In the 10 century BC, the Egyptians mastered the method of making this fermented bread, which was then called sour bread.
Egyptians are tight-lipped about the baking method of fermented bread. They wanted to keep this "patent" secret strictly, but the secret was known by the Romans and Greeks. European countries will bake fermented bread one after another, but no one understands why sour bread is soft.
1680, Levin Hooke observed yeast with a microscope and found that bread fermentation was the result of yeast action. 1870, Dutch Hansen invented the method of making artificial yeast for bread and beer.
People in China make bread very late, but steamed bread is white and mysterious. Steamed steamed bread is also inseparable from yeast. What exactly is yeast?
Yeast is a member of the microbial kingdom. Some of them are spherical and oval, others look like sausages, and most of them reproduce asexually by budding.
Yeast can decompose sugar (glucose) in fruit juice or wort into alcohol and carbon dioxide without oxygen, and turn sugar into wine. It can ferment free sugar in flour and produce carbon dioxide gas. During cooking, carbon dioxide expands when heated, so steamed bread becomes very soft.
Yeast cells contain a variety of vitamins, minerals and nucleic acids. The content of protein is the highest. It has been proved that every 100 kg of dry yeast contains protein, which is equivalent to 500 kg of rice and 2 17 kg of soybean or edible yeast developed by scientists. It looks like pork and beef, and people call it "artificial meat". During the Second World War, Germany produced edible yeast again, and then Britain and other countries rushed to study and produce this kind of "artificial meat". The development and utilization of edible yeast is considered to be the third great achievement after the invention of atomic energy and penicillin in World War II.
Yeast also helps to destroy people. If you have indigestion and loss of appetite, the doctor will prescribe some yeast tablets for you. After eating yeast tablets, your stomach will turn upside down, and those indigestible things in your stomach will be removed.
Yeast is widely distributed in nature, almost everywhere. When we mix dough, yeast comes uninvited and is called the mother of fermentation.