During the fermentation process, what are the possible abnormal phenomena and countermeasures?

During the fermentation process, what are the possible abnormal phenomena and countermeasures?

1.The "churning" of fermentation broth

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.

In addition, unstable pressure, rapid rise and fall can also cause churning.

Solution:

Check whether the instrument is normal;
Strictly control the cooling temperature to avoid excessive temperature of the upper liquor;
Keep pressure in tank stable.

2.The fermenter freezes

When the temperature of the lower part of the tank deviates from the process curve by about 2℃, the temperature in the storage age tank will reach the freezing point of beer (-1.8 ~ 2.3℃), which may lead to the freezing near the cooling zone.

Causes of icing: instrument failure, improper selection of temperature parameters, improper installation depth of thermal resistance, poor instrument accuracy, improper operation, etc.

Solutions:
Check the error of temperature measuring element and instrument, especially check whether the platinum resistance leaks. If it leaks, it should be sealed or replaced by paraffin after baking.
Select appropriate temperature measuring point position and thermal resistance insertion depth;
Strengthen process management and timely discharge of yeast;
The temperature of refrigerant liquid shall be controlled at -2.5 ~ -4℃, and -8℃ shall not be used.

3.Yeast autolysis

Cause of autolysis: When the temperature difference between the lower part of the tank and that between the middle and lower parts is more than 1.5 ~ 5℃, yeast sedimentation and autolysis will be difficult to occur. Too high temperature (16 ~ 18℃) and too long maintenance time can also cause yeast autolysis and yeast taste.
Solution: Check whether the instrument is normal; Timely discharge of yeast puree; The refrigerant temperature is maintained at -4℃, and the upper, middle and lower temperatures of the wine storage period are maintained between -1 ~ 1℃.

4.Suspension of fermentation

Suspension of fermentation broth is known as "hypoglycemic".
The reasons for this phenomenon include:
The wort is not nutritious enough, the content of oligosaccharides is too high, the content of -amino nitrogen is insufficient, and the acidity is too high or too low. The early flocculation precipitate was caused by the strong cohesion of yeast.
Yeast degrades and mutates to cause hypoglycemic;
Spontaneous mutation of yeast results in respiratory defect yeast.

Solutions:
If it is caused by yeast condensation strong, causing early flocculation precipitation. The fermentation temperature can be adjusted by increasing the wort ventilation, and then cooled down when the sugar content drops to near the final fermentation degree to prolong the high-temperature period. However, it can improve the cohesion of yeast, and it is better to isolate the yeast strains with weak cohesion to solve this problem.

If it is due to yeast degradation, mutation caused by hypoglycemic. It can be solved by changing new yeast strains.

If it is caused by spontaneous mutation of yeast, the production of respiratory defect yeast. It is possible to reexpand or replace the original strain.

In addition, in the process of wort preparation, the hydrolysis of protein should be strengthened, the decomposition temperature of protein should be reduced, and the decomposition time of protein should be prolonged.
During saccharification, the saccharification temperature should be adjusted appropriately, the hydrolysis at low temperature should be strengthened, the sufficient saccharification time should be ensured, and the PH value of good mash should be adjusted.

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