It is divided into pressed yeast, active dry yeast and fast active dry yeast. Pressed yeast is a blocky product with a 70 to 73% water content produced by Saccharomyces cerevisiae. Active dry yeast is a dry yeast product produced by Saccharomyces cerevisiae with a moisture content of about 8%, granular-shaped, and having a baking ability. Fast active dry yeast is a new fine granular (less than 1 mm diameter) product with fast and efficient fermentation. The moisture content is 4 to 6%.
In the actual production of bread, the fermentation of yeast is affected by the following factors:
Temperature: Within a specific temperature range, as the temperature increases, the fermentation speed of the yeast also increases, and the gas production also increases, but the maximum does not exceed 38 ° C ~ 39 ° C. Generally, the normal temperature should be controlled within 26 ° C ~ 28 ° C.
PH value: The pH of the dough is most suitable for between 4 and 6.
The effect of sugar: The sugar that can be directly used by yeast is glucose and fructose.
Osmotic pressure: In bread production, the main factors affecting the osmotic pressure are sugar and salt. When the amount of sugar in the formula is 0 to 5%, the fermentation of the yeast does not inhibit, but the yeast fermentation can be promoted. When it exceeds 6%, the fermentation will be inhibited. If it exceeds 10%, the fermentation rate will be significantly slower. The salt has a higher osmotic pressure and a more significant inhibitory effect on yeast fermentation. When the amount of salt reaches 2%, the fermentation is affected.