2~3 months. After opening the yeast powder, clamp the mouth with a clamp and place it in a dry and cool place. As long as it is not damp and does not clump, it can be left for 2 to 3 months. Unopened dry yeast has a shelf life of two years. Wet yeast (liquid yeast) can only be stored for 15 days and needs to be stored in a low temperature environment of 4 to 6 degrees.

1. After opening the yeast powder, clamp the mouth with a clamp and place it in a dry and cool place. As long as it is not damp and does not clump, it can be left for 2-3 months.

2. Unopened dry yeast generally has a shelf life of two years and only needs to be stored under vacuum at room temperature. This type of yeast is commonly used in China. Wet yeast (liquid yeast) can generally only be stored for 15 days and needs to be stored in a low temperature environment of 4-6 degrees.

3. Experiments have shown that when yeast is vacuum packed, yeast activity decreases by 0.6% per month at 5°C; by 1.7% per month at 20°C; and by 80% per month at 37°C. Therefore, after opening the yeast bag, be sure to seal the opening tightly and then refrigerate it to preserve the activity of the yeast. But it must be used up as soon as possible, otherwise the yeast will easily expire.