Yeast is a pure biological starter, which is made from starch or molasses, nitrogen-containing elements, disinfection and sterilization, introduction of sterile air, constant temperature culture, gradual expansion, collection of yeast mud, granulation, low-temperature boiling drying bed or fluidized bed drying and processing.

The principle of yeast fermentation

Yeast fermentation converts carbohydrates into carbon dioxide, alcohol and a small amount of alcohol, lactic acid and energy under suitable conditions, which is a very complicated biochemical change. Under suitable conditions, yeast produces a large amount of carbon dioxide gas, which makes the dough honeycomb, loose and elastic.

Function of yeast

1. Biological fluffy effect: During dough fermentation, yeast produces carbon dioxide, and the network formed by gluten remains in the dough, making the dough bigger, softer and porous.

2. Gluten spreading function: In addition to producing carbon dioxide, yeast also has the function of softening gluten, thus improving the extensibility and gas retention capacity of dough, while chemical leavening agents do not have this function.

3. Improve the aroma of steamed bread and fermented pasta: In addition to carbon dioxide and alcohol, yeast fermentation is accompanied by many volatile and nonvolatile compounds, forming the unique smell of steamed bread and fermented pasta.

How long does the yeast expire after unsealing?

Yeast will fail 2~3 months after opening. Generally, the shelf life of dry yeast is 2 years under vacuum and normal temperature. If it has been opened, it needs to be clipped and stored in a dry and cool place for 2-3 months. However, if it is stored at room temperature, it will melt very easily, and it will be invalid if it is stored at most 1 month.