1. Yeast Due to the poor performance of yeast itself, i […]
Due to the poor performance of yeast itself, it is manifested as senescence, mutation, and low yeast activity. It is easy to die and self-dissolve when the process conditions change.
2. Wort composition
The composition of wort nutrients is unreasonable, leading to malnutrition of yeast, especially lack of ɑ-amino nitrogen, fermentable sugars, vitamins, auxins, etc. Too much zinc in wort will also accelerate yeast autolysis.
3. The amount of yeast added
The addition of yeast is too high, causing some nutrients in the wort to be consumed in a short time, causing the yeast to be in a state of poor nutrition and "internal consumption" in the subsequent process. If the added amount is too high, the production of new yeast will be less, and it will also cause yeast senescence and autolysis.
4. Yeast uses algebra
Yeast uses a high number of generations, especially the continuous use of yeast without washing, bringing aging and dead yeast into the next batch of fermentation broth, causing the physiological function of the yeast to decline and autolysis.
5. Fermentation process conditions
Improper control of fermentation process conditions, such as temperature, pressure, and pH, promotes yeast mutation. For example, the initial temperature of a full tank of wort is high, the high temperature of the fermentation process lasts for a long time, the temperature and pressure fluctuate widely, the temperature of the cone is poor, the temperature is high, and the pH value is high.
6. Yeast recovery time
Yeast recovery time, method, pressure, yeast storage conditions, etc. have an important impact on the quality of yeast. The yeast recovery is not timely, the recovery method is improper, the pressure difference is too large during the recovery, and the pressure is too fast, which will cause the yeast cells to rupture and store the yeast. Long wine time and high cone temperature can cause the yeast performance to decline. Yeast mud can not be separated for a long time and stay in the fermentation broth will also cause the yeast cells to autolyze. China International Beer Net. From this, it can be seen that the yeast is collected too late and stored for a long time, and it is easy to auto-dissolve, which can be judged by the change in the pH value of the yeast mud. If the ph value displayed by the yeast mud is significantly higher than that of mature beer, it means that the yeast has been autolyzed. When the ph value of the yeast mud is higher than the beer ph value by more than 0.5, it is determined that the yeast has been autolyzed.
7. Microbial contamination
Once the harmful bacteria are contaminated, the changes in their metabolites and pH value will seriously affect the activity of the yeast, leading to autolysis of the yeast. After yeast autolysis, the polysaccharides, amino acids, proteins, nucleic acids, nucleotides, and a little salt in the cell juice solution will enter the beer. Autolysase can also degrade its own cell proteins and produce a series of nitrogen-containing compounds, thereby changing the ratio of solids in beer, leading to a decrease in beer colloidal stability and flavor stability.