Yeast. In anaerobic fermentation, yeast produces dense pores, large and small, which can make bread fluffy and soft. Yeast can be divided into fresh yeast and dry yeast. Fresh yeast has unstable activity, low fermentation ability, storage resistance, stable activity and high fermentation ability.

Bread is a kind of food made by grinding and heating grains. The main materials are wheat flour, yeast, eggs, oil, water, sugar and salt.

Breads include coconut bread, English bread, French bread, Danish bread, toast, buttered bread, honey bread and miscellaneous grains bread.

Bread can be divided into white bread, whole wheat bread, black bread, rye bread, sour fermented bread and unfermented bread by color.