Bitter taste is one of the characteristics that distinguishes beer from other beverages. Normal bitter taste generally disappear quickly, after drinking to give a person with refreshing feeling. In the process of beer production, if the technological conditions are not perfect, the quality of raw materials is defective, and the technological hygiene is poor, the bitter taste of beer will become rough, bitter and long after the bitter taste.

Phenomenon: slow clarification of the wine, more residue and poor quality. Causes: Mainly due to improper opening of the cooling jacket, the upper temperature deviated from the process curve by 1.5 ~ 4℃, and the middle temperature of the tank was higher, resulting in strong convection of the fermentation liquid.