The reason:
Malcomposition of wort;
Poor yeast quality;
Improper fermentation temperature control;
The PH of wort is not properly controlled;
Improved method：
Strictly control the use of yeast algebra;
Attention should be paid to proper storage methods and limited storage time;
Always check the mortality of the stored yeast and the budding rate of the added yeast；
The right method of adding yeast, including the right amount of adding, the right time to add, the necessary stirring and oxygenation；
For the fermentation broth with slow onset and slow hypoglycemia, high foam wine can be added to make up；
