To make the dough has risen, add Baker's yeast. Yeast is a single celled fungus. At low temperatures (in the fridge) they go into a hibernation - a state of temporary almost complete cessation of life. But if placed in the optimal environment, life processes are activated, and they begin to multiply. For this they need: a) heat b) water, C) food d) oxygen.
Baker's yeast (Saccharomyces cerevisiae)
In the test there is always moisture, as food for the yeast, put sugar or honey, and a bowl with the dough put in a warm place. And then the yeast in the dough "come alive". In the process of their activity sugar is fermented and fermented form alcohol and carbon dioxide. Just want to reassure you: in prepared baking no alcohol, it evaporates during baking. But carbon dioxide is the reason for the progress of the test.
Bubbles of carbon dioxide gas to inflate the dough, formed in the cavity - pores that make a loose dough.
Carbon dioxide light, he, like any other gas, is seeking to break out, but he does not do gluten is a substance that is formed in contact with starch flour with water. Malleable and durable, gluten envelops the bubbles of carbon dioxide and does not let them out. And the more gas is produced, the more the dough rises in volume.
The dough is "escaped"
When the dough is put into the furnace, gluten from the heat dries, its elasticity decreases, it becomes loose (and on the surface where the heat is the strongest, it turns into a flavorful crust). The walls of the bags, which were kept in captivity carbon dioxide, torn and gas to be released. Each hole in the pulp bread is a trace left over from the bubble of carbon dioxide.
In some types of unleavened dough, so it is not too tight, use a chemical reaction: it is added a solution of acetic acid (or citric) acid and soda. Interacting with each other, they form carbon dioxide. But, unlike yeast, which operate continuously and breed, highlighting all the new batch of carbon dioxide, acid and soda give a limited amount of carbon dioxide, and hostess try knead this dough and put it in the oven as quickly as possible. But still no yeast-free dough it is so lush and airy, delicious and fragrant, like yeast.
By the way...
- When excess carbon dioxide fermentation process slows down. To fix this, the dough obmanut - gently mix. Thus, the surplus of carbon dioxide leaving the test, and in addition, it is enriched with oxygen. All this stimulates the growth of yeasts.
- The optimum temperature for fermentation of yeast - 30-33°C, for reproduction is 25-28°C. At a temperature of 45-50°C and above yeast cells die.
- Frozen yeast retain their properties if them to thaw slowly at a temperature of 6-8°C.