twice its original size, the old yeast is ready.